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1454 THE JOURNAL OF BONE AND JOINT SURGERY
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
R. W. Brouwer, S. M. A. Bierma-Zeinstra, T. M. van Raaij, J. A. N. Verhaar
From Erasmus Medical Centre, Rotterdam, The Netherlands
�
R. W. Brouwer, PhD, Orthopaedic SurgeonDepartment of OrthopaedicsMartini Hospital, PO Box 30033, 9700 RM Groningen, The Netherlands.
�
S. M. A. Bierma-Zeinstra, PhD, Biomedical ScientistDepartment of General PracticeErasmus Medical Centre, PO Box 1738, 3000 DR Rotterdam, The Netherlands.
�
T. M. van Raaij, MD, Orthopaedic Surgeon
�
J. A. N. Verhaar, PhD, Orthopaedic SurgeonDepartment of OrthopaedicsErasmus Medical Centre, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
Correspondence should be sent to Dr R. W. Brouwer; e-mail: [email protected]
©2006 British Editorial Society of Bone and Joint Surgerydoi:10.1302/0301-620X.88B11. 17743 $2.00
J Bone Joint Surg [Br]
2006;88-B:1454-9.
Received 7 February 2006; Accepted after revision 1 June 2006
A prospective, randomised, controlled trial compared two different techniques of high tibial
osteotomy with a lateral closing wedge or a medial opening wedge, stabilised by a Puddu
plate. The clinical outcome and radiological results were examined at one year.
The primary outcome measure was the achievement of an overcorrection of valgus of 4˚.
Secondary outcome measures were the severity of pain (visual analogue scale), knee
function (Hospital for Special Surgery score), and walking distance.
Between January 2001 and April 2004, 92 patients were randomised to one or other of
the techniques. At follow-up at one year the post-operative hip-knee-ankle angle was 3.4˚
(± 3.6˚
SD
) valgus after a closing wedge and 1.3˚ (± 4.7˚
SD
) of valgus after an opening wedge.
The adjusted mean difference of 2.1˚ was significant (p = 0.02). The deviation from 4˚ of
valgus alignment was 2.7˚ (± 2.4˚
SD
) in the closing wedge and 4.0˚ (± 3.6˚
SD
) in the
opening-wedge groups. The adjusted mean difference of 1.67˚ was also significant (p =
0.01).
The severity of pain, knee score and walking ability improved in both groups, but the
difference was not significant.
Because of pain, the staples required removal in 11 (23%) patients in the closing-wedge
group and a Puddu plate was removed in 27 (60%) patients in the opening-wedge group.
This difference was significant (p < 0.001).
We conclude that closing-wedge osteotomy achieves a more accurate correction with
less morbidity, although both techniques had improved the function of the knee at one year
after the procedure.
Deformity increases the risk of progression ofosteoarthritis of the knee.
1
Patients with osteo-arthritis of the medial compartment of theknee which is refractory to conservative treat-ment can be treated by a valgus high tibialosteotomy, and various techniques are avail-able. These include a closing-wedge osteotomy,an acute opening-wedge osteotomy, a domeosteotomy and a hemicallotasis progressiveopening-wedge osteotomy controlled by anexternal fixator.
2-6
Each option has individualadvantages and complications.
7-9
The mostimportant message which has emerged fromretrospective studies is that the appropriateselection of patients and the achievement andmaintenance of an adequate operative correc-tion are required for a successful out-come.
2,4,6,10
Loss of correction correlates withthe type of fixation, the degree of correctionand the time to bony union.
11,12
A randomised, controlled trial comparingthe hemicallotasis opening-wedge with aclosing-wedge technique showed that there
was a significantly greater loss of correctionafter closing-wedge osteotomy at follow-up atone year.
3
We therefore undertook a prospective, ran-domised study to compare lateral closing-wedge and medial opening-wedge techniques,in regard to achievement and maintenance ofadequate operative correction.
