PDF hosted at the Radboud Repository of the Radboud ... · more reﬁned over time 3, 4. Furthermore, although the long term results of a total knee arthroplasty are good, a signiﬁcant

PDF hosted at the Radboud Repository of the Radboud University

Nijmegen

The following full text is a publisher's version.

For additional information about this publication click this link.

http://hdl.handle.net/2066/30190

Please be advised that this information was generated on 2020-03-15 and may be subject to

change.

http://hdl.handle.net/2066/30190

Hig

h T

ibial O

steoto

my Treatm

ent o

f varus o

steoarth

ritis of th

e knee R

ob

ert D. A

. Gaasb

eek

Uitnodiging

Voor het bijwonen vande openbare verdediging

van het proefschrift

‘High tibial osteotomy.Treatment of varus osteoarthritis

of the knee’

op vrijdag 21 september 2007om 10.30 uur in de Aula Major

van de Radboud UniversiteitComeniuslaan 2 te Nijmegen.

Receptie na afloop ter plaatse

Robert GaasbeekKruisweg 16bis3513 CT Utrecht

[email protected]

De Paranimfen Huub van der Heide, tel: 06-43001007

[email protected] van der Gragt, tel: 06-21881485

[email protected]

Uitnodiging

Graag nodig ik u en uw partner uit voor het feest ter gelegenheid van

mijn promotie

zaterdag 22 september 2007 vanaf 20.00 uur

“Oranjerie Landgoed Maarsbergen” Maarnse Grindweg 30 3953 LW Maarsbergen

tel. 0343-431 [email protected]

Paranimfen:Huub van der Heide, tel: 06-43001007


[email protected]

High Tibial Osteotomy Treatment of varus osteoarthritis of the knee

Robert D. A. Gaasbeek






De valgiserende tibiakop osteotomieBehandeling van varus gonartrose



De valgiserende tibiakop osteotomieBehandeling van varus gonartrose

een wetenschappelijke proeve op het gebied van de medische wetenschappen

Proefschrift

ter verkrijging van de graad van doctor

aan de Radboud Universiteit Nijmegen

op gezag van de Rector Magnificus prof. mr. S.C.J.J. Kortmann,

volgens het besluit van het College van Decanen

in het openbaar te verdedigen

op 21 september 2007 om 10.30 uur precies

door

Robert Dick Alexander Gaasbeek

geboren op 17 september 1969

te Zwolle

The publication of this thesis was financially supported by:

Nederlandse Orthopedische vereniging, Anna-Fonds te Leiden, Somas Chirurgische Techniek,

Bauerfeind Benelux BV, DePuy Implants, Zimmer Netherlands BV, Link Nederland,

Biomet Nederland BV, NTOC Medische Techniek, Eemland Orthopedie Techniek BV,

Mathys Orthopedics BV, Synthes BV, Hanssen Footcare, Roessingh Revalidatie Techniek BV,

Smith & Nephew BV, Janssen-Cilag BV, DJO/Aircast Benelux, Pro-Motion Medical BV Schiedam,

POM BV Nijmegen, Stryker BV.

High Tibial Osteotomy

Treatment of varus osteoarthritis of the knee

De valgiserende tibiakop osteotomie

Behandeling van varus gonarthrose

Thesis Radboud University Nijmegen Medical Centre

With summary in Dutch -136p.

© Copyright 2007 R.D.A. Gaasbeek

All rights are reserved. No part of this publication may be reproduced, stored in a retrieval system,

or transmitted in any form or by any means, mechanically, by photocopying, rcording, or otherwise,

without the written permission of the author.

ISBN/EAN: 978-90-9021884-7

Internet: http://webdoc.ubn.ru.nl/mono/g/gaasbeek _ r/hightios.pdf

Correspondence (e-mail) [email protected]

Cover: Harald Pieper

Lay-out: Harald Pieper

Print: Print Partners Ipskamp BV, Enschede, The Netherlands

Promotor:

prof. dr. A. van Kampen

Co-promotores:

dr. R.J. van Heerwaarden (Sint Maartenskliniek Nijmegen)

dr. ir. N.J.J. Verdonschot

Manuscriptcommissie:

prof. dr. A.C.H. Geurts

prof. dr. R.F.J.M. Laan

prof. dr. J.A.N. Verhaar (Erasmus Medisch Centrum Rotterdam)

Paranimfen:

drs. J.J. van der Gragt

drs. H.J.L. van der Heide

Voor mijn ouders

Contents

Chapter 1 General introduction, background and aims of the thesis

Chapter 2 Effects of valgus bracing on gait of patients with medial compartment

osteoarthritis of the knee

Gait Posture. 2007 June; 26 (1): 3-10

Chapter 3 Accuracy and initial stability of high tibial osteotomy;

A cadaveric RSA study of open versus closed wedge osteotomy

Knee Surg Sports Traumatol Arthrosc. 2005 Nov;13(8):689-94

Chapter 4 Correction accuracy and collateral laxity in open versus closed wedge

high tibial osteotomy. A one year randomized controlled study

J Bone Joint Surg Br.In revision

Chapter 5 Mechanism of incorporation of ß-TCP in patients in open wedge high

tibial osteotomy

Biomaterials. 2005 Nov;26(33):6713-9

Chapter 6 The influence of open and closed wedge high tibial osteotomy on patellar tracking

Knee Surg Sports Traumatol Arthrosc.2007 May 5; [Epub ahead of print] 2007

Chapter 7 Distal tuberosity osteotomy in open wedge high tibial osteotomy can

prevent patella infera; a new technique

Knee. 2004 Dec;11(6):457-6

Chapter 8 Summary, answers to research questions and closing remarks

Chapter 9 Samenvatting, beantwoording van de onderzoeksvragen

en afsluitende opmerkingen

Publications

Dankwoord

Curriclum Vitae

9

19

37

51

67

83

97

109

119

129

131

135

8

chapter 1General introduction, background

and aims of the thesis

10

Chapter 1

11

General introduction, background and aims of the thesis

Introduction

Osteoarthritis of the medial compartment of the knee in young active patients

represents a significant treatment challenge in orthopaedic practice. In most cases

medial compartment osteoarthritis of the knee is associated with varus leg alignment.

There is a wide range of treatment options, but the effectiveness of the different

treatments varies 1.

Non-operative treatment

Initial management for most patients should be non-operative and may include

physical therapy, bracing, orthoses, ambulatory aids, non-steroidal anti-inflammatory

medications, intra-articular steroid injections, and analgesics. Changes in habitual

activities including those related to work and recreation may also be necessary.

Obesity is a known risk factor for osteoarthritis of the knee, and weight loss has been

shown to slow the progression of the disease 1;2.

Operative treatment

Because of the progressive nature of the disease and because a varus malalignment

will lead to an ongoing unfavourable mechanical loading of the medial compartment,

many patients with medial osteoarthritis of the knee will eventually require operative

treatment. A variety of procedures have been described to treat the osteoarthritic knee,

ranging from arthroscopic lavage and debridement to total knee arthroplasty.

The choice of procedure depends on the patient’s age and activity expectations,

the severity of the disease, and the number of knee compartments involved.

One of these, high tibial osteotomy to the treat medial compartment osteoarthritis of

the knee, is the focus of this thesis.

High tibial osteotomy (HTO)

High tibial osteotomy is accepted as a valuable surgical option. Localized wear in

the knee results from a malalignment that has either produced the arthritis or has

aggravated it. For many years, the value of osteotomy was considered to be the load

transfer to the unaffected compartment of the knee which relieves symptoms and slows

disease progression. Osteotomy has been used extensively, with techniques becoming

more refined over time 3, 4. Furthermore, although the long term results of a total knee

arthroplasty are good, a significant concern remains regarding the longevity of the

prostheses which are placed, particularly in younger patients. In contrast, osteotomy

provides an alternative that preserves the knee joint, and when performed appropriately,

it should not compromise later arthroplasty if that becomes necessary. However,

although the results reported for a high tibial osteotomy vary considerably in the

literature, the procedure generally provides good pain relief and with restored function

at the 5-year follow up in approximately 80% to 90%, and at the 10-year follow up in 50%

to 65% 5-10. Most authors found that success was directly related to having achieved an

optimal alignment 6;9;11. Accurate preoperative assessment and technical precision are,

therefore, essential to achieve satisfactory outcomes. Many techniques have been

described for HTO, among them the lateral closed wedge and the medial open wedge.

Lateral closed wedge osteotomy (CWO)

The most commonly reported osteotomy for medial compartment osteoarthritis is the lateral

closed wedge osteotomy, popularized by Coventry and Insall et al. 4, 12. The goal is to

correct alignment as outlined earlier, which is achieved by removing a bone wedge from

the lateral tibia and closing the resultant defect. Many variations of this technique have

been described, but the general principle remains the same l 4;5;12;13. Traditionally,

the angular calculation is converted into the size of the wedge based on the tibial width

although newer instrument systems provide angled cutting jigs, thus eliminating the need

for this conversion. Many techniques can be used to treat the proximal tibiofibular joint,

including joint excision or disruption, fibular osteotomy, or excision of the fibular head.

12

Chapter 1

13


Medial open wedge osteotomy (OWO)

While medial opening wedge osteotomy has not been as widely reported in the

English-speaking literature as the CWO technique, its use in Europe continues to

increase in popularity 14;15. The theoretical advantages of the opening wedge in

comparison to the closing wedge include restoring the anatomy by adding bone to

the diseased medial side as well as being able to achieve predictable correction in

both the coronal and sagittal planes and to adjust the correction intra-operatively.

Furthermore, only one bone cut is required and there is no proximal tibiofibular joint

disruption or invasion of the lateral compartment, and it is relatively easy to combine

with other procedures such as ACL reconstruction. However, there are also disadvantages.

These include the creation of a defect that requires bone graft with attendant harvest

morbidity, a theoretically higher risk for nonunion, and a longer postoperative period

of restricted weight-bearing. Graft choices include autograft, allograft, or preprepared

bone substitutes. Each option has its own advantages and disadvantages. Although

iliac crest autograft probably remains the current gold standard, a tricalciumphosphate

(TCP) bone substitute was used in the open wedge osteotomies we performed.

This avoids donor site morbidity and decreases surgical time.

Complications of high tibial osteotomy

Complications reported for high tibial osteotomy include recurrence of deformity (loss of

correction), peroneal nerve palsy, non-union, infection, knee stiffness or instability,

intra-articular fracture, deep venous thrombosis, compartment syndrome, patella infera,

change of tibial slope, and avascular necrosis of the proximal fragment. Some of these

complications are related to the particular osteotomy technique used, to type of fixation

chosen or the postoperative management selected. Since the introduction of more

stable implants and early postoperative mobilisation, complication rates have decreased.

Most HTO literature pertains to CWO. Complications after OWO were generally the

same, but for instance peroneal nerve problems would be unlikely to occur as no fibular

osteotomy has been performed. However, the lowering of the patella seemed to be a

more profound issue after OWO 16;17.

Background, outline and aims of this thesis

To treat patients who suffer from medial osteoarthritis of the knee, the orthopaedic

surgeon has access to a range of treatment possibilities. The choice whether non-

operative or operative procedures should be used depends on multiple factors.

The treatment strategy selected is the result of intensive dialogue between patient and

doctor and has to be based upon accurate information. New treatment options for this

patient group are continually being developed and enjoy increasing popularity.

New unloading braces have frequently been introduced as well as new operations,

using bone substitutes and stable implants. Although all these new developments are

important, it is necessary to remain critical and to compare these new alternatives to

the known forms of treatment. The author’s interest in the different treatment strategies

for patients with varus osteoarthritis of the knee formed the background of this thesis.

During the preliminary research on current developments in the treatment of medial

osteoarthritis of the knee, several aspects stood out. In the non-operative treatment

spectrum, the clinical significance of valgus brace treatment forms a recurrent topic in

the literature 18-30. Unloading valgus braces have been used as the definitive treatment

as well as during the preoperative assessment to simulate the effect of a valgus high

tibial osteotomy. A new brace was developed and one of the goals of this thesis was to

analyse the effects of such a brace on gait (Chapter 2). Many patients will eventually

need operative treatment in the form of a HTO. Since the introduction of new rigid stable

implants, the OWO is more frequently performed in recent years. Only a few comparative

studies between these two techniques have been published 15;31-33. We investigated the

differences between CWO and OWO with respect to biomechanical characteristics,

clinical outcome and histological aspects (Chapters 3-5). Cutting the bone proximally to

the tibial tuberosity with the subsequent valgus correction will change the position of

the patella, and therefore, hypothetically lead to changes in patellar tracking 16;17;31;34-46.

Therefore, another aim of this thesis was to study the patellar height and tracking

following HTO. Again the effects of CWO and OWO were compared (Chapter 6).

Finally, the question arose whether a technique could be proposed which avoids these

effects on the patella (Chapter 7).

14

Chapter 1

15


The following research questions were formulated:

1. What is the effect of valgus bracing in patients with medial compartment osteoarthritis

of the knee and can this be explained by changes in gait?

2. What are the differences in accuracy and in postoperative stability between closed

and open wedge high tibial osteotomy?

3. What are the differences between closed and open wedge high tibial osteotomy in

patients with respect to correction accuracy, collateral laxity and clinical outcome?

4. Does the incorporation and remodelling of ß-TCP bone substitute in open wedge

tibial osteotomy in patients occur similarly to that in animals?

5. What are the effects of high tibial osteotomy on patellar tracking?

6. Can lowering of the patella which accompanies open wedge high tibial

osteotomy be prevented?

Reference List

1. Dabov G, Perez EA. Chapter 25: Miscellaneous Nontraumatic Disorders. In:Campbell’s Operative

Orthopaedics . Mosby , 2003;916.

2. Hanypsiak BT, Shaffer BS. Nonoperative treatment of unicompartmental arthritis of the knee.

Orthop Clin North Am 2005;36:401-411.

3. Amendola A, Panarella L. High tibial osteotomy for the treatment of unicompartmental arthritis of

the knee. Orthop Clin North Am 2005;36:497-504.

4. Coventry MB. Upper tibial osteotomy. Clin Orthop Relat Res 1984;46-52.

5. Billings A, Scott DF, Camargo MP, Hofmann AA. High tibial osteotomy with a calibrated osteotomy

guide, rigid internal fixation, and early motion - Long-term follow-up.

J Bone Joint Surg Am 2000;82A:70-79.

6. Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy. A critical long-term study of

eighty-seven cases. J Bone Joint Surg Am 1993;75:196-201.

7. Insall JN, Joseph DM, Msika C. High tibial osteotomy for varus gonarthrosis. A long-term follow-up

study. J Bone Joint Surg Am 1984;66:1040-1048.

8. Ivarsson I, Myrnerts R, Gillquist J. High tibial osteotomy for medial osteoarthritis of the knee.

A 5 to 7 and 11 year follow-up. J Bone Joint Surg Br 1990;72:238-244.

9. Naudie D, Bourne RB, Rorabeck CH, Bourne TJ. The Install Award. Survivorship of the high tibial

valgus osteotomy. A 10- to -22-year followup study. Clin Orthop 1999;18-27.

10. Rinonapoli E, Mancini GB, Corvaglia A, Musiello S. Tibial osteotomy for varus gonarthrosis.

A 10- to 21-year followup study. Clin Orthop 1998;185-193.

11. Yasuda K, Majima T, Tsuchida T, Kaneda K. A ten- to 15-year follow-up observation of high tibial

osteotomy in medial compartment osteoarthrosis. Clin Orthop 1992;186-195.

12. Insall J, Shoji H, Mayer V. High tibial osteotomy. A five-year evaluation.

J Bone Joint Surg Am 1974;56:1397-1405.

13. Dugdale TW, Noyes FR, Styer D. Preoperative planning for high tibial osteotomy. The effect of lateral

tibiofemoral separation and tibiofemoral length. Clin Orthop 1992;248-264.

14. Hernigou P, Medevielle D, Debeyre J, Goutallier D. Proximal tibial osteotomy for osteoarthritis with

varus deformity. A ten to thirteen-year follow-up study. J Bone Joint Surg Am 1987;69:332-354.

15. Magyar G, Ahl TL, Vibe P, Toksvig-Larsen S, Lindstrand A. Open-wedge osteotomy by hemicallotasis

or the closed-wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.

J Bone Joint Surg Br 1999;81:444-448.

16. Wright JM, Heavrin B, Begg M, Sakyrd G, Sterett W. Observations on patellar height following

opening wedge proximal tibial osteotomy. Am J Knee Surg 2001;14:163-173.

16

Chapter 1

17


17. Tigani D, Ferrari D, Trentani P, Barbanti-Brodano G, Trentani F. Patellar height after high tibial

osteotomy. Int Orthop 2001;24:331-334.

18. Davidson PL, Sanderson DJ, Loomer RL. Kinematics of valgus bracing for medial gonarthrosis:

technical report. Clin Biomech (Bristol , Avon ) 1998;13:414-419.

19. Draper ER, Cable JM, Sanchez-Ballester J, Hunt N, Robinson JR, Strachan RK. Improvement in

function after valgus bracing of the knee. An analysis of gait symmetry.


20. Hewett TE, Noyes FR, Barber-Westin SD, Heckmann TP. Decrease in knee joint pain and increase in

function in patients with medial compartment arthrosis: a prospective analysis of valgus bracing.

Orthopedics 1998;21:131-138.

21. Horlick SG, Loomer BA. Valgus knee bracing for medial gonarthrosis.

Clin J Sport Med 1993;251-255.

22. Kirkley A, Webster-Bogaert S, Litchfield R et al. The effect of bracing on varus gonarthrosis.


23. Komistek RD, Dennis DA, Northcut EJ, Wood A, Parker AW, Traina SM. An in vivo analysis of the

effectiveness of the osteoarthritic knee brace during heel-strike of gait. J Arthroplasty 1999;14:738-742.

24. Lindenfeld TN, Hewett TE, Andriacchi TP. Joint loading with valgus bracing in patients with varus

gonarthrosis. Clin Orthop 1997;290-297.

25. Matsuno H, Kadowaki KM, Tsuji H. Generation II knee bracing for severe medial compartment

osteoarthritis of the knee. Arch Phys Med Rehabil 1997;78:745-749.

26. Otis JC, Backus SI, Campbell DA et al. Valgus bracing for knee osteoarthritis: A biomechanical

and clinical outcome study. Gait Posture 2000;11:116-117.

27. Pollo FE, Otis JC, Wickiewicz TL, Sherryl I, Backu, Backus SI. Biomechanical analysis of valgus

bracing for the osteoarthritic knee. Arthritis Rheum 1995;241.

28. Pollo FE, Otis JC, Backus SI, Warren RF, Wickiewicz TL. Reduction of medial compartment loads

with valgus bracing of the osteoarthritic knee. Am J Sports Med 2002;30:414-421.

29. Self BP, Greenwald RM, Pflaster DS. A biomechanical analysis of a medial unloading brace for

osteoarthritis in the knee. Arthritis Care Res 2000;13:191-197.

30. van Heerwaarden RJ, Gaasbeek RD, Plitz W. A new valgus brace for medial knee osteoarthritis.

A short term patient evaluation study with the Softec OA brace.

Med-Orthopädische Technik 2005;57-65.

31. Brouwer RW, Bierma-Zeinstra SM, van Koeveringe AJ, Verhaar JA. Patellar height and the inclination

of the tibial plateau after high tibial osteotomy. The open versus the closed-wedge technique.


32. Hoell S, Suttmoeller J, Stoll V, Fuchs S, Gosheger G. The high tibial osteotomy, open versus closed

wedge, a comparison of methods in 108 patients. Arch Orthop Trauma Surg 2005;:1-6.:1-6.

33. Magyar G, Toksvig LS, Lindstrand A. Changes in osseous correction after proximal tibial osteotomy -

Radiostereometry of closed- and open-wedge osteotomy in 33 patients.

Acta Orthop Scand 1999;70:473-477.

34. Closkey RF, Windsor RE. Alterations in the patella after a high tibial or distal femoral osteotomy.

Clin Orthop 2001;51-56.

35. Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic

radiographic study. Knee Surg Sports Traumatol Arthrosc 1994;2:19-26.

36. Figgie HE, III, Goldberg VM, Heiple KG, Moller HS, III, Gordon NH. The influence of tibial-

patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee

prosthesis. J Bone Joint Surg Am 1986;68:1035-1040.

37. Goutallier D, Delepine G, Debeyre J. [The patello-femoral joint in osteoarthritis of the knee with genu

varum (author’s transl)]. Rev Chir Orthop Reparatrice Appar Mot 1979;65:25-31.

38. Heegaard J, Leyvraz PF, van Kampen A, Rakotomanana L, Rubin PJ, Blankevoort L. Influence of soft

structures on patellar three-dimensional tracking. Clin Orthop Relat Res 1994;235-243.

39. Hill NA, Fellows RA, MacIntyre NJ, Harrison MM, Ellis RE, Wilson DR. The effect of high tibial

osteotomy on three-dimensinal tibiofemoral and patellofemoral kinematics: an in vivi study using

magnetic resonance imaging. Proc 51st ORS Conference 2005;0481.

40. Kaper BP, Bourne RB, Rorabeck CH, Macdonald SJ. Patellar infera after high tibial osteotomy.

J Arthroplasty 2001;16:168-173.

41. Meyer SA, Brown TD, Pedersen DR, Albright JP. Retropatellar contact stress in simulated patella

infera. Am J Knee Surg 1997;10:129-138.

42. Scuderi GR, Windsor RE, Insall JN. Observations on patellar height after proximal tibial osteotomy.


43. Singerman R, Davy DT, Goldberg VM. Effects of patella alta and patella infera on patellofemoral

contact forces. J Biomech 1994;27:1059-1065.

44. van Kampen A, Huiskes R. The three-dimensional tracking pattern of the human patella.

J Orthop Res 1990;8:372-382.

45. Weidenhielm L, Wykman A, Lundberg A, Brostrom LA. Knee motion after tibial osteotomy for

arthrosis. Kinematic analysis of 7 patients. Acta Orthop Scand 1993;64:317-319.

46. Windsor RE, Insall JN, Vince KG. Technical considerations of total knee arthroplasty after proximal

tibial osteotomy. J Bone Joint Surg Am 1988;70:547-555.

18

chapter 2Valgus bracing in patients with medial compartment

osteoarthritis of the knee

A gait-analysis study of a new brace

Robert D. A. Gaasbeek, Brenda E. Groen, Brieke Hampsink,

Ronald J. van Heerwaarden, Jacques Duysens

Gait Posture 2007 June 26(1):3-10

20

Chapter 2

21

Valgus bracing in patients with medial compartment osteoarthritis of the knee

Abstract

A new valgus brace was evaluated in fifteen patients with medial osteoarthritis of the

knee and a varus leg axis. Significant improvement of pain and function were found

after six weeks of brace treatment. Gait analysis showed that the brace had a tendency

of lowering the peak varus moment about the knee. This effect was more profound at

higher initial varus deformity angles of the knee. Furthermore, a small decrease of knee

extension at the end of the swing phase and an increase of walking velocity were

related to brace wearing. The working mechanisms of valgus brace treatment found with

the gait analysis in this study may be of clinical importance for future developments in

brace treatment.

Introduction

Osteoarthritis of the knee is most often located in the medial compartment 1.

A progressive varus leg axis develops as a result of the cartilage loss associated with

this unicompartmental osteoarthritis. The varus deformity causes an overload of the

medial compartment with increasing symptoms during weight bearing. Decrease of

the varus leg alignment unloads the arthritic medial compartment which results in a

decrease of symptoms. Based on this principle, functional braces have been designed

to produce a valgisation force about the knee. The general working mechanism is a

distraction of the medial compartment and a transfer of the weight bearing axis

towards the lateral compartment of the knee. In several patient studies symptoms relief

and functional improvement were found after short term and longer term treatment with

valgus knee braces 1-6.

Gait analysis studies have been used to evaluate the working mechanisms that cause

improvements with brace wear. The results range from no effect to a significant

improvement in gait symmetry and a reduction in external varus moments 2, 5, 7-10.

A study using fluoroscopy during treadmill gait demonstrated articular surface

separation at heel strike in subjects wearing valgus knee braces 11. However, it remains

unclear how these changes relate to functional gait improvements. Furthermore, most

Figure 1

The SofTec OA valgus

brace. On the left:

airchamber inflation with

a bulb pump to adjust

brace valgisation force

and on the right:

schematic 3-point

mechanism producing

valgus.

22

Chapter 2

23


valgus braces offer little flexibility and there is a need for more adjustable braces.

A new valgus brace, the SofTec OA brace (Bauerfeind GmbH), has been constructed

with only a lateral hinge including an airchamber that enables adjustment of the valgus

force by the patient (Fig. 1). In the past few years, the authors used this brace in

clinical practice in the nonoperative treatment of patients with medial compartment

osteoarthritis of the knee with satisfactory results 12. No research on the effects of this

brace on pain, function scores and gait characteristics has been published. Therefore,

the present study was conducted to assess the effects of the use of this new brace

in patients with medial compartment osteoarthritis of the knee with respect to pain,

function and several gait parameters.

Materials and methods

Subjects

Fifteen consecutive patients, (12 male and 3 female) with a mean age of 52 (± 11)

years were included in the study. Inclusion criteria were an age between 18 and 70

years, unilateral medial compartment osteoarthrosis (OA) and pain localized primarily

to the medial compartment of the knee. Varus deformity of the knee was confirmed on

standing long leg X-rays (range 2 to 11° with a mean of 5.1°). Standard knee X-rays

confirmed the presence of medial compartment OA with absence of lateral and

patellofemoral compartment OA of the knee in all patients. Exclusion criteria were

health problems prohibiting full weight bearing gait, pre-existing skin problems, the

inability to apply a brace because of physical limitations and previous operative

treatment for the medial compartment OA. Informed consent was obtained. After the

subjects were fitted with the valgus brace, they were instructed to inflate the air

chamber with the bulb pump to a level at which the arthritic symptoms would subside

and asked to wear the brace for at least 6 weeks.

