Case report

A 16 year old girl developed insidious left groin pain after an 18 month period of limping before being seen in the department of rheumatology. No other complaint or remarkable history was noted. Pain was relieved by bed rest but was worse at night in particular after sport practice at school. Non-steroidal anti-inflammatory drugs (diclofenac, 75 to 100 mg/day) and analgesics (paracetamol, 2 to 3 g/day) were both effective. Physical examination revealed only decreased internal rotation of the left hip joint (5°) and atrophy of the left thigh (a 2 cm decrease in the circumference). Initial pelvicx rays performed nine months after onset were normal. Technetium-99m bone scan performed six months after initialx rays showed diffuse increased uptake over the hip including the femoral head, femoral neck, and acetabulum (fig 1A). Magnetic resonance imaging (MRI) showed decreased bone marrow signal intensity on T1 weighted images and increased signal intensity on T2 weighted images in the femoral neck with joint effusion. These changes were interpreted as depicting a possible stress fracture. However, computed tomography with 4 mm contiguous sections showed only joint effusion. On admission, a new pelvic x ray showed a 1 mm joint space narrowing with osteophytes ringing the femoral head and diffuse articular osteoporosis (fig 1C). Erythrocyte sedimentation rate was 16 …