Fatigue Fx Military Conscripts

8/13/2019 Fatigue Fx Military Conscripts

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From the Department o Orthopaedics and raumatology,Helsinki University Central Hospital, University o Helsinki,

and Centre o Military Medicine, Helsinki

FATIGUE FRACTURES IN MILITARY CONSCRIPTS

A STUDY ON RISK FACTORS, DIAGNOSTICS AND

LONG-TERM CONSEQUENCES

Juha-Petri Ruohola

Academic Dissertation

o be presented with the permission o the Faculty o Medicine o theUniversity o Helsinki,

or public discussion in the Auditorium o l Hospital, Helsinki Uni-

versity Central Hospital,On March 9th, 2007, at 12 oclock noon.


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Supervised by

Docent Harri Pihlajamki, MD, PhDCentre o Military MedicineHelsinki, Finland

Reviewed by

Proessor Ilkka Arnala, MD, PhDDepartment o Orthopaedics and raumatologyKuopio University HospitalKuopio, Finland

Docent Jari Parkkari, MD, PhDUniversity o ampere and UKK Institute

ampere, Finland

Opponent

Proessor Hannu Aro, MD, PhDDepartment o Orthopaedics and raumatologyurku University Hospitalurku, Finland

ISBN 978-952-92-1681-9 (paperback)ISBN 978-952-10-3771-9 (PDF)

http://ethesis.helsinki.fiHelsinki University Printing House


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To my buffers against the world,

Tiina-Mari, Laura and Saku-Petteri


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Contents

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

LIST OF ORIGINAL PUBLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

ABBREVIATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. REVIEW OF THE LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.1. Fatigue ractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2. erminology o bone stress injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.3. Bone anatomy, remodeling and reaction to stress . . . . . . . . . . . . . . . 152.4. Incidence o bone stress injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.5. Risk actors or bone stress injuries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.6. Diagnosis o bone stress injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.6.1. Clinical diagnosis o bone stress injuries . . . . . . . . . . . . . . . . . 20

2.6.2. Radiological imaging in diagnosis o bone stress injuries. . . 22

2.7. Differential diagnosis o bone stress injuries . . . . . . . . . . . . . . . . . . . . 24

2.8. reatment and long-term consequences o bone stress injuries. . . . 253. AIMS OF THE PRESENT STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4. MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.1. Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.2. Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.2.1. Study description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.2.2. Clinical diagnosis and treatment . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.2.3. Imaging methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.2.4. Statistical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33


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5. RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.1. Serum 25OHD concentration as a potential predisposingactor or atigue bone stress racture, incidence andanatomic distribution o these ractures, and their relationshipwith age, weight, height, BMI, muscle strength, and result o

running test. (I). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.2. RACP-5b bone resorption marker as a potential indicator

o enhanced bone remodeling in military conscripts withstress ractures, and the incidence and anatomic distributiono these ractures. (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.3. Fatigue bone stress injuries associated with anterior lowerleg pain; incidence and distribution, MRI based injury gradesdepending on injury location and duration o symptoms. (III). . . . 38

5.4. Incidence, symptomatology, morphologic characteristics,

clinical course, risk actors, and long-term outcomes odisplaced and non-displaced atigue ractures o the emoralneck. (IV, V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

6. DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

6.1. Prevalence and anatomic distribution o atigue bone stressinjuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

6.2. Diagnosis and characteristics o atigue bone stress injuriescausing stress-related lower leg pain. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

6.3. Serum 25OHD concentration as a predisposing actoror atigue bone stress injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.4. RACP-5b bone resorption marker as an indicator oatigue bone stress injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

6.5. Other risk actors or atigue bone stress injuries . . . . . . . . . . . . . . . 51

6.6. Te long-term outcomes o atigue ractures othe emoral neck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

7. CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

8. SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

9. ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

ORIGINAL PUBLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75


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ABSTRACT

Fatigue racture is an overuse injury commonly encountered in militaryand sports medicine, and known to relate to intensive or recently intensi-fied physical activity. Bone responds to increased stress by enhanced re-modeling. I physical stress exceeds bones capability to remodel, accumula-tion o microractures can lead to bone atigue and stress racture. Clinicaldiagnosis o stress ractures is complex and based on patients anamnesisand radiological imaging. Bone stress ractures are mostly low-risk inju-ries, healing well afer non-operative management, yet, occurring in high-

risk areas, stress ractures can progress to displacement, ofen necessitatingsurgical treatment and resulting in prolonged morbidity.

In the current study, the role o vitamin D as a predisposing actor oratigue ractures was assessed using serum 25OHD level as the index. Teaverage serum 25OHD concentration was significantly lower in conscriptswith atigue racture than in controls. Evaluating RACP-5b bone resorp-tion marker as indicator o atigue ractures, patients with elevated serumRACP-5b levels had eight times higher probability o sustaining a stressracture than controls. Among the 154 patients with exercise induced an-terior lower leg pain and no previous findings on plain radiography, MRIrevealed a total o 143 bone stress injuries in 86 patients. In 99% o the cases,injuries were in the tibia, 57% in the distal third o the tibial shaf. In patientswith injury, orty-nine (57%) patients exhibited bilateral stress injuries. In a20-year ollow-up, the incidence o emoral neck atigue ractures prior to theFinnish Deence Forces new regimen in 1986 addressing prevention o theseractures was 20.8/100,000, but rose to 53.2/100,000 aferwards, a significant2.6-old increase. In nineteen subjects with displaced emoral neck atigueractures, ten early local complications (in first postoperative year) were evi-dent, and afer the first postoperative year, osteonecrosis o the emoral head

in six and osteoarthritis o the hip in thirteen patients were ound.It seems likely that low vitamin D levels are related to atigue ractures, and

that an increasing trend exists between RACP-5b bone resorption markerelevation and atigue racture incidence. Tough seldom detected by plainradiography, atigue ractures ofen underlie unclear lower leg stress-relatedpain occurring in the distal parts o the tibia. Femoral neck atigue ractures,when displaced, lead to long-term morbidity in a high percentage o patients,whereas, when non-displaced, they do not predispose patients to subsequentadverse complications. Importantly, an educational intervention can dimin-

ish the incidence o racture displacement by enhancing awareness and pro-viding instructions or earlier diagnosis o atigue ractures.


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LIST OF ORIGINAL PUBLICATIONS

Tis thesis is based on the ollowing papers, which are reerred to in thetext by their Roman numerals:

I Ruohola J-PS, Laaksi I, Ylikomi J, Haataja RI, Mattila VM, Sahi, uohimaa PJ, Pihlajamki HK. An Association between Serum25OHD3Concentrations and Bone Stress Fractures in Finnish YoungMen. J Bone Miner Res 21:1483-1488, 2006.

II Ruohola J-PS, Mulari M, Haataja RI, Ettala O, Vnnen HK, Pihla-jamki HK. Elevated Serum Levels o RACP-5b Predict Bone StressInjuries: A Prospective cohort study, submitted.

III Ruohola J-PS, Kiuru MJ, Pihlajamki HK. Fatigue Bone InjuriesCausing Anterior Lower Leg Pain. Clin Orthop Relat Res 444:216-223, 2006.

IV Pihlajamki HK, Ruohola J-PS, Kiuru MJ, Visuri . Displaced Fem-oral Neck Fatigue Fractures in Military Recruits. J Bone Joint Surg(Am) 88A:1989-1997, 2006.

V Pihlajamki HK, Ruohola J-PS, Weckstrm M, Kiuru MJ, Visuri I.Long-term prognosis o non-displaced atigue ractures o the emoralneck in young male adults. J Bone Joint Surg (Br) 88:1574-1579, 2006.

Te publishers have kindly granted permission to reprint the original

articles.


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ABBREVIATIONS

25OHD 25-hydroxyvitamin D

99mc technetium-99m

BMC bone mineral content

BMI body mass index = a persons weight in kilogramsdivided by height in meters squared

CECS chronic exertional compartment syndrome

C computerized tomography

HHS Harris hip score

LSD least significant difference

MR magnetic resonance

MRI magnetic resonance imaging

NSAID nonsteroidal anti-inammatory drug

P probability

PH parathyroid hormone

RACP5b tartrate-resistant acid phosphatase 5b

VAS visual analogue scale


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1. INTRODUCTION

Bone stress ractures are overuse injuries associated with intensive or re-cently intensified physical activity. Consequently, they are common amongathletes and military conscripts involved in strenuous training programmes(Pentecost et al. 1964, Milgrom et al. 1986, Matheson et al 1987b, Jones etal. 1989, Sterling et al. 1992, Clanton and Solcher 1994). Plenty o researchhas been conducted investigating actors predisposing to stress ractures,and although the results have been inconsistent, several proposals havebeen published (Jones et al. 2002, Vlimki et al.2005). Tat the bone stress

injuries detected with radiographic imaging methods (e.g. scintigraphy,MRI) are ofen not only multiple and simultaneous but also symptomless(Ha et al. 1991, Giladi et al. 1991, Kiuru et al. 2002, Niva et al. 2005) sug-gests, however, a greater susceptibility to stress ractures among certainpersons compared to others. Furthermore, considering the wide evidenceregarding the association o vitamin D with bone health (Compston 1998,Utiger 1998, Lips 2001, Holick 2003a), a possible association o vitamin Dstatus with stress ractures would seem well worth intensified research.

