Surgical treatment of common peroneal nerve injuries: indications and results. A series of 62 cases.

AIM: Common peroneal nerve (CPN) injuries represent the most common nerve lesions of the lower limb and can be due to several causative mechanisms. Although in most cases they recover spontaneously, an irreversible damage of the nerve is also likely to occur. Nerve regeneration following CPN repair is poorer if compared to other peripheral nerves and this can explain the reluctant attitude of many physicians towards the surgical treatment of these patients. Among the several factors advocated to explain the poor outcome following surgery, it has been suggested that reinnervation might be obstacled by the force imbalance between the functioning flexors and the paralysed extensors that eventually results in the fixed equinism of the foot, due to the excessive contracture of the active muscles and the shortening of the heel cord. Therefore the early correction of these forces might favour nerve regeneration. Following such hypothesis, the authors treat irreversible CPN injuries performing a one-stage procedure of nerve repair and tibialis tendon transfer. We report our experience, describing the indications to surgical treatment, the operative technique and the postoperative clinical outcome correlated with the causative mechanisms of the injuries.
METHODS: A 62-patient series controlled over a period of 15 years with a post-traumatic palsy of the CPN is reported. All the patients underwent surgery. In open wounds, when a nerve transection was suspected, surgery was performed at emergency (2 cases). In closed injuries, operative treatment was advised when no spontaneous regeneration occurred 3-4 months after the injury. From 1988 till 1991, 9 patients were elected for surgery : in 6 cases treatment consisted of neuroma resection and nerve repair by means of a graft. In 3 patients it was performed only a CPN decompression at the fibular neck. Since 1991, surgical treatment has always consisted of nerve repair associated with a tendon transfer during the same procedure. Fifty-three patients were elected for surgery. Nerve repair was achieved by direct suture in 1 case and by means of a graft in 46 patients. Decompression of the CPN at the fibular neck was performed in 6 patients where nerve continuity was demonstrated.
RESULTS: In the first group of patients, nerve repair outcome was highly disapponting: no recovery in 5 cases, reinnervation occurred in 1 patient only (M1-2). CPN decompression was followed by complete recovery in 2 cases, no improvement was observed in 1 case. Nerve repair associated with tibialis tendon transfer dramatically improved the postoperative outcome: at 2 year follow-up, neural regeneration was demonstrated in 90% of the patients. Surgical outcome depends on the causative mechanisms of the lesion: sharp injuries and severe dislocations of the knee had an excellent recovery, while in crush injuries and gunshot wounds good recovery was less common.
CONCLUSION: Surgical treatment of CPN injuries can nowadays be highly rewarding. CPN palsies in open wounds should undergo surgical exploration at emergency. In close injuries with no spontaneous recovery within 4 months after the injury, patients should be advised to seek surgical treatment regardless the causative mechanism of the lesion. According to our experience, the association of a transfer procedure to nerve repair enhances neural regeneration, dramatically improving the surgical outcome of these injuries.