Anterior Approach Total Ankle Arthroplasty: Superficial Peroneal Nerve Branches at Risk

In ankle arthroplasty, little attention has been given to intraoperative nerve injury and its postoperative sequelae. The aim of the present anatomic study was to determine the relationship of the superficial peroneal nerve to the standard anterior approach for total ankle arthroplasty. The superficial peroneal nerve was dissected in 10 below-the-knee cadaver specimens. The medial and intermediate dorsal cutaneous branches were identified. A needle was placed at the ankle joint. The following measurements were recorded: bifurcation into the medial and intermediate dorsal cutaneous branches, reference needle to the branches of the medial and intermediate superficial peroneal nerve, and the crossing branches of the medial dorsal cutaneous nerve. Two specimens (20%) had a medial dorsal cutaneous branch cross from medially to laterally. Eight specimens (80%) had a crossing branch of the medial dorsal cutaneous branch within 5 cm of the incision. No intermediate dorsal cutaneous branches were within the incision. The results from the present cadaver study suggest that during an anterior ankle approach, aberrant branches of the superficial peroneal nerve could require transection in 20% of patients at the joint level and ≤80% of patients with distal extension >35 mm from the ankle joint. The risk of injury to branches of the superficial peroneal nerve is substantial. The risk of nerve injury can be decreased with meticulous operative technique, smaller incisions, and the avoidance of aggressive retraction.