When bone is subject to elevated stress levels, it accelerates its remod-eling process in which the damaged bone cells dissolve and new matrixis laid down to permit ormation o new cells. Should the physical stressexceed bones remodeling capacity, the repair process may remain incom-plete, thus making way to microractures in the bone and bone atigue.Tese changes in the bone structure increase proneness to stress ractures(Li et al. 1985, Jones et al.1989, Boden and Osbahr 2000).

A clinical diagnosis o a atigue bone stress injury, as well as a differentialdiagnosis distinguishing it rom other imitating conditions can be compli-cated (Mubarak et al. 1982, McBryde 1985, Michael and Holder 1985, Mil-grom et al. 1986, Rosors et al. 1992, Hutchinson and Ireland 1994). Stress

related anterior lower leg pain, which is very common among military re-cruits and certain athletes (Milgrom et al. 1986, Clanton and Solcher 1994),is ofen reerred to under categories like shin splints or medial tibial stresssyndrome that cover a wide spectrum o conditions behind the pain (Millset al. 1980, Dettmer 1986). Radiographic imaging in its various orms hasbeen widely exploited to confirm the diagnosis. Since many stress injuriesare not detectable even by plain radiography, magnetic resonance imaging(MRI) has been increasingly preerred as offering superior sensitivity ordetecting these injuries even at an early stage (Lee and Yao 1988, Anderson

and Greenspan 1996, Kiuru et al. 2002). Unortunately MRI is not widelyavailable, which can delay the diagnosis and treatment o stress injury, thus


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possibly contributing to severe consequences and prolonged morbidity(Salminen et al. 2003). Partly because o this, development o a new useulinstrument is attracting wide interest to permit more accurate detectiono bone stress ractures already in primary health care units with limitedimaging acilities. Here, the knowledge regarding biochemical markers o

bone resorption, such as RACP5b, which mirror the bodys rate o boneloss (Stepan 2000), should encourage research about their potential instress racture prediction.

Generally classified as benign low-risk injuries, bone stress injurieshave mainly been treated non-operatively with reduced exercise and non-weight-bearing. Occurring in high-risk areas e.g. the emoral neck, theseinjuries can, nonetheless, progress to displacement and other severe conse-quences and prolonged morbidity (Salminen et al. 2003, Boden and Oshbar2000, Visuri et al. 1988). However, previous reports on the long-term con-

sequences o emoral neck atigue ractures have mainly been case reports.Tus, systematically collected data on the long-term outcome o both dis-placed and non-displaced emoral neck atigue ractures are lacking.


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2. REVIEW OF THE LITERATURE

2.1. Fatigue fractures

A German military surgeon J. Breithaupt was the first doctor in history(Breithaupt 1855) to describe atigue racture in literature. However, heailed to recognize the main reason or painul and swollen eet associ-ated with marching in Prussian soldiers, mistaking a atigue racture or

a traumatic inammatory reaction. Since the year 1855, the majority opublications describing stress reactions o bone have been based on stud-ies among military recruits until, in the last our decades, an increasingnumber o studies concerning stress injuries o bone among athlete popu-lations have appeared in the medical literature (Jones et al. 1989). Te actthat military publications are so well presented in medical literature withrespect to bone atigue ractures is due to military populations having beenin the past the only populations large enough, with their type and level ophysical activity, to provide suffi cient amounts o stress reactions o boneto raise general interest among medical researchers. Only later, with theever-growing number o people participating in fitness and sports trainingprograms, have stress ractures become increasingly common in civilianathlete populations as well.

Once the condition behind the painul oot was detected using X-raysinvented by Wilhelm Rntgen in 1895, and actually identified as bone rac-tures (Stechow 1897), also other bones o the lower extremities exhibitingsymptoms o stress-related pain were subjected to observation. During thefirst hal o the 19thcentury, along with more widely available native radi-ography, it became clear that sites like tibial and emoral shaf as well as

emoral neck could be affected by atigue racture more ofen than pre-viously thought. Another obvious finding was that the majority o theseractures typically occurred during the first weeks or months o militarytraining when physical activity intensified. For the atigue racture itsel,several names were used, including march racture, stress racture, exhaus-tion racture, spontaneous racture, and others, some o which have re-mained in use until today (Branch 1944, Jones et al. 1989, Ha et. al 1991,Anderson and Greenspan 1996).

Clinically it was, and still is, diffi cult to make differential diagnosis be-

tween stress racture and other pathological conditions simulating it. Con-sequently, radiographs played a remarkable role in the diagnosis until the


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1970s, when scintigraphy and MRI, offering a much better sensitivity andspecificity, became valuable tools or the purpose. Interestingly, at same timewhen these improved imaging methods with higher accuracy were adoptedor diagnosis o stress ractures, the most diagnosed racture location in thelower extremities moved rom the metatarsal bones to the tibia in military

populations. Owing to its lower costs and good availability in primary healthcare units, however, plain radiography has stayed long as the first line toolor racture imaging. Only recently are there signs that MRI is becomingcommon in medical practice (Lee and Yao 1988, Shin et al. 1996, Deutschet al. 1997, Boden and Osbahr 2000, Spitz and Newberg 2002, Kiuru et al.2004, Niva et al. 2005, Niva et al. 2006a and 2006b, Sormaala et al. 2006a and2006b).

oday, stress-related ractures have been described or nearly every boneo our body. Te most common sites or stress ractures are the weight-bear-

ing bones o the lower extremities and the pelvis. Both sites have been typi-cally noted among military recruits due to the type o physical training theyundergo, and among athletes, o whom runners in particular have emergedas the main subgroup suffering rom these injuries (Hallel et al. 1976, Rupaniet al. 1985, Hulkko and Orava 1987, Matheson et al. 1987b, Boden and Osh-bar 2000, Jones et al. 2002, Kiuru et al. 2004, Kiuru et al. 2002).

2.2. Terminology of bone stress injuries

Stress racture as a term in itsel can be potentially misleading, because stress

injuries o the bone, although diagnosed and classified under the rubric o

stress ractures, do not necessarily result in a racture line or a break in bone

continuity (Jones et al. 1989). Pathophysiology o these injuries covers a wide

spectrum o events, rom accelerated remodeling to stress racture (Anderson

and Greenspan 1996).

Stress reaction is the first phase indication that a stress injury is develop-

ing to a bone. Tis reaction starts, when adaptability o the bone to increased

repetitive stress is overloaded. In these early phases, native radiography ofen

shows normal findings, whereas on MRI, marrow edema can be seen (Lee andYao 1988, Kiuru et al. 2002).

Stress fracture occurs when the abnormal stress continues without the

needed recovery periods or the bone, and the bone responds by incomplete

remodeling. Callus or racture line can then be visualized with plain radi-

ography, and more certainly with MRI (Lee and Yao 1988, Anderson and

Greenspan 1996). Bone stress ractures can be classified into two main types,

atigue ractures and insuffi ciency ractures (Pentecost 1964, Daffner and Pav-

lov 1992).

Fatigue fracturesoccur when normal bone, with normal elastic resist-ance, is exposed to abnormal repetitive stress (Pentecost 1964, Daffner and

Pavlov 1992).


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Insuffi ciency fracturesoccur when abnormal bone, with deficient elasticresistance, is exposed to normal stress (Pentecost 1964, Daffner and Pavlov1992).

Pathological fracturesoccur in bone which is affected and weakened by

another pathological lesion, such as inection or neoplasm (Daffner andPavlov 1992).

Compressive fracturesmay occur when bone is exposed to compressiveorces along the concave margin o the bone. Stress ractures o the emoralneck located at the inerior surace o the neck are typical compression-side ractures (Fullerton et al. 1988, Flinn et al. 2002).

Tension fractures may occur when bone is exposed to tensile orcesalong the convex margin o the bone. Stress ractures o the emoral necklocated at the superior surace o the neck are typical tension-side ractures

(Fullerton et al. 1988, Flinn et al. 2002).Low-risk stress injuriescan usually be diagnosed on the basis o care-

ul anamnesis, physical examination, and radiographs. Moreover, they canbe treated with rest periods without a ear o problematic consequences(Boden et al. 2001). According to Boden et al. (2001), the low-risk sitesare, with some exceptions, the upper extremities, the ribs, the pelvis, theemoral shaf, the tibial shaf, the fibula, the calcaneus, and the metatarsalshaf.

High-risk stress injuriescan, unortunately, progress to complete rac-ture, displacement, delayed union, or nonunion, and they thereore requirea more aggressive approach. Tey commonly occur on the tensile side obone, or in bone areas with critical blood supply. Te problematic sites arethe emoral neck (tension side, Fig 1), the patella, the anterior cortex o thetibia, the medial malleolus, the talus, the tarsal navicular, the fifh metatar-sal, the second metatarsal base, and the first digit sesamoids (Boden andOshbar 2000, Lassus et al 2002).

Risk factoris an attribute or circumstance associated with enhanced risko developing a specific disease. Identification and understanding o a riskactor can provide an opportunity to create preventive strategies against

the disease related to that particular risk actor.


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Figure 1. ension and compression sides o the emoral neck.

