Analysis of the Sural Nerve Complex in North American Adult Cadavers: Distribution, Population Specific Morphology, and Anatomic Variants.

BACKGROUND The Sural nerve complex (SNC) consists of four components: the medial sural cutaneous nerve, lateral sural cutaneous nerve, sural communicating branch, and sural nerve proper. The sural nerve is a cutaneous nerve that innervates the distal posterolateral leg and dorsolateral foot. The SNC is highly variable and has six defined morphological types each representing different patterns in which the SNC can form the sural nerve proper. Because of variability amongst different populations the SNC may frequently become a site of iatrogenic injury. PURPOSE The purpose of this study was to determine if the morphological type and spatial characteristics of the SNC we found in North Americans aligned with that described in the current literature. METHODS Six defined morphologic types of SNC have been described, each representing different patterns in which the SNC forms the sural nerve proper (Pirarvin, KR, Annals of Anatomy, 202, 36–44, 2015). Cadaveric data was obtained bilaterally in from 49 formalin‐ and three Thiel‐embalmed body donors (n=104 limbs) from KCUMB via superficial dissection methods revealing the SNC in the posterior leg. Measurements were obtained using forensic rules and calipers and documented using a digital camera. This study first approved by the KCUMB Institutional Biosafety Committee. RESULTS Our results showed a predominance of two major types of SNCs. In the first type (53%), the SNC originated from the lateral sural cutaneous nerve or common fibular cutaneous nerve. In the second type (34%), the SNC originated from the medial sural cutaneous nerve independent of the sural communicating branch, with or without the presence of lateral sural cutaneous nerve contribution. We also found a prevalence of bilateral asymmetry (67%) in the formation of the SNC. Lastly, were found higher frequencies of previously described SNC variants including connections of the SNC with the posterior femoral cutaneous nerve (30%) and terminal branches of the medial sural cutaneous nerve connecting with other cutaneous nerves adjacent the lateral malleolus (22%). CONCLUSION Our data showed there are two prevalent forms of SNCs within the North American population and that bilateral asymmetry is more common than previously reported. A more complete understanding of the variation in the SNC is important for clinical electrophysiology evaluations, neurological disease testing, lower extremity tissue repair, and sural nerve use in autogenous nerve grafts.