Data collection

Subjects were tested before fitting and wearing the brace (T0) and after wearing

the brace continuously for 6 weeks (T1). Symptoms of osteoarthritis were assessed

by the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index 13.

Pain intensity, during walking was scored with a Visual Analog Scale (VAS).

Gait analysis was performed on T0 without wearing the brace and on T1 without and

with wearing the brace.

To determine the external knee moments in the frontal plane, force data and 3D

kinematic data were collected simultaneously. Forces were measured at 2400 Hz by a

force plate (Kistler) embedded in the floor. The 3D positions of reflective markers were

recorded by a six-camera motion analysis system (Primas) at 100 Hz. For the walking

trials 18 markers were attached to the left and right leg. Four frames consisting of three

markers were tied to the femur and tibia of both legs. The remaining markers were

placed on the lateral malleolus, the dorsal aspect of the calcaneus, and the lateral

aspect of the fifth metatarsal head of both feet.

Data collection started with a reference trial in standing to define the joint centres,

therefore six extra markers were used : on the greater trochanter, the lateral femoral

epicondyle (or the hinge of the brace during the brace conditions) and the medial

aspect of the first metatarsal head of both feet. Then, the extra markers were removed.

During the walking trials the subjects walked at their preferred velocity. Five trials were

collected from both feet for each of the testing conditions.

To calculate the external moment in the frontal plane, inverse dynamics were applied

on a 2D-linked segment model. The centre of the ankle joint was defined medial to the

marker on the lateral malleolus at half the ankle width. The centre of the knee joint was

defined medial to the marker on the lateral femoral epicondyle at half the knee width

The ankle and knee joint centres were determined relative to the frames on the femur

and tibia respectively. For the walking trials the positions of the joint centres were

calculated based on the position of the marker frames. The moment was calculated

with use of the mass and inertia characteristics of the foot and lower leg and force

data 14. Prior to calculations the position data were low-pass filtered by a second order

Butterworth filter with a cut-off frequency of 6Hz and the force data were resampled to

100Hz. After normalization to the stance phase duration (=100%) the peak varus

moment was derived (maximum external moment about the knee in the frontal plane)

and averaged for both the left and right foot. All moments were normalized by the

product of body weight multiplied by height and were expressed as a percentage of

that product (%BW.HT). For the calculations, programs written in Matlab (The Math

Works Inc.) were used. Finally, the preferred walking velocity was determined, using

24

Chapter 2

25


the reflective marker on the calcaneus (average of five trials).

A pressure platform (RS-scan, 0.5m x 0.4m x 0.008m) was used to determine the

foot progression angle (FPA) during walking conform to our previous studies 15.

For the definition of FPA, see figure 2. For each subject the mean FPA of each

condition of the left and right foot was determined.

Treadmill walking, to determine ankle and knee kinematics, was introduced to have the

benefit of a more consistent gait pattern at a fixed speed. During treadmill walking the

joint angles of the knee and ankle were determined with twin axis goniometers as

used by others 16, 17. To indicate the beginning (heel contact) of the each step cycle,

reflective markers were placed on the heel of both feet. The experiment started with a

period of walking to familiarize the patients to treadmill walking. A trial during standing

with the knee and ankle joints in neutral positions provided reference data. Subjects

walked at two speeds, 3 and 4 km/h for each testing condition 18. The speed of 3 km/h

corresponds with the self selected walking velocity of patients with OA and the speed

of 4 km/h with the fast velocity that was feasible for all patients 19, 20. The subjects

performed three trials of each condition at each velocity. The average of 15 sequential

cycles was calculated and normalized for gait cycle.

The knee and ankle joint angles for the walking trials were calculated with use of the

average angles of the reference data. The following variables were derived: range of

motion (ROM) in the saggital plane, maximum flexion during (early) stance, maximum

extension during (mid) stance, maximum flexion during (mid) swing, maximum

extension at the end of the swing phase. Average step frequency (steps/min) and step

length were calculated, using the heel marker position.

Statistical analysis

Paired t-tests were used to determine the effect of the brace on the VAS and WOMAC

scores and to determine differences between the affected and unaffected leg.

Multivariate analysis of variance (MANOVA) for repeated measurements with three

brace conditions (T0, T1without brace and T1with brace) were used to determine if the other

variables were affected by condition (main effect). For treadmill walking the speed

was added as between factor variable, to determine the (interaction) effects of speed

on the kinematic and spatiotemporal variables. For peak varus moment the varus

deformity was used as a covariate. Post hoc, paired t-tests were performed to

determine between which conditions the differences existed. Level of significance

was set at p=0.05 for all tests.

Results

The brace was worn 7 days a week by all patients. Following the 6 weeks of brace

wear, statistically significant improvements were found for the WOMAC and VAS-scores

(Table 1).

The effects on the moments at the knee were evaluated with inverse dynamics.

The mean group knee moment as a function of the stance phase for both the affected

and unaffected leg for all conditions are shown in figure 3. Typically the peak varus

moment was larger in the affected leg as compared with the non-affected one and the

Figure 2

Definition of the foot

progression angle (FPA)

using a plantar pressure

print. The FPA was defined

as the angle between the

direction of progression and

the foot axis defined as the

axis through the base of the

heel and MTP2. The foot

axis through the heel and

MTP2 was set manually on

the maximum pressure

image of the foot, while the

direction of progression was

in forward direction.

26

Chapter 2

27


moment was reduced after wearing the brace (Fig. 3). Figure 4a shows the group

peak varus moment of the affected and unaffected leg for all conditions. For the whole

group, the peak varus moment was significantly higher in the affected than in the

unaffected leg on T0 (p=0.021). The varus moment was also influenced by the various

brace conditions. For the affected leg, the MANOVA indicated a significant main effect

of brace condition (e.g. T0, T1without brace and T1with brace) on peak varus moment

(p=0.046). Post hoc testing showed that the peak varus moment was significantly

higher during the T1without brace condition compared to the T0 condition (p=0.019).

No significant difference was found between the braced and unbraced condition

on T1 (p=0.125). In addition, a significant interaction effect between the peak varus

moment and the varus deformity of the knee (covariate) (p=0.05) was indicated.

The interaction was significant between brace condition T1without brace and T1with brace

(p=0.010). The larger the varus deformity of the knee, the more reduction in the peak

varus moment was achieved by the brace during walking.

As shown in figure 4b, no significant differences in FPA were observed but step length

was affected.

With brace (T1with brace), the steps were shorter than without brace (T1without brace)(p=0.017

and p<0.001) (Fig. 4c). The MANOVA indicated a significant main effect of brace

condition for both affected (p=0.017) and unaffected leg (p<0.001).

Figure 3

Group mean of the knee varus moment as a function of the stand phase for both the

unaffected and affected leg for all conditions. The moments are normalized to body weight

(BW) and height (HT) and expressed as a percentage. Note that the maximum varus moment

in this figure differs from the peak varus moments shown in figure 4a, because in the present

plot all values were averaged while in figure 4a only the peak values were averaged (due to

peak varus occurred at different times in the cycle for the various subjects).

Affected leg

T0: without braceT1: without braceT1: with brace

Valgus

Knee

mom

ent (

%BW

.HT)

% Standphase % Standphase

Knee

mom

ent (

%BW

.HT)

Valgus

VarusVarus


Unaffected leg

*a

c *

** ***

*

d

b


Peak

var

us m

omen

t kne

e (%

BW.H

T)

Foot

pro

gres

sion

ang

le (d

egre

es)

Step

leng

ht (c

m)

Knee

rang

e of

mot

ion

(deg

rees

)

Affected leg Unaffected leg Affected leg Unaffected leg

Affected leg Unaffected leg Affected leg Unaffected leg

Figure 4

Diagrams showing the group mean ± standard deviation of the a. Peak knee varus moment

(normalized to body weight (BW) and height (HT)), b. Foot progression angle (degrees),

c. Step length (cm) and d. Knee range of motion in the saggital plane (degrees) for both

the unaffected and affected leg at all conditions. Significant differences are indicated with

an asterisk (*).

28

Chapter 2

29


Post hoc testing showed that the patients walked with longer steps during T1without brace

than on T0 (p=0.007 and p=0.005 for the affected an unaffected leg, respectively).

The effects were independent of speed.

The shorter steps with the brace suggest that there was a limitation in ROM due to

the braces. This was confirmed by the analysis. For the affected knee ROM in the

saggital plane, the MANOVA indicated a main effect of brace condition (p=0.0045).

The ROM was significantly reduced in the braced condition (T1with brace) compared to

the unbraced condition (T1without brace) (p=0.02) independent of walking velocity

(Fig. 4d). The reduction in ROM during walking with the brace was mainly expressed

as a reduction in knee extension at end swing and end stance, as is illustrated in Fig. 5.

The MANOVA’s for ankle and knee angles indicated a main effect of brace condition

for the maximal knee extension during the end of the swing phase of the affected leg

only (p<0.001). On T1, knee extension was significantly decreased by brace wear

(p<0.001) (Fig. 5).

The three brace conditions had an effect on preferred walking velocity as well. Indeed,

the MANOVA indicated that there was a significant main effect of brace condition

(e.g. T0, T1without brace and T1with brace) on preferred walking velocity (p=0.014).

Post hoc testing showed that the patients walked faster on the second testing day

(T1 vs. T0; p=0.026). On T1, there was no significant difference between conditions

without (T1without brace) and with brace (T1with brace) (p=0.063) (Fig. 6).

Discussion

The purpose of this study was to evaluate the SofTec OA valgus brace on patients

suffering from medial compartment OA of the knee with a clinical assessment and

a gait analysis. After six weeks of bracing, improvements in pain and function scores

were observed. Although little weight can be placed on these results because of the

small number of patients and because we did not use an alternative to the brace as

a control, these findings were consistent with results presented in previous studies

with this brace 12 and other braces 1, 4, 5, 13.

As expected, the peak varus moments about the knee during the stance phase of

walking were significantly higher in the affected leg as compared with the unaffected

leg on the first testing day (before brace treatment). The values found in the present

study were within the range of those reported in literature 2, 5, 10, 21. The values for the

unaffected leg were comparable with the values for controls as reported by Goh et al.

Figure 5

The group mean knee angle as a function of the gait cycle for both the unaffected and affected

leg for all conditions during treadmill walking of 3 km/h. Note that the ROM in this figure differs

from the ROM shown in figure 4d, because in the present plot all values were averaged while in

figure 4d only the peak values were averaged (related to the maximum flexion and extension

occurring at different times in the cycle for the various subjects).

Affected leg Unaffected leg



Flexion

Knee

flex

ion/

exte

nsio

n (d

egre

es)

% gait cycle % gait cycle

Knee

flex

ion/

exte

nsio

n (d

egre

es)

Extension

Flexion

Extension


Pref

erre

d w

alki

ng v

eloc

ity (m

/s)

Figure 6

Preferred walking velocity

(group mean ± standard

deviation) (m/s) during all

conditions. Significant

differences are indicated

with an asterisk (*).

30

Chapter 2

31


and Lindenfeld et al. 5, 22 For the affected leg, the peak varus moment about the knee

was lower during the braced condition as compared to the unbraced condition on T1

although the differences did not reach significance. The variability and the small

number of patients could explain the lack of significance. In previous brace studies a

significant reduction in peak varus moment was not found either 1, 2, 5. Pollo et al. did

not find a decrease in peak varus moment, although they observed a reduction in the

load of the medial compartment of the knee (as estimated by an analytical model) in

the brace condition 1. However, others found significant reductions in varus moments

about the knee during brace wear 5, 10. In the present study a significant interaction

effect was shown between the peak varus moment and varus deformity of the knee.

This means that patients with more varus deformity, showed more reduction of the

peak varus moment during the braced condition (p<0.05). This suggests the brace

is more effective at higher varus deformities. No other studies were found in which

the interaction effect was examined. Although reduction of the peak varus moment

was not consistently found in all patients the clinical assessment showed significant

improvement of pain and knee function in all patients. This might be due to the fact

that valgus braces do not actually change the varus alignment of the leg but might

prevent the increase in varus at mid-stance. The peak varus moments are found at

early and late stance. This raises the question whether peak varus moment analysis

is the most accurate way to study the presumed unloading effect of any brace.

The unloading of the medial compartment may be caused by other factors, especially

gait adaptations, as well.

Earlier studies observed a significant correlation between the toe angle and peak

varus moment, which suggests that the varus moment can be decreased by increa-

sing toe-out of the foot 19, 23-25. Patients with medial compartment OA could use this

compensatory mechanism to reduce the varus moment 23, 26. This was not observed in

the present group since the FPA was within normal limits 22 and showed no significant

difference between the affected and unaffected leg. Furthermore, no effect of the

brace on the FPA was observed, in agreement with others 2, 5. Hence, differences in

varus moment between the conditions found in the present study are not caused by

the rotation of the foot.

It has been speculated that these patients walk at slower velocities to reduce loading

in the medial compartment of the knee 21. The average preferred walking velocity of our

group of patients at the first testing day corresponded with values for velocity of

healthy adults and was higher than was expected on the basis of gait analysis of OA

patients 27-29. At the second testing day, after a 6 weeks period of brace wear, the

patients walked without brace with a significant faster preferred walking velocity.

This could be due to the improvement of function and reduction of pain after brace

treatment. The difference in velocity could explain the difference found in the peak

varus moment between the unbraced conditions at the first and second testing day.

However, walking with the brace did not change the walking velocity significantly on

the second testing day. Earlier studies also reported no difference between the

unbraced and braced condition after a period of brace treatment 1, 2, 5, 7. We concluded

that the tendency of peak varus moment reduction by brace wear was not due to a

reduction in walking velocity in this study.

Another adaptive mechanism that could be used to lower the adduction moment

during gait is shortening the stride or step 23. During treadmill walking on the second

testing day the patients had a significant increase of stride length as compared to the

first testing day in the unbraced situation (T1without brace). This could be due to pain

reduction. Surprisingly, the step and stride length returned to the values measured

before brace treatment in the braced condition (T1with brace). Earlier brace studies have

not found a significant difference in stride length between the unbraced and braced

conditions after a period of brace treatment 7, 9. An explanation for the reduction of

stride length after application of the brace could be a reduction of the range of motion

of the knee i.e. the brace could have altered the mobility of the knee by which the

stride and step length is affected.

The ROM of the knee in the saggital plane was similar to other studies 17, 20, 27, 30, 31.

The knee range of motion in the saggital plane was significantly reduced in the braced

condition. The knee angles at different events of the gait cycle were investigated.

The results showed that the brace prevented full extension at the end of the swing

phase. Possibly, the duration of the swing phase was decreased which could explain

the decreased step and stride length during treadmill walking with brace. These data

are consistent with the gait analysis of Davidson et al., who demonstrated that during

valgus brace wear the knee angle during the stance phase is altered 32. More specifically,

in the analysis performed full extension was prevented by the resisting valgus forces in

the coronal plane. In the present study, the kinematic parameters are obtained during

32

Chapter 2

33


treadmill walking and the peak varus moment during overground walking. Although

previous studies have indicated that the kinematics of the knee of treadmill and

overground walking are very similar 33, it is important to point out that cross-referencing

represents a minor limitation of the present study.

Whether the new hinge construction with inflatable airchamber that is applied in this

brace or a general effect of valgus producing hinged knee braces is responsible for

the changes in the gait cycle remains unclear as in the present study no comparisons

were made with other braces. In the clinical assessments no scores were found

indicating that the small decrease in range of motion was perceived by the patients.

Longer follow up of clinical assessment and gait analysis may reveal whether the

effects of brace treatment found in this study persist. The analysis of the working

mechanisms of brace treatment with gait analysis studies will enable objective evaluation

of the effects of brace treatment and may improve future brace design.

In conclusion, the SofTec OA brace significantly decreased pain and improved knee

function. The working mechanism of this new valgus brace may be explained by

reduction of the peak varus moment about the knee, this effect being more profound

at higher initial varus angles of the knee, an increased walking velocity and a small

decrease in knee ROM with prevention of full extension during gait.

Acknowledgments

The authors thank Ms Joan Evers, orthopaedic technician, for her assistance in brace

fitting and patient instruction as well as, Drs J. Hiemstra and I. Barck of Bauerfeind

Benelux and Bauerfeind GmbH for technical and administrative assistance. This study

was supported by POM, Nijmegen, The Netherlands and Bauerfeind GmbH.

Reference List

1. Pollo FE, Otis JC, Backus SI, Warren RF, Wickiewicz TL. Reduction of medial compartment

loads with valgus bracing of the osteoarthritic knee. Am J Sports Med 2002; 30: 414-421

2. Hewett TE, Noyes FR, Barber-Westin SD, Heckmann. TP Decrease in knee joint pain and increase

in function in patients with medial compartment arthrosis: a prospective analysis of valgus bracing.

Orthopedics 1998; 21: 131-138

3. Horlick SG, Loomer BA. Valgus knee bracing for medial gonarthrosis. Clin J Sport Med 1993;251-255

4. Kirkley A, Webster-Bogaert S, Litchfield R, Amendola A, MacDonald S, McCalden R, Fowler P.

The effect of bracing on varus gonarthrosis. J Bone Joint Surg Am 1999; 81: 539-548

5. Lindenfeld TN, Hewett TE, Andriacchi TP. Joint loading with valgus bracing in patients with varus

gonarthrosis. Clin Orthop 1997; 290-297

6. Matsuno H, Kadowaki KM, Tsuji H. Generation II knee bracing for severe medial compartment

osteoarthritis of the knee. Arch Phys Med Rehabil 1997; 78: 745-749

7. Otis JC, Backus SI, Campbell DA. Valgus bracing for knee osteoarthritis: A biomechanical and

clinical outcome study. Gait Posture 2000; 11: 116-117

8. Draper ER, Cable JM, Sanchez-Ballester J, Hunt N, Robinson JR, Strachan RK. Improvement in

function after valgus bracing of the knee. An analysis of gait symmetry.

J Bone Joint Surg Br 2000; 82: 1001-1005

9. Pollo FE, Otis JC, Wickiewicz TL, Sherryl I, Backu, Backus SI. Biomechanical analysis of valgus

bracing for the osteoarthritic knee. Arthritis Rheum 1995; 241

10. Self BP, Greenwald RM, Pflaster DS. A biomechanical analysis of a medial unloading brace

for osteoarthritis in the knee. Arthritis Care Res 2000; 13: 191-197

11. Komistek RD, Dennis DA, Northcut EJ, Wood A, Parker AW, Traina SM. An in vivo analysis of

the effectiveness of the osteoarthritic knee brace during heel-strike of gait.

J Arthroplasty 1999; 14: 738-742

12. Van Heerwaarden RJ, Gaasbeek RD, Plitz W. A new valgus brace for medial knee osteoarthritis.


Med-Orthopädische Technik 2005; 57-65

13. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC:

a health status instrument for measuring clinically important patient relevant outcomes to

antirheumatic drug therapy in patients with osteoarthritis of the hip or knee.

J Rheumatol 1988; 15: 1833-1840

14. Winter DA, Patla AE, Frank JS, Walt SE. Biomechanical walking pattern changes in the fit and

healthy elderly. Phys Ther 1990; 70: 340-347

34

Chapter 2

35


15. Jaarsma RL, Ongkiehong BF, Gruneberg C, Verdonschot N, Duysens J, van Kampen A.

Compensation for rotational malalignment after intramedullary nailing for femoral shaft fractures.

An analysis by plantar pressure measurements during gait. Injury. 2004 Dec;35(12):1270-8.

16. Rowe PJ, Myles CM, Walker C, Nutton R. Knee joint kinematics in gait and other functional

activities measured using flexible electrogoniometry: how much knee motion is sufficient for normal

daily life? Gait Posture 2000; 12: 143-155

17. Myles CM, Rowe PJ, Walker CR, Nutton RW. Knee joint functional range of movement prior to

and following total knee arthroplasty measured using flexible electrogoniometry.

Gait Posture 2002; 16: 46-54

18. Kirtley C, Whittle MW, Jefferson RJ. Influence of walking speed on gait parameters.

J Biomed Eng 1985; 7: 282-288

19. Wada M, Imura S, Nagatani K, Baba H, Shimada S, Sasaki S. Relationship between gait and

clinical results after high tibial osteotomy. Clin Orthop 1998; 180-188

20. Gok H, Ergin S, Yavuzer G. Kinetic and kinematic characteristics of gait in patients with medial

knee arthrosis. Acta Orthop Scand 2002; 73: 647-652

21. Mundermann A, Dyrby CO, Hurwitz DE, Sharma L, Andriacchi TP. Potential strategies to reduce

medial compartment loading in patients with knee osteoarthritis of varying severity: reduced wal-

king speed. Arthritis Rheum 2004; 50: 1172-1178

22. Goh JC, Bose K, Khoo BC. Gait analysis study on patients with varus osteoarthrosis of the knee.

Clin Orthop 1993; 223-231

23. Wang JW, Kuo KN, Andriacchi TP, Galante JO. The influence of walking mechanics and time on

the results of proximal tibial osteotomy. J Bone Joint Surg Am 1990; 72: 905-909

24. Hurwitz DE, Ryals AB, Case JP, Block JA, Andriacchi TP. The knee adduction moment during

gait in subjects with knee osteoarthritis is more closely correlated with static alignment than

radiographic disease severity, toe out angle and pain. J Orthop Res 2002; 20: 101-107

25. Andrews M, Noyes FR, Hewett TE, Andriacchi TP. Lower limb alignment and foot angle are related

to stance phase knee adduction in normal subjects: a critical analysis of the reliability of gait

analysis data. J Orthop Res 1996; 14: 289-295

26. Torgerson WR, Jr., Kettelkamp DB, Igou RA, Jr., Leach RE. Tibial osteotomy for the treatment

of degenerative arthritis of the knee. Clin Orthop 1974; 101: 46-52

27. Al Zahrani KS, Bakheit AM. A study of the gait characteristics of patients with chronic

osteoarthritis of the knee. Disabil Rehabil 2002; 24: 275-280

28. Kaufman KR, Hughes C, Morrey BF, Morrey M, An KN. Gait characteristics of patients with

knee osteoarthritis. J Biomech 2001; 34: 907-915

29. Larsson LE, Odenrick P, Sandlund B, Weitz P, Oberg PA. The phases of the stride and their

interaction in human gait. Scand J Rehabil Med 1980; 12: 107-112

30. Baliunas AJ, Hurwitz DE, Ryals AB, Karrar A, Case JP, Block JA, Andriacchi TP. Increased

knee joint loads during walking are present in subjects with knee osteoarthritis.

Osteoarthritis Cartilage 2002; 10: 573-579

31. Messier SP, Loeser RF, Hoover JL, Semble EL, Wise CM. Osteoarthritis of the knee: effects

on gait, strength, and flexibility. Arch Phys Med Rehabil 1992; 73: 29-36

32. Davidson PL, Sanderson DJ, Loomer RL. Kinematics of valgus bracing for medial gonarthrosis:

technical report. Clin Biomech (Bristol , Avon ) 1998; 13: 414-419

33. Alton F, Baldey L, Caplan S, Morrissey MC. A kinematic comparison of overground and treadmill

walking. Clin Biomec 1998; 13: 434-440

36

chapter 3Accuracy and initial stability of open and closed

wedge high tibial osteotomy; A cadaveric RSA study

Robert D. A. Gaasbeek, Roy T. C. Welsing, Nico Verdonschot,

Willard J. Rijnberg, Corné J. M. van Loon, Albert van Kampen

Knee Surg Sports Traumatol Arthrosc. 2005 Nov;13(8):689-94

38

Chapter 3

39

Accuracy and initial stability of open and closed wedge high tibial osteotomy; a cadaveric RSA study

Abstract

We analyzed the difference in angle correction accuracy and initial stability between

open-wedge (OWO) and closed-wedge tibial valgus osteotomy (CWO). Five fresh

frozen pairs of human cadaver lower limbs were used, their bone mineral density (BMD)

was measured with DEXA and a planned 7 degree valgus osteotomy was performed,

either with an open (right knees) or closed (left knees) technique.

All osteotomies were fixed with a rigid locked plate. In OWO tricalcium phosphate

(TCP) wedges were inserted. The knees were subjected to an increasing cyclic axial

load until failure, while measuring the relative displacement of the bony

segments with roentgen stereophotogrammetric analysis. The mean postoperative

valgus correction angle was 9.5º ± 2.8º for CWO (over-correction of 2.5º) and 6.2º

± 2.0º for OWO (under-correction of 0.8º) (p = 0.08). The data of displacement under

load-bearing showed no significant differences in rotations and translations in any

direction. No significant correlation between BMD and the moment of failure was found

(p=0.27).

This study has shown that both methods gave an acceptable correction with high

variation of postoperative correction angles. There was a tendency of overcorrection

in the CWO group but no significant difference was found. There was no difference in

initial stability between CWO and OWO with a rigid locked plate fixation.

Introduction

Medial osteoarthritis of the knee is often associated with a varus deformity.

Valgus high tibial osteotomy (HTO) is the treatment for varus deformity, especially for

the younger active patient 4, 5. The goal of HTO is reduce the load on the medial

compartment by shifting the mechanical axis towards the lateral compartment with a

slight over-correction 17, 18. For good long-term clinical results the recommended post-

operative femorotibial valgus angle has to be in the region of 8 to 16 degrees 5, 7, 9, 12.