Figure 2. Te macroscopic and microscopic structure o bone


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2.3. Bone anatomy, remodeling and reaction to stress

Bone consists o two different components characterizing the widelyvarying gross arrangement o this connective tissue. Te gross anatomyis greatly inuenced by the position and unction o the bone within the

body. Cortical bone is typically present along the outer margin o longbones. Cancellous (trabecular or spongy) bone is usually ound at the endo long bones and internal to cortical bone, or it can compose some bones,e.g. the calcaneus, almost alone (Fig 2). Te basic histological structure othese bone types is equal to both, but differences exist. Cortical (compactor dense) bone has, as justly indicated by its name, a solid architecture,which only the narrow canals o the Haversian systems interrupt. Corti-cal bone has a low surace-to-volume ratio, with the cells completely sur-rounded by bone matrix. Cancellous bone is a meshwork o longitudinal

(primary) and transverse (secondary) trabeculae separated by hematopoi-etically active red marrow or hematopoietically inactive, yellow (atty)marrow. Cancellous bone has a high surace-to-volume ratio, with the cellsdirectly inuenced by bone marrow cells, ensuring that the bone is undera better metabolism control when compared to cortical bone. Te extracel-lular matrix o bone tissue, with its chemical composition o both organicand inorganic elements, enables bone to withstand physical stresses betterthan other tissues.

Trough a microscope, bone is composed mainly o extracellular ma-trix and cells that represent the lesser amount o organic matter in bone.Osteoblasts, osteoclasts, osteocytes and osteoprogenitor cells are the ouractive matrix cell types ound in bone. Bone metabolism is regulated bybone cells and the regulation depends on the cell activity. Since osteob-lasts main unction is to synthesize and mineralize bone matrix, they areregarded as bone orming cells. I the osteoblast becomes surrounded bythe matrix it has been producing, it can become an osteocyte with meta-bolically inactive appearance. Osteocytes are numerous in the mineralizedbone matrix o both cancellous and cortical bone. Teir unction is notcompletely understood, but they are assumed to play a role in the mechani-

cal regulation and regeneration o bone (Cowin et al. 1991, Lanyon 1993,Mullender and Huiskes 1995 and 1997). Osteoclasts are cells that unctionin the resorption process o calcified bone matrix. Osteoprogenitor cellsare ound throughout the bones, and, under relevant stimulation, they candifferentiate into unctional osteoblasts (Buckwalter et al. 1995).

Bone is a dynamic connective tissue that requires stress or normal de-velopment and health (Sterling et al. 1992). Metabolically, bone is never atrest. In a continual ormation, resorption and remodeling process takingplace throughout the bone, the osteoblasts orm and the osteoclasts remove

bone matrix without remarkably affecting the shape or density o the bone.In healthy bone, under a constant load, normal bone remodeling occurs


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through osteoclast resorption and osteoblast reconstruction o the bonetissue, meaning that these two are in balance with each other. One com-ponent both contributing to osteoclast activity and enhancing the differ-entiation o osteoclast and osteoblast precursors is vitamin D (Riggs 1997,Utiger 1998, Holick 2003b), which also lowers intact parathyroid hormone

(iPH) secretion and controls both calcium absorption and reabsorption(Utiger 1998). With the calcium and phosphate homeostasis having a ma-jor effect on bone mineralization, in the event o dietary calcium inad-equacy, vitamin D causes osteoclasts to mature and resorb calcium romthe bone (Compston 1998, Lips 2001, Vlimki et al. 2004). A possible re-lationship between calcium intake and stress racture has been investigatedin some studies, but the evidence is still lacking (Lips et al. 1991, McKaneet al. 1996).

Under an increasing load, with the bone subject to prolonged, recurrent

or excessive stress, the remodeling process accelerates through stimulatedbone resorption, resulting in incomplete remodeling response (Li et al.1985, Burr et al. 1990). Dominant osteoclastic activity at bone stress sitesmay cause local weakening o the bone, thus predisposing it to microdam-age (Werntz and Lane 1993). With continuing abnormal loading, thesemicrodamages, also called microractures, can gradually progress to com-plete ractures (Knapp and Garrett 1997). On the other hand, i the load isreduced, diminishing stress to the bone and giving the remodeling processtime to normalize, the development o bone racture can be avoided.

2.4. Incidence of bone stress injuries

Stress racture is a commonly seen injury type in sports clinics as well asthe primary health care units o military health services (able 1) (Morrisand Blickenstaff 1967, Mills et al.1980, Milgrom et al.1985, Hulkko andOrava 1987, Matheson et al. 1987b, Beck et al. 1996). Te overall incidenceo stress ractures in military recruits has varied between 0.9% and 12.3%,but incidences as high as 31% have been reported (Brudvig et al. 1983, Sahi

1984, Milgrom et al. 1985, Jones et al. 1993, Macleod et al. 1999, Givon etal. 2000, Armstrong et al. 2004, Lappe et al. 2005). In the Finnish DeenceForces, the current published incidences o bone stress injuries have stayedwithin these values (Sahi et al. 1996, Vlimki et al. 2005). However, withmost o the stress ractures in the Finnish Deence Forces occurring dur-ing the first two or three months o military service, the military conscriptsrepresent a homogenous exposure group regarding physical stress duringthe 8-week basic training period equal or all. In contrast, there is consid-erable variation internationally between armed orces, and even military

branches, with respect to training procedures, physical fitness o traineesand methodology o diagnosis (Kiuru et al. 2004).


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Table 1. Previous studies o bone stress injuries o the lower extremities

Author and year Participants Number of participants,

male/female

Method Incidence of bone

stress injuries,

male/female (%)

Hallel et al. 1976 military not reported prospective 5/-

Protzman and Griffi s, 1977 military 1228/102 prospective 1.0/9.8

Brudvig et al. 1983 military 20442 overall retrospective 0.9/3.4

Milgrom et al. 1985 military 295/- prospective 31/-

aimela et al. 1990 military 108/- prospective 7.4/-

Finestone et al. 1991 military 392/- prospective 24/-

Jones et al. 1993 military 124/186 prospective 2.4/12.3

Goldberg and Pecora, 1994 athletes approx. 1000 overall retrospective 1.9 overall

Johnson et al. 1994 athletes 914 overall prospective 2.6 overall

Beck et al. 1996 military 626/- prospective 3.7/-

Bennell et al. 1996 athletes 49/46 prospective 20.4/21.7

Macleod et al. 1999 military 3367/855 retrospective 2.8/10.8

Armstrong et al. 2004 military 1021/203 prospective 2.3/8.4

Lappe et al. 2005 military -/4139 prospective -/4.7

Vlimki et al. 2005 military 179/- prospective 8.4/-

In the general athletic population, the incidence has remained below3.7% (Matheson et al. 1987b, Jones et al. 1989, Goldberg and Pecora 1994).In runners and some other groups o athletes, the occurrence o bone stressinjuries might be somewhat higher, rom 10% to 31% (Matheson et al.1987b, Boden and Oshbar 2000, Jones et al. 2002, Kiuru et al. 2004).

Almost all stress ractures among military trainees and athletes areound in the lower extremities or the pelvis (Milgrom et al. 1985, Math-

eson et al. 1987a, Jones et al. 1989, Ha et al. 1991, Jones et al. 2002, Kiuruet al. 2002, Kiuru et al. 2004, uan et al. 2004). Although the variation re-ported in different studies concerning the distribution o stress injuries inthe lower extremities is remarkable, these injuries have been encounteredin nearly every bone o the oot and leg, as well as around the hip joint(Visuri et al. 1988, Visuri 1997, Williams et al. 2002, Lee et al. 2003, Song etal. 2004, Niva et al. 2005). However, the most common sites or bone stressinjuries are the tibia and the metatarsal bones. (Milgrom et al. 1985, Joneset al. 1989, Bennell et al. 1996).


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2.5. Risk factors for bone stress injuries

Numerous reports have documented that the main cause predisposingbone to stress injuries is repeated or recently started mechanical loading(Lassus et al. 2002, uan et al. 2004). In addition, various potential risk

actors have been proposed to explain, more or less, why some sustain astress racture while others do not. Tese etiological risk actors can becategorized as extrinsic (external) or intrinsic (internal) (able 2). Ex-trinsic actors are characteristics o the environment in whose activitiesthe individual participates. Extrinsic causes include training conditions,methods and equipment, and training errors, such as excessive intensity orvolume, duration and change o each strain cycle, excessive muscle atigue,and aulty or wrong technique. Intrinsic actors, e.g. mechanical, muscu-lar, nutritional or hormonal actors, are characteristics o the individuals

themselves. Intrinsic causes include muscle atigue leading to transmis-sion o excessive orces to underlying bone (Blickenstaff and Morris 1966,Boden and Osbahr 2000), muscle imbalance, insuffi cient exibility dueto generalized muscle tightness, ocal muscle thickening, limited range ojoint motion, lack o bone strength due to decreased bone mineral density(Pouilles at al 1989), and psychological actors like nutritional intake andeating disorders (Matheson et al 1987b, Bennell et al. 1999)

Table 2. Possible risk actors or bone stress injuries according to Bennell et al. 1999

Intrinsic risk factors Extrinsic risk factors

Bone mineral density . . . . . . . . . . . . . . . . . . . . . . . Volume o training

Bone geometry . . . . . . . . . . . . . . . . . . . . . . . . . . Pace o training

Skeletal alignment. . . . . . . . . . . . . . . . . . . . . . . . . Intensity o training

Body size and composition. . . . . . . . . . . . . . . . . . . . Recovery periods

Bone turnover . . . . . . . . . . . . . . . . . . . . . . . . . . . Faulty training technique

Muscle exibility and joint range o motion . . . . . . . . . . raining surace

Muscular strength and endurance . . . . . . . . . . . . . . . . Footwear/insoles/orthotics

Calcium intake . . . . . . . . . . . . . . . . . . . . . . . . . . External loading

Caloric intake/eating disorders

Nutrient deficiencies

Sex hormones

Menarcheal age

Other hormones

Physical fitness

Age

Gender


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Several publications have studied risk actors contributing to a predis-position to stress ractures, and quite ofen the results have been, in wholeor in part, conicting with each other. Moreover, there exists a possibil-ity that risk actors have the potential to predispose bone to developingstress ractures alone or through the joint effect o various actors. O the

risk actors or stress ractures, emale gender, age, body composition,bone characteristics, low bone density and bone strength, low aerobic fit-ness, low past physical activity level, smoking, and excessive running havebeen identified in an epidemiologic review (Bennell et al. 1999, Jones et al.2002).