Patients and Methods
This randomised controlled trial was carriedout on 92 patients between January 2001 andApril 2004, after approval of the Ethics Com-mittee.
The criteria for inclusion in the study wereradiological evidence of medial compartmentosteoarthritis (OA) with medial joint pain andvarus malalignment. The grade of OA wasscored according to Ahlbäck
13
and measuredon standing short posteroanterior (PA) radio-graphs.
Malalignment was assessed using the hip-knee-ankle angle and the mechanical axis was
OSTEOTOMY FOR MEDIAL COMPARTMENT ARTHRITIS OF THE KNEE USING A CLOSING WEDGE OR AN OPENING WEDGE 1455
VOL. 88-B, No. 11, NOVEMBER 2006
obtained on a full-length standing radiograph from themechanical axis of the femur (from the centre of the femo-ral head, using Mose circles to the central point between thetibial spines), and the mechanical axis of the tibia (from thecentre of the tibial spines to the centre of the ankle). Weused lateral fluoroscopic control by superimposing the dor-sal aspect of the femoral condyles to ensure a perfectanteroposterior full-length exposure.
14
The criteria for exclusion were symptomatic OA of thelateral compartment, rheumatoid arthritis, range ofmovement of < 100˚, grade-3
15
collateral ligament laxity,history of fracture or previous open operation of thelower limb and a flexion contracture of > 10˚. Patientswith a contralateral high tibial osteotomy were excludedif the first knee had been included in this trial; thus, ifboth knees were symptomatic, only the first knee wasincluded.
After obtaining informed consent and baseline measure-ments, the patients were randomised by a computer-generated procedure in blocks of 16. Sealed envelopes con-tained the group assignment. An independent assistant notdirectly involved in the study opened these sealed envelopesafter enrolment of the patients by one of the four orthopae-dic surgeons (RWB, JANV and two who are not authors),who performed the operations. All surgeons were experi-enced with both techniques.
Treatment groups.
Randomisation was to one of the fol-lowing procedures: a) closing-wedge high tibial osteotomyand a plaster cylinder cast for six weeks post-operatively(Fig. 1) or b) opening-wedge osteotomy fixed using a Pudduplate (Arthrex; Naples, Florida) (Fig. 2). For the closing-wedge technique we used the Allopro (Zimmer; Winterthur,Switzerland) calibrated osteotomy guide to obtain accurateresection of bone. The common peroneal nerve was
Fig. 1
Radiograph of a closing-wedge high tibial osteotomy stabilised by twostaples.
Fig. 2
Radiograph of an opening-wedge high tibial osteotomy secured by aPuddu plate and ipsilateral iliac-crest bone graft.
1456 R. W. BROUWER, S. M. A. BIERMA-ZEINSTRA, T. M. VAN RAAIJ, J. A. N. VERHAAR
THE JOURNAL OF BONE AND JOINT SURGERY
exposed and retracted. Subsequently, the anterior part ofthe proximal fibular head representing the anterior part ofthe proximal tibiofibular syndesmosis, was resected. Theosteotomy was fixed with two staples. At the end of theprocedure a fasciotomy of the anterior compartment wasperformed to prevent compartment syndrome.
The extent of the opening-wedge depended on the lengthof the osteotomy and the diameter of the proximal tibiaand was calculated pre-operatively. The Arthrex instructionmanual provides a goniometric formula table, which givesthe extent of the opening-wedge for a specific correction.Additionally, the degree of correction performed during theprocedure was controlled by fluoroscopic assistance inwhich the centre of the hip and the centre of the ankle weremarked. If the opening-wedge was > 7.5 mm, the open gapwas filled with bone harvested from the ipsilateral iliaccrest. There was a second randomisation (in blocks ofeight) for treatment after the osteotomy, namely, with orwithout a plaster cast to determine whether a cast influ-enced the outcome.
In both techniques the goal was to achieve a correction of4˚ physiological valgus.