Excessive over-correction leads to poor results 10. Under-correction and loss of

correction results in a poor clinical outcome 5, 7. Hence, it is of critical importance that

the angle correction is as accurate as possible.

In some cases deterioration of the angle correction occurs after HTO because of lack

of fixation and stability 14. Therefore, adequate stability is important to maintain the

angle correction for a longer period of time. Closed-wedge osteotomy (CWO) has

been the treatment of choice for many years 5, 13, 16, 17. However, open-wedge osteotomy

(OWO) is frequently used today. OWO is a less demanding surgical procedure, without

having to perform a fibula osteotomy. It gained popularity because of the shorter

rehabilitation and sick leave periods, reduced chance of nerve and vascular damage

and the availability of stable implants 6, 15, 16.

However, at present it is unclear which of the two methods (OWO or CWO) is more

accurate in terms of angle correction and which of the two methods leads to the

strongest reconstruction.

Therefore we analyzed the accuracy and initial postoperative stability of HTO on five

pairs of human cadaver lower limbs, operated with both OWO and CWO, with roentgen

stereophotogrammetric analysis (RSA) under dynamic loading conditions.


This study was conducted on 5 pairs of fresh frozen human cadaver lower limbs.

AP and lateral radiographs of the knee joint were made to exclude major degenerative

40

Chapter 3

41


changes. Before preparation or testing a Dual Energy X-ray Absorptiometry scan

(DEXA) was made to measure the bone mineral density (BMD) in five different regions

of interest of the proximal tibia. All soft tissues were left in place. The femur was cut

20 cm above the knee joint and the tibia 20 cm under the knee joint and cemented

in metal sockets.

Operative technique

One surgeon performed all operations under fluoroscopic guidance. The aimed angle

of correction in all knees was 7º.

CWO: (five left knees). A standard anterolateral approach was used. An osteotomy and

2 cm resection was performed in the middle third part of the fibula. Two centimeters

below and parallel to the joint line a Kirschner wire was inserted to aim the osteotomy.

First, the proximal cut was performed and the medial cortex was preserved. Using an

aiming device the distal cut was made and the bone wedge was removed. The aiming

device we used consists of a blade which is put in the first saw cut. The second cut is

performed through a cleft in the device with a fixed angle to the blade. The defect was

closed and the osteotomy was fixed with 4 locked screws and a L-plate (Numélock 2

system, Numédic, Cholet, France).

OWO: (five right knees). A medial approach was performed, shifting the pes anserinus

and the superficial medial collateral ligament dorsally. A Kirschner wire was inserted

parallel to the joint space. Using a guide instrument a second wire was inserted just

proximal of the tuberositas in lateral cranial direction in order to obtain an equal

osteotomy angle in all knees. Along this wire the osteotomy was performed. The lateral

cortex was left intact. The gap was opened and a resorbable tricalcium phosphate

(TCP) wedge (Otis, Lourdes, France) of 7 mm (6.6º) was inserted. No fibular osteotomy

was performed. Internal fixation was performed using the Numélock 2 system,

a T-plate with 4 locked screws.

Load bearing measurement

Standardized conditions of cyclic axial load bearing were achieved by placing the

knees subsequently in a material testing system (MTS) loading machine (MTS Systems

Corporation, Minneapolis, USA). The femur was attached proximally in a position of

free movement and the tibia was fixed distally (Figure 1). A constant load of 500 N was

applied to the quadriceps tendon. A dynamic load was applied to the knees in a 1 Hz

cyclic zero-to maximal loading pattern for 10 minutes and increased in steps of 250 N

until failure occurred.

RSA

RSA was performed according to the standard procedure 2, 11. The accuracy in our

laboratory in determining the three-dimensional rotation is 0.1 degrees and for

translation about 0.05 mm. Ten tantalum markers were placed: four markers proximal

to the osteotomy in the tibial plateau, and six on the distal tibia. The bones proximal

and distal to the osteotomy were considered to represent two rigid bodies. To obtain

the most accurate data of translation we added an additional marker in the plane

of osteotomy and considered this an origin of the rigid body. The positions of the

tibial markers were reoriented to their initial position and the rotation and translation

of the markers in the tibial plateau was calculated before surgery and during loading.

Before surgery and after every load bearing step RSA recordings were obtained.

In the coordinate system we determined the postoperative tibial wedge angle (rotation

around the Z-axis), the internal and external rotation of the tibia (rotation around the

Y-axis) and the retro- and anteflexion of the tibial plateau (rotation around the X-axis).

Figure 1

Setting of the load bearing

experiment in the MTS

machine.

42

Chapter 3

43


Statistics

The linear correlation between displacement of the bony segments and load bearing was

analyzed using linear regression analysis (mean and 95% CI), followed by the paired

t-test to assess whether failure loads were different. Pearson’s correlation coefficient

was used to correlate BMD and moment of failure. Postoperative correction angles were

analyzed using the non-parametric Mann-Whitney U-test. Significance was set at p<0.05

Results

The bone mineral density (BMD) in all knees showed no significant differences

(p = 0.42) between pairs. The BMD in all knees, except one, was higher in the lateral

section than in the medial section of the tibia). AP and lateral radiographs showed no

major degenerative changes and no differences between pairs.

Postoperative correction angles

The planned angle of correction was 7º of valgus. The mean postoperative tibial

wedge angle was 9.5º ± 2.8º for CWO and 6.2º ± 2.0º for OWO. Hence, there was

a tendency that the mean correction angle was smaller with the OWO as compared to

the CWO. This difference was not significant (p = 0.08). There was a high variation

in both groups. The range of tibial wedge angles for CWO was 5.1º-12.1º and for OWO

3.7º-9.2º (Figure 2). Both CWO and OWO showed postoperative retroflexion of the

tibial plateau which means an increase in posterior slope (4 of 5 knees with CWO and

3 of 5 with OWO). Furthermore there was a postoperative external rotation of the

distal tibia (3 of 5 knees with CWO and 4 of 5 with OWO). The mean retroflexion of

the tibial plateau was not significantly different (p = 0.48): -0.1º ± 4.8º for CWO

and -3.5º ± 5.5º for OWO. The mean external rotation of the tibia was 3.7º ± 4.9º

for CWO and 2.6º ± 3.2º for OWO (p = 0.65).

Stability of the reconstruction during load bearing

From the RSA data the displacement of the bony segments was calculated. The rotations

and translations of all knees were plotted in diagrams and tables (Figure 3). The data

of the measurement just before failure of the knee were not included in the calculation

of the regression analyses. Increasing rotation and translation were seen with increasing

load bearing. The means of linear regression analysis found in CWO were compared

with those found in OWO. No differences were found in internal and external rotations

of the tibia (rotation Y-axis), tibial wedge angles (rotation Z-axis), anterior-posterior

translations; medial-lateral translations and superior-inferior translations (Table 1).

Moment of failure and bone mineral density

Seven knees failed in valgus and three in varus. The moments of failure of the

reconstruction, e.g. the maximum load the knees could bear, are shown in table 2.

The difference between the means of the maximum load bearing of the CWO- and

the OWO-knees was not significant (1750 ± 586 N and 2000 ± 637 N, respectively)

(p = 0.49). We found no significant correlation between the BMD and the moment

of failure (p=0.27).

Left / CWO

Right / CWO

Angle(degrees)

Knee

Figure 2

Postoperative tibial wedge

angles in open and closed

wedge osteotomies.

Translation alongY-axis (mm)

Load bearing (N)

Figure 3

Diagram showing

translations and moment

of failure along the Y-axis

during load bearing of

all ten knees.

44

Chapter 3

45


Discussion

The precision of the predicted postoperative angle of correction is an important factor

in the long-term clinical results. To avoid under-correction or extreme over-correction,

the achieved tibial wedge angle must approach the planned correction angle as much

as possible. Because we used human cadaver knees it was not possible to trace the

mechanical axis of the limb on whole leg X-ray’s. In contrast to the usual clinical

setting we had to perform osteotomies in knees without varus deformity. Therefore, we

could not determine the desired angle of over-correction and we set our goal at a 7º

tibial wedge angle. With OWO we placed a 7 mm/ 6.6º tricalcium phosphate wedge in

all right sided knees. The angle of required correction is determined by the height of

the medial opening and the length of the osteotomy 8. (Figure 4). Post-experimentally

we measured the length of the osteotomy of the knees operated with OWO.

The mean length was 60.6 ± 4.9 mm (range 55-68). Inserting a tricalcium phosphate

wedge of 7 millimeters the calculated mean tibial wedge angle was 6.6º ± 0.5º

(range 5.9º – 7.2º) (Table 3). We found a final tibial wedge with a mean angle of 6.2º.

The loss of correction of 0.4º might be the result of bone loss caused by cutting.

Billings et al. reported good clinical results with CWO, rigid internal fixation and early

motion, when using a calibrated osteotomy cutting guide 3. In our study we also used

a guide instrument for CWO. With CWO we found a higher mean post operative tibial

wedge angle compared to OWO (9.5º ± 2.8º resp. 6.2º ± 2.0º, p=0.08).

Thus, resulting in a minor under-correction of 0.8º with OWO and a major over-correction

Table 1

Mean regression analysis of rotation and translation

CWO= closed wedge osteotomy, OWO= open wedge osteotomy

Displayed are mean values (*10-3) (95% confidence intervals)

CWO OWO p-value

Rotation

X-axis -1.8 (-4.3-0.7) -0.2 (-1.5-1.1) 0.07

Y-axis 0.4 (-0.7-1.6) 0.4 (-0.1-0.8) 0.90

Z-axis -0.2 (-1.7-1.3) -0.9 (-1.8-0.1) 0.37

Translation

X-axis -0.1 (-0.7-0.5) -0.3 (-0.7-0.2) 0.45

Y-axis -0.5 (-0.9- -0.1) -0.7 (-0.9- -0.2) 0.21

Z-axis -0.5 (-1.2-0.3) -0.1 (-0.4-0.2) 0.36

Table 2

Bone Mineral Density and moment of failure

OWO= open wedge osteotomy, CWO= closed wedge osteotomy

BMD= bone mineral density

OWO CWO

BMD failure load BMD failure load

(g/cm2) (Newton) (g/cm2) (Newton)

mean lateral medial mean lateral medial

A 0,3 0,4 0,4 2250 0,3 0,4 0,3 2000

B 0,3 0,4 0,6 2000 0,3 0,5 0,3 2250

C 0,4 0,5 0,4 2250 0,5 0,6 0,4 2000

D 1,0 1,1 1,0 2750 0,7 0,7 0,8 1250

E 0,4 0,5 0,4 1000 0,4 0,5 0,4 1000

α = tan -1 ( y/x )

x

y

α

Figure 4

The angle of correction (α)

is determined by

the height of the medial

opening(Y) and the length

of the osteotomy (x).

46

Chapter 3

47


of 2.5º with CWO but with high variation in the two groups. Although no statistical

difference was found , there is a tendency of overcorrection in the CWO group.

In a clinical situation an achieved tibial wedge angle larger than planned may result in

an excessive over-correction, which has poor long-term results 10. Our findings

correspond to those of Magyar et al., who used hemicallostasis osteotomy (HCO),

a different technique of OWO, and reported HCO to be more precise than CWO in the

predicted postoperative tibial wedge angle 16. OWO might be more accurate because

only one bone cut is performed. The correction angle is than merely achieved by

placing the TCP wedge. With CWO one has to perform two bone cuts, which can

introduce more loss of accuracy. Bone loss as a result of performing the osteotomies

depends on the thickness of the saw blade and surgeon skills, and will be of influence

on the achieved correction angle. With CWO, a residue of the medial top of the bony

wedge can act as a hinge when the wedge is closed. The achieved correction will be

higher than planned in this case. These might be factors in explaining the overcorrection

we found with CWO. Furthermore, in this study the absolute values of the postoperative

correction angles are the mathematical results of RSA data calculated to rotational

displacement in the frontal, transverse and sagittal plane. As can be seen from

the wide ranges and rather high standard deviations it seems that the highly sensitive

RSA reveals the truth in the three dimensional obtained correction angles.

The achieved correction angles we found in both the OWO and CWO group in this

study will probably be sufficient in clinical practice. To be more specific informed about

the clinical significance of the difference between OWO and CWO, there is need for

further randomized clinical research, which we currently perform in a two centre study.

Osseous displacement, defined as rotation and translation of the bone segments

relative to each other, started immediately after axial load bearing albeit in relatively

small amounts. A linear correlation between load magnitude and osseous displacement

could be seen until just prior to failure. This indicates that the reconstruction is stable

until the moment of gross failure. The data of osseous displacement under the influence

of load bearing showed a relative large osseous displacement just before failure.

This would bias the regression analysis and therefore we decided not to include these

last data points in our regression analyses. The regression analyses of both groups

were compared and no significant difference was found between CWO and OWO

in rotation and translation in any direction. Hence, both methods provide for a stable

situation prior to failure. This leads to the conclusion that there is no significant

difference in initial stability between CWO and OWO.

The direction of failure was probably mainly influenced by the way the knees were

positioned in the MTS. The axial loading was along the axis of the femur and the tibia

was placed in valgus, therefore the axial loading made the tibia translate laterally.

This resulted in high compression forces on the lateral tibial plateau. In the OWO-knees

this also seemed to be the most vulnerable area and longitudinal split fractures occurred

just lateral of the tips of the proximal screws. In the CWO-knees the surgical implants

withstood most of the compression forces on the lateral aspect of the tibia resulting in

different failure patterns. In one case, the screw directly distal to the osteotomy was

pulled through the plate. Because of the dependence of the position in the MTS these

failure mechanisms might not be similar to clinical practice.

Failure did not occur beneath loading of two times bodyweight, indicating a good initial

stability of the reconstruction in both CWO and OWO. In clinical practice, the stability

will further increase with bone healing and ingrowth of the TCP wedge. Considering this,

initial (partial) weight bearing might be possible.

DEXA-scans were made to be informed about the BMD of all knees and to exclude

differences between paired knees. The DEXA-scan showed in all knees, except one,

Table 3

Length of osteotomy and calculated postoperative correction angles in

open wedge osteotomy using a 7 mm wedge

Knee length osteotomy (mm) tan-1(y/x )(degrees)

Ao 68 5.9

Bo 62 6.4

Co 58 6.9

Do 55 7.2

Eo 60 6.7

Mean ± SD 60.6 ± 4.9 6.6 ± 0.5

48

Chapter 3

49


a higher BMD in the lateral condyles than in the medial condyles. With DEXA-scan

measurements on condyles Akamatsu et al. reported higher BMD’s in condyles along

the mechanical axis of the leg 1. This corresponds to our findings, because we used

‘normal’ human cadaver knees and not knees with a varus deformity. We found no

significant correlation between BMD and the moment of failure (p=0.27). BMD does

not seem to be critical using this rigid locked plate fixation system. Based on the

results of this study we conclude that both methods gave an acceptable correction

with high variation of postoperative correction angles. There was a tendency of

overcorrection in the CWO group but no significant difference was found. We found no

difference in initial stability between CWO and OWO with a rigid locked plate fixation.

Although OWO seems to become more popular further clinical research has to be

performed to determine if it has major advantage over CWO or not.

References

1. Akamatsu Y, Koshino T, Saito T, Wada J (1997) Changes in osteosclerosis of the osteoarthritic knee

after high tibial osteotomy. Clin Orthop 334: 207-214

2. Aronson A S, Hoist L, Selvik G (1974) An instrument for insertion of radiopaque bone markers.

Radiology 113: 733-734

3. Billings A, Scott D F, Camargo M P, Hofmann A A (2000) High tibial osteotomy with a calibrated

osteotomy guide, rigid internal fixation, and early motion - Long-term follow-up.

J Bone Joint Surg Am 82A: 70-79

4. Closkey R F, Windsor R E (2001) Alterations in the patella after a high tibial or distal femoral

osteotomy. Clin Orthop 389: 51-56

5. Coventry M B, Ilstrup D M, Wallrichs S L (1993) Proximal tibial osteotomy. A critical long-term study

of eighty-seven cases. J Bone Joint Surg Am 75: 196-201

6. Fowler J L, Gie G A, MacEachern A G (1991) Upper tibial valgus osteotomy using a dynamic

external fixator. J Bone Joint Surg Br 73: 690-691

7. Hernigou P, Medevielle D, Debeyre J, Goutallier D (1987) Proximal tibial osteotomy for osteoarthritis

with varus deformity. A ten to thirteen-year follow-up study. J Bone Joint Surg Am 69: 332-354

8. Hernigou P, Ovadia H, Goutallier D(1992) Mathematical modeling of open wedge tibial osteotomy

and correction tables. Rev Chir Orthop Reparatrice Appar Mot 78: 258-263

9. Insall J N, Joseph D M, Msika C(1984) High tibial osteotomy for varus gonarthrosis. A long-term

follow-up study. J Bone Joint Surg Am 66: 1040-1048

10. Ivarsson I, Myrnerts R, Gillquist J (1990) High tibial osteotomy for medial osteoarthritis of the knee.

A 5 to 7 and 11 year follow-up. J Bone Joint Surg Br 72: 238-244

11. Kärrholm J (1989) Roentgen stereophotogrammetry: Review of orthopedic applications.

Acta Orthop Scand 60: 491-503

12. Kettelkamp D B, Wenger D R, Chao E Y, Thompson C (1976) Results of proximal tibial osteotomy.

The effects of tibiofemoral angle, stance-phase flexion-extension, and medial-plateau force.

J Bone Joint Surg Am 58: 952-960

13. Koshino T, Morii T Wada J et al.(1989) High tibial osteotomy with fixation by a blade plate for medial

compartment osteoarthritis of the knee. Orthop Clin North Am 20: 227-243

14. van Loon C J, de Waal Malefijt M C, Breemans E, Veth R P(1995) Complications of high tibial

osteotomy. Orthop Int Ed 3: 484-488

15. Lobenhoffer P, Simoni C D, Staubli A E (2002) Open-wedge high tibial osteotomy with rigid plate

fixation. Techn in Knee Surgery 2: 1-11

50

Chapter 3

16. Magyar G, Toksvig-Larsen S, Lindstrand A (1998) Open wedge tibial osteotomy by callus distraction

in gonarthrosis: Operative technique and early results in 36 patients. Acta Orthop Scand 69: 147-51

17. Maquet P (1976) Valgus osteotomy for osteoarthritis of the knee. Clin Orthop 120: 143-148

18. Odenbring S, Egund N, Hagstedt B et al. (1991) Ten-year results of tibial osteotomy for medial

gonarthrosis. The influence of overcorrection. Arch Orthop Trauma Surg 110: 103-108

19. Sprenger T R, Doerzbacher J F (2003) Tibial osteotomy for the treatment of varus gonarthrosis.

Survival and failure analysis to twenty-two years. J Bone Joint Surg Am 85A: 469-474

chapter 4Correction accuracy and collateral laxity in

open versus closed wedge high tibial osteotomy

a one year randomized controlled study

R.D.A. Gaasbeek, L. Nicolaas, W.J. Rijnberg, C.J.M. van Loon, A. van Kampen

Submitted J Bone Joint Surg Br

52

Chapter 4

53

Correction accuracy and collateral laxity in open versus closed wedge high tibial osteotomyA one year randomized controlled study

Abstract

In a randomized clinical trial in 50 patients with symptomatic osteoarthritis of the

medial compartment of the knee, the clinical results of high tibial osteotomy (HTO)

according to the open wedge osteotomy (OWO) and closed wedge osteotomy (CWO)

were compared. In both groups angle stable plate fixation was used.

Clinical and radiological assessments were performed preoperative and after one year.

Postoperative hip-knee-ankle (HKA) correction angles were monitored on standing

leg X-rays. The effect of HTO on collateral laxity of the knee was measured with a

specially designed varus-valgus device. The WOMAC osteoarthritis index, the modified

knee society score (KS) and visual analogue scales (VAS) were used to assess

symptoms of osteoarthritis, function, pain and patient satisfaction.

At one year follow-up we found accurate corrections in both groups and the planned

correction angles were achieved. No loss of correction was observed. Furthermore,

the medial collateral laxity and the patellar height significantly decreased after OWO.

Significant improvements of WOMAC and KS scores were found in both groups.

All patients had significantly less pain and were significantly satisfied with the results.

Surgery time was significant longer in the CWO group, and complications were more

frequent in this group. Both techniques led to good and comparable clinical results.

The choice whether to perform an open or a closed wedge osteotomy may be based

on preoperative patellar height or concomitant collateral laxity.

Introduction

Young active patients with medial compartment osteoarthritis of the knee combined

with a varus deformity can be treated with a valgus high tibial osteotomy 1,2-4,5.

High tibial osteotomy (HTO) is performed to stop or inhibit progression of osteoarthritis

and to avoid or postpone total knee arthroplasty. In order to unload the medial

compartment, a valgus producing correction is applied by performing either a closed

wedge osteotomy (CWO), or an open wedge osteotomy (OWO). OWO is a relatively

new technique and is less involving in terms of surgical technique than CWO: only one

tibial cut needs to be made, and osteotomy of the fibula is not necessary 6.

In recent years, with the introduction of new rigid locked implants in combination with

new bone-substituting biomaterials, OWO has become more popular than CWO,

avoiding co-morbidity associated with the fibular osteotomy. Hypothetically OWO is

more accurate than CWO. However, in terms of clinical outcome these possible

advantages have not yet been thoroughly investigated in well conducted randomized

studies. Furthermore, positioning the osteotomy proximal to the tibial tuberosity and the

insertion of the medial and lateral collateral ligament will lead to potential changes in

patellar height and collateral laxity. Previous studies which compared CWO and OWO

in patients do not answer important clinical questions in terms of outcome, safety and

ligamentous stability 7-9.

The aim of the current study was to compare OWO and CWO with angle stable plate

fixation, regarding the accuracy of achievement of the planned correction, the influence

on collateral laxity and patellar height and the clinical outcome in a randomised

prospective study.

Methods and materials

Patients

Fifty consecutive patients, suffering from medial compartment osteoarthritis of the knee

were included in the study. Between January 2003 and March 2005 they visited the

Orthopaedic outpatient clinics of the Rijnstate Hospital in Arnhem or the University

Medical Centre Saint Radboud in Nijmegen, in the Netherlands. Included were active

54

Chapter 4

55


patients between 18 and 70 years of age, suffering from medial osteoarthritis of the

knee with a hip-knee-ankle (HKA) varus alignment. Patients with rheumatoid arthritis or

previous osteotomy of the same knee were excluded from this study. All patients gave

their informed consent. Approval of the local Medical Ethics Committee was obtained.

Patients were randomized for their treatment according to a sealed envelopes procedure.

Primary outcome measures

Achievement of the planned correction angle of an over-correction of 4º of the

mechanical femur-tibial axis was measured on standing whole leg radiographs.

HKA angles were measured by one observer (RG). Medial and lateral collateral laxity of

the knee was measured pre- and post-operatively at one year follow-up and quantified

using a varus/valgus testing device 10. This device consisted of a base plate with a

support in which the knee could be fixed in 20º of flexion in a standardised fashion.

The foot was fixed in a mobile shoe with an attached pointer. The varus and valgus

laxity was measured by putting a load of 50 N on the leg which produced a varus or

valgus force on the knee which was quantified on a scale on the base plate (Fig 1).

Previously the intra- and inter observer reliabilities of this device were determined and

showed acceptable intra class correlation coefficients: ICC= 0.78; 95%CI=0.75-0.79

and ICC= 0.71; 95% CI= 0.69- 0.72, respectively.

Secundary outcome measures

Symptoms of osteoarthritis were assessed by the Western Ontario and McMaster

Universities (WOMAC) osteoarthritis index. A higher WOMAC score represents worse

symptom severity, with 96 points being the worst possible total score. Function was

determined using the modified Knee Society score (KS) which assesses pain, range

of movement, stability and the ability to walk and climb stairs with 200 points maximum

representing the best possible function 11;12. Pain intensity and patient-satisfaction

were scored with a 0-10 Visual Analogue Scale (VAS). A high VASknee pain score

represents more pain, whereas a low VASsatisfaction score reveals an unsatisfactory

situation for the patient.

Patellar height according to Caton’s Index (CI) was measured by one observer (RG) on

true lateral radiographic views in 30º of flexion. Furthermore, surgery time, duration of

hospital stay and complications were recorded.

Operation techniques

Closed wedge osteotomy (Fig. 2)

A standard anterolateral approach was used. An osteotomy and resection was performed

through the fibular head. Two centimetres below and parallel to the joint line a Kirschner

wire was inserted to aim the osteotomy. First, the proximal cut was performed and the

medial cortex was preserved. Using an aiming device the distal cut was made and the

bone wedge was removed. The aiming device we used consists of a blade which is

put in the first saw cut. The second cut is performed through a cleft in the device with

an adjustable angle to the blade. The defect was closed and the osteotomy was fixed

with a four hole angle stable plate (Numélock II system, Stryker, Switzerland).

Figure 1

Measuring the medial

and lateral laxity of

the knee with the varus-

valgus device.

56

Chapter 4

57


Open wedge osteotomy (Fig. 3)

A medial approach was performed, shifting the pes anserinus and the superficial

medial collateral ligament dorsally. A Kirschner wire was inserted parallel to the

joint line. Using a guide instrument a second wire was inserted just proximal of the

tuberosity in lateral cranial direction in order to obtain an equal osteotomy angle in all

knees. Along this wire the osteotomy was performed. The lateral cortex was left intact.

