Osteochondroma of the femoral neck: a rare cause of sciatic nerve compression.

A 39-year-old man presented with weakness and a nonmobile mass in the buttock of 5 months' duration. Hip flexion was limited to 70 degrees. Strength was diminished for both ankle/foot plantar and dorsiflexion. Sensation was decreased on the plantar and dorsal foot. A pedunculated osseous mass measuring 6x4 cm on the posterior femoral neck was seen on plain radiographs and magnetic resonance imaging. Electromyography showed moderate sciatic neuropathy of the peroneal and tibial branches. The patient underwent excision of the tumor through a posterior approach. Due to the risk of weakening the neck, two 7.3-mm cannulated screws were passed percutaneously into the head with fluoroscopic guidance. The final pathological report indicated the tumor was an osteochondroma. At 22-month follow-up, he had full resolution of the neurologic findings. Postoperatively, the patient reported improvement in numbness and tingling in the leg but continued to have moderate buttock pain. Left hip flexion increased to 115 degrees at last follow-up.The importance of protecting the medial femoral circumflex artery during approaches to the hip is paramount. In this case, the tumor arose from the central aspect of the quadratus femoris, with the superior muscle protecting the medial femoral circumflex artery from harm. Although osteochondromas are a rare cause of mass effect, they should be considered in the differential diagnosis of sciatic nerve compression in this anatomical location.