Several studies based on bone scintigraphy or MRI regarding the lowerextremities or the pelvis, have reported occurrence o multiple simultane-ous bone stress injuries in the same individual (Ha et al. 1991, Giladi et al.1991, Nielens et al. 1994, Kiuru et al. 2002, Niva et al. 2005). Multiple rac-

tures may imply that the subjects overall bone composition is deective,and thus some general actor be present or predisposing bone to stressractures (Fig 3AB).

Figure 3AB.A 19-year-old male conscript suffering rom knee pain. Plain radiographyreveals bone stress injuries in both the right (A) and the lef (B) knee.

A B


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2.6. Diagnosis of bone stress injuries

2.6.1. Clinical diagnosis of bone stress injuries

Clinical diagnosis o bone stress injuries with no specific signs or findings

is a diffi cult task. However, the complexity should not deter the physicianrom action, since an early suspicion and diagnosis o a possible stress in-jury is essential or adequate treatment (Fig 4AB). Te clinical diagnosis obone stress injury is based on the patient history o physical activity, dura-tion and type o symptoms, and a number o uncertain clinical findingsneeding confirmation by radiological imaging methods.

Figure 4AB.An 18-year-old male conscript suffering rom oot pain. Te stress racturein the third metatarsal bone is hardly detectable on the primary radiographic image (A),yet despite a rest period, displacement o racture is observed a week later (B).

Te symptoms o a developing stress injury ofen appear 2 to 3 weeksafer the beginning or remarkable intensification o training. However, du-

ration o the evolution o injury may vary rom days to months (Greaney etal. 1983, Jones et al. 1989, Ha et al. 1991). At the early stages o stress injury,

A B


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the patient may be symptomless on clinical examination. Stress-related painwith no previous trauma can occur suddenly or gradually, and may varyrom radiating to very unspecific. Furthermore, at least among military re-cruits, the motivation or duty and service combined with personal charac-teristics can produce very diverse reactions to exercise-induced pain (Hallel

et al. 1976). At the onset, pain can be exercise-induced only, generally disap-pearing with rest. However, even then, and more probably so i loading con-tinues non-reduced, pain will be present also at rest and during nights. Telocation o pain and suspected racture can be clinically very important, a-ecting decision making concerning appropriate treatment. Some high-riskstress ractures, e.g. displaced emoral neck racture, can cause severe com-plications and prolonged recovery, leading all the way to avascular necrosisand joint replacement surgery (Blickenstaff and Morris 1966, Fullerton andSnowdy 1988, Visuri et al. 1988, Johansson et al. 1990, Mendez and Eyster

1992). In these specific locations o suspected racture, early suspicion andaccurate diagnosis are even more important to avoid racture displacementand surgical treatment.

Swelling and discolouration with local warmth (Anderson and Green-span 1996) may be seen, and localized pain and possible periosteal thicken-ing indicating new bone ormation, callus, may be palpable (Sterling et al.1992). Pain at a distant site produced by the percussion o bone, e.g. in thetibia, can signal a stress injury. A ew special tests exist, the ulcrum test orexample, or diagnosing a stress injury (Johnson et al. 1994) in the emoralbone, which is otherwise diffi cult to palpate due to strong muscles coveringit (Fig 5).

No appropriate laboratory tests exist to assist the diagnosis o stressractures in primary health care units with no advanced imaging modali-ties. However, biochemical markers o bone resorption reecting the rateo bone loss (Stepan 2000) have been the ocus o recent research, aimedat developing an adequate diagnostic test. Tese markers are relatively in-expensive, widely available and, expressing both bone quantity and qual-ity, they would be conceivable aspossible racture predictors.One o thesepotential bone turnover markers, RACP5b is secreted into circulation

during osteoclast resorption, mirroring this osteoclastic activity in enzymesecretion and bone degradation (Nesbitt and Horton 1997, Salo et al. 1997,Vrniemi et al. 2004). RACP5b has been suggested to be an independ-ent, specific, and sensitive serum markero bone resorption (Halleen et al.,2000, Halleen 2003, Nenonen et al. 2005). It has so ar been successullyused in monitoring response to the treatment o bone metastases in cancerpatients (Wada et al. 1999, erpos et al. 2003).


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Figure 5.Fulcrum test: Patient is seated with the lower legs dangling. Examiners arm isused as ulcrum under the patients distal thigh moving the arm towards the proximalthigh, while applying gentle pressure to the dorsum o the patients knee with the oppo-site hand. Pain occurs when the arm as ulcrum is located under the stress racture.

2.6.2. Radiological imaging in diagnosis of bone stress injuries

Imaging studies are needed to confirm the diagnosis o stress injuries(McBryde 1985, Michael and Holder 1985, Milgrom et al. 1986, Clantonand Solcher 1994, Anderson and Greenspan 1996). Plain radiography hasgenerally been used as the primary imaging tool since the end o the 19 thcentury. Only two years afer Wilhelm Rntgen discovered X-rays was thetechnology already used to detect stress ractures in the metatarsals (Ste-chow 1897), and it has maintained its position as the first-line imagingtool owing to its common availability and cost effectiveness. However, inimaging o stress injuries, the sensitivity o radiography at the early stageso injury may be as low as 10%, although in the ollow-up o these injuries,

it rises to 30% and up to 70% (Prather et al. 1977, Orava 1980, Greaneyet al. 1983, Rupani et al. 1985, Matheson et al 1987a, Nielsen et al. 1991).Because o the somewhat low sensitivity, diagnosis has ofen been based onbone scintigraphy or MRI in patients with stress related pain and no visiblestress injury on radiographs.

Bone scintigraphy was considered the gold standard or detecting earlystages o bone stress injuries rom the 1970s until the early 2000s, when itbegan to give way to MRI (Kiuru et al. 2002). Acceleration in bone metabo-lism related to stress injuries is visible on scintigraphy long beore changes

are seen on radiography. Bone scintigraphy is substantially more sensitive(nearly 100% sensitivity) than radiography, but its specificity is inerior,


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so that identification o pathological conditions in particular, such as tu-mors, inections and traction periostitis, remains deficient (Anderson andGreenspan 1996, Kanstrup 1997). Te radiation dose received at a scinti-graphic examination is equal to a dose o two years o background radia-tion (Kanstrup 1997). oday, MRI is overriding scintigraphy in terms o

availability as well.Magnetic resonance imaging (MRI) offers not only a high sensitivity

but also a superior specificity in detecting the early changes related to bonestress injury, yet without exposing the body to ionizing radiation (Lee andYao 1988, Anderson and Greenspan 1996, Kiuru et al 2002). It is thereoreully understandable that MRI is currently considered the gold standardin stress injury imaging. Moreover, its high contrast and spatial resolutionpermit visualization oassociated sof tissue involvement (Anderson et al1997, Deutsch et al. 1997). On MRI, a developing bone stress racture can

be detected already at its earliest stages, with the initial signs o bone stressinjury being displayed as periosteal or endosteal marrow edema. However,as such endosteal edema may signal other pathological conditions as well,the finding should be considered non-specific (Schweitzer and White 1996,Lazzarini et al. 1997). Endosteal bone marrow edema has also been docu-mented in healthy, physically active asymptomatic patients, and becausethese asymptomatic low grade injuries do not seem to possess a tendencyto progress to higher grade injuries, MR imaging o asymptomatic militarytrainees or athletes is not recommended (Kiuru et al. 2005). Evolution o astress-related bone injury comprises several varying stages, characterizedby an equally large variety o MRI signs. For the purpose o assessmento these signs, several stress reaction or racture grading scales have beenpublished (Lee and Yao 1988, Kiuru et al. 2001). According to the scalingsystem by Kiuru et al. bone stress injuries are classified on the basis o MRIfindings as: Grade I, endosteal marrow edema; Grade II, periosteal edemaand endosteal marrow edema; Grade III, muscle edema, periosteal edema,and endosteal marrow edema; Grade IV, racture line; and Grade V, callusin cortical bone. A disadvantage o MR imaging is still today the generalunavailability o the technology. Moreover, its costs might be considered as

another limitation to its use.


