The Knee 11(2004) 327–329

0968-0160/04/$ - see front matter� 2003 Elsevier B.V. All rights reserved.doi:10.1016/S0968-0160Ž03.00078-4

Case report

Patello-femoral joint pain due to unusual location of localised pigmentedvillonodular synovitis—a case report

M.R. Edwards , S. Tibrewal*1

Queen Elizabeth Hospital NHS Trust, London, UK

Received 28 January 2003; accepted 11 April 2003

Abstract

Localised pigmented villonodular synovitis(PVNS) is a rare condition usually affecting the knee. It can be a difficult conditionto manage with an average delay in diagnosis of 4.4 years. We describe a case of a localised PVNS lesion interposed betweenthe patello-femoral joint, presenting as ‘anterior knee pain’. To our knowledge this has not previously been reported. The lesionwas completely excised at arthroscopy resulting in complete resolution of symptoms. Solitary lesions of PVNS should also beconsidered in the differential diagnosis of unexplained ‘anterior knee pain’.� 2003 Elsevier B.V. All rights reserved.

Keywords: Physiotherapy; Pigmented villonodular synovitis; Chondromalacia pattellae

1. Introduction

Pigmented villonodular synovitis(PVNS) is a prolif-erative disorder of the synovium of unknown aetiology.It affects the larger joints, knee and hip predominantlyw1x. The localised form of the disease is rare, it isusually monoarticular and affects the kneew2,3x. Themost common presentation of PVNS is of intermittentdeep joint pain, which is exacerbated by movement withthe addition of mechanical symptomsw4x. However, thevariety of clinical presentations can add to difficulty ofmaking a diagnosis, with the average delay in diagnosisof 4.4 yearsw5,6x. Localised lesions of the knee areusually located in the supra-patellar pouch, and do notinterfere with patello-femoral joint function.In this report we discuss a case of the localised form

of PVNS of the knee. Unusually, the lesion was inter-posed between the patello-femoral joint and presented

*Corresponding author. Queen Elizabeth Hospital, Stadium Road,London SE18 4QH, UK. Tel.:q44-208-836-5450; fax:q44-208-836-5458.

E-mail addresses: s.b.tibrewal@virgin.net(S. Tibrewal),drmaxedwards@hotmail.com(M.R. Edwards).

Queen Elizabeth Hospital, 33 Union Road, London SW4 6JQ,1

UK. Tel.: q44-771-8585-901

as ‘anterior knee pain’. After an English languageliterature search the authors believe this is the first suchreported case.

2. Case report

A 19-year-old pregnant woman presented to clinicwith left monoarticular anterior knee pain and clickingfor several years. Movement precipitated the clicking,which gave rise to the anterior knee pain. She reportedno locking or giving way. A knee injury with no bonyinvolvement was reported 8 years previously. On exam-ination the knee was not swollen and there was noevidence of any effusion. The patella was noted to tracklaterally to a mild extent. Crepitus was felt on flexionof greater than 108. Her symptoms were initially thoughtto be due to chondromalacia pattellae. Physiotherapywas commenced and review with respect to furtherinvestigation after the completion of the pregnancy wasarranged. Six months later the patient reported noimprovement of symptoms with the physiotherapy, soan arthroscopy was arranged.At arthroscopy, a pigmented lesion arising from the

synovium was noted to be interposed between the patellaand distal femur(Fig. 1). The lesion was completely

328 M.R. Edwards, S. Tibrewal / The Knee 11 (2004) 327–329

Fig. 1. Arthroscopic photographs showing the localised pigmented villonodular synovitic lesion interposed between the patella and femur.

Fig. 2. Histological specimen showing the giant cells of PVNS.

excised and removed through a small transverse incisionunder direct vision. This lesion was confirmed to bePVNS histologically(Fig. 2).At 6-month follow-up, the patient reported complete

resolution of her symptoms, and her patella trackingwas noted as normal.

3. Discussion

PVNS is uncommon, with an incidence of 1.8 casesper million per year, the localised form is even rarerw7x. The investigation of choice when considering PVNSis magnetic resonance imaging(MRI). Characteristic

329M.R. Edwards, S. Tibrewal / The Knee 11 (2004) 327–329

findings include low signal on both T1 and T2 weightedimages, hyperplastic synovium(as a lobulated synovialmass), and bony erosions with preservation of bonedensity. Occasionally there is evidence of joint effusion,and increased density at the periphery secondary tohaemosiderin depositsw8,9,4x. In this case an MRI wasconsidered at the second consultation, but diagnosticarthroscopy was arranged after discussion with thepatient. Resection of localised PVNS is usually curative,but the patient should always be informed of thepossibility of recurrence.Chondromalacia pattellae is a diagnosis that is often

assumed in young patients with ‘anterior knee pain’.This case highlights that other rare and potentiallycurable conditions that can give rise to the symptomsmimicking chondromalacia pattellae. PVNS should thusbe included in the differential diagnosis of patients withunexplained anterior knee pain.

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