Long-term evaluation of functional nerve recovery after reconstruction with a thin-walled biodegradable poly...

This study was performed to evaluate the long-term functional nerve recovery after reconstruction of a 10-mm gap in the sciatic nerve of the rat, with a thin-walled nerve guide, composed of a biodegradable copolymer of DL-lactide and epsilon-caprolactone [p(DLLA-epsilon-CL)]. To evaluate both motor and sensory nerve recovery, walking track analysis and electrostimulation tests were carried out after implantation periods ranging from 3 to 52 weeks postoperatively. The first signs of both motor and sensory nerve recovery could be observed after 5 weeks. After 15 weeks, 70% of the sciatic function and 90% of the sensory nerve function had been recovered. After this period, the sciatic function index (SFI) did not improve further, whereas the sensory nerve function appeared to return to normal. When the results of the SFI measurements, minus those obtained from rats with severe automutilation, are extrapolated, further improvement of the SFI might be expected after 52 weeks. The fact that 100% sensory nerve recovery was obtained, as measured by the electrostimulation test, could be explained by sensory reinnervation from surrounding areas. The SFI was not fully reestablished because automutilation had a great impact on the use of walking track assessment.