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2.7. Differential diagnosis of bone stress injuries

Stress-related pain in the lower extremities is common in military recruitsand athletes (Milgrom et al. 1986, Clanton and Solcher 1994). It is diffi cult,or even impossible, to differentiate a bone stress injury rom other patho-

logical conditions mimicking it based on clinical examination alone, eventhough a patient history in terms o physical activity level and symptoms isusually quite typical when concerning stress injuries to bone (able 3). Tus,in the majority o cases, the history combined with characteristic radio-graphic findings suffi ces to reach the diagnosis. Diagnosis can, however, beurther conused by imitating conditions, including exertional conditionslike the compartment syndrome, and nonexertional inammatory,inectious, vascular, neurological and tumorous conditions in sof tissuesand bones (DAmbrosia 1977, Mubarak et al. 1982, McBryde 1985, Michael

and Holder 1985, Milgrom et al. 1986, Rosors et al. 1992, Hutchinson andIreland 1994). Tis again emphasizes the importance o sensitivity and spe-cificity o the imaging method used in unclear cases to ensure rapid andadequate diagnosis and treatment, usually meaning the MRI. Stress-relatedpain in the lower extremities is most commonly located in the anteriorlower leg. Although a stress-related bone injury is by no means an unusualcause o lower leg pain, yet with no findings suggestive o bone injury, thepain is ofen reerred to as shin splints (traction periostitis), or the medialtibial stress syndrome(Mills et al 1980, Detmer 1986). However, the termslack accuracy covering so broad a spectrum o possible conditions behindthe pain (Johnell et al 1982, Mubarak et al. 1982, Michael and Holder1985, Gerow et al. 1993, Beck 1998). Te differential diagnosis can be evenmore demanding, because conditions like traction periostitis, chronic ex-ertional compartment syndrome and bone stress injury can occur sepa-rately or combined, and urthermore, because stress injuries ofen affectseveral bones simultaneously. Such cases o simultaneous and combinedsymptoms, diffi cult or both the patient and the physician to pinpoint, cangreatly disturb the diagnosis (Giladi et al. 1991, Ha et al. 1991, Kiuru etal. 2002, Niva et al. 2005). In patients with lower grade injuries, treated by

reducing load with rest period, there exists already a suspicion o a possiblestress racture. Nonetheless, the final diagnosis may remain open, because,with decreased stress, the bone can heal a developing stress injury beoreit becomes visible on radiographs, and later, with less or no symptoms, apatient is likely never to undergo repeated plain radiography or MRI scanto confirm the diagnosis (Devas 1958, Li et al. 1998, Kiuru et al. 2005).


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Table 3.Differential diagnosis o bone stress injuries

Conditions imitating bone stress injuries

Exertional compartment syndrome

Bone tumors and metastaseInammatory disease

Inectious condition

ransient bone marrow edema

raction periostitis

Osteonecrosis

Vascular pathological condition

Neurological pathological condition

Osteomyelitis

Osteomalacia

Bursitis

Iliotibial band syndrome

Distal emoral cortical deect

Femoral cortical excavation

Internal derangement o the knee

Mortons neuroma

Osteochondral racture

2.8. Treatment and long-term consequences of

bone stress injuries

Te anatomic location o the injury carries mentionable prognostic im-portance or the possible long-term consequences o bone stress injury,since some injuries involving bones like the emoral neck are more prone

to displacement and severe complications than those ound at other bonesand sites (able 4). Te majority o low-risk stress ractures seen in clinicsare managed conservatively with reduced exercise, and heal with no earo complications (Fig 6AB). In more severe cases, use o crutches, splints,or casts may be necessary. In displacements or other ractures where non-operative treatment is insuffi cient, surgical treatment, mainly internal fixa-tion, is warranted (Hulkko and Orava 1987). Regarding the nature andextent o reduced exercise as a treatment method, these depend on the siteand grade o injury, varying rom a period o cutting down daily physical

exercise to a hal to a period o complete inactivity including a possiblenon-weight-bearing period or up to 8 weeks. In military service, this o-


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Figure 6AB.A stress acture in the third metatarsal bone o a 20-year-old male conscript

(A) was treated conservatively with rest periods and reduced exercise. Te healed ractureshown six months later (B).

A B


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3 AIMS OF THE PRESENT STUDY

I. o assess the effect o serum 25OHD concentration as a predisposingactor on atigue bone stress injuries, and to evaluate the incidence andanatomic distribution o these injuries and their relationship with age,weight, height, BMI, muscle strength, and result o running test.

II. o determine i RACP-5b bone resorption marker indicates enhancedbone remodeling in military conscripts with stress ractures, and to evalu-ate the incidence and anatomic distribution o these bone stress injuries.

III. Based on MR imaging, to determine the incidence o atigue bonestress injuries causing stress related anterior lower leg pain, and to assesstheir anatomic distribution, grade o injury with respect to location, andduration o symptoms beore diagnosis.

IV/V. o evaluate the incidence, symptomatology, morphologic charac-teristics, clinical course, risk actors and long-term outcomes o displacedand non-displaced atigue ractures o the emoral neck, and to assess theeffects o instructions by the Finnish Deence Forces, Department o Medi-cal Services in 1986 or the prevention o emoral neck atigue ractures inmilitary service.


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4 MATERIALS AND METHODS

Te two prospective cohort studies (I, II) were conducted at the Pori Bri-gade, Skyl, at the Research Institute o Military Medicine, Central Mili-tary Hospital, Helsinki, at the University o ampere (I), ampere, and atthe University o urku (II), urku. Te third, retrospective study (III) wasconducted at the Department o Radiology and at the Research Institute oMilitary Medicine, Central Military Hospital, Helsinki. Te studies IV andV were conducted at the Departments o Radiology and Surgery, and theResearch Institute o Military Medicine, Central Military Hospital, Hel-

sinki. All the studies (I-V) were approved by the appropriate Ethics Com-mittees. All study designs (I-V) were approved by the Deence Staff o theFinnish Deence Forces.

4.1. Patients

All the participants included in Studies I-V were or had been conscriptsperorming their military service in the Finnish Deence Forces. All malecitizens o Finland become liable or a mandatory military service at theage o 18, whereas emale citizens have had the opportunity to volunteeror the service since year 1995. Annually, on average 26,500 male con-scripts and 500 emale conscripts underwent military training within thetime periods o studies I-III, and the annual number o male conscriptswas between 34,723 and 36,606 during studies IV and V.

Study I

In July 2002, eight hundred young men (aged 18-28 years, mean 19.8years) entering into military training as conscripts o the same inantry

unit (Pori Brigade) o the Finnish Deence Forces were randomly selectedor the study. Tey had no known diseases or medications and they all hadpassed the entrance medical examinations as healthy. Te subjects repre-sented the common conscript population o the Finnish Deence Forceswith no specific eatures. During their military service, the conditions werehomogenous in that physical activity, nutrition, clothing, accommodation,and exposure to sunlight were the same or all participants. From the origi-nal sample, we excluded patients whose ollow-up data was incomplete asa result o ailed blood samples drawn during the study, and patients who

were compelled to interrupt their military service, which lef the total o756 patients or the ollow-up.


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Study II

Eight hundred and twenty Finnish young men and women (aged 18-28years, mean 19.8 years; mean BMI 23.4) entering military training in July2002 as conscripts o the same inantry unit (Pori Brigade) o the FinnishDeence Forces were randomly selected or the study. Tey had no previous

medication or diseases and they all passed their entry medical examinationas healthy. Te subjects represented the general conscript population othe Finnish Deence Forces without specific eatures. During the militaryservice, the conditions related to physical activity, nutrition, clothing, andaccommodation were homogenous or all subjects.

Study III

Material or Study III covered a study period o five years, rom March1, 1997 to February 28, 2002. A total o 154 patients, seven emale and

147 male (age range, 1725 years; mean, 19.6 years) meeting the inclu-sion criteria were identified rom the MRI archives o the Central MilitaryHospital. Te inclusion criteria or the present study were exercise-inducedanterior lower leg pain during military service, at least one negative plainradiograph taken at a primary health care unit, physical examinationbyan orthopaedic surgeon, diagnosis o injury still unclear, and one MR im-age taken at the Central Military Hospital. Patients with a recent traumaor presentingsymptoms on arrival at their military service were excludedrom the study.Te patients came rom different units and represented thegeneral conscript population o the Finnish Deense Forces with no spe-cific eatures. Te mean population at risk per year during the study periodconsisted o 14,640 conscripts within the service area o the hospital.

Studies IV and V

During the study periods o twenty years, rom January 1, 1975 to Decem-ber 31, 1994 (IV) and twenty-one years, rom January 1, 1970 to Decem-ber 31, 1990 (V), a total o twenty-one consecutive displaced (IV) and 106non-displaced (V) emoral neck atigue ractures were treated in militaryconscripts within the catchment area o concern in the present study. Iden-

tification o the ractures was perormed by running a computer searchon the National Hospital Discharge Register, using the appropriate diag-nostic codes o the 8th (1969-86) and the 9th (1987-1995) editions o theInternational Classification o Disease (ICD), and by linking them with thecodes o the military hospitals nationwide. During the study periods, inStudy IV, on average 34,723 males, and in Study V, on average 36,606 malesstarted their military service annually, constituting the populations at riskor sustaining a stress racture o the emoral neck. At the beginning o themilitary service, the majority o the conscripts were 19 to 20 years old in

both studies.


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4.2. Methods

4.2.1. Study description

Study I

In this study, the effect o serum 25OHD concentration on atigue bonestress injuries was evaluated. For this purpose, serum samples were gath-ered rom all participants o the study at the beginning o their militaryservice. Te samples were rozen or later analysis perormed with OCEIAenzyme immunoassay by IDS (Immunodiagnostic Systems Inc, Foun-tain Hills, AZ, USA). Computer-based data on conscript height, weightand physical fitness obtained during the first weeks o their service werecollected. Physical fitness was assessed using a 12-min running test and

five measures o muscle strength. Te conscripts were ollowed or threemonths to identiy possible stress injuries to bone. All the patients whoby clinical examination and anamnesis were suspected to have developeda bone stress injury during the said period underwent plain radiographicimaging, and those whose symptoms continued and radiographs remainednegative urther underwent MR imaging. Te subjects without stress rac-tures under observance constituted controls or the stress racture cases.

