Variability of the sural nerve and its clinical significance in peripheral nerve grafting

Abstract

Introduction. The sural nerve is a sensory nerve of the lower limb, originating from the S1–S2 roots, and exhibits significant anatomical variability. Typically, it is formed by the union of the medial sural cutaneous nerve with a communicating branch from the common peroneal nerve; however, multiple variations exist, including rare cases of direct origin from the sciatic nerve. The clinical significance of the sural nerve arises both from its increased risk of iatrogenic injury during surgical procedures and from its frequent use as an autologous nerve graft. Materials and Methods. A narrative review of the literature was conducted through searches in electronic databases including PubMed, Medline, and UpToDate. The macroscopic study included 20 adult lower limbs and museum exhibits from the Nicolae Testemițanu State University of Medicine and Pharmacy. Results. The literature describes six main types of sural nerve formation, with several subvariants. These variations may influence the nerve’s course, the level of branch union, and its relationships with adjacent structures such as the small saphenous vein and the calcaneal tendon. Identified variants are following: an expanded zone of innervation of the obturator nerve to the middle of the leg, significant anatomical variability in origin and level of formation of the sural nerve. Its superficial location in the posterolateral calf and ankle exposes it to iatrogenic injury during orthopedic, vascular, or calcaneal tendon repair procedures. Anatomical variability may also affect techniques for nerve block and the interpretation of imaging findings. From a reconstructive standpoint, the sural nerve is considered the gold standard for autologous nerve grafts due to its adequate length, relatively consistent caliber, and accessible harvesting. Grafts are indicated for segmental nerve defects exceeding 1–2 cm and are used in facial nerve reconstruction and brachial plexus injuries, providing suitable support for axonal regeneration. Conclusions. Accurate identification of the nerve’s course and formation type allows for the appropriate harvesting technique and increases the success rate of peripheral nerve reconstruction. Integrating detailed anatomical knowledge into surgical practice directly contributes to improved postoperative functional outcomes.