Nerve regeneration through side-to-side neurorrhaphy sites in a rat model: a new concept in peripheral nerve surgery.

Despite great improvement and refinements in nerve repair techniques, there were still problems in repair of peripheral nerve injuries for which proximal stumps were not available. In these circumstances for which classic end-to-end neurorrhaphy was impossible, new treatment modalities, benefiting by an adjacent healthy nerve, have been under investigation to overcome this problem. Therefore, end-to-side nerve repair with its modifications came to view and axonal passages through this site were shown. Moreover, the results were unsatisfactory or necessitating sacrifice of another healthy nerve. Three groups, containing 10 rats each, were included in the study. First was the control group, with end-to-end repair of the peroneal nerve. Second was the end-to-side repair group, in which the distal stump of the peroneal nerve trunk was anastomosed to the lateral side of the tibial nerve. The third was the side-to-side repair group. In this technique, 1-mm diameter epineural windows, both from peroneal and tibial nerve trunks facing each other, were removed and side-to-side neurorrhaphy was performed. After 3 weeks, as the second step, the peroneal nerve was sectioned proximally. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed by using walking track analysis. The number of myelinated fibers and fiber diameters were measured and an electron microscopic evaluation was carried out. Statistically, both in morphometric and gait analysis, the differences in values between the groups were significant in favor of the control group, followed by the side-to-side group. The study showed that axonal passage was possible with side-to-side technique and the functional results were satisfactory and superior to the end-to-side technique. Continuous supply of neurotrophic factors from their target cells was the probable cause of superior functional return in side-to-side repair, because both joining nerves were intact and healthy during the anastomosis procedure and after 3 weeks. It was concluded that this technique could be indicated in salvage of nerves in cases for which any intermediate segments would be removed, as in tumor ablation surgery, harvesting of nerve grafts, or both.