Study II

In this study, serum RACP-5b concentrations were measured to deter-mine whether they can be used to identiy enhanced bone remodeling re-lated to bone stress ractures. Te baseline blood samples or determiningRACP-5b levels were drawn rom all subjects o the study at their arrivalto military service. Tese subjects were then ollowed or three months toidentiy possible occurrence o stress ractures. Te subjects with symp-toms suggestive o bone stress injury were clinically examined, and, later,the diagnosis was confirmed by plain radiography, subsequently repeatedi necessary. From the patients with diagnosed or strongly suspected stressracture, our additional blood samples were drawn at 3-4-day intervals to

measure RACP-5b activity. Blood was also drawn rom two non-symp-tomatic controls with matching BMIs or each racture case. Te analysiso serum samples rom patients with a confirmed stress racture togetherwith corresponding samples rom controls was subcontracted to SuomenBioanalytiikka Oy (SBA sciences, Oulu, Finland), and conducted by usingan immunoassay protocol described by Alatalo et al. (Alatalo et al. 2000)

Study III

In this study, the original medical records and MR images o the conscripts

who underwent MRI or unclear stress-related anterior lower leg pain wereretrospectively obtained and evaluated. Te MR images were interpreted


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with the aim to determine the incidence, anatomic location and grade othe possible stress injury involved. Te normal procedure among the or-thopaedic surgeons at the Central Military Hospital was to prescribe MRIor cases with prolonged stress-related lower leg pain when no other, cleardiagnosis was known.

Studies IV and V

Inormation retrieved rom the medical records and imaging examinationsconcerning the military service period o the subjects was evaluated, and thelong-term outcome data o the subjects was collected by asking all the pa-tients in the studies (IV, V) to participate in a ollow-up examination. imerom the initial injury to ollow-up examination varied between eight andthirty-two years. In Study IV, o the 21 patients with a diagnosed displacedemoral neck atigue racture, long-term ollow-up data was available on

19 patients. In Study V, 66 o 106 patients invited agreed to participate inthe ollow-up. Moreover, in connection with the long-term ollow-up visit,inormation regarding possible examinations and treatments perormed inother hospitals afer patients previous visits to the military hospital wereasked, and the medical records and radiographs rom those hospitals wereretrieved or review and analysis. Fracture patterns were determined ac-cording to Garden and Orthopaedic rauma Association classifications(Garden 1961, Muller et al. 1990, Orthopaedic rauma Association Com-mittee or Coding and Classification 1996). Te body mass index (BMI) atthe time the racture was detected was computed (World Health Organiza-tion 1995)and classified according to Llwellyn-Jones and Abraham clas-sification (Llwellyn-Jones and Abraham 1984). Te BMIs o the patientsin the study were compared with those o 223 conscripts born in 1958and serving their time o compulsory military service in 1978 (Dahlstrm1981).

Te impact o the new instructions implemented in the army nation-wide in 1986, designed to increase awareness o the diagnosis and treat-ment o atigue ractures, was assessed by calculating the incidence o allatigue ractures o the emoral neck as well as the incidences o displaced

and non-displaced emoral neck atigue ractures beore and afer 1986within the time periods o the studies.

Te ollow-up visit consisted o a physical examination, including esti-mation o the unctional status o the hip joint using the Harris Hip Score(Harris 1969), conventional anteroposterior radiography, and MRI o thepelvic area. A ten-point (0 to 100 mm) visual analogue scale (VAS), withzero denoting none, rom 10 to 30 light, rom 40 to 60 moderate, rom 60to 90 hard, and 100 denoting the worst imaginable pain, was used to assessthe degree o subjective pain experienced by the patients one week beore

the ollow-up examination.


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4.2.2. Clinical diagnosis and treatment

In Studies I-III, the physical examinations conducted at patients primaryhealth care units adhered to identical care policies, including careul his-tory taking, inspection o skin changes, and palpation. In addition, the or-thopaedic examination (III-V) included observation o joint movements

and ligamentous stability o the lower extremities as well as checking ordistal pulse and sensation. Each unit participating in the studies ollowedidentical procedures or diagnosis, treatment, and patient reerral or addi-tional examinations. Beore orthopaedic evaluation, patients were treatedconservatively, as necessitated by pain, with rest periods or reduced exer-cise, NSAID, and prescribed crutches i walking caused pain.

4.2.3. Imaging methods

In all studies, the same accepted radiological assessment procedure was

adhered to during the plain radiographic examinations at both the primaryhealth care units and the Central Military Hospital (Kiuru et al. 2004). Tegrey cortex sign, periosteal callus, endosteal callus, sclerotic band, andracture line were accepted as the radiographic signs marking a bone stressinjury. In Study III, based on MRI, bone stress injuries were classified as:Grade I, endosteal marrow edema; Grade II, periosteal edema and end-osteal marrow edema; Grade III, muscle edema, periosteal edema, andendosteal marrow edema; Grade IV, racture line; and Grade V, callus incortical bone (Kiuru et al. 2001). In Study IV, in the radiographic classifi-cation o osteonecrosis o the emoral head, the method o Ficat and Arlet(Ficat and Arlet 1980) was used, and in Studies IV and V, the radiographicseverity o osteoarthritis was classified according to the criteria o nnis(nnis 1987). In study V, MRI was used in the detection o osteonecrosiso the emoral head and osteoarthrotic changes o the hip joint. Both hipjoint spaces were measured rom the original digital MR imaging data andstatistically compared with each other in each patient. Moreover, in Stud-ies IV and V, the original diagnoses o the stress ractures were thoroughlychecked and verified at the ollow-up examination by means o evaluatingthe whole series o radiographic images or each patient. All the images

were evaluated by a musculoskeletal radiologist.

4.2.4. Statistical methods

Te data analyses or all studies (I-V) were perormed using SPSS or Win-dows (versions 11.0/11.5/12.0/12.0.1, SPSS Inc, Chicago, Illinois, USA). InStudy II, logistic regression analysis was perormed using Stata or Win-dows (version 7.0). Te limit or statistical significance was set at a P-valueequal to 0.05. Various methods were used or statistical analysis in the di-erent studies.


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In Study I, the differences in serum 25OHD levels between the twogroups ormed by dividing the skew continuous data based on the me-dian were tested by the Pearson chi-square test, and the results were cor-roborated by the Mann-Whitneys U-test using the original values. TeStudents t-test was used to test differences in age, BMI, height, weight,

muscle strength, and result o 12-min running test between the groups.Te association between these variables and stress racture was studied us-ing logistic regression. Odds ratios were calculated with a 95% confidenceinterval.

In Study II, the relationship between RACP-5b activity and an out-come o being a case or a control was estimated using conditional logis-tic regression. Sensitivity and specificity were investigated using area un-der the ROC curve with confidence interval and coordinate points o theROC curve. Because the values were not normally distributed, logarithmic

transormations were used to analyze changes in RACP-5b activity. estswere perormed using analysis o variance or repeated measures.

In study III, the relationship between the locations o tibial stress in-juries and their MRI grades was tested using the Fishers test. Differencesbetween the groups were tested using the Kruskal-Wallis test or skew con-tinuous data.

In Studies IV and V, the Chi-square test was used to determine the sig-nificance o differences between two independent groups at the 0.05 P-level. Te Students t-test and the Mann-Whitney exact U-test were usedor comparing independent means. Incidence rate ratios with 95% confi-dence intervals were calculated or the ractures occurring in 1975-86 and1987-1994 in Study IV, and or the ractures occurring in 1970-1985 and1986-1990 in Study V, correspondingly.

Te Least Significant Difference (LSD) test in Study II and the Mann-Whitney U test in Study III were used as post-hoc tests or additional in-ormation.


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5 RESULTS

5.1. Serum 25OHD concentration as a potential

predisposing factor for fatigue bone stress fracture,

incidence and anatomic distribution of these fractures,

and their relationship with age, weight, height, BMI,

muscle strength, and result of running test. (I)

Te median serum 25OHD level was 75.8 nmol/l (25.2-259.0) or all theconscripts in Study I, but it was significantly lower in conscripts with stressracture than in controls (p = 0.017). In the multivariate regression model,the conscripts with serum 25OHD levels below the median were at 3.6(95% CI: 1.2-11.1) times higher risk or stress racture than conscripts withconcentrations above the median level, a difference ound statistically sig-nificant (p = 0.002) (able 5).

In Study I, conscripts results in the 12-min running test and in the mus-cle strength test were significantly poorer compared with controls (mean2480 m vs. 2670 m, p = 0.007; and mean 7 vs. 9, p = 0.025, respectively).However, in the multivariate regression model, when all significant varia-bles rom the univariate observation were adjusted, a non-significant asso-ciation emerged with stress ractures. No significant associations betweendaily smoking, BMI, age, height, and weight and bone stress racture wereound in this study population.

In this study, the incidence o stress ractures was 11.6 (95% confidenceinterval 6.8-16.5) per 100 person-years (2.9%). A total o thirty stress rac-tures were diagnosed in the twenty-two patients o this study. Tirteen

ractures (43%) were located in the tibia, ten (33%) in the metatarsal bones,three (10%) in the calcaneus, two (7%) in the tarsal navicular bone, oneracture in the inerior ramus, and one in the emur.


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Table 5. Te characteristics o the study population by stress racture status.

