Comparative Study Of Small Gap Bridge And Collagen Nerve Sheath For Repair Of Peripheral Nerve Rupture

Background and Objective: The treatment of the peripheral nerve rupture has been a thorny problem for a long time in clinic.The traditional nerve anastomosis,such as the epineurium or perineurium neurorrhaphy,often induces the misorientated docking of the nerve bundle,neuroma formation,and axonal outgrowth from the coaptation sites,which seriously affects neural function recovery.The “peripheral nerve selective regeneration theory” provides a basis for small gap anastomosis to repair peripheral nerve repair rupture.Recently,many scholars have centered on the small gap sleeve bridging fields including natural and synthetic conduits to build an nerve regeneration chambers.This study was to explore the effects of autologous epineurium small gap anastomosis and collagen nerve sheath in repairing the rupture of peripheral nerves.Methods: Forty-eight two-month old Sprague-Dawley rats weighing 250g~300g were selected and randomly divided into two groups.Each groups had twenty-four rats(n=24).Sciatic nerve injury models were constructed by cutting at a breakpoint located 10 mm above the left sciatic nerve crotch.Autologous epineurium small gap anastomosis group(Group A): small gap anastomosis bridging the sciatic nerve by scissoring and sleeve jointing the autologous epineurium(with 2 mm gap between the two stumps);Collagen nerve sheath group(Group B): the injured sciatic nerves were repaired by collagen nerve sheath.we generally observed autonomic activities,the ulcer healing situation.On week four,eight and twelve post-operation,the sciatic function index of the rats was measured.Twelve weeks after surgery,the electrophysiological examination was performed to evaluate the functional recovery of the regenerated nerve.Local morphology of the appearance of the regeneration chamber and anastomotic place the site was observed under a microscope.Histopathological and immunohistochemical analysis,observation of theultrastructure with transmission electron microscope and Western Blot analysis to detect the protein expression results of GAP-43 were performed to evaluate the effects of the two different repair method on nerve regeneration and functional recovery after peripheral nerve rupture functionally,morphologically and molecular biologically.Results: 1.General observation: Postoperatively,the rats in the two groups were all paralyzed.The rats in the autologous epineurium small gap anastomosis group recovered automomic activities and ulcer healing quicker than those in the collagen nerve sheath group.2.The sciatic functional index(SFI):Two week after surgery,the rats in each group showed the toes were flexion deformity and the plantar prolapsed,so that the value of the SFI cannot measure and calculate.From week four to week twelve,the SFI value of the two groups revealed varying degrees of improvement.The statistics analysis showed that significantly better recovery was observed in the autologous epineurium small gap anastomosis group compared to the collagen nerve sheath group at week 4,8 and 12 respectively(P < 0.05).3.The electrophysiological examination: At twelve weeks post-operation,amplitude and conduction velocity of the autologous epineurium small gap anastomosis group was higher than the collagen nerve sheath group(P < 0.05).4.Local morphology of the anastomotic site:At twelve weeks post-operation,there was no evidence of neuroma formation and axonal outgrowth from the coaptation sites at the anastomotic stoma in the two groups.The anastomotic site of the autologous epineurium small gap anastomosis group was less adhesion to surrounding tissue than the collagen nerve sheath group.5.Histopathological and immunohistochemical analysis: At twelve weeks post-operation,the degree of adhesion with surrounding tissue,the axon swelling,the structure of myelin sheaths and the expression and distribution of S-100 in the autologous epineurium small gap anastomosis group was better than the collagen nerve sheath group.6.Observation of the ultrastructure with transmission electron microscope: Thelayers of myelin sheath were arranged in concentric circles,compacted and regular,without differences from the normal nerve structure,and Schwann cell hyperplasia was obvious in the autologous epineurium small gap anastomosis group.But the layers of myelin sheath were arranged irregularly and sparsely,and the myelin sheath was tortuous and blurry in the collagen nerve sheath group.The number and morphological structure of the nerve fiber,the diameter of the axons and the morphological structure of the myelin sheath in the autologous epineurium small gap anastomosis group was better than the collagen nerve sheath group.7.Western Blot analysis to detect the protein expression of GAP-43: Content of GAP-43 of the autologous epineurium small gap anastomosis group is higher than the collagen nerve sheath group at twelve weeks after surgery.Conclusions: Autologous epineurium small gap anastomosis for repair of peripheral nerve rupture is better than the collagen nerve sheath.Autologous nerve epicardial small gap bridging method is more suitable for the regeneration of axons to provide an ideal microenvironment,promote nerve regeneration and functional recovery,is to repair the peripheral nerve rupture of a more effective small gap anastomosis.