Conduit-based Nerve Repairs Provide Greater Resistance to Tension Compared with Primary Repairs: A Biomechanical Analysis on Large Animal Samples

BACKGROUND: When primary repair of transected peripheral nerves is not possible due to large gaps, nerve grafts or repair using conduits are other options to bridge the gap such that the nerve is repaired without tension. When nerve gaps are repaired primarily, there is a worry about tension, failure, and poor healing. In this biomechanical study comparing nerves repaired primarily versus those repaired with conduits, we hypothesized that conduit repair provided greater mechanical breaking strength. METHODS: We dissected fresh cadaveric sheep hooves and transacted their peripheral nerves. Subsequently, we divided these transacted nerves into 2 groups: primary repair versus repair using a nerve conduit. After repair using a standardized technique, we tensioned each of these repairs via a load tester and recorded the force required till repair failure occurred. RESULTS: Six nerves using primary nerve repair and 6 nerves repaired with a nerve conduit (10 mm length × 2.5 mm diameter) were studied. The average breaking strength of the nerves repaired with the nerve conduit was 0.92 N and that using the primary nerve repair technique was 0.46 N (P = 0.001). All the nerves repaired using nerve conduit repair had an additional 5 mm added to their total length as compared with the nerves in the other group. CONCLUSIONS: Nerve repair using a nerve conduit ensures a higher breaking strength and potentially a greater tension-free repair as compared with primary nerve repairs in a sheep model. This study supports the use of conduits in the bridging of nerve gaps.