VariableStress fracture group

(n=22)

Control group

(n=734)

Significance

(Test)

Median (Range)

Concentration of 25OHD,nmol/l

64.3 (40.1-159.0) 76.2 (25.2-259.0) 0.017 (M-W)

Number (Frequency)

25OHD (nmol/l)

< median

median (75.8 nmol/l)

Missing N

18 (81.8%)

4 (18.2%)

0

362 (49.3%)

372 (50.7%)

0

0.002 (P)

Daily smoking

Yes

No

missing

7 (36.8)

12 (63.2)

3

93 (34.7)

175 (65.3)

466

0.85 (P)

Mean (Range)

Age (years)

Missing N

20.0 (18.6-22.3)

0

19.8 (18.0-28.5)

0

0.27 ()

BMI (kg*m-2)

Missing N

24.0 (15.4-37.4)

1

23.2 (16.6-39.2)

14

0.41 ()

Height (cm)

Missing N

177 (168-184)

1

179 (161-203)

14

0.15 ()

Weight (kg)

Missing N

75.3 (47.2-121.1)

1

74.3 (50.3-139.4)

13

0.70 ()

Muscle strength

Missing N

7 (0-15)

67

9 (1-15)

67

0.025 ()

Cooper test/12-minute run(m)

Missing N

2480 (1650-3200)

0

2670 (1540-3580)

49

0.007 ()

M-W:Mann-Whitney U-test

P: Pearson Chi-square test

T: Students -test


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5.2. TRACP-5b bone resorption marker as a potential

indicator of enhanced bone remodeling in military

conscripts with stress fractures, and the incidence and

anatomic distribution of these fractures. (II)

Te conscripts with elevated serum RACP-5b activity levels had an eighttimes higher probability o stress racture existence than controls whencomparing the ratio o sample IV (taken within 10-11 days afer detectiono stress racture) to baseline sample in the racture and control groups(OR 7.95 95% CI 0.41-153.72) (able 6).

Although an increasing trend in the RACP-5b levels was ound whencomparing the baseline samples to samples I-IV in the conscripts o theracture group, the finding did not show statistical significance (p = 0.072).

It is noteworthy, however, that the difference between the baseline andsample III was statistically significant (p = 0.039) (Fig 7).

Using a cut-off value o 1.09 or the ratio between sample IV and base-line, both the sensitivity (0.62) and the specificity (0.65) o RACP-5b levelas an indicator o stress racture exceeded 0.6. Sensitivity (0.62-0.54) andspecificity (0.55-0.70) were both over 0.5 when the cut-off point varied be-tween 1.05 and 1.14. Te area under the ROC-curve, as calculated or theratio between sample IV and baseline, was 0.60.

Table 6.Results o comparisons o the RACP-5B activity between racture and control

groups

Fracture group Control group Regression analysisa Area under ROC-curve (AUC)b

n mean(sd) n mean(sd) n P OR(95%CI) AUC (95%CI) Pc

Baseline 13 3.40(0.77) 20 3.31(0.93) 33 0.780 1.12(0.51, 2.46) 0.54(0.34, 0.74) 0.726

IV 14 3.91(1.13) 28 3.65(1.13) 42 0.471 1.23(0.70, 2.18) 0.55(0.37, 0.73) 0.603

IV/Baseline 13 1.21(0.34) 20 1.09(0.19) 33 0.170 7.95(0.41,153.72) 0.60(0.38, 0.82) 0.338

a Conditional logistic regression analysis

b Te test result variable(s): Baseline and IV has at least one tie between the positive actual state group and the negativeactual state group. Statistics may be biased.

c Null hypothesis: true area = 0.5


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In this study, the prevalence o stress ractures was 2.4%. A atigue rac-ture was detected in a total o twenty patients. Six patients were lost to finalanalysis on account o unsuccessul serum samples, incomplete ollow-updata, and termination o military service caused by a long recovery timeafer stress injuries. In the remaining ourteen patients, altogether twenty-

one stress ractures were diagnosed. welve ractures (57%) were locatedin the tibia, six (29%) in the metatarsal bones, and three (14%) in the cal-caneus.

Figure 7. Changes in RACP-5b activity o racture group. Calculations were doneusing logarithmic transormation and the values were retranserred to original scale(N=14).

5.3. Fatigue bone stress injuries associated with anterior

lower leg pain; incidence and distribution, MRI based

injury grades depending on injury location and

duration of symptoms. (III)

During the 5-year period o this study, the incidence o bone stress injuries

requiring orthopaedic consultation and MRI among conscripts was 117per 100,000 person-years o military service. Te findings on MRI revealed143 bone stress injuries in 86 patients (56%) o the study population o154 patients. In 141 cases, the injury was located in the tibia and in twocases, in the fibula. Forty-nine patients had stress injuries bilaterally. Fourpatients had two injuries in the same lower leg, and two patients had threeinjuries in the same lower leg. One patient had simultaneous bone stressinjuries in the tibia and in the fibula. In the tibia, 57% o the injuries werenoted in the distal, 30% in the middle, and 10% in the proximal third o

the tibial shaf, and 3% in the medial condyle. Moreover, the findings in-cluded two legs with symptomatic osteoid osteomas, seven with tractionperiostitis, and three with sof tissue edemas. Other, clinically irrelevant

3

3,1

3,2

3,3

3,4

3,5

3,6

3,7

3,8

TRACP5b

Baseline I II III IV


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findings consisted o two non-ossiying fibromas and one healed corticaldeect. In 53 patients, all findings on MRI were normal. O all the 143 a-tigue stress injuries detected by MRI, 17% (24) appeared in legs withoutany symptoms.

According to the MRI grading system that was used, 50% (71) o the

tibial stress injuries represented grade I, 33% (47) grade II, 8% (11) gradeIII, 7% (9) grade IV, and 2% (3) grade V. Te correlation between the loca-tions o tibial stress injuries and the MRI grades I-V was statistically sig-nificant (p < 0.001) (able 7). Te injuries displayed higher grades in themedial condyle and the proximal third compared to the middle and distalthirds o the tibia. Symptom duration beore the stress injury diagnosiswas significantly dependent on the MRI grade o the injury (p = 0.002).Patients with minor bone lesions (Grade I) on MRI had a greater mediano symptom days compared with Grade II (p < 0.001) and Grade IV (p =

0.040). Statistical significance was also seen in the relationship betweenpatients symptom duration and MRI based injury location in the tibia (p= 0.025) (able 8). Symptom duration preceding the injury diagnosis wassignificantly shorter in the medial condyle than in the middle (p = 0.004)and distal tibia (p = 0.006), whereas in the proximal tibia, the differencebordered significance (p = 0.053). No changes were noted in the resultsafer persons with more than one bone stress injury finding were excludedrom the data.

Due to a clinical suspicion o a chronic exertional compartment syn-drome (CECS), 44 patients (with 74 legs involved) o this study also un-derwent an intracompartmental pressure measurement, perormed using aslit catheter technique (Rorabeck et al. 1981, Moed and Torderson 1993).Values o 40 mmHg or higher were considered pathological (Whitesideset al. 1975, Hutchinson and Ireland 1994). In these 44 patients, 11 o the39 legs were confirmed by MRI to suffer rom bone injuries with elevatedpressure in the anterior tibial compartment.

Table 7.Locations o tibial stress injuries and mri findings classified as grades iv

Location MRI grade of bone stress injury Total

GI GII GIII GIV GV

Medical condyle 0 3 0 2 0 5

Proximal tibia 2 4 2 4 2 14

Middle tibia 20 18 2 2 0 42

Distal tibia 49 22 7 1 1 80

Fishers test, p value < 0.001


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5.4. Incidence, symptomatology, morphologiccharacteristics, clinical course, risk factors, and long-

term outcomes of displaced and non-displaced

fatigue fractures of the femoral neck. (IV, V)

Study IV

Incidence (per service-years) o displaced emoral neck atigue racturesduring 1975-1986, prior to the new regimen o 1986 addressing preven-tion o atigue ractures, was 5.3/100,000, decreasing 2.3 old during1987-1994 to 2.3/100,000 (95% CI 0.11-1.31). Detection o non-displacedsymptomatic emoral neck atigue ractures increased rom 15.5/100,000to 53.2/100,000 (95% CI 2.27-5.21) service-years, correspondingly. Tetotal incidences o the emoral neck atigue ractures in the correspond-ing years were 20.8/100,000 and 53.2/100,000 service-years (in 1987-90no displacements were observed), respectively, indicating a significant 2.6old increase (95% CI 1.7-4.0). Garden-type IV ractures decreased sig-nificantly rom 3.8 to 0/100,000 (95% CI 0-0.66) service-years between thetime-periods concerned.

Nineteen ractures were ollowed up in the study (ables 9A and 9B),including eight ractures o Garden-type III and eleven o Garden-type IV.Assessment o the ractures using the system o the Orthopaedic raumaAssociation revealed eighteen transcervical (type-31B2) ractures and onesubcapital (type-31B1) racture. During the first postoperative year, tencases showed early local complications, but in the remaining nine cases,racture healing was uneventul. Altogether six cases sustained delayed ornonunion o the racture. In our cases, a repeat operation was necessaryduring the first postoperative year.

