Anatomy of the sural nerve with an emphasis on the incision for medial displacement calcaneal osteotomy.

An inappropriately positioned skin incision for medial displacement calcaneal osteotomy can put the sural nerve at risk; however, unanimous agreement has not been reached about the optimal strategy for making this incision. In the present cadaveric study, 20 cadaveric specimens were dissected to describe the anatomic course of the sural nerve within the operative area and to provide a more practical reference for surgeons to make a safe incision. The following points were used in the analyses: point A, the tip of the lateral malleolus; point B, the inferior margin of the calcaneus on the plumb line through point A; point C, the posteroinferior margin of the calcaneus; and point D, the lateral border of the Achilles tendon on the same level (collinear) with point A. With careful dissection, the distances of the sural nerve to points A and B in the vertical direction (lines D1 and D2, respectively), to points A and C in the diagonal direction (lines D3 and D4, respectively), and to points A and D in the horizontal direction (lines D5 and D6, respectively) were measured. The landmarks were identified and the distances measured by 3 independent researchers. The median ratio of D1 to D1+D2, D3 to D3+D4, and D5 to D5+D6 was 0.36 (range 0.20 to 0.47), 0.26 (range 0.19 to 0.32), and 0.43 (range 0.34 to 0.52), respectively. Accordingly, we believe it is relatively safe to make an oblique incision that runs through the point that is no less than one third of the distance from the tip of the lateral malleolus to the posteroinferior margin of the calcaneus.