Sural Nerve Graft Harvest

Sural nerve (aka, short saphenous nerve) is an entirely sensory cutaneus nerve, except for some unmyelinated autonomic fibers. The nerve originated from S1 and S2 roots. The sural nerve innervate lateral & posterior third of leg and lateral aspect of foot & heel, & lateral portion of the ankle.The sural nerve grafts are frequently used as cable grafts. With a relatively easy technique, up to 25 cm of nerve graft may be harvested.

Indications
Segmental loss of a motor or sensory nerve with viable distal and proximal segments accessible for grafting.

Contraindications (specific to sural nerve graft harvest)
If the patient requires intact foot and lower leg sensation (for employment or sports reasons), alternative donor sites should be considered. Peripheral neuropathy with existing compromise of sensation to the lower extremity also may create an contraindication.

The anatomy of the sural nerve

Anatomy of the Sural Nerve There are two sural nerves: medial and lateral sural cuteus nerves (see picture below). Medial sural cutaneus nerve borns from the tibial nerve just below knee joint. It runs downward across between the heads of gastronemius. Lateral sural cutaneous nerve arises from common peroneal nerve above knee joint and runs down posterolateral aspect of calf. Medial and lateral sural cutaneus nerves are connected by peroneal communicating branch. Thus, the union of these 3 nerves constitutes the sural nerve. Sural nerve passes down posterolateral side of leg & onto dorsal aspect of lateral side of foot, giving rise to lateral calcaneal branches (medial branch supplied by tibial nerve). The nerve runs with the small saphenous vein on the posterior leg just lateral to the achilles tendon, and its terminal branches consist of lateral dorsal cutaneous nerve and the lateral calcaneal branches.

Graft Harvesting Technique
The sural nerve is best identified approximately 2 cm posterior to the lateral malleolus and approximately 2 to 3 cm proximal. In this area, the nerve has not undergone significant branching. A longitudinal incision is made in the region above. If the small saphenous vein is visible, the nerve or a branch of it will be close by. The nerve is traced proximally with a longitudinal incision as required, or a "stair step" transverse incisions can be used on the trajectory of the nerve. By gently pulling the nerve at the distal incision, the locations of proximal incisions can be determined. After the necessary exposition, the nerve is cut proximally and distally and placed on moist gauze. The donor site is closed with subcutaneous sutures of 4-0 vicryl, and the skin is closed with 3-0 nylon or staples.