Peripheral Nerve Injury and Repair
Steve K. Lee, MD, and Scott W. Wolfe, MD
Peripheral nerve injuries are common, and there is no easily available formula for successful treatment. Incomplete injuries are most frequent. Seddon classified nerve injuries into three categories: neurapraxia, axonotmesis, and neurotmesis. After complete axonal transection, the neuron undergoes a number of degenerative processes, followed by attempts at regeneration. A distal growth cone seeks out connections with the degenerated distal fiber. The current surgical standard is epineurial repair with nylon suture. To span gaps that primary repair cannot bridge without excessive tension, nerve-cable interfascicular autografts are employed. Unfortunately, results of nerve repair to date have been no better than fair, with only 50% of patients regaining useful function. There is much ongoing research regarding pharmacologic agents, immune system modulators, enhancing factors, and entubulation chambers. Clinically applicable developments from these investigations will continue to improve the results of treatment of nerve injuries. J Am Acad Orthop Surg 2000;8:243-252
sheath. The perineurial layer is the major contributor to nerve tensile strength. The endoneurium is the innermost loose collagenous matrix within the fascicles. Axons run through the endoneurium and are protected and nourished by this layer.1 Sunderland has demonstrated that fascicles within major peripheral nerves repeatedly divide and unite to form fascicular plexuses.1 This leads to frequent changes in the cross-sectional topography of fascicles in the peripheral nerves. In general, the greatest degree of fascicular cross-branching occurs in the lumbar and brachial plexus regions. Several studies have demonstrated greater uniformity of fascicular arrangement in the major nerves of the extremities; in fact, the palmar cutaneous and motor branches of the median nerve may be dissected proximally for several...