CASE REPORT

Transient bilateral osteoporosis of the hip mistaken for septic arthritis:unusual presentation in a non-pregnant woman

Received: 16 February 2003 / Accepted: 15 July 2003 / Published online: 13 September 2003� Springer-Verlag 2003

Abstract Transient osteoporosis of the hip is anuncommon condition that affects young and middle-aged men, and women during the third trimester ofpregnancy. Its incidence and aetiology in pregnancy isunknown. It is bilateral in approximately one third ofpatients. The patient characteristically gives a historyof gradual onset of groin pain increasing in severityover a number of weeks, with pain worse on weightbearing. There is no history of trauma or systemicupset. Differential diagnoses are avascular necrosis ofthe hip, neoplasm, osteomyelitis and synovitis. Clinicaldiagnosis can be elusive, and symptoms are oftenmisinterpreted leading to unnecessary tests and mor-bidity. Diagnosis is by radiological investigation.Treatment is conservative, including protected weightbearing, physical therapy and non-steroidal analgesics.We present a highly unusual case of sequential bilateraltransient osteoporosis of the hip in a non-pregnantwoman. Initial presentation mimicked septic arthritisleading to arthrotomy.

Keywords Transient osteoporosis Æ Hip Æ Pain Æ MRI

Osteoporose transitoire bilaterale de hanche

Resume L’osteoporose transitoire des hanches est uneaffection peu commune, qui affecte les hommes jeunes etd’age moyen et les femmes durant le dernier trimestre deleur grossesse. Son incidence et son etiologie chez la

femme enceinte ne sont pas connus. Il existe approxim-ativement un tiers des patients presentant une affectionbilaterale. Le patient type presente une histoire dedouleurs de hanche, augmentant rapidement en intensiteen quelques semaines. La douleur est aggravee par lamise en charge. On ne retrouve pas de notion trauma-tique ou de maladie systemique dans les antecedents. Lesdiagnostics differentiels sont la necrose avasculaire dehanche, les lesions cancereuses, l’osteomyelite et lessynovites. Le diagnostic est souvent difficile, les sy-mptomes etant mal interpretes ou le raisonnement etanttrouble par des tests biologiques non necessaires ouparfois generant eux-memes de la morbidite. Le diag-nostic est fait radiologiquement, le traitement est con-servateur : mise en decharge, traitement autalgique etantiinflammetaire non stera. Nous presentons le cas in-habituel d’une osteoporose transitoire bilaterale dehanche chez une femme enceinte, dont l’aspect initial afait evoquer une arthrite septique qui a conduit a unearthrotomie.

Mots cles Osteoporose transitoire Æ Hanche ÆDouleur Æ IRM

Case report

A 38-year-old woman presented with a 2-week history of increasingpain and stiffness in her right hip 8 months after the birth of hersecond child. Her previous child was 11 years old. She had a regularmenstrual cycle, had not breast fed her baby and was on no form ofcontraception. She had marked pain at rest and walked with anantalgic gait. She had pyrexia of 37.9�C. Otherwise there was nosystemic upset. Examination revealed her to be holding her hip in10� of flexion. All movements of the hip were reduced due to pain,with complete abolition of internal rotation, flexion to 80� andabduction of 20�.

A roentgenogram of the hip demonstrated that the femoralhead had normal morphology but that there was an area ofpatchy radiolucency in the superior part of the head. Full bloodcount and plasma viscosity were within their normal ranges. Adecision was made that septic arthritis of the hip joint needed to

Eur J Orthop Surg Traumatol (2003) 13: 248–250DOI 10.1007/s00590-003-0098-x

Hammad Malik Æ Shazia Malik Æ Anil Gambhir

Anthony Clayson

H. Malik (&) Æ A. Gambhir Æ A. ClaysonDepartment of Pelvic Surgery,North Manchester General Hospital,Delaunays Road, Crumpsall, Manchester, M8 5RB, UK

H. Malik14 The Boulevard, Didsbury, Manchester, M20 2EU, UKE-mail: hammymalik@hotmail.comTel.: +44-161-2320487

S. MalikDepartment of Obstetrics and Gynaecology,Rosie Maternity Hospital, Cambridge, UK

be excluded. At arthrotomy of the right hip joint a turbid, non-purulent effusion was relieved. The articular surfaces appearednormal and there was no evidence of synovitis. Gram stain of theeffusion demonstrated no micro-organisms. Laboratory analysisconfirmed the effusion to be caused by a non-inflammatoryarthropathy with no evidence of infection. By 2 days post-ar-throtomy the patient’s pain was greatly decreased and she hadregained a full range of hip movement.

