| Objective: Peripheral nerve compression syndrome is one of the most common peripheral neurophathies in hand surgery. Although primary neurolysis has become a very successful procedure, complications and treatment failures have been shown to occur in 14% to 32% of patients, which approximately 12% requiring secondary surgery. Botte et al felt that fibrous proliferation or painful scar were two of the predominant causes responsible for the treatment failure of recurrent neuropathies. So to improve blood supply of peripheral tissue bed and to prevent postoperative adhesion between nerves and surrounding tissues become one of the important subjects of hand surgery in recently years.To determine the efficacy of biomemberance or free fat wrapping scared nerves to prevent readhension and reduce scar formation after decompression in chronic nerve compression model in rat, we designed this experiment.Methods: The first step of the study was to create a chronic nerve compression model using the sciatic nerve of rats. A Machinnonic's method was used and the left sciaticnerve was exposed and identified. A 6-mm length of silastic tub with an internal diameter of 1.2-mm was cut longitudinally and placed around the left sciatic nerve. The cut of the tub was sewn closed with three 7-0 sutures and the tub was reconstituted to its original diameter. The growing sciatic nerve was gradually compressed in the silastic tub with a consistent diameter. All of the operations were done by the same person.After 4 months 6 animals were randomly selected and evaluated with functional and electrophyologic testing. The sciatic nerve function index(SFI) reached to -80.2?.96 and the nerve conduction velocity(NCV) was lower 1/6 than normal and the demyelination can be seen in histologic observations, the chronic nerve compression model were confirmed.The second phase of the study was to divide the 120 rats into three groups randomly. In the first group the compressive nerves were simple decompressed. The second and third groups were decompressed and wrapped with biological membrane or free fat respectively. The sciatic nerves of the three groups were evaluated by sciatic nerve index, electrophsiologic examination, gross appearance, light and electron microscopic observation at 4, 8, 12, 16 weeks after operation.Results: In naked observation, there were no wound infections and foot ulceration observed in any of the animals.In biofilm-wrapped group, there was part absorption of the biologic membrane in 4 weeks and completely absorbed in 12 and 16 weeks. In fat-wrapped group, there was no absorbed in 4 weeks and still a little remained in 16 weeks. No inflammatory and immunologic reactions can be seen around the nerves in both biofilm-wrapped group and fat-wrapped group. Minimal scar tissue and adhesions were noticed between the nerve and the biological membrane or free fat. When pulled slightly the nerve trunk, the better gliding along the tissue bed was observed. In some specimens before resection, the nutrient blood vessels for the nerve were seen from the surface of the nerve. In the simple decompressive group, adhesion of the nerve to surrounding tissue was common, extensive scaring was noticed around the nerve trunk in some animals. The compressed segment of nerve had a slightly smaller diameter than the uncompressed region of the nerve.Functional assessment revealed that the SFI of the biofilm-wrapped group and the fat-wrapped group were better than that of the simple decompressed group at all subsequent time intervals. There was a statistically significant difference between the simple decompression group and two wrapped groups at 12, 16 weeks after surgery (p<0.05). In particular, at 16 weeks in the biologic membrane and free fat groups, the SFI returned to a normal level (0+15).Electrophysiologic examination showed that the motor nerve conduction velocity (NCV) were faster in the biofilm-wrapped and fat-wrapped groups than that of simple decompression group ,the difference were significant at 12, 16weeks...
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