Introduction and Objectives: Muscular neurotisation is one of the reconstructive techniques used in peripheral nerve surgery. A funded study was designed to evaluate function and maturation of the motor endplate in reconstructions done using free and vascularized nerve grafts.

Materials and Methods: An experiment was designed with 3 groups of female Wistar rats: a control group which underwent heterotopic neurotization of the superior gastrocnemius through the peroneal nerve. Group A consisted of 25 animals (free nerve graft, FNG) which underwent neurotisation of the gastrocnemius using an autologous EPS nerve graft. Group B consisted of 25 animals (vascularised nerve grafts, VNG) which underwent neurotisation of the gastrocnemius using vascularized peroneal nerve grafts. Animals were sacrificed and studied in groups of 5 individuals at 4, 8, 12, 16, and 20 weeks. Results were obtained using electromyographic and nervous conduction studies measuring graft conduction latency, motor action potential, and wave duration. Statistical analysis was done using Student’s t-test, Wilcoxon, Kruskal–Wallis, and Mann-Whitney U tests.

Results: Latency: There was no difference in latency between VNG and FNG groups except during the first and last month, although latencies tended to shorten and approach normal values. There was no difference in the control group. Amplitude: The FNG group never showed a normal amplitude, while the VNG group did only in the fifth month. No difference was noted between the control and VNG group in the first month. Potential duration: This parameter normalised in the VNG group in the fifth month but never normalised in the FNG group. In fact, during the fifth month there was no difference between the VNG and control groups, and by the second month, it was different from the FNG group.

Discussion and Conclusions: 1) There was no significant difference between FNG and VNG neurotisation in conduction latency as measured by nerve fiber conduction speed or motor unit excitement. 2) There was no significant difference in conduction amplitude between FNG and VNG as measured by the number of excited motor units. 3) There was a statistically significant difference in motor action potential duration between the FNG and VNG groups, with a shorter duration in the VNG group as measured by synchrony and maturation of motor unit conduction.