During the subsequent long-term ollow-up, starting rom the 2nd

post-operative year, late, slowly developing complications, such as osteonecrosiso the emoral head in six and osteoarthritis o the hip in thirteen patients,

Table 8.Median (range) duration o symptoms in locations o MRI findings

Location o mri finding N Duration o symptoms (days) P value*

medial condyle 5 36(23,59)^~ 0.025

proximal condyle 14 51(30, 105)^

middle tibia 42 66(16, 210)

distal tibia 80 67(2, 224)~

* Kruskal-Wallis test

Mann-Whitney u-test was used as a post-hoc test, significant or almost significant p-values:^0.053, 0.004, ~0.006


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were detected among the nineteen cases (Fig 8A-E). According to nnisclassification, we discovered our Grade 1, one Grade 2, and eight Grade 3cases o osteoarthritis o the hip. Te correlation between severe (nnisGrade 2 and Grade 3) hip osteoarthritis and osteonecrosis o the emoralhead was statistically significant (p = 0.020). Revision surgery was neces-

sary in our cases due to these complications. Altogether three patientsreceived total hip prostheses by the final ollow-up examination.

In thirteen patients, a mean 32.7% (range 4 to 100%) shortening o theemoral neck compared to the uninjured contralateral side was observedat the latest radiological ollow-up examination. Garden-type IV atigueracture emerged as a significant risk actor both or osteonecrosis o theemoral head (p = 0.018) and or the shortening o the emoral neck (p= 0.009). A significant association was also noted between osteonecrosisand shortening o the emoral neck in that the shortening was significantly

greater in patients with than without osteonecrosis (p = 0.001).

Study V

Te incidence (per service-years) o non-displaced emoral neck atigueractures was examined separately or the period prior to and the periodafer the new regimen o 1986 or the prevention o atigue ractures was in-troduced. In the ormer period, 1970-1985, the incidence was 10.2/100,000and in the latter period, 1986-1990, it was 51.2/100,000, indicating a 5 oldincrease (p < 0.000). Te overall incidence or the 21-year study period was19.4/100,000 service-years.

None o the non-displaced emoral neck atigue ractures diagnosedduring the study progressed to displacement. With only one exception, allconscripts included in the study returned to normal duty service ollowingrecovery afer conservative treatment.

Te risk actor analysis perormed or the two studies (IV, V) ailed toreveal any predisposing or risk actors. A significant deviation (p = 0.013)was, however, ound between the BMIs o the contemporary control con-scripts (born in 1958) and the conscripts with displaced emoral neck a-tigue ractures (IV) (able 10). Measurements o the neck-shaf angle rom

the radiographs (V) did not reveal any angles outside normal limits (125to 135). MRI assessments o the average joint spaces in the injured 2.05mm (SD 0.63) and uninjured 1.97 mm (SD 0.61) hips (V), respectively,showed no significant deviations (p = 0.297).

At the final ollow-up (V), the intensity o subjective pain and pain ex-periences was expressed by 62 patients using VAS. Te mean score o painintensity was 5.85 mm (SD 10.48) on a scale o 100 mm. Forty-three pa-tients were completely painless and two patients reported pain levels be-tween 40 mm and 44 mm, correspondingly. Te mean HHS was 97 (70

to 100). Tirty-seven (60%) patients did not report any physical disabilityaccording to HHS, seven (11%) patients had HHS o 70 to 90 and 19 (31%)had HHS o 91 to 99.


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Table9AC

linicaldatao19patientswithdisplace

datigueractureotheemoralneck,typeoprimarytreatment,earlycomplicationsandsecondarym

easures

Casenoandyea

r

offractureonset

Age(yr)/

affectedside

Bmi*

(kg/m2)

Smoker

Durationofmilitary

serviceatonsetof

fracture(months)

Activitypreceding

fractu

re

Ongoingevent

leadingto

onsetoffracture

Fracture

type**

Primary

treatment

Early

complicationsandsec-

onda

rymeasureswithinone

year

afterprimaryoperation

1/1975

20/right

20.2

-

6

Marching

Stumbling

III/type-31B2

raction

Malunion(varusangulation)

2/1977

18/lef

19.1

+

2

Combattraining

None

IV/type-31B2

AngledplateDelay

edunionwithbrokenscrews

otheplate

3/1977

20/right

19.6

-

7

Marching

None

IV/type-31B2

DHS

Delay

edunionwithbrokenscrews

oDH

Splate

4/1977

18/lef

17.7

-

5

Marching

Stumbling

IV/type-31B2

DHS

5/1978

20/right

20.6

+

4

Marching

Stumbling

IV/type-31B2

DHS

Nonu

nion,removalohardwareand

finallymalunion

6/1979

19/lef

21.0

-

3

Running

Stumbling

IV/type-31B2

AngledplateNonu

nion,refixationwithDHS,and

bonegrafing(6mo.)

7/1981

20/right

20.1

-

4

Running

Ridinghard

onabicycle

IV/type-31B2

AngledplateDeep

inection,removalohardware

andbonegrafing(3mo.)

8/1983

19/right

20.8

+

4

Combattraining

Stumbling

IV/type-31B2

DHS

Heterotopicossification

9/1983

20/right

19.6

-

2

Marching

Slipping

IV/type-31B2

DHS

Nonu

nion,intertrochantericoste-

otomy,bonegrafing(7mo.)

10/1983

20/lef

23.5

-

3

Marching

Stumbling

IV/type-31B2

DHS

11/1983

23/lef

18.6

+

5

Marching

None

III/type-31B2

DHS

12/1983

19/right

18.9

+

1

Bicyclemarch

None

IV/type-31B1

DHS

Failur

eofixation,refixation(1mo.),

delayedunionandfinallymalunion

13/1984

20/right

16.1

+

6

Running

Applyingcarbrakes

III/type-31B2

DHS

14/1985

19/lef

20.2

+

4

Marching

Stumbling

III/type-31B2

DHS

15/1986

20/right

26.1

-

2

Marching

Stumbling

IV/type-31B2

DHS

16/1991

19/right

26.2

+

3

Marching

None

III/type-31B2

DHS

17/1993

19/right

19.3

-

2

Running

None

III/type-31B2

DHS

18/1993

20/lef

22.2

-

6

Marching

None

III/type-31B2

DHS

19/1994

27/right

24.0

-

6

Marching

None

III/type-31B2

DHS

Break

ageoDHS

Mean:

Range:

20years

18-27years

20.716.1-26.2

3.9months

2-7months

*BMI=BodyMassIndex,**GardenClassification/ClassificationSystemotheOrthopaedicra

umaAssociation,DHS=DynamicHipScrew,OA=Osteoarthritis,OFH=O

steonecrosisotheFemoralHead,

=NoEarlyComplicationsorSecondaryMeasuresWithinOneYearAferPrimaryOperation


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Table9B

Finalollow-updataonthePatients

Case

Follow-up

time

(years)

Latecomplicationsand

reoperationsmore

thanoneyearafterprimary

operation

(timeofreoperationinmon

thsafter

primaryoperation)

Radiographic

findings

Vas-score

Professionoremploymen

t

attimeoffinalfollow-up

Shorteningofthe

femoralneck

(%)*

Gradeof

osteoarthritis**

1

26

OA

10

Gr3

10

Assistantmanager

2

9

0

Gr0

NR

Lawyer

3

25

0

Gr0

0

Projector

4

26

OFHandOA,HA(231mo.)du

etoOFH

60

Gr3***

NR

Engineer

5

23

OFHandOA

100

Gr3

50

Service-man

6

22

OFHandOA

10

Gr3

13

Chieinspector

7

20

OA,HA(228mo.)duetoOA

10

Gr3***

50

Masterbuilder

8

19

OA

30

Gr1

36

Plumber

9

18

OFHandOA,HA(172mo.)du

etoOFH

100

Gr3***

55

Retired

10

19

OFHandOA

20

Gr3

NR

Engineer

11

19

OA

0

Gr1

45

Lawyer

12

20

OFHandOA,1

)vascularboneg

raf,(25mo.)dueto

OFH2)osteotomy(59mo.)duetoOFH

50

Gr3

28

Qualitysupervisor

13

22

0

Gr0

25

Sparepartssalesman

14

18

10

Gr0

0

Appraiser

15

16

OA

11

Gr2

2

Officemanager

16

11

OA

4

Gr1

0

Cook

17

9

0

Gr0

61

Farmer

18

11

0

Gr0

0

Waiter

19

8

OA

10

Gr1

0

echnicalmanager

Mean:

Range:

20years

8-26years

22.4%

0-100%

23mm

0-61mm

*Ascomparedwith

theuninjuredhip,**Accordington

nisClassification,***BeoreHA,

=NoLateComplicationsorReoperationsMoreTanOneYearAferPrimaryOperation,

HA=otalHipArthroplasty,DHS=DynamicHipScrew,NR=NotReported,OA=Osteoarth

rosis,OFH=OsteonecrosisotheFem

oralHead,VAS-score=VisualAnalogueScalescore


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44

A B

C D


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45

Figure 8A-E.

A. Case 5. A 20-year-old recruit with Garden-type IV atigue racture o the right emoral neck 10days afer a long march.

B. Acceptable anatomical position afer open reduction and fixation o the racture with dynamichip screw shows in ollow-up radiograph six weeks afer the index operation. Minor signs obeginning osteonecrosis in the medial aspect o the emoral neck can be seen.

C. Advanced resorption o the emoral neck, varus bending, and a still detectable racture line canbe seen three and a hal months afer the index operation.

D. Dynamic hip screw has been removed as its supportive and fixative unction was lost due toadvanced osteonecrosis. Because o the condition, refixation was not possible. Malposition, astill visible racture line, advanced emoral neck shortening and increased osteonecrosis o theemoral head developed ourt

Documents

Fatigue Fx Military Conscripts