The gap was opened gradually and the preoperatively calculated correction angle was

checked with a measuring device. After this height of the medial gap was measured

and the appropriate resorbable tricalcium phosphate (TCP) wedge (Otis, Lourdes,

France) was inserted. Internal fixation was performed using a four hole angle stable

plate (Numélock II system, Stryker, Switzerland).

All surgery was performed under fluoroscopic guidance. All patients received antibiotic

prophylaxis preoperatively and postoperative antithrombotic therapy during six weeks.

Postoperative management was equal for both groups. Mobilisation started the first post-

operative day with partial weight bearing and full range of motion exercises for six weeks.

Statistical analysis

A multivariable linear regression method was used to analyze the effect of OWO versus

CWO on HKA angles, WOMAC, KS and VAS scores, CI, medial and lateral collateral

laxity of the knee and complication rate. Age, gender, BMI, baseline values for the HKA

angle were considered as possible confounders and included in the regression model.

For statistical analysis the SPSS program was used and p<0.05 was considered

statistically significant.

Table 1 Baseline parameters

Open wedge osteotomy Closed wedge osteotomy Total group (n=25) (n=25) (n=50)

Male/female 14/11 16/9 30/20

Age (yrs) mean (SD) 47.0 (8.5) 49.8 (7.4) 48.4 (8.0)

BMI (kg/m2) mean (SD) 29.7 (4.2) 28.4 (2.9) 29.0 (3.7)

HKA varus angle(°) mean (SD) 4.3(2.2) 4.1 (2.1) 4.1 (2.4)

WOMAC (0-96) mean (SD) 51.9 (18.5) 46.5 (14.9) 49.2 (16.9)

KS (0-200) mean (SD) 111.7 (24.1) 113.6 (15.9) 112.6 (20.2)

VAS knee pain (0-10) mean (SD) 6.6 (1.7) 6.4 (1.3) 6.5 (1.5)

VAS satisfaction (0-10) 2.3 (1.8) 2.8 (1.8) 2.6 (1.8)

Medial laxity (°) mean (SD) 5.5 (1.8) 5.4 (1.2) 5.5 (1.5)

Lateral laxity (°) mean (SD) 5.2 (1.1) 5.2 (1.3) 5.2 (1.2)

Caton Index 1.0 (0.2) 1.0 (0.2) 1.0 (0.2)

Figure 2

An example of the closed

wedge high tibial osteotomy

(CWO)

Figure 3

An example of the open

wedge high tibial osteotomy

(OWO)

58

Chapter 4

59


Results

No patients were lost to follow-up. 36 patients were treated in Arnhem (19 CWO and

17 OWO) and 14 patients were treated in Nijmegen (6 CWO and 8 OWO).

Table 1 shows all baseline parameters of the total study population and of each of

the treatment groups separately. In total, the group of patients consisted of 20 women

and 30 men, with an mean age of 48.4 (SD 8.0) years and a mean HKA angle of 4.1°

varus (SD 2.4). The mean BMI was 29.0 kg/m2 (SD 3.7).

Preoperatively the mean WOMAC score was 49.2 (SD 16.9) and the mean KS score

was 112.6 (SD 20.2). Furthermore, the mean VASknee pain score was 6.5 (SD 1.5) and the

mean VASsatisfaction was 2.6 (SD 1.8) before surgery. The mean medial and lateral laxity of

the knee was 5.5º (SD 1.5) and 5,2º (SD 1.2) respectively. The mean Caton Index was

1.0 (SD 0.2).

There were no statistical differences between the groups.

Primary outcome measures

Table 2 presents the results at 1- year follow-up. We found no difference between OWO

and CWO in the achieved postoperative correction angles. The mean postoperative

HKA angle was 3.8º valgus (SD 2.2) in the OWO group, and 4.4º valgus (SD 2.7) in the

CWO group (p=0.474).

The OWO group showed a mean postoperative reduction of the mean medial collateral

knee laxity to 4.5º (SD 1.5) versus 5.3º (SD 1.2) in the CWO group. This difference was

significant (p=0.041). The mean lateral collateral laxity did not change significantly:

5.3º (SD 1.1) after OWO and 5.5º (SD 1.0) after CWO (p=0.505).

Secundary outcome measures

The results are presented in table 2. The WOMAC and KS scores showed equal

effects between the groups. The mean WOMAC score decreased to 20.0 (SD 19.4)

and 16.0 (SD 15.0) after OWO respectively CWO. The mean KS score increased to

176.6 (SD 23.4) in the OWO group and 180.2 (SD 22.2) in the CWO group.

The mean VASknee pain decreased in both groups: 2.5 (SD 1.9) after OWO and 1.8

(SD 1.5) after CWO. In both groups the patients were content with the result after one

year. The mean VASsatisfaction increased to 7.8 (SD 1.8) in the OWO group and 8.7

(SD 1.4) in the CWO group. There were no significant differences between the groups.

The patellar height significantly decreased after OWO. The small increase of patellar

height following CWO was not significant. The mean CI after OWO was 0.86 (SD 0.14)

and after CWO it was 1.04 (SD 0.17). This difference was significant (p<0.001).

The mean surgery time of 54.8 min (SD 10.8) in the OWO group was significantly

shorter than the mean surgery time for the CWO of 68.0 min (SD 22.2) (p=0.010).

No difference was detected for the mean hospital stay, with 3.4 days (SD 1.8) for

the OWO group and 3.9 days (SD 1.5).

Table 2 Results at one-year follow-up

Primary outcomes

HKA valgus angle(°) mean (SD) 3.8 (2.2) 4.4 (2.7) 0.6 -0.82; 1.93 0.420

Medial laxity (°) mean (SD) 4.5 (1.5) 5.3 (1.2) 0.8 0.09;0.27 0.041*

Lateral laxity (°) mean (SD) 5.3 (1.1) 5.5 (1.0) 0.2 -0.39;0.78 0.505

Secondary outcomes

WOMAC (0-96) mean (SD) 20.0 (19.4) 16.0 (15.0) 4.0 -13.85;5.85 0.418

KS (0-200) mean (SD) 176.6 (23.4) 180.2 (22.2) 3.6 -9.36;16.56 0.579

VAS (0-10) knee pain mean (SD) 2.5 (1.9) 1.8 (1.5) 0.6 -1..60;0.38 0.221

VAS (0-10) satisfaction 7.8 (1.8) 8.7 (1.4) 0.9 -0.07; 1.78 0.07

Caton Index 0.86 (0.14) 1.04 (0.17) 0.18 0.09;0.27 <0.001*

Surgery time (min) 54.8 (10.8) 68.0 (22.2) 13.2 3.27;23.12 0.010*

Hospital stay (days) 3.4 (1.8)) 3.9 (1.5) 0.5 -0.46;1.42 0.311

*significant p-value

Open wedge

osteoto

my

mean (S

D) (n=

25)

Close

d wedge

osteoto

my

mean (S

D) (n=

25)

Mean d

iffere

nce

95% c

onfidence

inte

rval

p-valu

e

60

Chapter 4

61


Complications during follow-up (Table 3)

All patients reported a local hypoesthesia on the lateral side of the lower leg as a result

of cutting branches of the infra-patellar nerve. These findings were equal for both the

OWO and CWO group. One patient in the CWO group suffered a temporary peroneal

nerve neuropathy. In the CWO group one case of deep venous thrombosis was

presented. One deep wound infection was treated in the CWO group and healed after

surgical lavage and antibiotics. In this group, two superficial wound infections were

successfully treated with antibiotics.

In the OWO group, one superficial wound infect was treated with antibiotics.

Because of pain the osteosynthesis material was removed in 2 patients in the OWO

group and in 1 patient in the CWO group.

Discussion

The purpose of this study was to compare the OWO and the CWO in a randomized

clinical setting. Randomized clinical research in this field is very limited. At the time of

design of this study, two randomized trials concerning OWO versus CWO had been

published by Magyar et al 13;14. However, neither of these studies is directly comparable

to the current project, since in both studies the OWO was performed by the

hemicallotasis technique (HCO) and the CWO was fixated with staples. They found

significant loss of correction in the CWO group and a significantly more stable fixation

with HCO. Furthermore, they found more complications in the HCO group, mainly

pin-track infections. The clinical scores were improved in both groups with no

significant difference between the groups. Hospital stay of the HCO group was

significantly shorter.

Adili et al. performed a case controlled study of HTO with the Ilizarov external fixator

versus the Coventry-type CWO. The found significantly better WOMAC scores but also

more complications in the Ilizarov group 15.

Nakamura et al. compared the HCO to the dome osteotomy (DMO) in a randomized

clinical trial. The HCO group had significantly less changes in patellar height and tibial

slope. The femur-tibia angles were not significantly different 16.

Recently, Brouwer et al. performed a prospective randomised trial in 92 patients.

At one year follow-up they concluded that CWO achieved a more accurate correction

and that both OWO and CWO reduce pain and improve function. A relevant difference

to our study is the fact that they used a non-stable implant (Puddu, Arthrex, Naples

Florida, USA) in the OWO and staples in the CWO group. Furthermore, a plaster cast

was part of the after-treatment 17.

Hoell et al. presented the clinical results of open versus closed wedge HTO techniques

in a retrospective study in 108 patients 18. They analysed the results and outcome of

OWO with a Puddu plate versus a Coventry-type CWO with staples. They observed no

differences in outcome between the two methods. Both groups showed a significant

improvement of clinical scores. Drawback of this study was the non-randomized

setting. Furthermore, the statistical analysis was not transparently reported.

Rudan and Simurda 19 found in their study that optimal clinical results were associated

with a correction of the femur-tibial angle between 6° and 14° . Under-correction was

associated with a high failure rate. Over-correction to a femur-tibial angle larger than

15° appeared to have an even better clinical outcome, but these results were

cosmetically unappealing to the patients. Other authors also recommend over-

correction of the femur-tibial angle 20;21. Hernigou on the contrary found that an

overcorrection of more than 6° is associated with progressive degeneration of the

lateral compartment and a under-correction is associated with poorer result and

reappearance of the medial compartment osteoarthritis 22. A previous cadaveric RSA

Table 3 Complications during follow-up

Open wedge osteotomy Closed wedge osteotomy (n=25) (n=25)

Peroneal nerve neuropathy 1

Deep venous thrombosis 1

Deep wound infection 1

superficial wound infections 1 2

removal of osteosynthesis material 2 1

62

Chapter 4

63


study showed that both CWO and OWO gave an acceptable correction with a high

variation of postoperative correction angles. This study showed a tendency of

overcorrection in the CWO group and no difference in initial stability between CWO

and OWO with a rigid locked-plate fixation 23.

In the present clinical trial the aim was a HKA valgus angle of 4°. We found a post-

operative angle of 3.8° (SD 2.2, range 1.0-10.6) in the OWO group and 4.3° (SD 2.7,

range 1.0-12.0) in the CWO group. We observed no loss of correction after one year

follow-up. Thus, we conclude that both techniques led to an accurate and reliable

correction with the angle stable plate fixation.

In varus osteoarthritis of the knee, often a pseudo medial hyperlaxity is observed due

to the loss of medial joint space. Because the osteotomy is located proximally to the

superficial medial collateral ligament, opening the osteotomy will (re-)tighten the medial

structures. Hoell et al. investigated the influence of HTO on the medial and lateral

collateral stability. After OWO they found a shift from second degree (5-10mm) and

third degree(>10mm) to first degree (<5mm) medial instability. In their study, the level

of instability was determined by physical examination, which is not very objective 24.

We observed a significant decrease in medial collateral laxity of the knee after OWO.

The lateral and medial collateral laxity was measured with a special developed device

which enables objective reliable and reproducible varus and valgus measurements 25.

If the medial collateral ligament is tensioned excessively, e.g. in large corrections, the

pressure in the medial joint compartment may increase. To prevent this and to obtain

the desired correction the superficial medial collateral ligament should be partially

released to allow for proper opening of the osteotomy.

OWO proximal to the tibial tuberosity has been reported to cause patella baja 26,27;28.

CWO has been shown to lead to both patella baja and alta. These alterations in patellar

height have been attributed to the proximalisation (CWO) or distalisation (OWO) of the

tibial tuberosity following HTO. Furthermore, scarring, adhesions and contracture of the

patella ligament are mentioned to cause lowering of the patella in CWO 29. As expected,

we observed that the mean patellar height significantly decreased in the OWO group.

We saw no significant change in patellar height after CWO. We advice to perform a

distal tuberosity osteotomy to prevent distalisation of the tibial tuberosity with OWO in

large corrections or in case of preexistent patella baja 30.

To our knowledge, the present study is the first randomized clinical trial comparing

OWO and CWO using rigid angle stable implants and the same functional

postoperative treatment protocol in both groups. At one year follow-up we found

significant improvements of WOMAC and KS scores in both groups. Furthermore,

all patients had significantly less pain and were significantly satisfied with the treatment.

There were no differences in outcome between the groups. The medial collateral laxity

and the patellar height significantly decreased after OWO.

The authors are aware that the present study concerns only a short term follow-up.

Longer follow-up is essential to obtain information about the ongoing clinical results in

both groups. Nevertheless, this study has shown that both osteotomy techniques

led to good and comparable clinical results. Surgery time was significant longer in

the CWO group, and complications were more frequent in this group. In large OWO

corrections, the tightening of the medial collateral ligament and lowering of the patella

should be addressed by the surgeon. Along with the fact that the OWO procedure is

less demanding and that it offers the surgeon more opportunities to vary the amount of

valgus and slope correction intraoperatively, the authors prefer the OWO in their clinical

practices. In this study OWO has showed comparable results to CWO and it was a safe

and reproducible technique. Furthermore, the osteotomy of the fibula along with its

rather high co-morbidity of pain, pseudoarthrosis and peroneal nerve palsy, is not

necessary with OWO. Especially in teaching hospitals, this technique seems to be

more predictable for correcting varus deformities of the knee.

64

Chapter 4

65


Reference List

1. Aglietti P, Buzzi R, Vena LM, Baldini A, Mondaini A. High tibial valgus osteotomy for medial

gonarthrosis: a 10- to 21-year study. J Knee Surg 2003;16:21-26.

2. Amendola A. Unicompartmental osteoarthritis in the active patient: the role of high tibial osteotomy.

Arthroscopy 2003;19 Suppl 1:109-116.

3. Choi HR, Hasegawa Y, Kondo S, Shimizu T, Ida K, Iwata H. High tibial osteotomy for varus

gonarthrosis: a 10- to 24-year follow-up study. J Orthop Sci 2001;6:493-497.



5. Odenbring S, Egund N, Hagstedt B, Larsson J, Lindstrand A, Toksvig-Larsen S. Ten-year results of

tibial osteotomy for medial gonarthrosis. The influence of overcorrection.

Arch Orthop Trauma Surg 1991;110:103-108.





8. Magyar G, Ahl TL, Vibe P, Toksvig-Larsen S, Lindstrand A. Open-wedge osteotomy by

hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of

50 operations. J Bone Joint Surg Br 1999;81:444-448.




10. Rasenberg EI, Lemmens JA, van Kampen A et al. Grading medial collateral ligament injury:

comparison of MR imaging and instrumented valgus-varus laxity test-device. A prospective

double-blind patient study. Eur J Radiol 1995;21:18-24.

11. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC:

a health status instrument for measuring clinically important patient relevant outcomes to

antirheumatic drug therapy in patients with osteoarthritis of the hip or knee.

J Rheumatol 1988;15:1833-1840.

12. Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system.

Clin Orthop Relat Res 1989;13-14.

13. Magyar G, Ahl TL, Vibe P, Toksvig-Larsen S, Lindstrand A. Open-wedge osteotomy by

hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of

50 operations. J Bone Joint Surg Br 1999;81:444-448.

14. Magyar G, Toksvig LS, Lindstrand A. Changes in osseous correction after proximal tibial

osteotomy - Radiostereometry of closed- and open-wedge osteotomy in 33 patients.

Acta Orthop Scand 1999;70:473-477.

15. Adili A, Bhandari M, Giffin R, Whately C, Kwok DC. Valgus high tibial osteotomy. Comparison

between an Ilizarov and a Coventry wedge technique for the treatment of medial compartment

osteoarthritis of the knee. Knee Surg Sports Traumatol Arthrosc 2002;10:169-176.

16. Nakamura E, Mizuta H, Kudo S, Takagi K, Sakamoto K. Open-wedge osteotomy of the proximal

tibia hemicallotasis. J Bone Joint Surg Br 2001;83:1111-1115.

17. Brouwer RW, Bierma-Zeinstra SM, van Raaij TM, Verhaar JA. Osteotomy for medial compartment

arthritis of the knee using a closing wedge or an opening wedge controlled by a Puddu plate:

a one-year randomised, controlled study. J Bone Joint Surg Br 2006;88:1454-1459.



19. Rudan JF, Simurda MA. High tibial osteotomy. A prospective clinical and roentgenographic review.




21. Kettelkamp DB, Wenger DR, Chao EY, Thompson C. Results of proximal tibial osteotomy.

The effects of tibiofemoral angle, stance-phase flexion-extension, and medial-plateau force.




23. Gaasbeek RD, Welsing RT, Verdonschot N, Rijnberg WJ, van Loon CJ, van Kampen A. Accuracy

and initial stability of open- and closed-wedge high tibial osteotomy: a cadaveric RSA study.

Knee Surg Sports Traumatol Arthrosc 2005;Nov;13(8):689-694.



25. Rasenberg EI, Lemmens JA, van Kampen A et al. Grading medial collateral ligament injury:

comparison of MR imaging and instrumented valgus-varus laxity test-device. A prospective

double-blind patient study. Eur J Radiol 1995;21:18-24.




27. Kesmezacar H, Erginer R, Ogut T, Seyahi A, Babacan M, Tenekecioglu Y. Evaluation of patellar height

and measurement methods after valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2005.

66

Chapter 4





30. Gaasbeek RD, Sonneveld H, van Heerwaarden RJ, Jacobs WC, Wymenga AB. Distal tuberosity

osteotomy in open wedge high tibial osteotomy can prevent patella infera: a new technique.

Knee 2004;11:457-461.

chapter 5Mechanism of bone incorporation of

ß-TCP bone substitute in open wedge tibial

osteotomy in patients

Robert DA Gaasbeek, Hanneke G Toonen, Ronald J van Heerwaarden, Pieter Buma

Biomaterials. 2005 Nov;26(33):6713-9

68

Chapter 5

69

Mechanism of bone incorporation of ß-TCP bone substitute in open wedge tibial osteotomy in patients

Abstract

A histological study was performed of bone biopsies from 16 patients (17 biopsies)

treated with open wedge high tibial osteotomies for medial knee osteoarthritis.

The open wedge osteotomies were filled with a wedge of osteoconductive beta

tricalcium phosphate (ß-TCP) ceramic bone replacement. At the time of removal of

the fixation material, core biopsies of the area where the ß-TCP was located were

taken at different follow-up periods (6 to 25 months). ß-TCP resorption, bone ingrowth

and bone remodelling were studied. We hypothesized that the incorporation and

remodelling process occurs similarly as in animals.

Histology showed a good resorption of the ß-TCP with complete incorporation

and remodelling into new bone. The different phases as described in animal studies

were found. A correlation was found between histological findings and radiological

assessment.

In conclusion, ß-TCP appeared to be a bone replacement material with optimal

biocompatibility, resorption characteristics and bone conduction properties for

the clinical use.

Introduction

A valgus high tibial osteotomy (HTO) is the treatment of choice for medial knee

osteoarthritis and may be performed with a lateral closing wedge or a medial open

wedge technique 1-10. In case of a medial open wedge osteotomy, the bone gap

created during the osteotomy can be left open, or filled with autograft or allografts.

Furthermore, nonresorbable or resorbable bone substitutes can be used 1;11-15.

Autograft bone is generally considered to be the most successful bone filling material

because of its osteoconductive, osteoinductive and osteogenic properties 16-19.

Drawbacks of autograft use are increase of operation time and co-morbidity following

the bone harvesting at the iliac crest. Allografts entail the risk of virus transfer or may be

less potent to stimulate new bone formation. To encounter these problems, synthetic

bone substitutes have become more popular in the last twenty years 16;18;20.

Because of their synthetic origin, these materials cannot cause disease transmission.

It has been suggested that bone substitutes can accelerate bone growth and bone

remodelling which may lead to earlier full weight-bearing after open wedge HTO 11;17-20.

Particularly porous beta tricalcium phosphate (ß-TCP) is a very promising osteo-

conductive, ceramic bone substitute. ß-TCP has slightly different ratios of calcium

and phosphate than bone, but, in essence, the material properties are much like

the inorganic phase of bone, which constitutes 60% to 70% of human bone 18;20.

The macro-porosity of the material facilitates bone ingrowth. The resorption

characteristics depend on the mineral composition and the degree of sintering as

well as the porous structure 18;20-22. In animal studies tricalcium phosphates have

shown favourable biocompatibility, osteoconduction and resorption properties.

It appeared that the ß-TCP gradually resorbs and in the end is completely replaced

by remodelled bone 11;16-21;23-28.

The resorption of ß-TCP and its conversion into bone takes place in different phases.

In the first phase, there is some resorption of host bone, followed by apposition of

new bone on the TCP scaffold. During this phase the appearance on X-rays is that

of dense bone. In the following phase, there is further resorption of the ß-TCP and

remodelling of the bone and the density on X-rays decreases 11;17.

70

Chapter 5

71


In patients, the incorporation was until recently assessed with standard radiographic

examination. However, it is not easy to classify bone healing and distinct between

bone and the remaining synthetic calcium phosphates on radiographs alone 16.

Based on an expected similarity of X-rays of patients with that of animals, a more

refined radiological classification system was proposed to monitor bone healing in

open wedge HTO with resorbable substitutes 11. In this classification system

(see materials and methods for details) five distinct phases can be discriminated.

So far it is not known if the resorption of ß-TCP and its conversion into bone occurs in

a similar way as in animals, but based on the similarity in x-rays we hypothesize that in

patients the same sequence of events takes place during the incorporation of the

ß-TCP scaffold as in animals. However, the only method to confirm this is histology.

This study concerns a radiological and histological follow-up examination of 16 patients

with medial osteoarthritis of the knee treated with medial open wedge high tibial osteo-

tomies (in one patient a bilateral procedure). The gap was filled with a wedge of ß-TCP.

At the time of the plate removal, a biopsy was taken through the implant site, which was

processed for histology. The process of incorporation is described and quantitative

measurements of ß-TCP resorption and new bone formation were carried out.

The histology was correlated with the radiological classification of bone healing and

related to the time frame between osteotomy and plate removal.


In 16 patients (17 procedures: mean age at the time of taking the biopsy 43.6 ± 9.5 yrs),

with a medial uni-compartmental knee osteoarthritis, the open wedge osteotomy was

filled with a wedge of porous ß-TCP (Ca3(PO4)2 with 70% interconnected macropores

with a size of 100-500 µm (Fig. 1a) and micropores of 1 – 10 µm (chronOS™, Synthes

Biomaterials, Switzerland). One patient was operated on bilaterally. Preoperatively the

degree of correction was determined on a standing long-leg film. The mean knee

varus angle was 4.9 (SD ± 2.37) with a range between 2 and 11 degrees. The aim was

a correction to 3 degrees valgus creating medially based bone gaps between 5 and

14 mm. To preserve the correction, the osteotomy was fixed with a rigid angle stable

plate (TomoFix, Synthes). Postoperatively the patients were allowed partial weight

bearing of 10-15 kg for 6 weeks. Conventional AP and lateral radiographs were made

immediately after the operation, at six weeks, three months, six months, and at one

year postoperatively. The last X-ray before the removal of the fixation material was used

for the radiological classification of bone healing.

A radiological classification system to monitor bone healing in open wedge HTO with

resorbable substitutes was used 11. In Phase 0 of this classification (Table 1) no

remodelling takes place. In phase 1 there is a slight porosis of the bone. In phase 2

the ß-TCP is denser and the interface between ß-TCP and bone is blurred. In phase 3

the osteotomy is healed. In phase 4 the ß-TCP is not longer recognizable as distinct

entity, and in phase 5 the bone is normal again (complete remodelling).

Bone healing was studied histologically from bone biopsies taken during plate and

screws removal between 6 and 25 months postoperatively (mean 14.7 ± 5.82 months).

At that time, a core biopsy was taken from the medial 1/4 part of the bone region where

the ß-TCP was implanted (Fig. 1b). The biopsy was long enough to contain both sides

of the host bone. Serial non-decalcified sections along the long axis of all biopsies

were made, which were stained with HE and Goldner. A TRAP-staining was applied for

the visualization of osteoclasts. Two biopsies could not be analysed with TRAP-staining

Figure 1

A. b-TCP wedge. B. Location of biopsy.

72

Chapter 5

73


since they were broken after taking the biopsy or not processed according to the

standard protocol. In all remaining biopsies the surface area of fibrous tissue, active

incorporation (fibrous invasion of the ß-TCP with osteoclast and osteoblast activity) and

that of newly formed trabecular bone that still contained some ß-TCP remnants at the

location of the original ß-TCP material, were estimated by two observers (HGT, PB).

In areas with new bone formation the surface area of the remaining ß-TCP and of bone

was quantified with an automated image analysis system (AnalySIS) and expressed as

percentage of the total region of interest.

Results

There were no complications during surgery or directly postoperative. Also, the

clinical healing process was without complications in all cases (i.e. normal time until

full weightbearing, no infection or non-union). Radiological follow-up showed

complete consolidation at 12 months in all cases (Fig. 2). According to the radiological

classification system all unions were classified as phase 4 or 5.

