Nerve regeneration and functional recovery after a sciatic nerve gap repaired by an acellular nerve allograft made through chemical extraction

Objective To observe the nerve regeneration and functional recov er y in canines, in which a large gap was made in the continuity of the sciatic ner ve and the gap was repaired by acellular allograft through chemical extraction. Methods 15 canines were divided into acellular nerve allografting group (ANG, 6 canines), autografting group (AG, 6 canines) and fresh nerve allografting group (FNG, 3 canines). The sciatic nerves on the right side of all animals were expos ed and 5.0 cm long segments were removed from the mid-thigh level and replaced by one of the three types of grafts. The motor recovery was assessed by gait tes t at month 6 postoperatively. The sensory and motor conducting functions were as sessed by electrophysiological experiments. The nerve regeneration was revealed by morphological studies on the grafting segments, the distal tibial nerves and motor end-plate of the target muscle. Results All the animals in ANG and AG gro ups had similar patterns of right posterior limb gait cycle and right ankle move ments. Stimuli (1.0-2.0 mA, 0.1 ms, 1.0 Hz) to the sciatic nerves proximal to t he implanted segment resulted in motor-evoked potentials recorded from the musc ulus triceps surae. The motor conducting velocities of the grafting segments wer e on average 47.2 m/s in ANG, 60.9 m/s in AG and 122.0m/s in normal controls. St imuli (5.0-10.0 mA, 0.2 ms, 1.9 Hz) to the right distal tibial nerves resulted in sensory-evoked potentials recorded from the cortical area in all the canines in ANG and AG groups. Axons regeneration and Schwann cells migration had reoccu pied the empty basal lamina tubes of the acellular allografting segments without excessive sign of inflammation. ANG and AG had similar nerve regeneration with massive large nerve fibers in the distal tibial nerves and vast motor end-plate in the target muscle. Conclusions The patterns of functional recovery and nerve regeneration tend to be similar 6 months after implantation in the canines, in which a 5.0 cm gap in the continuity of the sciatic nerve is repaired by either chemical acellular nerve allografting or autografting.