Anatomy of the Sural Nerve Related to Calcaneal Tendon, Intermalleolar Line and Small Saphenous Vein

Sural nerve (SN) courses from the posterior aspect of leg to the lateral side of ankle and foot. Anatomy of the SN is of clinical importance due to its involvement in nerve biopsy, nerve graft harvesting including injuries during calcaneal tendon repair. Despite substantial knowledge in the literature, more easily located landmarks and data regarding the symmetry are still needed. Ninety-eight lower extremities from 31 males and 18 females were dissected in this study. The SN originated from the union between the medial and lateral sural cutaneous nerves in 52.0 % of the legs. The distance from the union point to the intermalleolar line (IML) was 16.3 +/- 8.4 (SD) cm. The ratio of this distance to the fibular length (apex of head to lateral malleolus or LM) was 0.47 +/- 0.23 cm. In 84.7 % of the legs, the SN initially coursed medial to and then crossed the lateral border of calcaneal tendon at the distance of 8.4 +/- 2.1 cm above the IML. The ratio to the fibular length was 0.25 +/- 0.06 cm. At the level of IML, the SN was posterior to the most prominent part of the LM in 95.9 % of the legs with the distance of 2.6 +/- 0.5 cm. At the closest point, the SN was lateral to the small saphenous vein in 74.5 % of the legs and the distance from this point to the IML was 10.6 +/- 4.7 cm. The ratio to the fibular length was 0.31 +/- 0.14 cm. Side difference or asymmetry was observed in a substantial number of specimens. These data are crucial for not only localizing the SN during biopsy and graft harvesting but also avoiding the nerve injury during relevant surgical procedures.