In 13 of 17 biopsy specimens, the original ß-TCP was still visible in the biopsies

(Fig. 3b, c). It had a granular appearance and in HE sections pink stained material

inside the ß-TCP indicated that material (fibrin or proteins) had penetrated into the

micropores of the ceramic (Fig.3b, c). Also small remnant areas of totally in bone

incorporated ß-TCP were present. In 6 of these 13 biopsies an also relatively larger

area of the original ß-TCP material was still present in the sections. In these biopsies

active incorporation of the ß-TCP was present. In 4 biopsies only totally remodelled

bone was found without any remnants of ß-TCP.

Particularly in the six biopsies with larger ß-TCP areas, different stages of incorporation

could be found. In the middle of the wedge, occasionally non-incorporated ß-TCP with

vascular fibrous tissue was found. More towards the osteotomy planes, the first bone

formation was found as lamellar bone apposition onto the surface of macropores in the

ß-TCP blocks (Fig. 3c). At the same locations, small mononuclear cells were found in

the pores between the ß-TCP that did not stain for TRAP (Fig. 3b). These cells were

Figure 2

Bone remodelling at different follow-up times after open wedge osteotomy filled with TCP.

A. at 6 weeks, B. at 3 months, C. at 6 months, D. at 12 months. (Adapted from van Hemert

et al. 11, with permission).

Figure 3

A. Thin section of ß-CP

material before

implantation. B. HE section

of first stage of incorpora-

tion. Fibrous tissue (FT)

has invaded the macro-

pores in the TCP blocks

and mononuclear cells

have penetrated into the

micropores of the TCP

(arrows). C. New lamellar

bone formation in macro-

pores of TCP. D. Pores of

TCP completely filled with

new bone (NB). Scale bar:

250 µm.

250 µm 250 µm

250 µm 250 µm

74

Chapter 5

75


always associated with red or dark green material in-between the ß-TCP granules in the

goldner sections. Apparently these mononuclear cells were osteoblasts that start to

produce osteoid that subsequently mineralises the micropores in the ß-TCP material.

Occasionally, in the same locations, multinuclear TRAP positive osteoclasts penetrated

into the micropores around the ß-TCP granules and start to resorb the ß-TCP (Fig. 4a, b).

More close to the osteotomy side more bone apposition in the pores is found.

Occasionally the pores are completely filled with bone (Fig 3d). Locally abundant

osteoclast activity is present dissolving the ß-TCP remnants by surface erosion

(Fig. 4c, d). The end result of this process is normal looking bone with only sparse

remnants of ß-TCP that are completely incorporated into new vital bone (Fig. 4 e, f).

No macrophages or giant cells were found during or after the incorporation of the ß-TCP.

The mean surface area of active incorporation was 8.53% (± 12.0%) in all specimens.

The surface area of normal looking bone, which contained occasionally only sparse

remnants of ß-TCP was 77.1% (± 21.1%) of the total area of the biopsy. The remaining

tissue is fibrous tissue (13.8% ± 24.1). This means that more then 80% of the surface

area of all biopsies consisted of bone or active incorporating bone. The surface area of

remaining ß-TCP in the regions with incorporated bone was 1.20% (SD 1.98) of the total

measured area. The surface area of bone in the bone region was 22.2% ± 11.6 which

is similar to normal human bone.

Discussion

The most important aim of this study was to compare the incorporation process in

patients with that in animals. Particularly the assessment of bone substitute incorporation

is very difficult on radiographs alone since the distinction between new bone and

biomaterial cannot be made. Therefore histology is the ultimate proof for incorporation

of bone graft replacement materials. As far as we know this is the first report on the

detailed description of the incorporation of ß-TCP in patients. Optimally, evaluation of

biopsy specimens on several time points is necessary to give more insight in the

completeness of bone remodelling, the type of incorporation process and the speed

of biomaterial resorption and incorporation. In the patient population of the present

study biopsies could only be taken after healing of the osteotomy.

In various animal studies in which the incorporation of ß-TCP was studied, it was

described that the resorption of ß-TCP and conversion into bone took place in a

number of distinct phases 16;20. Initially there is some resorption of host bone,

probably due to the surgical trauma. This phase is followed by a phase in which

apposition of bone occurs and the total density of bone plus ß-TCP on X-rays is high.

After about six months, resorption and remodelling of the ß-TCP and new bone takes

place, which decreases the total density again.

Although the biopsies were taken at considerable follow up periods, different aspects

of the incorporation process were found, although not in every specimen. Apparently

the incorporation of the inserted wedge takes a variable and in some cases considerable

time. The variation may be related to patient related variables (e.g. age, smoker or not

smoker), the thickness of the biopsy and differences in local environment (vascularity,

loading). As the first biopsies in this study have only been obtained six months after the

osteotomy, the local variation in incorporation enabled us to study also the first phases

of incorporation.

Figure 4

A. and B. HE (A) and

adjacent TRAP section of

multinuclear osteocalst

penetrating into the TCP.

C. and D. HE (C) and

TRAP (D) section of

surface erosion of TCP by

osteoclasts. E. and F.

HE and Goldner stained

section of remnants of

TCP incorporated into new

bone. Scale bar: 125 µm.

125 µm 125 µm

125 µm 125 µm

125 µm 125 µm

76

Chapter 5

77


Firstly there is invasion of fibro-vascular tissue in the large pores of the ß-TCP. Probably

simultaneous to this, there is preferential resorption of the necks linking the ß-TCP

microparticles. This might be caused by a process of chemical dissolution as suggested

by Zerbo et al.29. Next, bone apposition occurs on the inner surface of the large pores

in the ß-TCP. Simultaneously mononuclear osteoblast like cells start to mineralise the

microporous structure between the small ß-TCP agglomerates. This phase is in

animals associated with a sclerosing X-ray appearance. On the X-rays of human ß-TCP

incorporation this phenomenon is found during phase 2 of the radiological evaluation

system 11. Next multinucleated osteoclasts like cells penetrate the ß-TCP and start

resorbing it by a cellular mediated process visible as decreasing ß-TCP wedge density

in phase 3 of the radiological classification. During the whole resorption process

no macrophages or multinucleated giant cells are present confirming the good

biocompatibility of the ß-TCP. In later stages active resorption and bone apposition is

responsible for the conversion of the ß-TCP to healthy normal bone. This phase was

not abundant in our biopsy material because of timing of removal of plate and screws.

This is in general not performed before a phase 4 or 5 on the x-rays. In stage 4 some

of the ß-TCP may be present but in stage 5 the bone looks normal and indeed in the

histology the ß-TCP is then almost totally resorbed. What remains are small spots

of ß-TCP incorporated in bone at locations where no active remodelling takes place

any more.

Eggli et al. described an average incorporation of 45% in the vertebral bodies of apes

at six months and Buser et al. measured almost 70% bone matrix at six months in the

mandibles of piglets 16;23. Stoll et al. studied bone incorporation after 12 weeks into a

ß-TCP implant in a cylindrical defects of 8.5mm in the sheep tibia metaphysic and

found 10% bone ingrowth when the implant was impregnated with fresh blood and

18% when the implant was impregnated with fresh bone marrow 17. In all cases, the

expectation was that a further resorption of ß-TCP and incorporation of bone would

take place. Our study suggests that in human bone this expectation would have been

met. Although the results show a high variation, in general a good resorption of ß-TCP

is seen and after two years even 95% complete incorporation and remodelling of bone.

Concerning the quantification of bone healing used in this study and the variability of

results a few remarks can be made. First, the precise biopsy site is of interest. Because

of the wedge shaped ß-TCP-filled defect, the site where the biopsy has been removed

determines the quantity of ß-TCP and bone seen in the biopsy. Although certain criteria

are involved as to how and where the biopsy has to be taken (Fig.1), it is not possible

to obtain a biopsy from the exact same location in each patient. Also, the difference

in the amount of correction between patients may have influenced the results. A higher

number of degrees of correction means a larger defect that has to be filled and

with that a larger surface area of ß-TCP. Furthermore, the quality of the radiographs

(overexposure versus underexposure) may have influenced its classification. Finally,

smoking may have played a role in bone healing. From several studies, it has been

found that smokers have significantly poorer ( or worse) bone healing than

nonsmokers 30-35. In this study, out of 16 patients, there were 7 smokers. No difference

between smokers and non-smokers could be demonstrated. Due to the fact that this

involves a small study group, no conclusions can be drawn from this, however.

To obtain, as in animal studies, a complete and thorough overview of the process of

resorption of ß-TCP and conversion into bone, biopsies would have to be taken at

earlier points in time (six weeks, three months). In patients, however, the fixation material

can only be removed, without loss of correction, after sufficient bone consolidation.

In this study this was after at least six months and in phase 4 or 5 of the radiological

classification. Only through biopsies taken at specific intervals after the osteotomy, a

complete overview can be obtained. This would mean that the patient has to undergo

a separate intervention with the fixation material still in situ which poses medical-ethical

problems prohibiting a complete overview in the current study structure.

Conclusions

In conclusion, although in only a few biopsies the first stages of incorporation were

present, the overall conclusion is that the incorporation process of ß-TCP in patients

occurs similarly as in animals. The radiological classification system that was

developed correlates with the histological findings. Most of the ß-TCP is resorbed and

completely incorporated and remodelled into new bone. Further research will be

necessary to obtain more detailed information on the various phases incorporation

of ß-TCP in human bone though this will be difficult concerning the medical and

ethical limitations.

78

Chapter 5

79


Acknowledgements

The authors would like to thank Thierry Stoll, Synthes Biomaterials in Bettlach,

Switzerland, for the development and preparation of the ceramic implants and the

support of the study.

References

1. Amendola A. Unicompartmental osteoarthritis in the active patient: the role of high tibial osteotomy.

Arthroscopy 2003;19 Suppl 1:109-116.

2. Gaasbeek RD, Welsing RT, Verdonschot N, Rijnberg WJ, van Loon CJ, van Kampen A. Accuracy

and initial stability of open- and closed-wedge high tibial osteotomy: a cadaveric RSA study.

Knee Surg Sports Traumatol Arthrosc 2005;Nov;13(8):689-694.

3. Scott WN, Clarke HD. The role of osteotomy 2003: defining the niche. Orthopedics 2004;27:975-976.

4. Virolainen P, Aro HT. High tibial osteotomy for the treatment of osteoarthritis of the knee: a review of

the literature and a meta-analysis of follow-up studies. Arch Orthop Trauma Surg 2004;124:258-261.

5. Aglietti P, Buzzi R, Vena LM, Baldini A, Mondaini A. High tibial valgus osteotomy for medial

gonarthrosis: a 10- to 21-year study. J Knee Surg 2003;16:21-26.





8 Magyar G, ToksvigLarsen S, Lindstrand A. Open wedge tibial osteotomy by callus distraction in

gonarthrosis: Operative technique and early results in 36 patients. Acta Orthop Scand 1998;69:147-151.

9. Brouwer R, Jakma T, Bierma-Zeinstra S, Verhagen A, Verhaar

J. Osteotomy for treating knee osteoarthritis. Cochrane Database Syst Rev 2005;CD004019.

10. Koshino T, Yoshida T, Ara Y, Saito I, Saito T. Fifteen to twenty-eight years’ follow-up results of high

tibial valgus osteotomy for osteoarthritic knee. Knee 2004;11:439-444.

11. van Hemert WL, Willems K, Anderson PG, van Heerwaarden RJ, Wymenga AB. Tricalcium

phosphate granules or rigid wedge preforms in open wedge high tibial osteotomy: a radiological

study with a new evaluation system. Knee 2004;11:451-456.

12. Amendola A, Fowler PJ, Litchfield R, Kirkley S, Clatworthy M. Opening wedge high tibial osteotomy

using a novel technique: early results and complications. J Knee Surg 2004;17:164-169.

13. Koshino T, Murase T, Saito T. Medial opening-wedge high tibial osteotomy with use of porous

hydroxyapatite to treat medial compartment osteoarthritis of the knee. J Bone Joint Surg Am

2003;85A:78-85.

14. Hernigou P, Ma W. Open wedge tibial osteotomy with acrylic bone cement as bone substitute.

Knee 2001;8:103-110.

15. Koshino T, Murase T, Takagi T, Saito T. New bone formation around porous hydroxyapatite wedge

implanted in opening wedge high tibial osteotomy in patients with osteoarthritis. Biomaterials

2001;22:1579-1582.

80

Chapter 5

81


16. Buser D, Hoffmann B, Bernard JP, Lussi A, Mettler D, Schenk RK. Evaluation of filling materials in

membrane--protected bone defects. A comparative histomorphometric study in the mandible of

miniature pigs. Clin Oral Implants Res 1998;9:137-150.

17. Stoll T MOMTBS. New aspects in osteoinduction. Mat -wiss u Werkstofftech 2004;35:198-202.

18. LeGeros RZ. Properties of osteoconductive biomaterials: calcium phosphates. Clin Orthop 2002;81-98.

19. Eid K, Zelicof S, Perona BP, Sledge CB, Glowacki J. Tissue reactions to particles of bone-substitute

materials in intraosseous and heterotopic sites in rats: discrimination of osteoinduction,

osteocompatibility, and inflammation. J Orthop Res 2001;19:962-969.

20. Steffen T, Stoll T, Arvinte T, Schenk RK. Porous tricalcium phosphate and transforming growth factor

used for anterior spine surgery. Eur Spine J 2001;10 Suppl 2:S132-40.:S132-S140.

21. Bohner M. Calcium orthophosphates in medicine: from ceramics to calcium phosphate cements.

Injury 2000;31 Suppl 4:37-47.:37-47.

22. Bohner, M., van Lenthe, G. H., Grünenfelder, S., Hirsiger, W., Evison, R., and Müller, R. Synthesis

and characterization of porous b -tricalcium phosphate blocks. Accepted

Biomaterials March 2005. Ref Type: Generic

23. Eggli PS, Muller W, Schenk RK. Porous hydroxyapatite and tricalcium phosphate cylinders with

two different pore size ranges implanted in the cancellous bone of rabbits. A comparative

histomorphometric and histologic study of bony ingrowth and implant substitution.


24. Ogose A, Hotta T, Hatano H et al. Histological examination of beta-tricalcium phosphate graft in

human femur. J Biomed Mater Res 2002;63:601-604.

25. Chazono M, Tanaka T, Komaki H, Fujii K. Bone formation and bioresorption after implantation

of injectable beta-tricalcium phosphate granules-hyaluronate complex in rabbit bone defects.

J Biomed Mater Res 2004;70A:542-549.

26. Artzi Z, Weinreb M, Givol N et al. Biomaterial resorption rate and healing site morphology of

inorganic bovine bone and beta-tricalcium phosphate in the canine: a 24-month longitudinal

histologic study and morphometric analysis. Int J Oral Maxillofac Implants 2004;19:357-368.

27. Kovacs K, Velich N, Huszar T et al. Comparative study of beta-tricalcium phosphate mixed with

platelet-rich plasma versus beta-tricalcium phosphate, a bone substitute material in dentistry.

Acta Vet Hung 2003;51:475-484.

28. Wiltfang J, Merten HA, Schlegel KA et al. Degradation characteristics of alpha and beta

tri-calcium-phosphate (TCP) in minipigs. J Biomed Mater Res 2002;63:115-121.

29. Zerbo IR, Bronckers AL, de Lange G, Burger EH. Localisation of osteogenic and osteoclastic cells

in porous beta-tricalcium phosphate particles used for human maxillary sinus floor elevation.

Biomaterials 2005;26:1445-1451.

30. De Bruyn H, Collaert B. The effect of smoking on early implant failure.

Clin Oral Implants Res 1994;5:260-264.

31. Schwartz-Arad D, Samet N, Samet N, Mamlider A. Smoking and complications of endosseous

dental implants. J Periodontol 2002;73:153-157.

32. Wallace RH. The relationship between cigarette smoking and dental implant failure.

Eur J Prosthodont Restor Dent 2000;8:103-106.

33. Gullihorn L, Karpman R, Lippiello L. Differential effects of nicotine and smoke condensate on

bone cell metabolic activity. J Orthop Trauma 2005;19:17-22.

34. Stavropoulos A, Mardas N, Herrero F, Karring T. Smoking affects the outcome of guided tissue

regeneration with bioresorbable membranes: a retrospective analysis of intrabony defects.

J Clin Periodontol 2004;31:945-950.

35. Dahl A, Toksvig-Larsen S. Cigarette smoking delays bone healing: a prospective study of

200 patients operated on by the hemicallotasis technique. Acta Orthop Scand 2004;75:347-351.

82

chapter 6The influence of open and closed high tibial

osteotomy on dynamic patellar tracking

A biomechanical study

R. D. A. Gaasbeek, R. T. C. Welsing, M. Barink, N. Verdonschot, A. van Kampen

Knee Surg Sports Traumatol Arthrosc 2007 May 5; [Epub ahead of print].

84

Chapter 6

85

The influence of open and closed high tibial osteotomy on dynamic patellar tracking; a biomechanical study

Abstract

High tibial osteotomy (HTO) can cause alterations in patellar height, depending on

the surgical technique, the amount of correction and the postoperative management.

Alterations in patella location after HTO may lead to post-operative complications.

However, information on changes in dynamic patellar kinematics following HTO is

very limited.

We conducted a biomechanical study, to analyze the effect of open (OWO) and closed

wedge osteotomy (CWO) on patellar tracking. Using an inventive experimental set-up,

we studied the 3D dynamic patellar tracking in ten cadaver knees before and after

valgus HTO. In each specimen, corrections of 7º and 15º of valgus according to, both,

the OWO and CWO technique, were performed.

Patellar height significantly increased with CWO and decreased with OWO. Both, OWO

and CWO led to significant changes in the patellar tracking parameters tilt and rotation.

We also found significant differences between OWO and CWO. Valgus high tibial

osteotomy increased the medial patellar tilt and reduced the medial patellar rotation.

These effects were more profound after OWO. No significant differences were found

for the effect on medial-lateral patellar translation. These observations can be taken

into consideration in the decision whether to perform an OWO or a CWO in a patient

with medial compartment osteoarthritis of the knee.

Introduction

Young active patients suffering from medial compartment osteoarthritis of the knee with

a varus alignment can be treated with a high tibial osteotomy (HTO). Depending on the

surgical technique and postoperative management, alterations in patellar height can be

induced 1-7. Open wedge osteotomy (OWO) proximal to the tibial tuberosity, which is

gaining popularity in recent years, has been reported to cause patella baja 3;7. Closed

wedge osteotomy (CWO) has been shown to lead to both patella baja and alta 3;8.

These alterations in patellar height have been attributed to the proximalisation (CWO)

or distalisation (OWO) of the tibial tuberosity following HTO7. Furthermore, scarring,

adhesions and contracture of the patella ligament are mentioned to cause lowering of

the patella in CWO 5. Besides these changes in patellar height, other components of

patellar tracking may be affected by HTO. This may cause anterior knee pain, patella

locking, crepitus and limitation of knee motion. Eventually, the altered patellofemoral

congruency and contact stress may lead to patellofemoral osteoarthritis. Furthermore,

there is evidence that patellar height may affect the outcome of total knee arthroplasty

9;10. Conversely, pre-existing patellofemoral symptoms may diminish following HTO 11.

Former studies on the effect of HTO on the patellofemoral joint focus on the standard

plain radiographic measurements of patellar height at one position of knee flexion 1;8.

Furthermore, previous studies in this field restrict the dynamic patellar tracking to a

range of static measurements of the patella position in a few fixed positions of knee

flexion 12;13. As far as the authors are aware of, no study has been reported that

describes the true dynamic patellar tracking following HTO. The present study was

conducted to analyse the changes in dynamic patellar tracking after both, OWO

and CWO.

Materials and Methods

Specimens

Ten fresh frozen cadaver knees were obtained. Degenerative changes and dysplasias

were evaluated and excluded based on standard AP, lateral and patella radiographs.

The specimens were prepared for use in a knee joint motion and loading apparatus 14.

86

Chapter 6

87


Therefore, tibia and femur were transsectioned at about 20 cm from the knee joint

centre. The ends of the bones were potted in autopolymer which guaranteed identical

positioning during the different surgeries and measurements. All soft tissues were

preserved. The quadriceps muscle was separated in three parts: rectus femoris, vastus

medialis, and vastus lateralis/intermedius. Three mounting plates were rigidly fixed to

the femur, tibia and patella, respectively, which enabled the registration of the bony

segments visible on the CT scans to the global coordinate system. Hereafter, CT scans

of all knees were obtained.

Experimental set up

A specially designed metal frame with hinges on the medial and lateral side was put

on the tibia under fluoroscopic view. This frame was designed such that the position of

the hinges coincided with the planned rotation point (the apex) of the osteotomy.

The frame allowed a free moving distal part of the tibia. In this way, different valgus

angles within the same specimen could be simulated. The tibia positions could be

set at a predetermined angle.

After this, the specimen was positioned in the loading apparatus. An electromagnetic

motion tracking system (3SPACE Fastrak, Polhemus, Colchester, VT, USA) was used to

measure the patello-femoral and tibio-femoral kinematics of the knee. Three sensors

were fixed rigidly to the mounting plates on femur, tibia and patella. The kinematics

were recorded using continuous data acquisition. The three separated parts of the

quadriceps muscle were loaded with 27 N each and an additional 50 N axial

compressive load was applied to the knee, according to an earlier published protocol 14;15.

For the first reference measurement, three flexion-extension movements were

performed manually. Next, a standard anterolateral approach was used. Two centimetres

below and parallel to the joint line a Kirschner wire was inserted to aim the osteotomy.

First, the proximal cut was performed. Using an aiming device the distal cut was made

and a 15º bony wedge was removed proximal to the tibial tuberosity. The fibula was

cut, according to the closed wedge HTO technique of Coventry 16.

The knee was put back into the loading apparatus and the measurements were

repeated in three different positions of the distal tibia: neutral (Fig. 1a), 7º and 15º

valgus (lateral closed wedge) position (Fig. 1b).

After this, a medial approach was performed, shifting the pes anserinus and the

superficial medial collateral ligament dorsally. A Kirschner wire was inserted parallel to

the joint line. Using a guide instrument a second wire was inserted just proximal of the

tuberosity in lateral cranial direction in order to obtain an equal osteotomy level in all

knees. Along this wire the osteotomy was performed.

Hereafter, flexion-extension cycles were recorded in neutral, 7º and 15º valgus (medial

open wedge) position (Fig. 1c). All correction angles were checked with an electronic

inclinometer (Cybex, EDI 320). The surgery was performed under fluoroscopic view.

Data analysis

After the recordings were made, the Fastrak motion data were analysed and combined

with the CT-scanning data. The 3D motion data, which were measured in the global

coordinate system, were transformed to anatomic coordinates. The anatomic coordinate

systems were based on bony landmarks which were retrieved from the CT scan

contours 17. In this way, a 3D dynamic model of each knee was constructed with a local

anatomic coordinate system. As the patellar kinematics are also largely dependent on

the tibial movements the tibial kinematics were also measured. The calculated patellar

tracking parameters were: patellar height, tilt, rotation, and lateral-medial translation

(For definition of parameters see fig 2). To quantify the impact of the HTO for

each of the parameters, the differences of the patellar kinematics after HTO minus the

reference patellar kinematics of the neutral measurements were calculated.

Figure 1

Schematic presentation of the tibia positioned in the specially designed frame which enabled

testing of different valgus angles within the same specimen. A. neutral, B. valgus closed

wedge(7º and 15º) and C. valgus open wedge (7º and 15º).

A B C

88

Chapter 6

89


Statistics

The three reference measurements in neutral position were compared using a

Two-way ANOVA. The differences between the four groups, e.g. 7º and 15º lateral

closed wedge, and 7º and 15º medial open wedge, were analyzed by using a Two-way

ANOVA at every subsequent flexion step of 5º up to maximal knee flexion angle of

100º. To assess whether each group was statistically different from the non-operated

situation, we calculated whether the difference of the two measurements (intact minus

operated) was different from zero by calculating if the value zero was within the outcome

of the 95% confidence interval. Significance was set at p < 0.05.

Results

In general, the movement patterns of the patella in the non-operated knees were similar

to what clinically can be expected and is described by van Kampen and Huiskes 15.

Typical examples of the effects of HTO on patellar tilt and rotation in one of the specimen

are shown in figures 3a and b, respectively. The group results are graphically displayed

in figures 4a-d. They represent the change of patellar kinematics caused by the HTO,

not the absolute values.

Patellar height

As expected, larger tibial correction angles induced more patellar height changes

(Fig. 4a). The OWO resulted in significant lowering of the patella. Larger corrections in

the OWO group caused significant more patella lowering, whereas more correction

in the CWO group resulted in more increase in patellar height. The change of patellar

height was not related to the knee flexion. Hence, during knee flexion the position

of the patella in relation to the tibia was rather constant, which resulted in horizontal

curves. The mean decrease of patellar height following 7º OWO was 1.5 mm (range

0.7;1.7) which significantly increased to 4.2 mm (range 2.7;4.6) at 15º OWO.

The patellar height after 7º CWO increased on average with 2.2 mm (range 1.1;2.7).

At 15º CWO the mean increase was 3.0 mm (range 2.1;3.6). Figure 5 shows a schematic

presentation of the patellar height changes after open an closed wedge osteotomy.

Patellar tilt

A typical example of the effects of HTO on the patellar tilt is shown in figure 3a.

