Common peroneal nerve palsy from an untreated popliteal pseudoaneurysm after penetrating injury.

A 17-year-old boy presented with drop foot and loss of extension in his left knee after penetrating injury to the popliteal region. Color duplex ultrasonography and angiography revealed a popliteal artery pseudoaneurysm in the popliteal fossa. Electrodiagnostic tests demonstrated nearly total common peroneal nerve injury. The delay in diagnosis from the time of injury was 1 month. The pseudoaneurysm was repaired with primary suture through a medial incision. Epineurolysis of the common peroneal nerve was performed a week later through a posterolateral incision. Pain and knee contracture resolved after surgery. Drop foot recovered completely after 1 year.