The diagnostic and therapeutic challenge of femoral head osteoid osteoma presenting as thigh pain: a case report.

Osteoid osteoma, an infrequent but important cause of musculoskeletal pain, is often difficult to diagnose. We present a case of a 31-year-old man who, for 2 years, had left groin pain radiating to the thigh. Symptoms began 1 month after a motorcycle crash in which he sustained only shin abrasions. Initial spine and hip radiographs were negative. Treatment with naproxen provided significant relief, but the symptoms gradually worsened over 6 months. An electromyogram and lumbar magnetic resonance imaging (MRI) of the left lower leg were unremarkable. Hip MRI revealed edema without fracture. Prophylactic femoral pinning for impending stress fracture provided no relief. Rheumatologic evaluation revealed normal serologies and synovial fluid. Cyclobenzaprine and sulfasalazine were started and provided mild relief. At presentation to our institution, he was in significant discomfort, but could ride a bicycle for exercise and was completing a home exercise program. He had antalgic gait and globally restricted hip motion with end-range pain. A neurologic examination showed no abnormalities. Hip and pelvis computed tomography scan revealed increased sclerosis of the femoral head, with a central lucency suggestive of osteoid osteoma. This was confirmed by biopsy. Radiofrequency ablation provided significant symptom relief.