Simultaneous gradual lengthening of proximal and distal nerve stumps for repair of chronic peripheral nerve defect in rats.

We investigated nerve regeneration of rat sciatic nerves after chronic injury of 15 mm-defect by the gradual lengthening of proximal and distal nerve stumps. Thirty days after the primal injury, both stumps were grasped and lengthened at a rate of 1 mm per day using external nerve-lengthening devices for 15 days. Then end-to-end neurorrhaphy was performed. After the lengthening, both stumps were evaluated by immunohistochemical analysis. Nerve regeneration was evaluated by electrophysiological and histological studies at 12 weeks after the repair. In the lengthened proximal stump, Schwann cells and axons existed along the whole nerve stump. In the lengthened distal stump, Schwann cells exist along the overall length. The whole nerve trunk was lengthened. The nerve regeneration was comparable with the delayed end-to-end suture without nerve defect. We showed the feasibility of direct gradual lengthening of proximal and distal nerve stumps for the treatment of chronic segmental nerve defect.