Treatment of a segmental nerve defect in the rat with use of bioabsorbable synthetic nerve conduits: A comparison of commercially available conduits

Background: The use of biodegradable synthetic nerve conduits for the reconstruction of segmental nerve defects has been extensively reported in both animal and human studies, with a majority of studies evaluating sensory nerve recovery. However, few studies have compared these nerve conduits for functional motor recovery. The purpose of this study was to compare three commercially available, synthetic, bioabsorbable nerve conduits and autograft with respect to compound muscle action potentials, maximum isometric tetanic force, wet muscle weight, and nerve histomorphometry. Methods: Eighty Lewis rats were divided into four groups according to the type of repair of a 10-mm excision of the sciatic nerve: group I had a reversed autograft; group II, a poly-DL-lactide-ε- caprolactone conduit; group III, a type-I collagen conduit; and group IV, a polyglycolic acid conduit. All results were compared with the contralateral side. At twelve weeks, the rats underwent bilateral measurements of the compound muscle action potentials of the tibialis anterior and flexor digiti quinti brevis muscles, isometric tetanic force and muscle weight of the tibialis anterior, and peroneal nerve histomorphometry. Results: At twelve weeks, no difference in the percentage of recovery between the autograft and the poly-DL-lactide-ε-caprolactone conduit was observed with respect to compound muscle action potentials, isometric muscle force, muscle weight, and axon count measurements. The poly-DL-lactide-ε-caprolactone and collagen conduits remained structurally stable at twelve weeks, while the polyglycolic acid conduits had completely collapsed. The polyglycolic acid conduit had the poorest results, with a recovery rate of 15% for compound muscle action potentials and 29% for muscle force. Conclusions: The functional outcome in this rat model was similar for the autograft and the poly-DL-lactide-ε- caprolactone conduits when they were used to reconstruct a 10-mm sciatic nerve defect. Functional recovery following the use of the polyglycolic acid conduit was the poorest. Clinical Relevance: Differences were demonstrated between commercially available conduits in this rat model. These results will allow surgeons to choose the optimal bioabsorbable synthetic conduit for human segmental nerve defect reconstruction.