Arthroscopic treatment of lateral ankle instability. Is there a safe zone? An anatomic study.

BACKGROUND: The purpose of this study is to describe the relative location of superficial anatomic landmarks and likely location of structures at risk in order to predict the proximity of the later and avoid their injury during the arthroscopic treatment of lateral ankle instability. METHODS: Fifteen cadaver ankles were dissected. Based on superficial anatomic landmarks, the location and distances to the structures at risk (extensor tendons, peroneus tertius, peroneal tendons, main branch or intermediate branch of the superficial peroneal nerve, and the sural nerve) were measured. RESULTS: The distance from the lateral malleolus along the peroneus brevis to its intersection by the sural nerve was 38.5±10.5mm and from it to the superficial peroneal nerve was 32.0±7.4mm. Based on the minimum distances, a rectangular area of 25mm×22mm was obtained. The anterior talofibular ligament and the proximal border of the inferior extensor retinaculum were within this area. CONCLUSIONS: Our study suggests that based on superficial anatomic landmarks, it is possible to define an anatomic area in order to avoid structures at risk. In addition to the usual precautions, these anatomical references may contribute to lower the complication rate associated to the arthroscopic treatment of lateral ankle instability.