INITIAL EVALUATION OF VARIABLE GRAFT LENGTHS AND LESION LENGTHS IN THE REPAIR OF NERVE GAPS

This experiment evaluated the electrical and histologic differences between two groups of rats, one of which underwent same-length bilateral resection of posterior tibial nerves prior to being repaired with grafts of different lengths, while the other group underwent different-length resections with same-length graft repair. In this rat model, 18 animals were used and divided into two groups. The first group of animals underwent bilateral resection of 8-mm segments of posterior tibial nerve. To repair these nerves, one leg received two 8-mm sural nerve grafts (Group A), while the other leg received two 16-mm sural nerve grafts (Group B). The second group of rats underwent posterior tibial nerve resections of 8 mm and 16 mm, respectively. The leg with the 8 mm of posterior tibial nerve resected, received two side-by-side 16-mm sural nerve grafts (Group C); the other leg with 16 mm resected, received two 16-mm sural nerve grafts (Group D). Electrophysiologic comparison of nerve conduction velocity for Groups A and B showed a significant difference (p < 0.05), as did the same comparison for Groups C and D (p < 0.05). Histologic studies showed that Groups A and D had marked extrafascicular escape of the regenerating nerve axons, disorganizational growth of minifascicles, and loss of integrity of the donor fascicles, while Groups B and C had very minimal extrafascicular escape of regenerating axons. Results suggest that, in clinical situations, redundant nerve graft lengths are preferable to nerve grafts that produce even the slightest tension on the suture line: producing tension on the suture line seems to have a greater negative influence on axon regeneration in the rat than does either doubling the gap length or doubling the graft length.