The patients were mobilised on the first post-operativeday and partial weight-bearing was allowed in all groups.After six weeks any plaster cast used was removed.
Initial evaluation.
Age, gender, body mass index (BMI), theseverity of medial and lateral OA (Ahlbäck score, 0 to 3),the aetiology of the OA, primary
versus
secondary (postmeniscectomy or previous cruciate ligament injury), varusmalalignment (hip-knee-ankle angle), severity of pain mea-sured by a visual analogue scale (VAS),
16
knee functionusing the Hospital for Special Surgery score (HSS score),
15
and walking distance (km) were scored pre-operatively.
Outcome assessments at one year.
The primary outcomemeasure was achievement of an overcorrection of the hip-knee-ankle angle by 4º of valgus. The differences betweenthe achieved valgus correction and the objective of 4º ofovercorrection was determined. In addition a dichotomousoutcome was an achievement of a valgus alignmentbetween 0º and 6º.
RWB, together with the surgeon who performed theoperations, made the pre-operative radiological measure-ments; post-operative measurements were made by RWBand TMR.
Secondary outcome measures were severity of pain(VAS), walking distance and the knee function score (HSS).The HSS score is divided into six categories (pain, function,range of movement, muscle strength, flexion deformity, andinstability) and consists of a questionnaire and a physicalexamination. The examination was undertaken by onenon-blinded assessor (RWB). Complications, further sur-gery including removal of hardware and morbidity fromthe donor site in the iliac crest were noted.
Sample size.
The sample size was calculated based on anexpected increase in the success rate from 60% for theclosing-wedge to 85% for the opening-wedge osteotomy. A
successful operative result was defined as achievement ofapproximately 4º of valgus alignment. To detect such a dif-ference with one-sided testing (
α
= 0.05 and a power of80%) 46 patients were required in each group.
Statistical analysis.
A multivariate linear regression methodwas used to analyse the impact of closing-
versus
opening-wedge osteotomy on post-operative alignment, the VASand HSS knee scores, walking distance and complicationsat follow-up at one year. A multivariate logistic regressionmethod was used for the dichotomous outcome measures.
All data were analysed according to an intention-to-treatprinciple, implying that all patients who were randomisedwere included in the analyses, and that they were analysedaccording to the group to which they had been allocated.
Gender, age, BMI and baseline values for the hip-knee-ankle angle, pain, HSS score, walking distance, medial OAof more than loss of joint space alone, concurrent OA of thelateral compartment, contralateral arthritis of the knee andipsilateral arthritis of the hip were considered as possibleconfounders and were included in the regression modelsonly if they changed the relationship between the depend-ent variable and the type of osteotomy by at least 10%. Thesame was done for the relationship between these describeddependent variables and the type of post-operative treat-ment (plaster
versus
no plaster) in the group with theopening-wedge technique. For patients who were lost tofollow-up or had further surgery during follow-up, the lastavailable measurement was used.
The SPSS program (SPSS Inc., Chicago, Illinois) was usedfor the statistical analysis and a p-value of 0.05 was consid-ered to be statistically significant.
Results
One patient (closing-wedge group) was lost to follow-up.Another (opening-wedge group) had a one year post-operativepain and HSS score, a standing standard short PA radiograph,but no full-length radiograph because of emergency treatmentof an unrelated condition, precluding his full radiological eval-uation. Both were included in the analysis.
The mean age of the patients was 50.2 years (21 to 67). Themean pre-operative hip-knee-ankle angle was 6.3º (0º to 14º)of varus and differed significantly (p < 0.05) between the twogroups. In the closing-wedge group the mean was 6.8º (2º to14º) of varus and in the opening-wedge group it was 5.7º (0ºto 12º) of varus (Table I).
A total of 47 patients had a closing-wedge osteotomy and45 an opening-wedge osteotomy. In the opening-wedge group22 patients had a plaster cast after operation and 23 did not.
