Palsy of the deep peroneal nerve after proximal tibial osteotomy. An anatomical study.

Iatrogenic, isolated weakness or paralysis of the extensor hallucis longus muscle is a common complication in patients who have had a proximal tibial and fibular osteotomy. To investigate why this complication occurs, we dissected the deep peroneal nerve and neighboring structures, such as the tibia and fibula and the muscles of the leg, in twenty-nine specimens from cadavera, paying special attention to the motor branches supplying the extensor hallucis longus. Of forty-six motor nerves that were identified, eight entered the muscle from the lateral side in an area seventy to 150 millimeters distal to the fibular head; all of them ran close to the fibular periosteum. We suggest that, in some patients, the nerve supply to the extensor hallucis longus is at high risk for injury during a tibial osteotomy because of the proximity of the bone to the motor branches.