On average, OWO and CWO caused the patella to tilt more medially (Fig. 4b). A trend

was seen of more medial tilt with OWO than with CWO. Along the flexion-extension

movement we found no significant difference between CWO and OWO at 7º correction,

but during the first half of flexion significant differences were found between CWO and

Figure 2

Defenition of patellar movements.

Figure 3

Typical examples of the

effects of HTO on the

patellar tilt (a) and rotation

(b) of one specimen.

Ref : Reference curve of

neutral measurement.

Patellar Tilt

-6

-5

-4

-3

-2

-1

0

1

2

3

4

0 20 40 60 80 100

Knee Flexion (deg)

Pate

lla T

ilt (d

eg)

Medial

Lateral

Patellar Rotation

-5

-4

-3

-2

-1

0

0 20 60 80 100

Knee Flexion (deg)

Pate

lla R

otat

ion

(deg

)

Medial

Lateral40

Ref7 deg CWO15 deg CWO7 deg OWO15 deg OWO

a

b

90

Chapter 6

91


OWO with a 15º correction. OWO caused the patella to tilt more medially in extension

and showed a decrease in additional medial tilt while the knee was brought in flexion.

With increasing flexion the difference in medial tilt between the two HTO groups

decreased. All groups showed to be significant different from zero. The mean increase

of medial tilt following 7º OWO was 1.7º (range 0.3; 4.8) which increased to 2.9º

(range 1.8; 6.2) at 15º OWO. The mean medial patellar tilt after 7º CWO increased with

0.7º (range 0.0; 0.9). At 15º CWO the mean increase was 0.5º (range -0.3; 0.7)

Patellar rotation

A typical example of the effects of HTO on the patellar rotation is shown in figure 3b.

Both, OWO and CWO reduced the normal medial rotation of the patella along the flexion

movement of the knee. In general, OWO showed significant more reduction of medial

rotation than CWO (Fig. 4c). No statistical difference between CWO and OWO with

7º correction was found around the area in the curves where the two lines cross.

At 7º OWO correction, the reduction of the medial rotation declined with increased

flexion of the knee. In full flexion this group showed a small increase of medial rotation

of the patella. Increasing the correction angle from 7º to 15º resulted in a significant

reduction of medial rotation and in some specimen lateral rotation was induced.

Figure 4

Averaged group patellar

kinematics: patellar height

(a), patellar tilt (b), patellar

rotation (c) and patellar

medial-lateral translation

(d). The data represent

the change of patellar

tracking parameters

caused by the different

HTO techniques, not the

absolute values.

Because of clarity

standard deviations are

not shown.

-10

-8

-6

-4

-2

0

2

4

6

0 20 40 60 80 100

-8

-6

-4

-2

0

2

4

0 20 40 60 80 100

-10 -8 -6 -4 -2 0 2 4 6 8

0 20 40 60 80 100

-1,5

-1

-0,5

0

0,5

1

1,5

2

2,5

3

3,5

0 20 40 60 80 100 -

Ref7 deg CWO15 deg CWO7 deg OWO15 deg OWO

Patellar Height

Knee Flexion (deg)

Pate

lla H

eigh

t (m

m)

Low

High

Patellar Tilt

Knee Flexion (deg)

Pate

llar T

ilt (d

eg)

Medial

Lateral

Patellar Rotation

Knee Flexion (deg)

Pate

llar R

otat

ion

(deg

)

Medial

Lateral

Patellar medial-lateral Translation

Knee Flexion (deg)

Med

ial-l

ater

al T

rans

latio

n (m

m)

Medial

Lateral

a

b

c

d

Figure 5

Schematic presentation of the changes in patellar height after high tibial osteotomy.

a. preoperative, b. lowering of the patella after open wedge osteotomy and c. increased

patellar height after closed wedge osteotomy.

92

Chapter 6

93


No significant difference was found between CWO 7 and 15º. During the first half of

flexion movement the effect of CWO on the patellar rotation was not significantly

different from zero, and this was also seen for the 7ºof correction with OWO near full

extension. The mean reduction of medial rotation following 7º OWO was 1.6º

(range -0.6; 2.8) which increased to 5.2º (range 4.7; 5.5) at 15º OWO. The mean

medial rotation after 7º CWO decreased with 1.2º (range -0.1; 1.9). At 15º CWO

the mean reduction was 1.1º (range 0.0-1.9).

Patellar medial-lateral translation

We found a poor reproducibility of the differences in medial-lateral patellar translation

leading to high standard deviations. No significant differences were found between

groups in medial or lateral translation of the patella (p > 0.05). Also, all calculated

effects were not different from the reference patellar tracking pattern. (Fig. 4d).

Discussion

Previous observations of patellar height after HTO concern either the closed wedge or

the open wedge technique. To our knowledge, only three studies analyzed the effects

on patellar height in OWO versus CWO. Tigani et al. used Caton’s Index (CI) and

showed lowering of the patella more often with OWO than with CWO and a high degree

of patella proximalisation in the latter 6. Brouwer et al. found more patellar lowering after

an open wedge HTO. They applied both the Insall Salvati (ISI) and the Blackburne-Peel

Index (BPI) 1. Hoell et al. measured patellar height change with the ISI and found no

difference between OWO and CWO 18. However, this does not exclude a true change of

patellar height in relation to the joint line, as the ISI represents the length of the patellar

tendon. Furthermore, BPI and CI do not accurately measure the alteration of patellar

height after valgus HTO, because they are dependent of the tibial inclination and the

antero-posterior translation of the proximal tibia 8. The present study has the advantage

of continuous 3D monitoring of the patella movements, without the limitations of the

measurements of patellar height on plain roentgen films. We found a significant

increase in patellar height after CWO and a significant lowering of the patella after

OWO. These height changes were dependent on the amount of correction and more

profound after OWO as compared to CWO (Fig. 4a). Concerning the biomechanics of

the patella movement in relation to its anatomical position contradictory information in

literature is found. Investigations of the mechanics of patella baja have found that a

low-riding patella does not necessarily lead to an increase in patellofemoral contact

forces 19;20. However, others report an increase in patellofemoral joint reaction force as

a result of adhesions of the patella ligament 7.

During surgery we observed that the proximal translation after CWO was limited by

the medial and lateral retinaculum to such extend that the patellar tendon relaxed and

curled up. This phenomenon might well be one of the factors that lead to shortening

and adhesions of the patellar tendon that is reported after CWO 5.

Weidenhielm et al. reported on seven patients before and after CWO using kinematic

analysis with roentgen stereophotogrammetric analysis (RSA). They found no significant

change in patellar rotation and translation during knee motion, with inconsistent

changes in patella position 13. However, they were not informed about quadriceps

tension nor did they correct for relaxation or contraction of the quadriceps muscles

during the RSA measurements. This might have been a large confounder in their study.

During flexion of the knee, until the patella is well seated, its stability rests solely on

muscle tension. Hungerford et al. stated that the congruence of the patellofemoral joint

and the muscles forces provide considerable stability irrespective of restraining

ligaments 21. Because of this we applied a constant load to the quadriceps muscle

during our experiments (See Material and Methods). Hill et al. used magnetic resonance

imaging to measure patellofemoral kinematics through a range of loaded flexion before

and after CWO in 4 patients.

They found a decrease in patella flexion and internal spin (‘medial rotation’ in this

study), and an increase in medial patellar tilt and proximal translation 12. Although this

study represents a “semi-dynamic” setting, our results corroborate with their findings.

We found that valgus osteotomy increased the medial tilt and reduced the medial

patellar rotation. These effects were more profound after OWO. The increased medial

patellar tilt can be explained by the increased lateral pull on the patella. The tuberosity

is located more laterally after valgus high tibial osteotomy. The lateral patellar facet is

pressed against the lateral wall of the trochlea and the patella is forced up the lateral

groove leading to a medial tilt. As the quadriceps tendon remains to have the same

loading direction, the lateralization of the tuberosity induces lateral rotation (reduction of

medial rotation). Theoretically, the effect on the patellar medial-lateral translation is larger

94

Chapter 6

95


near full extension of the knee. During flexion the patella enters the trochlear groove

which will enhance medial-lateral stability. Furthermore, there is a relatively high variation

in patellar position in the lower range of flexion. These phenomena may explain why no

significant differences in patellar translation could be detected. Furthermore, during our

experiments we observed that OWO, led to more tension on the patella ligament and

the retinaculi in contrast to the closed wedge osteotomies, in which we observed a

relative relaxation of the patellar tendon. This may explain why more effect of the HTO

was observed in the OWO group. It seemed that the distalisation and increased tension

following OWO, enhances the forces at the patellofemoral joint, leading to more obvious

effects on the patellar tracking. If these effects are unwanted, a different operation

technique has been described recently, to prevent the distalisation of the tibial tuberosity

with OWO by performing a distal tuberosity osteotomy 3.

To our knowledge, the current paper is the first to describe the continuous 3D patellar

tracking changes following HTO, according to both the CWO as the OWO technique.

This study clearly shows the evident influence of HTO on patellar position and the

patellofemoral movements. The effects of OWO proof to be more profound than those

following CWO, especially at larger valgus corrections of the tibia. These effects of HTO

on patellar height and patellar tracking may be of minimal clinical relevance but in

extensive open wedge corrections the effects may be quite large and lead to adverse

events with respect to the patellofemoral joint (e.g. pain, maltracking or even patellar

(sub)luxation). On the other hand, patellofemoral complaints may subside after high

tibial osteotomy.

In conclusion, the decision whether a closed or an open wedge technique is performed,

for the treatment of patients suffering from medial osteoarthritis of the knee, the

presence of patellofemoral complaints or pre-existent patella baja should be taken into

consideration. Especially in large open wedge corrections significant changes in

patellar height and tracking can be induced. In the future, the effect of the kinematic

changes in the patellofemoral joint after high tibial osteotomy in terms of clinical

presentation and radiographic changes after long term follow-up have to be determined.

Reference List




2. Closkey RF, Windsor RE. Alterations in the patella after a high tibial or distal femoral osteotomy.


3. Gaasbeek RD, Sonneveld H, van Heerwaarden RJ, Jacobs WC, Wymenga AB. Distal tuberosity

osteotomy in open wedge high tibial osteotomy can prevent patella infera: a new technique.

Knee 2004;11:457-461.

4. Kaper BP, Bourne RB, Rorabeck CH, Macdonald SJ. Patellar infera after high tibial osteotomy.

J arthroplasty 2001;16:168-173.



6. Tigani D, Ferrari D, Trentani P, Barbanti-Brodano G, Trentani F. Patellar height after high tibial

osteotomy. Int Orthop 2001;24:331-334.



8. Kesmezacar H, Erginer R, Ogut T, Seyahi A, Babacan M, Tenekecioglu Y. Evaluation of patellar

height and measurement methods after valgus high tibial osteotomy.

Knee Surg Sports Traumatol Arthrosc 2005.

9. Figgie HE, III, Goldberg VM, Heiple KG, Moller HS, III, Gordon NH. The influence of tibial-

patellofemoral location on function of the knee in patients with the posterior stabilized condylar

knee prosthesis. J Bone Joint Surg Am 1986;68:1035-1040.

10. Windsor RE, Insall JN, Vince KG. Technical considerations of total knee arthroplasty after proximal

tibial osteotomy. J Bone Joint Surg Am 1988;70:547-555.

11. Goutallier D, Delepine G, Debeyre J. [The patello-femoral joint in osteoarthritis of the knee with

genu varum (author’s transl)]. Rev Chir Orthop Reparatrice Appar Mot 1979;65:25-31.

12. Hill NA, Fellows RA, MacIntyre NJ, Harrison MM, Ellis RE, Wilson DR. The effect of high tibial

osteotomy on three-dimensinal tibiofemoral and patellofemoral kinematics: an in vivi study using

magnetic resonance imaging. Proc 51st ORS Conference 2005;0481.

13. Weidenhielm L, Wykman A, Lundberg A, Brostrom LA. Knee motion after tibial osteotomy for

arthrosis. Kinematic analysis of 7 patients. Acta Orthop Scand 1993;64:317-319.

96

Chapter 6

14. Van Heerwaarden, H. J. Effects of pretension in reconstructions of the anterior cruciate ligament;

clinical, biomechanical and computer model analysis. 1998. University of Nijmegen.

1998. Ref Type: Thesis/Dissertation

15. van Kampen A, Huiskes R. The three-dimensional tracking pattern of the human patella.

J Orthop Res 1990;8:372-382.

16. Coventry MB. Osteotomy of the upper portion of the tibia for degenerative arthritis of the knee.

a preliminary report. J Bone Joint Surg Am 1965;47:984-90.:984-990.

17. Barink M, Meijerink H, Verdonschot N, van Kampen A, de Waal MM. Asymmetrical total knee

arthroplasty does not improve patella tracking: a study without patella resurfacing.

Knee Surg Sports Traumatol Arthrosc 2006.


wedge, a comparison of methods in 108 patients. Arch Orthop Trauma Surg 2005;125:638-643.

19. Meyer SA, Brown TD, Pedersen DR, Albright JP. Retropatellar contact stress in simulated patella

infera. Am J Knee Surg 1997;10:129-138.

20. Singerman R, Davy DT, Goldberg VM. Effects of patella alta and patella infera on patellofemoral

contact forces. J Biomech 1994;27:1059-1065.

21. Hungerford DS, Barry M. Biomechanics of the patellofemoral joint. Clin Orthop Relat Res 1979;9-15.

chapter 7Distal tuberosity osteotomy in open wedge

high tibial osteotomy can prevent patella infera;

a new technique

R.D.A. Gaasbeek, H. Sonneveld, R.J. van Heerwaarden, W.C.H. Jacobs, A.B. Wymenga

Knee. 2004 Dec;11(6):457-6

98

Chapter 7

99

Distal tuberosity osteotomy in open wedge high tibial osteotomy can prevent patella infera; a new technique

Abstract

To prevent patella infera in open wedge high tibial osteotomy, a new operation technique

was developed. Instead of a proximal tibial tuberosity osteotomy, a distal osteotomy

was performed and the tuberosity was fixed with one screw to the tibia. First experiences

in 17 patients were evaluated and compared with results of 20 patients with open wedge

high tibial osteotomy with proximal tuberosity osteotomy. Distal tuberosity osteotomy in

open wedge high tibial osteotomy appears effective in preventing patella infera.

Introduction

In medial open wedge high tibial osteotomy (OWHTO) for valgus correction of medial

compartment osteoarthritis of the knee the patellar height may change resulting in

postoperative patella infera 1,2,3. A decrease in patellar height associated with OWHTO

has been attributed to distalisation of the tuberosity as a result of valgisation and to

shortening of the patellar ligament by scarring 1,3,4. Reduced patellar height can be the

cause of patellofemoral problems and may complicate a conversion to total knee

replacement in progressive arthritis of the knee 2,3,5,6.

A new operation technique was developed by one of the authors (AW) to prevent

distalisation of the tuberosity and subsequently prevent patellofemoral problems.

In the normal OWHTO technique the tuberosity remains attached to the distal part of

the tibia by performing a proximal tuberosity osteotomy (PTO) or by positioning the

osteotomy above the level of the tuberosity. In our newly developed technique we

perform a distal tuberosity osteotomy (DTO) so the tuberosity remains attached to

the proximal part of the tibia. Opening of the wedge will not change the position of the

tuberosity and consequently, there will be less change of patellar height. The purpose of

this report is to describe a new operation technique: a distal tuberosity osteotomy in open

wedge high tibial osteotomy and to evaluate our first experiences in clinical practice.

Figure 1

OWHTO with PTO, leading to lowering of the patella. a: before opening of the wedge,

AP-view; b: after opening of the wedge, AP-view; c: after opening, lateral view

100

Chapter 7

101


Materials and Methods

Operation techniques:

Previous OWHTO technique with proximal tuberosity osteotomy

Through a midline incision, the tibial tuberosity and distal part of the patellar tendon is

exposed. Starting posterior to the patellar tendon insertion, a PTO is performed: an

osteotomy of the proximal tuberosity parallel to the anterior tibial cortex. After that, the

tibial osteotomy is made behind the tuberosity, which is protected by an angular blade.

Opening of the tibial osteotomy causes the tuberosity to move distally as it is attached

to the distal part of the tibia (figure 1).

New OWHTO technique with distal tuberosity osteotomy

In the new technique we perform a DTO, so the tuberosity remains attached to the

proximal part of the tibia. Therefore, the patellar height is not changed after opening of

the tibial osteotomy (figure 2). In contrast to the previous technique, first, the tibial

osteotomy is made leaving at least a 1 cm thickness of the tuberosity. After that, the

tuberosity osteotomy is performed posterior to the tuberosity. Starting from the tibial

osteotomy the tuberosity is cut distally in the frontal plane directed towards the anterior

tibial cortex. The length of the osteotomized tuberosity should be at least 2.5 cm for

small valgus corrections. In larger corrections the tuberosity length must be longer and

should be planned to at least overlap the distal tibial part for 2.0 cm after the wedge is

opened. After medial plate fixation of the tibial osteotomy, we fixate the distal part of

the tuberosity with a bicortical screw to the tibia. As a stable fixation is reached the

postoperative rehabilitation protocol for the OWHTO needs no adjustments due to the

new technique.

Figure 2

OWHTO with DTO, leaving the patellar height unchanged. a: before opening of the wedge,

AP-view; b: after opening of the wedge, AP-view; c: after opening, lateral view

Table 1

Data of patients with OWHTO with distal tuberosity osteotomy. Correction angle, pre- and

postoperative Caton index (CI) and change of CI (Δ-CI).

Nr Male/Female Age Correction Pre-CI Post-CI Δ-CI

1 m 41 9 0.78 0.82 0.03

2 m 27 10 0.72 0.72 0.00

3 m 51 15 0.74 0.68 -0.05

4 m 41 6 0.75 0.78 0.03

5 m 42 7 0.85 0.83 -0.03

6 m 46 10 0.97 0.87 -0.11

7 m 62 9 0.87 0.79 0.01

8 f 42 10 0.59 0.56 -0.03

9 m 59 10 1.00 0.97 -0.03

10 m 44 15 0.85 0.83 -0.02

11 m 64 13 0.79 0.76 -0.03

12 m 37 12 0.90 0.87 -0.03

13 f 53 14 0.67 0.64 -0.03

14 m 48 7 0.73 0.73 0.00

15 m 54 8 0.80 0.80 0.00

16 m 61 10 0.94 0.91 -0.03

17 m 48 7 0.74 0.74 0.00

Mean(SD) 48(10) 10(2.8) 0.80(0.11) 0.78(0.10) -0.02(0.03)

102

Chapter 7

103


Patient evaluation:

Between March 2001 and October 2002, seventeen consecutive patients operated

according to the new OWHTO technique with the DTO were included for the study.

An historical control group was formed from all patients operated upon from

June 2000. The only selection criteria was presence of a suitable pre-operative lateral

radiograph in 30º of flexion. All patients in this group were operated according to

the routine operation technique, with the PTO.

The tibial osteotomy was fixed by a Tomofix plate (Mathys Medical, Bettlach) after filling

of the wedge with tri-calcium phosphate (ChronOS-Mathys Medical Ltd). The patients

in both groups suffered from medial compartment osteoarthritis of the knee and were

operated by two surgeons (AW and RVH). For details on the demographics see table 1.

Postoperative care consisted of knee flexion and extension exercises starting the day

after the operation. For the first six weeks there was restricted weight bearing (10 kg)

with two crutches and thrombosis prophylaxis with low weight high molecular heparin.

After six weeks full weight bearing was allowed.

For each patient the patellar height was measured by the Caton (-Deschamps) index 7

(CI) on pre- and six weeks postoperative lateral radiographs at 30 degrees of knee

flexion. The CI, the ratio between the distance from the inferior tip of the patella and the

antero-superior angle of the tibia and the patellar articular surface length (figure 3),

decreases with patella baja and increases with patella alta. The normal value of CI is

0.96 (SD 0.13) in males and 0.99 (SD 0.13) in females. The patella is considered low

(patella baja) when CI<0.6 and high (patella alta) when CI>1.32. In the two groups the

pre-operative and post-operative CI was measured and compared using the paired

t-test with p < 0. 05 considered significant.

Figure 3

Calculation of the Caton

(-Deschamps) Index

(CI index). PA is the length

of the articular surface

of the patella; AT is the

distance from the inferior

tip of the patella to the

antero-superior aspect of

the tibia. The CI Index is

calculated as the ratio AT/PA.

Table 2

Data of patients with OWHTO with proximal tuberosity osteotomy. Correction angle, pre- and

postoperative Caton index (CI) and change of CI (Δ-CI).

Nr Male/Female Age Correction Pre-CI Post-CI Δ-CI

18 f 23 5 1.14 1.06 -0.08

19 f 44 7 0.83 0.74 -0.09

20 f 63 10 1.03 0.76 -0.26

21 m 29 8 0.71 0.58 -0.13

22 f 51 7 0.92 0.74 -0.18

23 m 52 7 0.92 0.79 -0.13

24 m 38 3 0.84 0.79 -0.05

25 m 21 9 0.93 0.83 -0.11

26 f 59 5 0.97 0.86 -0.11

27 m 37 8 0.85 0.78 -0.08

28 m 33 9 0.93 0.84 -0.09

29 m 53 10 0.74 0.62 -0.12

30 m 43 8 0.68 0.51 -0.16

31 f 48 13 0.48 0.24 -0.23

32 m 26 6 1.03 0.97 -0.06

33 f 45 7 0.72 0.66 -0.06

34 m 50 14 0.86 0.71 -0.14

35 m 51 14 0.85 0.63 -0.23

36 m 32 12 0.95 0.82 -0.13

37 m 42 10 0.73 0.65 -0.08

Mean(SD) 42(11) 8.6(3.1) 0.86(0.15) 0.73(0.17) -0.13(0.06)

104

Chapter 7

105


Results

Tables 1 and 2 show the calculated pre- and postoperative Caton indices (CI) of the

patients operated with the DTO and the PTO, respectively, together with the OWHTO

correction angles.

In the DTO group (table 1), the patella height was not essentially changed with a mean

preoperative CI of 0.80 (range: 0.59-1.00) and a mean postoperative CI of 0.78

(range: 0.56-0.97). The tuberosity osteotomy was radiographically healed at 6 weeks

postoperative in all but 2 patients. In one patient the tuberosity was fractured during

the tuberosity osteotomy due to a tibial osteotomy leaving less than 1 cm thickness

of the tuberosity. In another patient the tuberosity fixation screw was positioned too

proximal and slightly upward ending posteriorly in the opened wedge. At 6 weeks no

consolidation was found and the screw was repositioned more distally with uneventful

bone healing in 6 weeks. In none of the patients a secondary dislocation of the

tuberosity or the proximal tibia was found after the start of full weight bearing.

In the PTO group (table 2), the patella height decreased significantly (p< 0.001) with

a mean preoperative CI of 0.86 (range: 0.48-1.14) and a mean postoperative CI of 0.73

(range: 0.24-1.06). Bone healing of the tuberosity osteotomy was uneventful and

complete at 6 weeks follow-up in all patients.

In figure 4 the relation between the angle of correction of the OWHTO and the difference

between pre- and post-operative CI (Δ-CI) for both groups is displayed. The mean

correction angle was slightly larger in the DTO group as compared to the PTO group

(10 vs. 8.6 degrees). In the PTO group correction angle and patellar height were found

to be related: the larger the correction angle of the OWHTO the lower the postoperative

patellar height resulting in an increase of Δ-CI with increasing correction angles (figure 4).

Discussion

Open wedge high tibial osteotomy in medial osteoarthritis of the knee has gained a

lot of popularity in recent years. However, the traditional open wedge technique results

in a decrease of patellar height, which may lead to patella infera 2,3,4. Patella infera

following OWHTO causes anterior knee pain, patellar locking, crepitus and limitation of

knee motion. Eventually, the altered patellofemoral congruency and contact stress can

lead to patellofemoral osteoarthritis 8. The new distal tuberosity osteotomy technique

described in this paper encounters this problem. In addition specific difficulties with

conversion of failed HTO with patella infera to total knee arthroplasty 3,5,6 can be prevented.

Decrease of patellar height following OWHTO is mainly caused by the distalisation of

the tuberosity when a PTO is used or the tibial osteotomy is made proximal to the tibial

tuberosity. In those situations a decrease of patellar height is inevitable as was already

shown by Goutallier 8 in a mathematical model. Opening of the osteotomy causes a

distalisation and lateralisation of the tuberosity and the patella. With the OWHTO technique

with a DTO, the tibial tuberosity remains attached to the proximal tibia and opening the

osteotomy will leave patellar height unchanged. Hernigou 4 uses another strategy

to avoid patellar height decrease after OWHTO: positioning of a cement wedge

between the posterior tibial cortices and no wedge anteriorly which results in almost no

heightening of the anterior margin of the osteotomy. However, this technique will likely

lead to unwanted additional tibial slope correction, especially in large valgus corrections.

Furthermore, the decrease of patellar height can be the result of shortening of the

patellar ligament by scarring with adherence of the patellar tendon to the tibia proximal

of the tuberosity insertion 1,3,4. Methods used to avoid scarring of the patellar ligament

include meticulous surgical techniques avoiding large postoperative haematoma’s,

anti-inflammatory medication 9, continuous passive motion with flexion-extension

Figure 4

The relation between

change of Caton index

(Δ-CI) and correction

angles in PTO and DTO,

showing a decrease in CI

at higher correction angles

in the PTO group.

Δ-CI

Correction

DTO

DTO

106

Chapter 7

107


exercises preventing immobilisation 4, and daily manual patella mobilization exercises 3.

Small decreases of the Caton index in the DTO group in individual patients were

within the measurement error and not related to the amount of OWHTO-correction.

