Redistribution of nerve strain enables end-to-end repair under tension without inhibiting nerve regeneration

Abstract

End-to-end repair under no or low tension leads to improved outcomes for transected nerves with short gaps, compared to repairs with a graft. However, grafts are typically used to enable a tension-free repair for moderate to large gaps, as excessive tension can cause repairs to fail and catastrophically impede recovery. In this study, we tested the hypothesis that unloading the repair interface by redistributing tension away from the site of repair is a safe and feasible strategy for end-to-end repair of larger nerve gaps. Further, we tested the hypothesis that such an approach does not adversely affect structural and functional regeneration. In this study, we used a rat sciatic nerve injury model to compare the integrity of repair and several regenerative outcomes following end-to-end repairs of nerve gaps of increasing size. In addition, we proposed the use of a novel implantable device to safely repair end-to-end repair of larger nerve gaps by redistributing tension away from the repair interface. Our data suggest that redistriubution of tension away from the site of repair enables safe end-to-end repair of larger gap sizes. In addition, structural and functional measures of regeneration were equal or enhanced in nerves repaired under tension – with or without a tension redistribution device – compared to tension-free repairs. Provided that repair integrity is maintained, end-to-end repairs under tension should be considered as a reasonable surgical strategy. All animal experiments were performed under the approval of the Institutional Animal Care and Use Committee of University of California, San Diego (Protocol S11274).

Keywords

• tension; biomechanics; strain; end-to-end repair; peripheral nerve; nerve regeneration