Anterior transposition of the superficial peroneal nerve branch during the internal fixation of the lateral malleolus

Background: Because of the anatomic variations of the superficial peroneal nerve (SPN), it has long been stressed that caution should be exercised at the time of open reduction and internal fixation (ORIF) of the lateral malleolus. Methods: Blair and Botte described type B intermediate dorsal cutaneous nerve (IDCN) in which the SPN penetrates crural fascia posterior to the fibula about 5 cm proximal to the joint and crosses the lateral border of the fibulae. We hypothesized that the type B IDCN is especially vulnerable to direct surgical injury if present and the anterior transposition of this nerve may decrease the incidence of symptoms related to the SPN injury. Fifty-three ankle fractures in 53 adult patients treated by the ORIF of lateral malleolus using the lateral approach between the periods from May 2001 to December 2006 were included. Intraoperative documentation about the presence of the type B IDCN variant at the surgical field was performed, and preoperative and postoperative sensory changes were carefully evaluated. Results: We encountered Blair type B variant in 7 cases (12%). The IDCN was carefully dissected and transposed anteriorly before the plating. One of these seven patients had sensory deficit preoperatively, and it was recovered spontaneously 5 months after operation. There was one patient whose IDCN was inadvertently severed, and it was repaired. At the time of last follow-up, only partial recovery of the sensory deficit was noted. Five of seven patients did not show any neurologic deficit with anterior transposition. Conclusion: Recognition and anterior transposition of the type B IDCN could reduce the incidence of the SPN nerve injuries during the ORIF of the lateral malleolar fractures.