Location of the sural nerve during posterolateral approach to the ankle.

BACKGROUND: There is no consensus regarding the most appropriate surgical approach for the treatment of posterior malleolar fractures. The posterolateral approach facilitates more accurate reduction, but the sural nerve is potentially at risk during the approach. The location of this nerve in relation to this approach has not been clearly described in the literature.

MATERIALS AND METHODS: We performed cadaveric dissection of 12 legs using the posterolateral approach, a 10-cm incision midway between the tendo-achilles and the lateral malleolus, commencing at the tip of the lateral malleolus and extending proximally. The horizontal distances of the sural nerve and the short saphenous vein to the incision were measured at the proximal and distal ends and at the mid-point of the incision (positive towards the Achilles and negative towards the lateral malleolus).

RESULTS: In ten of the 12 cases, the sural nerve and short saphenous vein crossed the incision at an average of 56.7 mm and 61.0 mm along the incision, respectively. The median distances from the proximal end of the wound were -9.9 mm and -12.7 mm, 0.9 mm and -1.7 mm from the midpoint, and 6.3 mm and 7.7 mm from the distal end of the incision, respectively.

CONCLUSION: The sural nerve and saphenous vein are at risk of iatrogenic injury over the whole length of the incision for the posterolateral approach for posterior malleolar fractures.

CLINICAL RELEVANCE: When performing a posterolateral approach to the ankle, particular care should be taken at the midpoint of the incision.