This might also be attributed to scarring of the patellar tendon, despite the postoperative

immediate motion protocol that was used.

In this study we found that a distal tuberosity osteotomy during OWHTO prevents a

decrease of patellar height measured with the Caton Index. Wright et al. 3 used the

Blackburne-Peel ratio and the Insall-Salvati ratio as a measure of patellar height and

found patella infera in 64% of their patients after OWHTO and no significant change in

patellar ligament length. Tigani et al. 2 found a significant reduction of the Caton index

after OWHTO similar to the results that were found in the patients with the PTO in the

present study. In the PTO group, all patients showed lowering of the patella after the

OWHTO and a direct relation was found between the change in patellar height and the

amount of correction of the OWHTO. Small corrections in patients with normal patellar

height will not likely lead to symptomatic patella infera. However, based on the results

of this study, we advise to use the DTO-technique in cases in which higher valgus

corrections are indicated (>10°) and in patients with pre-existing patella infera.

We encountered two pitfalls of the DTO technique in the patients in this study:

a fracture of the tibial tuberosity due to a tuberosity thickness of less than 1 cm and

imprecise screw fixation with positioning of the tuberosity screw in the opened wedge

of the HTO. Another pitfall is the length of the saw cut, which should leave enough

room for distal screw fixation after the wedge of the HTO is opened. With meticulous

surgical technique and preoperative planning, these complications can easily

be prevented.

A weak point in our study is the formation of the experimental and the control group.

The choice for the control patients is based on availability of preoperative radiographs.

These patients might differ from those which did not require a lateral image in 30º

for diagnostics. The only way to scientifically show that the distal tuberosity osteotomy

technique leads to a more normal patella height is with a randomised controlled trial.

We conclude that the distal tuberosity osteotomy is a safe technique and that it can

prevent lowering of the patella following OWHTO, especially in patients who need a

high degree of valgus correction for medial compartment osteoarthritis of the knee.

References

1. Scuderi GR, Windsor RE, Insall JN Observations on patellar height after proximal tibial osteotomy.

J Bone Joint Surg [Am] 1989; 71A(2): 245-248

2. Tigani D, Ferrari D, Trentani P, Barbanti-Brodano G, Trentani F Patellar height after high tibial

osteotomy. Int Orthop 2001; 24(6): 331-334

3. Wright JM, Heavrin B, Begg M, Sakyrd G, Sterett W Observations on patellar height following

opening wedge proximal tibial osteotomy. Am J Knee Surg 2001; 14(3):163-73

4. Hernigou P, Ma W Open wedge tibial osteotomy with acrylic bone cement as bone substitute.

The Knee 2001; 8: 103-110

5. Figgie HE 3rd, Goldberg VM, Heiple KG, Moller HS 3rd, Gordon NH The influence of tibial-

patellofemoral location on function of the knee in patients with the posterior stabilized condylar

knee prosthesis. J Bone Joint Surg [Am] 1986; 68A(7):1035-1040

6. Windsor RE, Insall JN, Vince KG Technical considerations of total knee arthroplasty after proximal

tibial osteotomy. J Bone Joint Surg [Am] 1988; 70A(4):547-555

7. Dejour H, Walch G, Nove-Josserand L, Guier C Factors of patellar instability: an anatomical

radiographic study. Knee Surg Sports traumatol Arthrosc 1994; 2(1):19-26

8. Goutallier D, Delepine G, Debeyre J The patello-femoral joint in osteoarthritis of the knee with

genu varus. Revue de Chirurgic Orthopedique 1979; 65(1):25-31

9. Leuthof D, Tobian F, Perka C High tibial osteotomy for valgus and varus deformities of the knee.

Int. Orthop 2001; 25: 93-96

108

chapter 8Summary, answers to research questions,

and closing remarks

110

Chapter 8

111

Summary, answers to research questions, and closing remarks

Summary and answers to research questions

In chapter 1, six questions concerning the treatment of patients suffering medial

osteoarthritis of the knee in combination with varus alignment, were formulated.

In this chapter, the previous chapters are summarized and an attempt is made to

answer the research questions.

In chapter 1, a general introduction, background and aims of the thesis are formulated.

The treatment of medial osteoarthritis of the knee includes a wide spectrum of

approaches, e.g. pharmaceutical, physiotherapy, bracing, and surgical treatment.

Many of these treatments relieve pain and increase function. However, not all of them

change the course of the disease. Because of the progressive nature of the disease

and because a varus malalignment will lead to an ongoing unfavourable mechanical

loading of the medial compartment, re-aligning the knee joint is important to obtain

significant relief from the complaints. Bracing to unload the medial compartment and

high tibial osteotomy are treatments to obtain this realignment. In this thesis several

aspects of these treatments for patients with medial osteoarthritis of the knee and

varus deformity have been studied.

1. What is the effect of valgus bracing in patients with medial compartment

osteoarthritis of the knee and can this be explained by changes in gait?

In chapter 2 a new valgus brace was evaluated in fifteen patients with medial

osteoarthritis of the knee and a varus leg axis. Significant improvements of pain and

function were found after six weeks of brace treatment. Because of the small number of

patients and because we did not use an alternative to the brace as a control, these

results should be interpreted cautiously. However, these findings were consistent with

results presented in previous studies with this and other braces. Gait analysis showed

that the brace has a tendency to lower the peak varus moment about the knee.

This effect was more profound at higher initial varus angles of the knee. Furthermore,

a small decrease of knee extension at the end of the swing phase and an increase

of walking velocity occurred when the brace was worn. Whether the new hinge

construction introducing an inflatable air chamber that has been incorporated in

this brace is responsible for the changes in the gait cycle or whether this is a general

effect of valgus producing hinged knee braces remains unclear because in the present

study no comparisons were made with other braces. Longer follow up of clinical

assessment and gait analysis are necessary to reveal whether the effects of

brace treatment found in this study persist. Using gait analysis studies to assess

the working mechanisms of brace treatment will enable objective evaluation of brace

treatment and should permit improved brace design.

2. What are the differences in accuracy and in postoperative stability between

closed and open wedge high tibial osteotomy?

In chapter 3 we analyzed the difference in angle correction accuracy and initial stability

between open-wedge and closed-wedge tibial valgus osteotomy in a cadaver study.

A correction of 7º was planned. After performing high tibial osteotomies on five, fresh

frozen pairs of human cadaver lower limbs (one limb received a CWO, the other an

OWO) were subjected to an increasing cyclic axial load until failure during which

the relative displacement of the bony segments was determined with roentgen stereo-

photogrammetric analysis (RSA). No significant differences in rotations and translations

in any direction were found in the displacement data. Further, no significant correlation

between bone mineral density (BMD) and the moment of failure was found.

This study revealed that both methods gave an acceptable correction within the wide

variation of postoperative correction angles. There was a tendency for overcorrection

in the closed wedge osteotomy group but no significant difference was found.

There was no difference in initial stability between the closed and the open wedge

osteotomy with a rigid locked plate fixation. Part of the relatively wide variation in

correction angle found in this study may be due to the fact that the angle for the

required correction is determined by the height of the medial opening and the length

of the osteotomy. The highly sensitive RSA which is extremely precise can determine

the correction angles in three dimensions obtained by the high tibial osteotomy and

revealed that the desired correction angle was not always obtained.

The use of angle stable implants in both groups lead to perfect postoperative stability.

However, this study concerned a small number of knees, and the results showed a

wide variation (large standard deviation). Furthermore, the outcomes may have been

the result of the biomechanical in vitro set-up, and therefore, the results can not be

unconditionally extrapolated to a clinical practice.

112

Chapter 8

113


The correction angles we found for each group in this study will probably be sufficient

in clinical practice. However, to obtain certainty about the clinical significance of

differences between the closed and open wedge osteotomy, a randomized clinical

needed to be conducted.

3. What are the differences between closed and open wedge high tibial

osteotomy in patients with respect to correction accuracy, collateral laxity

and clinical outcome?

In chapter 4 the results of a randomized clinical trial are presented. In 50 patients with

symptomatic osteoarthritis of the medial compartment of the knee were randomised

between an open and a closed wedge osteotomy. In both groups angle stable plate

fixation was used. The clinical results of high tibial osteotomy according to the open

wedge osteotomy and closed wedge osteotomy were compared.

Clinical and radiological assessments were performed preoperative and after one year.

Postoperative hip-knee-ankle (HKA) correction angles were monitored on standing leg

X-rays. The effect of high tibial osteotomy on collateral laxity of the knee was measured

with a specially designed varus-valgus device. The WOMAC osteoarthritis index, the

modified knee society score (KS) and visual analogue scales (VAS) were used to

assess symptoms of osteoarthritis, function, pain and patient satisfaction.

At one year follow-up we found accurate corrections in both groups and the planned

correction angles had been achieved. No loss of correction was observed.

Furthermore, the medial collateral laxity and the patellar height significantly decreased

after the open wedge osteotomy. Significant improvements of WOMAC and KS scores

were found in both groups. All patients had significantly less pain and were significantly

satisfied with the results. The duration of the surgery was significant longer in the

closed wedge group, and complications were more frequent in this group.

Both techniques led to good and comparable clinical results. In conclusion, the choice

whether to perform an open or a closed wedge osteotomy may be made on the basis

of preoperative patellar height or concomitant collateral laxity.

Longer follow-up is essential to obtain information about the ongoing clinical results in

both groups.

4. Does the incorporation and remodelling of ß-TCP bone substitute in open

wedge tibial osteotomy in patients occur similarly to that in animals?

In chapter 5, a histological study is described which reports on the bone biopsies from

16 patients (17 biopsies) treated with open wedge high tibial osteotomies for medial

knee osteoarthritis. The open wedge osteotomies were filled with a wedge of

osteoconductive beta tricalcium phosphate (ß-TCP) ceramic bone replacement.

Biopties were taken at time of removal of osteosynthesis material at follow-up times

ranging between 6-25 months. The null-hypothesis was that the incorporation and

remodelling process occurs similarly as to that in animals. The histological analysis

showed a good resorption of the ß-TCP with complete incorporation and remodelling

into new bone. The different phases as described in animal studies were found.

A correlation was found between histological findings and radiological assessment.

ß-TCP appeared to be a bone replacement material with optimal biocompatibility,

resorption characteristics and bone conduction properties for the clinical use. However,

to make a thorough comparison to animal studies, biopsies would have to be taken

earlier during the healing process In patients the fixation material can only be removed

after sufficient bone consolidation, otherwise possible loss of correction might occur.

Further research will be necessary to obtain more detailed information on the various

phases of incorporation of ß-TCP in human bone though this will be difficult because of

the medical and ethical limitations.

5. What are the effects of high tibial osteotomy on patellar tracking?

Chapter 6 describes an in vitro biomechanical study to analyze the effect of open and

closed wedge osteotomy on patellar tracking. Using an inventive experimental set-up, we

studied the 3D dynamic patellar tracking in ten cadaver knees before and after valgus

high tibial osteotomy. In each specimen, following a protocol it was possible to perform

corrections of 7º and 15º of valgus with an CWO and then 7° and 15° with a OWO.

Patellar height increased significantly after the CWO and decreased after the OWO.

Both open and closed wedge osteotomy resulted in significant changes in the tilt and

rotation of the patellar tracking when compared to the initial condition. We also found

significant differences between the two techniques. Valgus high tibial osteotomy

increased the medial patellar tilt and reduced the medial patellar rotation. These effects

were more profound after the OWO. No significant differences were found for

114

Chapter 8

115


medial-lateral patellar translation. These observations can be taken into consideration

when deciding which technique to perform in a patient with medial compartment

osteoarthritis of the knee. In the future, the effect of the kinematic changes in the

patellofemoral joint after high tibial osteotomy in terms of clinical presentation and

radiographic changes after long term follow-up have to be determined.

6. Can lowering of the patella which accompanies open wedge high tibial

osteotomy be prevented?

To prevent patella infera in open wedge high tibial osteotomy, a new operation technique

was developed. This is presented in chapter 7. Instead of a proximal tibial tuberosity

osteotomy (PTO), a distal osteotomy (DTO) was performed with the tuberosity being

fixed with one screw to the tibia. The results of two case series were compared.

The first 17 patients receiving a DTO were evaluated and compared to results of

20 patients with open wedge high tibial osteotomy with the standard proximal tuberosity

osteotomy. Distal tuberosity osteotomy in open wedge high tibial osteotomy appears

to be effective in preventing patella infera. A weak point in our study is the formation of

the experimental and the control group. The control patients were selected based on

the availability of the appropriate preoperative radiographs. Results from a randomised

controlled trial are required to ascertain whether the difference between the two groups

can be attributed to the operation technique. However, based on the results of

this study, we advise the use of the distal tuberosity osteotomy technique for those

patients for which higher valgus corrections are indicated (>10°) and for patients with

pre-existing patella infera.

Closing remarks and future directions

Medial osteoarthritis of the knee combined with varus deformity is a frequently

encountered medical problem in daily orthopaedic practice. For patients the progressive

course of this disease will have significant consequences in their socio-economical,

recreational and sports activities.

The treatment of varus deformity by re-aligning the knee can be obtained by means of

a valgus brace or high tibial osteotomy. Unloading braces come in all shapes and

sizes. Patient-compliance forms a recurrent problem with brace treatment. Especially

the more rigid unloading braces have been poorly accepted by the patients because

of discomfort, adverse effects or little effect at all. In the future, well conducted controlled

trials with long term follow-up to investigate the working mechanism of unloading braces

and underlying gait changes will be necessary. Only after such studies can clinical

questions about the actual effectiveness be answered. This will clarify proper treatment

decisions. Gait analysis research methods as described in this thesis can be utilised

when performing further research. For example, different types of braces could be

compared. Furthermore, it would be interesting to compare gait analysis before and

after high tibial osteotomy in patients who have been treated pre-operatively with an

unloading brace.

Surgical interventions, including joint replacement and osteotomy, reverse the progress

of osteoarthritis and provide long-term improved function and pain relief.

During the last few years the open wedge high tibial osteotomy has gained in popularity

over the closed wedge technique. While the results are dependent of the

preoperative diagnosis and the surgeon’s skill and experience, the clinical results

of both techniques seem to be generally the same.

Both techniques have advantages and disadvantages. The closed wedge technique

has the benefit of primary stability and progressive bone healing. However, it may lead

to deformity of the tibial head with potential problems for future total knee placement.

The osteotomy of the fibula and its co-morbidity form another disadvantage.

The open wedge osteotomy is a more straightforward technique which does not involve

the fibula. Often the proximal medial tibial head is deformed in varus knees.

With the open wedge osteotomy, the shape of the medial tibial head is restored.

As the clinical results of high tibial osteotomy depend largely on the correction angle

which has been obtained, the use of angle stable implants should be mandatory,

especially for open wedge high tibial osteotomy. In this thesis, angle stable fixation

showed no loss of correction in either closed or open wedge high tibial osteotomies.

In future comparative study designs, it is essential to use the same fixation material

in both groups. Furthermore, randomized clinical trials are necessary to investigate

the differences in long-term clinical outcome, using total knee arthroplasty as the

end-point.

116

Chapter 8

117


Further research should also compare high tibial osteotomy with a knee athroplasty

using the unicompartmental knee prosthesis. And last but not least, it is essential that

clear patient criteria be established so that the most beneficial clinical outcome can

be obtained.

The recent evolutions in cartilage repair procedures are promising and will possibly

prove to be useful in the treatment of osteoarthritis of the knee. However, at present

no conclusive long-term data support this premise. Furthermore, when malalignment

is present, it is probably beneficial to combine cartilage repair with high tibial osteotomy

to unload the repaired joint surface.

With the revival of the open wedge technique, the high tibial osteotomy seems to have

reclaimed its position in the spectrum for treatment of varus osteoarthritis of the knee.

The large numbers of open wedge procedures recently performed worldwide contain

valuable information on clinical outcome, possible adverse events and pitfalls.

The biomechanical set-ups which were designed for the research reported in this thesis,

are extremely suitable for further future osteotomy research. For example, correction

accuracy, stability and effects on patellofemoral kinematics of supracondylar femur

osteotomies can be studied using these methods.

The results found in studies reported in this thesis clearly show the effects of high

tibial osteotomy on patellar height and tracking. While these effects may be of minimal

clinical relevance, for extensive open wedge corrections the effects may be quite

large and lead to adverse events with respect to the patellofemoral joint (e.g. pain,

maltracking or even patellar (sub)luxation). On the other hand, patellofemoral

complaints may subside after high tibial osteotomy. Furthermore, the (re-) tensioning

of the medial collateral ligament after open wedge osteotomy may lead to unfavourable

higher contact pressures in the medial compartment of the knee. Even so, pre-existent

medial instability can be reduced by tensioning the medial collateral ligament.

Surgeons should be aware and understand these effects in their choice for one of the

high tibial osteotomy techniques.

Finally, the straightforward surgical technique and the possibility of intra-operative

variation of the amount of valgus and slope correction are big advantages of the open

wedge osteotomy. Moreover, the potential treatment of medial collateral (pseudo-)

laxity can be beneficial. Furthermore, the possibility of preventing patellar height

and tracking changes by combining the open wedge with the distal tuberosity

osteotomy technique is another advantage. These aspects make the open wedge

high tibial osteotomy with angle stable internal fixation a very powerful treatment option

for patients with medial osteoarthritis of the knee.

118

chapter 9Samenvatting, beantwoording van de

onderzoeksvragen en afsluitende opmerkingen

120

Chapter 9

121

Samenvatting, beantwoording van de onderzoeksvragen en afsluitende opmerkingen

Samenvatting en beantwoording van de onderzoeksvragen

In de vorm van zes onderzoeksvragen betreffende de behandeling van patiënten met

varus gonarthrose, zijn de doelstellingen van dit proefschrift geformuleerd in hoofdstuk 1.

In deze samenvatting worden de verschillende hoofdstukken samengevat en zal er

getracht worden deze vragen te beantwoorden.

Hoofdstuk 1 bevat een algemene introductie, de achtergronden en de doelstellingen

van dit proefschrift. De behandeling van gonarthrose behelst een breed spectrum aan

mogelijkheden, e.g. medicamenten, fysiotherapie, brace behandeling en chirurgische

interventies. Deze behandelingen verlichten veelal de pijn en verbeteren de functie,

maar zullen niet allen het voortschrijden van de artrose voorkomen. Herstellen van het

alignement van de knie is belangrijk voor significante vermindering van klachten.

Behandelingen in de vorm van een ontlastende valgiserende brace of de valgiserende

tibiakop osteotomie hebben dit als doel. In dit proefschrift worden verschillende aspecten

van deze behandelingen van patiënten met varus gonarthrose nader bestudeerd.

1. Wat is het effect van behandeling met een valgus brace bij patiënten met

artrose van het mediale compartiment van de knie en kan dit verklaard worden

op grond van veranderingen in het looppatroon ?

Patiënten met arthrose van het mediale compartiment van de knie kunnen conservatief

behandeld worden met een valgiserende brace. Om de goede klinische ervaringen

met een nieuwe valgiserende knie brace nader te onderzoeken is een prospectieve

ganganalyse studie uitgevoerd naar de effecten van de Softec OA brace (Bauerfeind).

Deze studie staat beschreven in hoofdstuk 2. Vijftien patiënten, met een varus beenas

en mediale gonarthrose, werden geïncludeerd in de studie. Voor en na brace

behandeling gedurende zes weken, werden de WOMAC arthrose index en VAS

pijnscores afgenomen. Daarnaast werd een ganganalyse verricht voor aanmeten en

dragen van de brace en na het dragen van de brace gedurende zes weken.

De ganganalyse bestond uit het simultaan meten van de externe knie momenten in

het frontale vlak, krachten data en 3D kinematische data. De grondreactie krachten

werden gemeten met een in de vloer gelegen krachten platform. De 3D posities van

de reflecterende markers werd geregistreerd met behulp van een 6-camera motion

analysis system. Voor de plantaire druk metingen en de “foot progression angle” (FPA)

werd gebruik gemaakt van een drukplatform. De lopende band werd gebruikt om

gewrichtshoeken en range of motion (ROM) te meten met behulp van goniometers.

Verder zijn staplengte en stapfrequentie gemeten.

De klinische resultaten lieten een significante verbetering zien van de klinische scores

na zes weken de brace gedragen te hebben. Deze resultaten zijn echter gebaseerd op

een korte follow-up en bij een relatief kleine groep zonder dat er een controle brace is

gebruikt. Ganganalyse liet zien dat de brace een tendens vertoonde in het verlagen

van het peak varus moment rond de knie en dat dit effect meer uitgesproken was bij

een grotere varus deformiteit. Verder was er een kleine afname van de eindstrekking

van de knie aan het einde van de swingfase en een toename van de loopsnelheid

gerelateerd aan het dragen van de brace. Van belang is de vraag of een valgiserende

knie brace daadwerkelijk het varus alignement van het been vermindert of dat de brace

een toename in varus tijdens de mid-standfase verhindert. Aangezien het peak varus

moment zich juist aan het begin en aan het einde van de standfase bevindt, is het

maar de vraag of dit de juiste parameter is om te meten om het effect van valgiserende

braces aan te tonen. Mogelijk spelen ook andere factoren, zoals gang-adaptaties, een

rol bij het ontlasten van het mediale compartiment. Langere follow up van klinische

resultaten en ganganalyse moet aantonen of deze effecten persisteren. De analyse van

de werkingsmechanismen van brace behandeling met ganganalyse studies maakt

objective evaluatie van de effecten van brace behandeling mogelijk en kan toekomstige

brace ontwerpen verbeteren.

2. Wat is het verschil in nauwkeurigheid en postoperatieve stabiliteit tussen de

gesloten en open wig tibiakop osteotomie?

De valgiserende tibiakop osteotomie bij varus gonarthrosis kan bestaan uit een lateraal

gesloten wig osteotomie of een mediaal open wig osteotomie. In een biomechanische

kadaver RSA studie zijn beide operatiemethoden vergeleken voor wat betreft de

nauwkeurigheid in correctie hoek en initiële postoperatieve stabiliteit. Deze studie staat

beschreven in hoofdstuk 3. Vijf paar vers bevroren humane kadaver knieën werden

gebruikt en 7º correctie osteotomieën werden verricht. Er werd gebruik gemaakt van

de open en de gesloten techniek. De osteotomieën werden gefixeerd met hoekstabiele

interne fixatie. Vervolgens werden de knieën onderworpen aan een toenemende

122

Chapter 9

123


dynamische belasting waarbij de relatieve verplaatsing van de botstukken werd gemeten

met röntgen stereophotogrammetrische analyse (RSA).

Er werden geen verschillen gevonden in vlakken van rotatie en translatie. De RSA data

betreffende de verplaatsing van de botstukken onder invloed van de belasting lieten

geen statistische verschillen zien tussen de gesloten en de open wig osteotomie.

Middels DEXA metingen werd de botdichtheid van alle preparaten bepaald, maar er

werd geen significante correlatie gevonden tussen botdichtheid en verplaatsing van de

botstukken of het moment van falen.

Beide technieken gaven een acceptabele correctie geven met een hoge variatie van

postoperatieve correctie hoeken. Er is een tendens naar overcorrectie van de geplande

wig hoek bij de gesloten wig osteotomie, maar geen significant verschil kon worden

aangetoond. Er is geen verschil in initiële stabiliteit tussen gesloten wig en open wig

osteotomie met hoekstabiele implantaten. Dit onderzoek betrof een klein aantal knieën

en de resultaten hadden een grote variatie en grote standaard deviaties. Daarnaast zijn

de uitkomsten grotendeels afhankelijk van de biomechanische in vitro setting.

Daarom kunnen de resultaten niet eenvoudig worden geëxtrapoleerd naar de klinische

praktijk. De bereikte correctie hoeken bij zowel de gesloten als de open wig groep in

deze studie zijn waarschijnlijk toereikend in de klinische praktijk. Er is behoefte aan

gerandomiseerd klinisch onderzoek naar het verschil tussen beide osteotomie technieken.

3. Wat zijn de verschillen tussen de gesloten en open wig tibiakop osteotomie

voor wat betreft de correctie nauwkeurigheid, de collaterale stabiliteit en de

klinische resultaten?

Hoofdstuk 4 beschrijft een prospectieve gerandomiseerde klinische trial die is uitgevoerd

in twee ziekenhuizen. De patiënten werden gerandomiseerd voor een van de twee

operatie technieken: de lateraal gesloten wig en de mediaal open wig valgiserende

tibiakop osteotomie. Vijftig patiënten met symptomatische mediale gonarthrose werden

geïncludeerd en gerandomiseerd voor een van beide behandelingen zodat twee

groepen van 25 patiënten ontstonden. In beide technieken is een hoekstabiele

plaat gebruikt voor de fixatie van de osteotomie. Bij de open wiggen is een tricalcium-

phosphaat (TCP) wig geplaatst. In beide gevallen bestond de nabehandeling uit

aantippend belast mobiliseren met krukken en onbelast oefenen.

Uitkomstmaten waren nauwkeurigheid van correctie en het effect op de collaterale

stabiliteit van de knie. Daarnaast is vergeleken voor wat betreft klinische resultaten

(WOMAC en VAS pijnscores) operatieduur en complicaties. Na 1 jaar follow-up is de

geplande en de bereikte correctie vergelijkbaar voor beide technieken. Er werd geen

correctie verlies gezien. Bij de open wig osteotomie werd een afname gevonden van

de mediale collaterale laxiteit van de knie, waarschijnlijk als gevolg van het opspannen

van de mediale structuren. Daarnaast trad er een significante distalisatie op van de

patella bij de open wig osteotomie. Verder was er sprake van een vergelijkbare

significante verbetering van de klinische scores voor beide technieken. De operatie

duur van de gesloten wig osteotomie was significant langer, evenals de complicatie

frequentie. Beide technieken leiden tot goede en vergelijkbare klinische resultaten.

