The report of a 27-years-old man with presence of heterotopic ossification (HO) after femoral nailing 7 years ago who developed foot drop after falling to the ground on his buttocks. Radiographs revealed a prominence of the femoral nail with HO in his right hip. EMG confirmed peroneal nerve injury of the hip region. Femoral nail and the HO were removed and external neurolysis was performed. At 9 months after surgery, he had not regain motor power, thus posterior tibialis tendon transfer was performed to restore ankle dorsiflexion. Finally, at 2 years follow-up, he could ambulate well but did not regained sensation, extensor digitorum communis and peroneal muscle function.

Keywords: Sciatic nerve injury, Heterotopic ossification, Prominence of the femoral nail