Magnetic resonance imaging was performed that demonstratedextensive increase in signal in the femoral head, femoral neck andthe proximal femoral shaft on the T2 and STIR images (Fig. 1)with correspondingly low signal on the T1-weighted images. Nojoint destruction was demonstrated. No mass was visualised withinthe femur, and adjacent soft tissues were of normal signal. Adiagnosis of transient osteoporosis of the hip was made. The pa-tient was allowed home non-weight bearing on crutches with herpain well controlled with regular ibuprofen. At review at 3 weeks,all her symptoms had resolved, but an X-ray confirmed osteopo-rosis of the femoral head (Fig. 2).

The patient re-presented 19 months later with a similar clinicalpicture of left hip pain. She had, however, had depot-medroxy-progesterone acetate (DMPA) injections over the previous 6 monthsfor contraception. MR scanning of the hips demonstrated typicalchanges of transient osteoporosis of the left hip associated with ajoint effusion, and normal appearances in the right hip (Fig. 3).Treatment of physical therapy, non-steroidal anti-inflammatory

medication and restricted weight bearing was initiated [3]. Hersymptoms resolved after 4 months. She has had no further episodesof joint pain.

Discussion

Transient osteoporosis of the hip is well described inmiddle-aged men, in women in the third trimester ofpregnancy and during lactation [1]. It is bilateral inapproximately one third of patients [2]. The actualincidence is unknown, as are its pathogenesis or thedynamics of bone density during the acute and recoveryphases. It very rarely presents in other groups. As such,the presentation of the subject described in this case washighly unusual and led to the initial concern of septicarthritis.

Although its radiographic appearance is very specific,its rarity and aspecific clinical presentation can makeearly diagnosis difficult. In particular, osteonecrosis ofthe femoral head can be high on the list of differentials.MR imaging is regarded as the most sensitive investi-gation of choice for most disorders of the hip joint [6],including transient osteoporosis, but it may not bereadily available and aspiration can be technicallychallenging. In the acute situation, ultrasonography mayhave a place [4]. Aspiration can easily and effectively beperformed using this method as both a diagnostic andtherapeutic intervention. Arthrotomy for biopsy, reliefof effusion or as a therapeutic measure is not to berecommended due to the risk of iatrogenic fracture inosteoporotic bone.

Although this condition is well described duringpregnancy, we have not come across a case that oc-curred post-partum in the absence of lactation, whichis a known cause of hypo-oestrogenism. Even moreunusual is the occurrence of this problem some 19months after delivery and in the contralateral hip. Thepatient was using DMPA as a contraceptive at this

Fig. 1 STIR MRI image demonstrating low signal in the affectedright hip

Fig. 2 Plain roentgenogram demonstrating osteoporosis of the rightfemoral head

Fig. 3 STIR MRI image demonstrating low signal in the affectedleft hip and normal appearances in the now unaffected right hip

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point. Cross-sectional studies on the effects of DMPAon bone mineral density (BMD) have been contro-versial. One study showed that the duration of DMPAuse was not significantly correlated with the rate ofbone loss and that the annual rate of this loss in thelumbar spine, neck of femur and ward’s triangle wassubstantially less than the projected values [7]. There isprobably a non-linear loss in bone, with a rapid lossin the first 5 years and a levelling off afterwards. Infact, this patient had only used this for 6 months.Short-term administration of DMPA is associated withstable values in bone density [5]. We do not, however,have a baseline bone densitometry measurement inthis case.

Having made the diagnosis with the first episode ofhip pain, we had a high index of suspicion at thesecond presentation. This was important for manage-ment, as such a late attack has not been describedpreviously.

References

1. Bijl M, van Leeuwen M, van Rijswick M (1997) Transientosteoporosis of the hip: presentation of atypical cases and areview of the literature. Clin Exp Rheumatol 17:601–604

2. Bramlett K, Killian JT, Nasca RJ, Daniel WW (1987) Transientosteoporosis. Clin Orthop 222:197–202

3. Kaplan SS and Stegman CJ (1985) Transient osteoporosis of thehip. A case report and review of the literature. J Bone Joint SurgAm 67:490–493

4. Koski JM, Mullykangas-Luosujarvi R (1997) Transient osteo-porosis of the hip with joint effusion detected by ultrasonogra-phy. Clin Rheumatol 16:404–408

5. Naessen T, Olsson SE, Gudmunson J (1995) Differential effectson bone density of progestogen-only methods for contraceptionin premenopausal women. Contraception 52: 35–39

6. Sandro C (2000) Current concepts in magnetic resonance imagingof the adult hip and pelvis. Semin Roentgenol 35:231–248

7. Tang OS, Tang G, Yip PS, Li B (2000) Further evaluation onlong-term depot-medroxyprogesterone acetate use and bonemineral density: a longitudinal cohort study. Contraception62:161–164

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