[New treatment for peripheral nerve defects: nerve elongation].

Peripheral nerve defects are still a major challenge in clinical practice, and the most commonly used method of treatment for peripheral nerve defects is nerve transplantation, which has certain limitations and shortcomings, so new repair methods and techniques are needed. The peripheral nerve is elongated in limb lengthening surgery without injury, from which we got inspirations and proposed a new method to repair peripheral nerve defects: peripheral nerve elongation. The peripheral nerve could beelongated by a certain percent, but the physiological change and the maximum elongation range were still unknown. This study discussed the endurance, the physiological and pathological change of peripheral nerve elongation in detail, and got a lot of useful data. First, we developed peripheral nerve extender which could match the slow and even extension of peripheral nerve. Then, our animal experiment result confirmed that the peripheral nerve had better endurance for chronic elongation than that of acute elongation and cleared the extensibility of peripheral nerve and the range of repair for peripheral nerve defects. Our result also revealed the histological basis and changed the rule for pathological physiology of peripheral nerve elongation: the most important structure foundation of peripheral nerve elongation was Fontana band, which was the coiling of nerve fibers under the epineurium, so peripheral nerve could be stretched for 8.5%-10.0% without injury because of the Fontana band. We confirmed that peripheral nerve extending technology could have the same repair effect as traditional nerve transplantation through animal experiments. Finally, we compared the clinical outcomes between nerve elongation and performance of the conventional method in the repair of short-distance transection injuries in human elbows, and the post-operative follow-up results demonstrated that early neurological function recovery was better in the nerve elongation group than in the conventional group. On the whole, all of these experimental results revealed the physiological phenomenon of peripheral nerve elongation, and described the physiological change and stretch range in detail. The systematic research results have filled the blank in this field, which is very helpful for clinical limb lengthening surgery, the design of elongation surgery and the evaluation of the peripheral nerve stretch injury. Peripheral nerve elongation will become an innovative treatment technology in repairing peripheral nerve defects.

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.

New treatment for peripheral nerve defects: reconstruction of a 2 cm, monkey median nerve gap by direct lengthening of both nerve stumps.

We have developed a new treatment for peripheral nerve defects: nerve-lengthening method, and confirmed the efficacy and safety of our method using cynomolgus monkeys. A 20-mm defect in the median nerve of monkey's forearms was repaired through the simultaneous lengthening of both nerve stumps with original nerve-lengthening device. To evaluate nerve regeneration after neurorrhaphy, electrophysiological, histological, and functional recovery were examined and compared to the standard autografting. Nerve conduction velocity, axon maturation, and the result of functional test were superior in the nerve-lengthening method than in the autografting. And there were no adverse events associated with our method. We concluded that this method is practical for clinical application.

Prefabricated nerve conduits advance histomorphological and functional outcomes in nerve regeneration of the sciatic nerve of the rat.

Bridging a nerve defect is sometimes necessary to achieve nerve regeneration after injury. Different methods and conduit designs have been considered, but only isograft transplants or prefabricated conduits are available. This study presents a comparison of prefabricated conduits and isograft transplants in rats, with the aim of making suggestions for clinical settings. In rats of inbred strains LEW and DA, a 1.5cm defect of the sciatic nerve was reconstructed by isograft (n=10) or conduit (n=10). Untreated rats (n=10), sham-operated rats (n=10) and nerves of the non-operated contralateral limb served as controls. Regeneration was evaluated by histomorphological examination and with walking track analysis of the ankle stance angle (ASA) and the sciatic functional index (SFI). After 16 weeks, myelinization and ASA in the conduit group were significantly superior to that in the isograft group. There was no significant difference in SFI between the groups. Reconstruction in the isograft group showed a negative impact on the non-operated side. Conduits and isografts did not reach the morphological or functional levels of untreated or sham-operated animals. The results suggest preferential conduits should be used for nerve reconstruction.