Primary outcome measures
(Table II)
.
The power calculationwas based on one-sided testing, because we expected ahigher success rate in the opening-wedge group. However,because the raw data showed better results for the closing-wedge group, it was decided to test two-sided with a signi-fiance level of 0.05.
At follow-up of one year the mean post-operative hip-knee-ankle angle was 3.4º (
�
3.6º
SD
) of valgus in the clos-
OSTEOTOMY FOR MEDIAL COMPARTMENT ARTHRITIS OF THE KNEE USING A CLOSING WEDGE OR AN OPENING WEDGE 1457
VOL. 88-B, No. 11, NOVEMBER 2006
ing-wedge group and 1.3º (
�
4.7˚
SD
) of valgus in the open-ing-wedge high tibial osteotomy group. The adjusted meandifference of 2.12º (95% confidence interval (CI) 0.38 to3.86) was significant (p = 0.019).
The mean deviation from valgus alignment of 4˚ was 2.7˚(
�
2.4˚
SD
) in the closing-wedge group and 4˚ (
�
3.6˚
SD
) inthe opening-wedge group. The adjusted mean difference of1.67˚ (95% CI 0.42 to 2.92) was also significant (p =0.011).
The dichotomous outcome measure (achievement of avalgus alignment within 0˚ to 6˚) was achieved in 37 (79%)in the closing-wedge group and in 25 patients (56%) in theopening-wedge, resulting in an odds ratio for successfulovercorrection of 3.44 (95% CI 1.29 to 9.16) in the clos-ing-wedge compared with the opening-wedge group. Thisdifference was also significant (p = 0.01).
Secondary outcome measures
(Table II)
.
The mean pain(VAS) score decreased in both groups, 2.3 points after
Table I.
Baseline characteristics for the total series and separately for both groups
Total group (n = 92)
Closing-wedge osteotomy (n = 47)
Opening-wedge osteotomy (n = 45)
Women (%) 33 (
36
) 20 (
43
) 13 (
29
)Mean age in yrs (range) 50.2 (21 to 67) 50.8 (22 to 64) 49.6 (21 to 67)Mean body mass index in kg/m
2
(range) 28.1 (19 to 47) 28.0 (19 to 47) 28.2 (21 to 40)Mean visual analogue scale knee pain (range) 6.1 (2 to 10) 5.9 (2 to 10) 6.3 (3 to 9)Mean Hospital for Special Surgery knee score
15
(range) 71.2 (46 to 93) 70.9 (46 to 93) 71.5 (51 to 90)Mean walking distance in km (range) 3.0 (0 to 10) 2.9 (0 to 10) 3.1 (0 to 10)Mean hip-knee-ankle angle in ˚ (range)
*
6.3 (0 to 14) 6.8 (2 to 14) 5.7 (0 to 12)
†
Medial osteoarthritis more than joint space loss alone (%) 12 (
13
) 5 (
11
) 7 (
16
)Primary osteoarthritis (%) 36 (
39.1
) 19 (
40.4
) 17 (
37.8
)Left knee affected (%) 42 (
45.7
) 22 (
46.8
) 20 (
44.4
)Concurrent contralateral symptomatic knee osteoarthritis (%) 25 (
27.2
) 17 (
36.2
) 8 (
17.8
)Concurrent ipsilateral symptomatic hip osteoarthritis (%) 1 (
1.1
) 1 (
2.1
) 0 (
0
)Concurrent lateral compartment osteoarthritis (%) 8 (
9
) 5 (
11
) 3 (
7
)Concurrent patellofemoral osteoarthritis (%) 22 (
24.0
) 14 (
30
) 8 (
18
)
* positive angle represents varus alignment, negative angle represents valgus alignment† p < 0.05 for difference between the two groups
Table II.
