Long-term evaluation of functional nerve recovery after reconstruction with a thin-walled biodegradable poly (DL-lactide-epsilon-caprolactone) nerve guide, using walking track analysis and electrostimulation tests

This study was performed to evaluate the long-term functional nerve recover y after reconstruction of a IO-mm gap in the sciatic nerve of the rat, with a thin-walled nerve guide, composed of a biodegradable copolymer of DL-lac tide and epsilon-caprolactone [p(DLLA-epsilon-CL)]. To evaluate both motor and sensory nerve recovery, walking track analysis and electrostimulation t ests 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 functio n and 90% of the sensory nerve function had been recovered. After this peri od, the sciatic function index (SFI) did not improve further, whereas the s ensory nerve function appeared to return to normal. When the results of the SFI measurements, minus those obtained from rats with severe automutilatio n, are extrapolated, further improvement of the SFI might be expected after 52 weeks. The fact that 100% sensory nerve recovery was obtained, as measu red by the electrostimulation test, could be explained by sensory reinnerva tion from surrounding areas. The SFI was not fully reestablished because au tomutilation had a great impact on the use of walking track assessment. (C) 1999 Wiley-Liss, Inc.