Sural Nerve Grafting

Abstract

Peripheral nerve injuries frequently occur as a consequence of trauma. They may arise from various mechanisms, including laceration, contusion, stretching, compression, and iatrogenic injury. Although generally not life-threatening, they can significantly affect a patient's daily activities and overall quality of life. Restoration of nerve continuity will aid in functional recovery. Primary end-to-end neurorrhaphy is the preferred technique for the repair of transected peripheral nerves. Unfortunately, it is not always possible to perform tension-free primary repair due to retraction of nerve stumps, scarring, or destruction of neural tissue; these may result in gaps that cannot be bridged without putting undue tension on the repairs or that cannot be bridged with the remaining tissue at all. Excessive tension across a nerve repair decreases perfusion at the neurorrhaphy site and may reduce the quality of the functional outcome. In this situation, autologous nerve grafting plays a major role, with the sural nerve being a commonly selected donor. Sural nerve harvesting was originally described as an open technique, but surgical technology improvements have led to the development of minimally invasive techniques over the last several years. The goal of peripheral nerve reconstruction with a nerve graft is to provide a scaffold that guides the regenerating axons towards the distal nerve stump and permits end-organ reinnervation. The graft also provides Schwann cells that aid in axonal regeneration. Nerve coaptation should be performed under magnification; localization of healthy proximal and distal stumps with a “bread-loafing” technique is preferred before nerve graft interposition, and a tension-free neurorrhaphy should be performed even under a full range of motion of the joint, if applicable. Careful fascicle orientation and alignment is critical to prevent axonal loss and obtain the best results. Under optimal conditions, axonal regeneration within a graft will occur at a speed of 1 mm to 1.5 mm per day. Although surgical restoration of the nerve may improve the motor, sensory, and autonomic function of the end organ, reinnervation does not invariably produce complete functional recovery. Many factors, including the site of nerve disruption, the timing of reconstruction, the length of nerve gap, and patient characteristics like age and smoking status, will influence the final outcome. Because it is difficult to optimize all of the variables that affect neural regeneration, complete functional recovery after nerve graft reconstruction remains the exception rather than the norm.