Continuous outcomes (mean,
SD
) for closing-wedge osteotomy
versus
opening-wedge osteotomy at follow-up at one year
Closing-wedge osteotomy(n = 47)
Opening-wedge osteotomy(n = 45) Mean difference
*
95% confidence interval p-value
Primary outcomesHip-knee-ankle angle (˚)
†
-3.4 (3.6) -1.3 (4.7) -2.12 0.38 to 3.86 0.019Deviation from 4˚ of valgus 2.7 (2.4) 4.0 (3.6) -1.67 0.42 to 2.92 0.011
Secondary outcomesVisual analogue scale knee pain 3.6 (2.2) 3.6 (2.9) 0.05 -0.97 to 1.07 0.93Hospital for Special Surgery knee score 79.4 (12.0) 80.9 (13.5) -0.26 -5.68 to 5.17 0.93Walking distance (km) 4.6 (3.6) 5.3 (4.4) -0.01 -1.51 to 1.5 0.99
* adjusted for confounders (possible confounders tested: gender, age, body mass index, and baseline values for hip-knee-ankle angle, visual analoguescale knee score, Hospital for Special Surgery knee score, walking distance, medial osteoarthritis more than joint space loss alone, concurrent osteo-arthritis lateral compartment, concurrent contralateral symptomatic knee osteoarthritis, concurrent ipsilateral symptomatic hip osteoarthritis)† positive angle represents varus alignment, negative value represents valgus alignment
Table III.
Continuous outcomes (mean,
SD
) for plaster
versus
no plaster in the opening-wedge osteotomy after follow-up at one year
Plaster (n = 22)
No plaster(n = 23) Mean difference
*
95% confidence interval p-value
Primary outcomesHip-knee-ankle angle (˚)
†
-1.0 (5.3) -1.6 (4.0) -0.73 -2.2 to 3.7 0.62
Secondary outcomesVisual analogue scale knee pain 4.0 (2.8) 3.1 (3.0) 0.6 -1 to 2.2 0.46Hospital for Special Surgery knee score 78.0 (13.9) 84.1 (12.7) -3.4 -11.4 to 4.7 0.41Walking distance (km) 3.8 (3.3) 6.8 (4.9) -2.3 -4.6 to 0.1 0.07
* adjusted for confounders (possible confounders tested: gender, age, body mass index, and baseline values for hip-knee-ankle angle, visualanalogue scale knee score, Hospital for Special Surgery knee score, walking distance, medial osteoarthritis more than joint space loss alone,concurrent osteoarthritis lateral compartment, concurrent contralateral symptomatic knee osteoarthritis, concurrent ipsilateral symptomatichip osteoarthritis)† positive angle represents varus alignment, negative value represents valgus alignment
1458 R. W. BROUWER, S. M. A. BIERMA-ZEINSTRA, T. M. VAN RAAIJ, J. A. N. VERHAAR
THE JOURNAL OF BONE AND JOINT SURGERY
closing-wedge and 2.7 points after opening-wedge osteot-omy which was not significant (p = 0.93).
The mean HSS knee score and the mean walking distanceincreased in both groups, 8.5 points and 1.7 km after clos-ing-wedge and 9.4 points and 2.2 km after opening-wedgeosteotomy. These differences were also not significant (p =0.78, p = 0.65, respectively).
Plaster
versus
non plaster in the opening-wedge group.
The baseline characteristics in the subgroup were similarfor the plaster and the non-plaster groups, without any sig-nificant differences. There were no significant differences inprimary or secondary outcome measures between the plas-ter and non-plaster subgroups (Table III).
Complications during follow-up.
One patient in the closing-wedge group required a corrective varus osteotomy becauseof overcorrection of the initial osteotomy and anotherunderwent total knee replacement because of progressionof symptoms. Three patients in the opening-wedge grouphad a further valgus osteotomy because of recurrent varusalignment.