De keuze voor een open of een gesloten wig osteotomie zou gebaseerd kunnen zijn

op de preoperatieve patella hoogte of bijkomende collaterale laxiteit. Langere follow-up

is noodzakelijk om aan te tonen of verschillen optreden tussen beide technieken wat

betreft klinische scores en late complicaties.

4. Verloopt de bot-incorporatie en remodelering van ß-TCP botvervanger bij de

open wig tibiakop osteotomie bij patiënten het zelfde als in proefdieren?

In patiënten is het niet gemakkelijk de incorporatie en botgenezing te beoordelen op

standaard röntgenfoto’s. In eerder onderzoek werd een radiologische classificatie

ontwikkeld die de verschillende stadia van incorporatie en remodelering van ß-TCP

beschrijft. Histologische data zijn echter niet bekend. Een histologische studie

werd verricht naar de incorporatie, resorptie en remodeling van ß-TCP. Hiertoe zijn

16 patiënten (17 osteotomieën) geïncludeerd. Deze studie staat beschreven in hoofd-

stuk 5. Deze patiënten hadden allemaal mediale compartiments gonarthrose, waarvoor

zij een open wig tibiakop osteotomie ondergingen. De geopende osteotomie werd

opgevuld met een ß-TCP wig. Ten tijde van het verwijderen van het osteosynthese

materiaal na verschillende follow-up duur (6-25 maanden) werden biopten genomen

van de tibiakop ter plaatse van de ß-TCP wig. De biopten werden onderzocht op

resorptie, incorporatie en bot remodelering van de ß-TCP wig. De hypothese van de

studie was dat de incorporatie en remodelering hetzelfde patroon zouden laten zien als

in proefdieren. Histologie toonde een goede resorptie van de ß-TCP met een complete

incorporatie en remodelering in nieuw bot. De verschillende fases zoals beschreven in

proefdierstudies werden gevonden. Een correlatie tussen de histologische bevindingen

124

Chapter 9

125


en de radiologische classificatie bleek te bestaan. Concluderend, de ß-TCP wig blijkt

een botvervanger met optimale biocompatibiliteit, goede resorptie en osteoconductieve

eigenschappen voor klinisch gebruik. Medisch ethische bezwaren maken het nemen

van biopten in eerdere fasen van de incorporatie onmogelijk.

5. Wat zijn de effecten van de tibiakop osteotomie op het de patella-sporing?

De valgiserende tibiakop osteotomie kan veranderingen in patella hoogte veroorzaken,

afhankelijk van de operatie techniek, de grootte van de correctie en het postoperatieve

beleid. Veranderingen in patella hoogte kunnen leiden tot postoperatieve complicaties,

maar er is weinig informatie over de effecten op de dynamische patella kinematica na

een tibiakop osteotomie. Daarom is er een biomechanische kadaver studie uitgevoerd

naar het effect van de open en gesloten wig osteotomie op de patella sporing.

Deze studie staat beschreven in hoofdstuk 6. In deze studie is de 3D dynamische

patella sporing bestudeerd, in tien kadaver knieën, voor en na een valgiserende

tibiakop osteotomie. Met behulp van een speciaal ontwikkeld frame, konden in elke

kadaver knie, correcties worden verricht van 7º en 15º valgus volgens zowel de open

als de gesloten wig techniek. Zowel de open als de gesloten wig osteotomie gaven

significante veranderingen van de patella sporings parameters tilt en rotatie.

We vonden significante verschillen tussen de open en gesloten wig osteotomie.

De valgiserende tibiakop osteotomie gaf een toename van de mediale patella tilt en

een afname van de mediale patella rotatie. Door de verplaatsing van de tuberositas

treedt een verandering op in de trekkrachten van de patellapees en dientengevolge de

beschreven veranderingen in de stand en sporing van de patella. Deze effecten waren

meer uitgesproken bij open wig techniek. Er werden geen verschillen gevonden in het

effect op de mediale-laterale translatie. De patella hoogte nam significant toe bij de

gesloten wig osteotomie. Bij de open wig osteotomie trad een significante laagstand

van de patella op. Van belang is het de observaties uit deze studie in het achterhoofd

te houden bij de keuze voor een open of een gesloten wig osteotomie.

Toekomstig onderzoek moet uitwijzen wat de klinische en radiologische implicaties zijn

van deze effecten op de patella sporing op langere termijn na een open of gesloten

wig valgiserende tibiakop osteotomie.

6. Kan de patella laagstand die optreedt na een open wig tibiakop osteotomie

worden voorkomen?

Bij de valgiserende mediaal open wig osteotomie ter behandeling van mediale

compartiments gonarthrose zal een distalisatie optreden van de tuberositas tibiae.

Laagstand van de patella na mediaal open wig tibiakop osteotomie kan leiden tot

patellofemorale klachten en moeilijkheden bij een eventuele totale knie prothese

plaatsing in de toekomst. Ter voorkoming van distalisatie van de patella, werd een

nieuwe techniek ontwikkeld. Dit staat beschreven in hoofdstuk 7. In plaats van een

proximale tuberositas osteotomie (PTO), is gebruik gemaakt van een distale

tuberositas osteotomie (DTO). Hierbij wordt de tuberositas tibiae losgezaagd naar

distaal. Bij openen van de wig blijft de tuberositas nu op zijn oorspronkelijke plaats,

zodat geen distalisatie van de patella optreedt. De tuberositas wordt gefixeerd met een

schroef. De eerste ervaringen met de DTO bij 17 patiënten zijn geëvalueerd en

vergeleken met een groep van 20 patiënten waarbij een PTO werd verricht.

Ter bepaling van de patella-hoogte werd bij alle patiënten de Caton index (CI) gemeten

op de pre- en zes weken postoperatieve laterale knie röntgenfoto’s. In beide groepen

werden de pre- en postoperatieve CI vergeleken met de gepaarde t-toets. In de PTO

groep trad een significante vermindering op van de patella-hoogte. In de DTO groep

was er geen essentiële verandering van de patella-hoogte. Er werd een relatie

gevonden tussen de correctiehoek en de mate van vermindering van de CI bij PTO.

Er gingen twee pitfalls gepaard met deze nieuwe techniek: een fractuur van de

tuberositas als gevolg van onvoldoende dikte van het fragment en verkeerde

schroefplaatsing in de osteotomie. De lengte van de osteotomie is ook van belang

om voldoende overlap en ruimte voor de schroef te bewerkstelligen, voornamelijk bij

de grotere correcties. De distale tuberositas osteotomie kan laagstand van de patella

voorkomen en wordt geadviseerd bij open wig valgiserende tibiakop osteotomieën

met een correctie van meer dan 10º, of bij preëxistente patella infera.

126

Chapter 9

127


Afsluitende opmerkingen en toekomstig onderzoek

Mediale compartiments arhrose van de knie in combinatie met een varus malalignement

is een veel voorkomend probleem in de dagelijkse orthopedische praktijk. Voor de

patiënt zal de progressief verlopende aandoening aanzienlijke consequenties hebben

voor zijn of haar activiteiten tijdens werk, recreatie en sport.

De behandeling van de varus stand kan plaatsvinden door middel van een valgiserende

brace of een tibiakoposteotomie. Unloader braces zijn er in alle soorten en maten.

Therapie trouwheid vormt een probleem bij brace behandeling. Vooral de meer rigide

valgiserende braces worden matig verdragen door de patiënt vanwege te weinig

draagcomfort, drukplekken of beperkt effect. In toekomstig onderzoek is er behoefte

aan goed opgezette gecontroleerde studies met lange termijn follow-up om de

werkingsmechanismen en de gangadaptaties van deze braces nader te onderzoeken.

Dit moet er toe leiden dat klinische vragen betreffende de effectiviteit beantwoordt

worden en dat behandel-indicaties duidelijker worden. De ganganalyse onderzoeks-

methode zoals beschreven in dit proefschrift is zeer geschikt voor verder toekomstig

onderzoek. Bijvoorbeeld om verschillende braces met elkaar te vergelijken. Verder zou

het interessant zijn om ganganalyse voor en na een tibiakop osteotomie te vergelijken

met ganganalyse bij dezelfde patiënten met pre-operatief brace gebruik.

Chirurgische ingrepen, inclusief gewrichtsvervangende behandeling en osteotomie,

stoppen de progressie van arthrose en leiden tot verbeterde functie en pijn verlichting

op lange termijn. Op dit moment is er een tendens te zien van een groeiende

populariteit van de open wig tibiakop osteotomie ten opzichte van de gesloten wig

osteotomie. Afhankelijk van de indicatiestelling, de chirurgische vaardigheden en

ervaring, lijken de klinische resultaten van beide technieken vergelijkbaar te zijn.

Beide technieken hebben hun voor- en nadelen. De gesloten wig osteotomie heeft het

voordeel van stabiel direct bot-op-bot contact, met een gunstige uitgangssituatie voor

de bot heling. De eventuele plaatsing van een totale knieprothese in de toekomst kan

echter bemoeilijkt worden door de opgetreden deformiteit en het botverlies van de

tibiakop. Daarnaast vormt de met mogelijke co-morbiditeit gepaard gaande fibula

osteotomie een nadeel van de gesloten wig osteotomie. De open wig osteotomie is

een betrekkelijk eenvoudige operatie zonder de nadelen van een fibula osteotomie.

Omdat de klinische resultaten van de tibiakoposteotomie voor een groot deel

afhankelijk zijn van de bereikte correctie, zou het gebruik van hoekstabiele implantaten

de gouden standaard moeten zijn, voornamelijk bij de open wig osteotomie. Bij zowel

de gesloten als de open tibiakoposteotomie werd geen correctieverlies gezien met

hoekstabiele plaatfixatie. Het is daarom essentieel dat in toekomstige vergelijkende

studies in beide groepen de zelfde hoekstabiele plaat wordt gebruikt. In de toekomst

zijn gerandomiseerde klinische trials nodig om de onderlinge verschillen verder te

onderzoeken evenals de klinische uitkomsten op de lange termijn met de totale

knieprothese als eindpunt.

Toekomstig onderzoek is ook nodig voor de vergelijking van de tibiakop osteotomie

met de hemi-knieprothese. Er is nog altijd behoefte aan heldere criteria voor een zo

goed mogelijk klinisch resultaat.

De recente ontwikkelingen in kraakbeen chirurgie zijn veelbelovend en mogelijk in de

toekomst een goed alternatief bij de behandeling van gonarthrose. Echter, er zijn op

dit moment geen conclusieve lange termijn data die dit ondersteunen. De tibiakop

osteotomie zal mogelijk gecombineerd dienen te worden met kraakbeen procedures

bij varus (of valgus) deformiteiten teneinde het aangedane gewrichtsoppervlak te

ontlasten.

Met de open wig osteotomie lijkt het erop dat de valgiserende tibiakop osteotomie zijn

plek heeft heroverd binnen het behandelspectrum van de varus gonarthrose.

De grote aantallen open wig osteotomieën die in de recente periode wereldwijd zijn

verricht vormen een bron van waardevolle informatie over klinische uitkomst mogelijke

complicaties en pitfalls. De biomechanische test modellen zoals beschreven in dit

proefschrift zijn zeer geschikt voor toekomstige osteotomie studies. De nauwkeurigheid

van correctie, de stabiliteit en de effecten op de patellofemorale kinematica van

bijvoorbeeld de supracondylaire femur osteotomie kunnen in deze opstellingen

bestudeerd worden.

In de recente literatuur en in dit proefschrift worden de effecten beschreven van de

tibiakoposteotomie op de hoogte en sporing van de patella. Vaak zullen deze effecten

weinig klinsche relevantie hebben, maar bij grote open wig correcties kunnen er

behoorlijke consequenties zijn voor het patellofemorale gewricht (e.g. pijn, laterale

sporing, (sub)luxatie van de patella). Aan de andere kant, patellofemorale klachten

128

Chapter 9

129

Publications

Rutten GJ, Gaasbeek RD, Franssen H.

Decrease in nerve temperature: a model for increased temporal dispersion.

Electroencephalogr Clin Neurophysiol. 1998 Feb;109(1):15-23.

Gaasbeek RDA, Sonneveld H, van Heerwaarden RJ, Jacobs WC, Wymenga AB.

Distal tuberosity osteotomy in open wedge high tibial osteotomy can prevent

patella infera: a new technique. Knee. 2004 Dec;11(6):457-61.

Gaasbeek RD, Rijnberg WJ, van Loon CJ, Meyers H, Feith R.

No local recurrence of enchondroma after curettage and plaster filling.

Arch Orthop Trauma Surg. 2005 Feb;125(1):42-5.

van Heerwaarden RJ, GaasbeekRDA, Plitz W. A new valgus brace for medial knee osteoarthritis.


Med-Orthop Technik 2005: 57-65.

Gaasbeek RDA, Welsing RT, Verdonschot N, Rijnberg WJ, van Loon CJ, van Kampen A.

Accuracy and initial stability of open- and closed-wedge high tibial osteotomy: a cadaveric RSA study.

Knee Surg Sports Traumatol Arthrosc. 2005 Nov;13(8):689-94.

Gaasbeek RDA, Toonen HG, van Heerwaarden RJ, Buma P.

Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in

patients. Biomaterials. 2005 Nov;26(33):6713-9.

Gaasbeek RD, Groen BE, Hampsink B, van Heerwaarden RJ,

Duysens JEJ. Valgus bracing in patients with medial compartment osteoarthritis of the knee.

A gait-analysis study of a new brace. Gait Posture 2007 Jun; 26(1):3-10.

Gaasbeek RD, Welsing RTC, Verdonschot N, van Kampen A.

The influence of open and closed high tibial osteotomy on dynamic patellar tracking:

a biomechanical study. Knee Surg Sports Traumatol Arthrosc. 2007 May 5; [Epub ahead of print]

kunnen ook verminderen na een tibiakoposteotomie. Daarnaast kan het opspannen

van de mediale collaterale band na een open wig osteotomie leiden tot ongewenste

verhoogde drukken in het mediale compartiment van de knie. Echter, preëxistente

mediale instabiliteit kan worden verminderd door dit zelfde mechanisme. Orthopedisch

chirurgen moeten zich bewust zijn van deze effecten bij het maken van een keuze voor

een van beide osteotomie technieken.

Tenslotte vormen de relatief eenvoudige techniek en de mogelijkheid om tijdens de ope-

ratie de valgus correctie en eventuele slope correctie te kunnen variëren, grote voordelen

van de open wig techniek. Daarnaast is er de mogelijkheid om mediale (pseudo-)laxiteit

te behandelen. De mogelijke combinatie van de open wig techniek met de distale tube-

rositas osteotomie ter preventie van patella laagstand en sporingsproblemen vormt een

ander voordeel. Deze eigenschappen maken de open wig osteotomie met hoekstabiele

fixatie tot een sterke keuze als behandeling voor patiënten met mediale gonarthrose.

130 131

Dankwoord

Dit proefschrift is het tastbare resultaat van een vruchtbare samenwerking van de

drie opleidingsziekenhuizen in regio Oost: het Rijnstate Ziekenhuis te Arnhem,

de Sint Maartenskliniek en het UMC St. Radboud te Nijmegen. Op alle drie locaties

is gewerkt aan de studies in dit boekje. Dit is het bewijs van de vele verschillende

klinische en wetenschappelijke disciplines die de assistent Orthopedie ter beschikking

staan tijdens zijn of haar opleiding in dit cluster. Vele mensen hebben een bijdrage

geleverd aan de studies in deze thesis. Enkele van hen wil ik graag in het bijzonder

bedanken:

Prof. Dr. A. van Kampen, mijn promotor. Beste Albert, toen ik je medio 2002 benaderde

betreffende de promotie mogelijkheden reageerde je gelijk enthousiast. De avondjes

met de “hele ploeg” bij jou thuis waren steeds zeer vruchtbaar en motiverend.

Tijdens mijn opleiding en ook als trauma-fellow heb ik naast wetenschappelijke ook

veel praktische vaardigheden van je geleerd. Vooral jouw onuitputtelijke drive voor het

vak, in combinatie met een gezonde dosis humor vormen voor mij een groot voorbeeld.

Dr. R.J. van Heerwaarden, mijn co-promotor. Beste Ronald, tijdens mijn opleiding in

de Sint Maartenskliniek is er een stevige basis gelegd voor dit boekje en dankzij jouw

volhardendheid en ongekende gedrevenheid is de missie geslaagd. Er waren snelle

successen en ook wat zwaardere bevallingen, maar uiteindelijk is het een mooi “kindje”

geworden. Ik hoop dat we nog veel samen zullen werken in de toekomst.

Dr. Ir. N.J.J. Verdonschot, mijn co-promotor. Beste Nico, jouw wetenschappelijk

verantwoorde input en biomechanische benadering waren van onschatbare waarde

voor deze thesis. De flexibele wijze waarop ik aanvankelijk als “buitenstaander” aan de

slag kon in het lab, en de laagdrempeligheid voor overleg heb ik zeer gewaardeerd.

Jij hebt het Orthopaedic Research Lab de laatste jaren wereldwijd op de kaart gezet,

en ik hoop dat toekomstige samenwerking mogelijk blijft.

Gaasbeek RD, Nicolaas L, Rijnberg WJ, van Loon CJM, van Kampen A.

Correction accuracy and collateral laxity in open versus closed wedge high tibial osteotomy

A one year randomizes controlled. J Bone Joint Surg Br. 2007 In revision

132 133

Dr. W.J. Rijnberg, mijn opleider. Beste Willaart, het idee om de open en de gesloten wig

tibiakop osteotomie met elkaar te vergelijken kwam uit jouw koker. Ik was een van jouw

eerste opleidings-assistenten en de wetenschappelijke trein kwam maar traag op gang.

Zoals blijkt uit dit proefschrift, heb je mij toch op het juiste spoor gezet. Hartelijk dank

voor de ruimte die mij tijdens mijn opleiding geboden is om dit onderzoek te doen.

Dr. C.J.M. van Loon. Beste Corné, als zeer efficiënte schrijver met een enorme output,

ben jij tijdens de eerste jaren van mijn opleiding, een drijvende kracht geweest.

Samen met jou heb ik het “recept” van dit boekje bedacht. Daarbij was het erg fijn dat de

nodige paden door jou al waren bewandeld. Je snelle beoordeling van de manuscripten

en je oprechte verbazing als een stuk geweigerd werd hebben mij enorm gesteund.

Dr. P. Buma. Beste Pieter, de vrij plotselinge en kortstondige samenwerking in het kader

van dit proefschrift heeft geleid tot een mooie publicatie. Ik realiseer mij terdege dat,

zonder jouw uitgemeten histologische expertise, dit nooit zover was gekomen.

Prof. Dr. J.E.J. Duysens. Beste Jaak, toen ik met mijn ganganalyse studie onder de arm

bij je langs kwam, was je gelijk enthousiast. Hartelijk dank voor de snelle en kritische

beoordeling van het manuscript en de perfecte formulering van de antwoorden voor de

reviewers.

Prof dr. A.C.H. Geurts, Prof dr. R.F.J.M. Laan, Prof dr. J.A.N. Verhaar, leden van de

manuscript-commissie, dank u voor uw tijd en de interesse.

Dhr. W.S.J. van de Wijdeven, Beste Willem, ik denk dat maar weinig mensen zich

realiseren aan hoeveel proefschriften jij je bijdrage hebt geleverd. Hartelijk dank voor je

praktische tips en tomeloze inzet bij het uitvoeren van de experimenten op het ORL.

Wilco Jacobs, Roy Welsing, Brieke Hampsink, Brenda Groen, Loes Nicolaas, medisch

studenten van het klinisch score station, alle patiënten, medewerkers van de klinieken,

poliklinieken en secretariaten, medewerkers van het ORL, allen zeer veel dank voor jullie

inspanningen. Patsy Anderson, bedankt voor de correctie van het Engels.

De onderzoeken en het grootste deel van het schrijfwerk van dit proefschrift hebben

plaatsgevonden tijdens mijn opleiding tot orthopedisch chirurg en mijn trauma

fellowship. Mijn opleiders, Dr. B.J. Dwars, Dr. A.B. Wymenga en Prof. dr. R.P.H. Veth,

Prof. dr. A. van Vugt, evenals alle stafleden van de opleidingsklinieken dank ik voor mijn

opleiding en voor de mogelijkheden om dit onderzoek voort te zetten.

Mijn paranimfen: Huub van der Heide en Jack van der Gragt. Huub, natuurlijk ben jij één

van mijn paranimfen. Dank je voor de enorme gastvrijheid tijdens de diensten in de

UMC tijd. Jack, daar staan we dan straks weer in rok, net als 16 jaar geleden. Wie weet

is er ooit tijd voor de derde keer...

Mijn schoonouders, pa en ma Mulder, jullie dank ik voor de ondersteuning en

enorme toewijding aan ons gezin. Thom en Marilou kunnen zich geen betere opa en

oma wensen!

Mijn zus, Pauline en haar mannen René, Laurens en Rutger, dank voor jullie steun

en hulp de afgelopen tijd.

Mijn ouders, pa en ma, mijn basis ligt bij jullie. Dank jullie voor de liefde en kansen

die jullie mij hebben gegeven. Aan jullie draag ik dit proefschrift op.

Lieve Anne-Marie, de zekerheid van jouw liefde en steun zijn voor mij een rustpunt

van waaruit alles mogelijk (b)lijkt. Op naar de volgende mijlpaal!

Thom en Marilou, jullie zijn de twee grootste cadeaus op aarde.

Nu is het verhaaltje uit. Maar we gaan nog lang niet slapen!

134 135

Curriculum Vitae

Robert Dick Alexander Gaasbeek werd geboren op 17 september 1969 te Zwolle.

In 1987 behaalde hij het VWO diploma aan de Thorbecke Scholengemeenschap

te Zwolle. Na een onbezorgde jeugd vertrok hij naar Utrecht. Daar werd in 1991

de studie Fysiotherapie afgerond aan de Internationale Academie voor Fysiotherapie

Thim van der Laan te Utrecht. Hierna volgde de studie Geneeskunde aan de

Universiteit van Utrecht. Tijdens deze studie was de auteur werkzaam als fysiotherapeut

en verrichtte hij wetenschappelijk onderzoek naar zenuwgeleiding bij de vakgroep

klinische neurofysiologie van het UMC Utrecht (begeleiding: Dr. H. Franssen).

Het artsexamen werd in 1997 behaald. Van 1997-1998 werkte hij als arts-assistent op

de afdeling orthopedie van het Onze Lieve Vrouwe Gasthuis te Amsterdam.

(opleider: Prof. dr. J.W. van der Eijken). In het kader van de opleiding tot orthopedisch

chirurg, werd de tweejarige vooropleiding heelkunde eind 1999 voltooid in het

Slotervaart Ziekenhuis te Amsterdam. (opleider: Dr. B.J. Dwars).

Op 1 januari 2000 werd gestart met de opleiding orthopedie in het Rijnstate Ziekenhuis

te Arnhem (opleider: W.J. Rijnberg). Van 2001 tot 2003 werden stages doorlopen in de

St. Maartenskliniek (opleider Dr. A.B. Wymenga) en in het UMC st. Radboud

(opleider: Prof. dr. R.P.H. Veth) te Nijmegen. Tijdens de opleiding werd op alle drie de

locaties gewerkt aan onderzoek dat tot dit proefschrift heeft geleid. De opleiding werd

eind 2004 afgerond.

Het jaar 2005 was hij als orthopedisch chirurg/trauma-fellow, werkzaam in het UMC

St. Radboud te Nijmegen (opleiders: Prof. Dr. A. van Kampen en Prof. dr. A.B. van Vugt).

Per 1 januari 2006 is de auteur werkzaam als orthopedisch chirurg in het Meander

Medisch Centrum te Amersfoort in associatie met J.B. van Lent, M.P.J. van der List,

H. Sonneveld, A.B. Stibbe, H.G.W. Vermeer en H.J.J Zwart. De auteur is getrouwd

met Anne-Marie en zij hebben twee kinderen: Thom en Marilou.

Hig

h T

ibial O

steoto

my Treatm

ent o

f varus o

steoarth

ritis of th

e knee R

ob

ert D. A

. Gaasb

eek

Uitnodiging

Voor het bijwonen vande openbare verdediging

van het proefschrift

‘High tibial osteotomy.Treatment of varus osteoarthritis

of the knee’

op vrijdag 21 september 2007om 10.30 uur in de Aula Major

van de Radboud UniversiteitComeniuslaan 2 te Nijmegen.

Receptie na afloop ter plaatse

Robert GaasbeekKruisweg 16bis3513 CT Utrecht

[email protected]

De Paranimfen Huub van der Heide, tel: 06-43001007


[email protected]

Uitnodiging

Graag nodig ik u en uw partner uit voor het feest ter gelegenheid van

mijn promotie

zaterdag 22 september 2007 vanaf 20.00 uur

“Oranjerie Landgoed Maarsbergen” Maarnse Grindweg 30 3953 LW Maarsbergen

tel. 0343-431 [email protected]

Paranimfen:Huub van der Heide, tel: 06-43001007


[email protected]







Documents

PDF hosted at the Radboud Repository of the Radboud ... · more reﬁned over time 3, 4. Furthermore, although the long term results of a total knee arthroplasty are good, a signiﬁcant