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.