Because of pain, the staples or plate was removed in 11patients (23%) in the closing-wedge and in 27 patients(60%) in the opening-wedge group. This difference was sig-nificant (p < 0.001; odds ratio 0.15; 95% CI 0.06 to 0.41).
In the opening-wedge group 33 patients required bonegrafting. Two patients in this group developed nonunion,one with an opening-wedge of 7.5 mm without bone graftand the other with an opening-wedge of 12.5 mm who hadbone graft. Persistent pain at the iliac crest was reported ineight patients. One of these had further surgery because ofa symptomatic exostosis at the donor site. Another sus-tained an injury to the lateral femoral cutaneous nerve. Theremaining complications are shown in Table IV.
Discussion
Our results showed that the closing-wedge osteotomyachieved significantly more accurate correction with lessdeviation from our objective of 4˚ valgus overcorrection atfollow-up at one year.
We expected a better outcome in the opening-wedgegroup, because of the precise positioning possible with thePuddu plate and because it is performed under fluoroscopic
control. Additionally, it is easier to create an opening wedgethan to remove a wedge of bone from the proximal tibia. Inour experience, with the closing-wedge technique it can bedifficult to remove the wedge totally, especially at its apexat the medial side. An important reason for inadequate cor-rection noted at one year is that the Puddu plate is notstrong enough to maintain the per-operative correction.
17
Anew design, in which the screw-head locks into a more rigidplate, may provide more stability and give better results.Lobenhoffer and Agneskirchner
5
used a medial plate in 92opening-wedge osteotomies without loss of correction.
There was no statistical difference in the improvementsin both groups. However, a follow-up of one year may betoo short to demonstrate whether the benefit of the slightovercorrection approximating to 4˚ greater than physio-logical valgus remains true as previously suggested.
3
Todetermine whether one type of osteotomy delays therequirement for total knee replacement more than the otherrequires a much longer follow-up.
Application of a plaster cast after an opening-wedgeosteotomy did not appear to prevent loss of correction,with no difference in the mean hip-knee-ankle anglesbetween the plaster and non-plaster groups at one year.However, the sample size in our study was calculated todetect a difference between the closing-wedge and opening-wedge techniques. This study lacks sufficient power tomake a confident statement about the advantages or other-wise of using a plaster cast in conjunction with an opening-wedge osteotomy.
There were some limitations to our study. First, we wereunable to obtain the standing full-length radiographs on thefirst day after operation because the patients could notstand on their operated leg.
Secondly, four orthopaedic surgeons were involved.Although all had experience of both techniques, one singlesurgeon would have been preferable to reduce possibleoperator-dependent variability but this was not clinicallyfeasible. Finally, the outcome assessor was not blinded forphysical examination of the HSS score and post-operativehip-knee-ankle angle.
Based on our study we conclude that closing-wedge hightibial osteotomy achieves a more accurate correction and
Table IV.
Complications after closing-wedge and opening-wedge osteotomy
Closing-wedge osteotomy (n = 47)
Opening-wedge osteotomy (n = 45)
Wound infection 0 1Nonunion 0 2Palsy of the common peroneal nerve 1 0Pain in proximal tibiofibular joint 1 0Iliac-crest morbidity 0 9Fracture of the tibial plateau 1 2Re-operation (further valgus correction) 0 3Re-operation (reduction of valgus correction) 1 0Revision to joint replacement 1 0Removal of osteosynthesis material 11 27
OSTEOTOMY FOR MEDIAL COMPARTMENT ARTHRITIS OF THE KNEE USING A CLOSING WEDGE OR AN OPENING WEDGE 1459
VOL. 88-B, No. 11, NOVEMBER 2006
that both techniques reduce pain and improve function atfollow-up of one year. The opening-wedge osteotomy witha Puddu plate is associated with a higher number of com-plications.
We thank R. M. D. Bernsen for the statistical analysis.No benefits in any form have been received or will be received from a com-
mercial party related directly or indirectly to the subject of this article.
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