Experimental Study Of Amniotic Soft Tissue Filling Material After Release Of Nerve Entrapment

Objective: Through SD chronic rats sciatic nerve compression models tostudy the role and impact of the amniotic soft tissue filling material forpostoperative of nerve compression release. By observing indicators, todetermine whether the material can effectively prevent compressed nerve andthe surrounding tissue adhesion and promote nerve regeneration.Methods:1Animal grouping: Take64adult SD rats, weighing250to300gram, were randomly divided into2groups of32each. Group A was thecontral group, only removing the entrapment; group B for the experimentalgroup, amniotic soft tissue filler material wrapped compressed nerve part afterremoval of entrapment.2Animal model：A chronic nerve compression animal model was madeaccording the method described by Mackinnon, using two different methodsfor the experimental study after2weeks.3Surgical methods: Animals were intraperitoneal anesthetized afterweighing, skin preparation for surgery area, fixed in the prone position,disinfecting and draping, cutting the incision at the posterolateral unilateral(right) thigh, length about2.5cm, exposing sciatic nerve and using a verniercaliper to measure the diameter of sciatic nerve(average1.25mm).A5mmlength of silicone tube with diameter of1.2mm was cut longitudinally andplaced around the nerve. The cut of tub was sewn closed with7-0sutures andthe tub was reconstituted to its original diameter. drip gentamicin0.4ml aftersaline flushing to prevent infection. Suture muscle and skin, iodophor smearincision not covering any accessories. The postoperative not brake, left to itsown activities. Conventional breeding two weeks, the EMG confirmed thedecline in nerve conduction velocity. Group A and B according to the aboveprocedure. 4Detection methods and indicators（:1）General observation：Observationof wound healing in rats, the local rejection (postoperative wound swelling,inflammation and other symptoms), with or without foot ulcer formation andautophagy. Whether the action will limp and postoperative recovery. Coatcolor change observed in rats and calf muscle atrophy. When drawn to observethe absorption of amniotic soft tissue filling material; entrapment segmentnerve diameter, outer membrane thickness changes and nerve with local tissueadhesions separate neural bleeding and nerve activity.（2）Neurophysiologicalexamination:2,4,6and8weeks later the two groups each randomly grabeight rats underwent and did bilateral sciatic nerve EMG measure under thesame stimulation frequency (1HZ) and duration (0.02ms). Nerve ConductionVelocity, Compound Muscle Action Potential (CMAP) amplitude andperipheral latency will be obtained. The same location in the contralateralsciatic nerve also be measured. Calculate operative side sciatic nerve CMAPamplitude and peripheral latency accounted for a percentage of the normalside.（3）Histological observation: Including light and electron microscopy.The specimens of4and8weeks later will be observed the number ofdegeneration of nerve fibers, the thickness of the myelin and the proliferationof beam connective tissue between and blood vessels under light microscope.8weeks later the specimens will be put in the electron microscope to observethe arrangement of its lamellar structure of myelin, axonal diameter, Schwanncells, microfilaments, microtubules, mitochondrial ultrastructuralchanges.(4)Recovery rate of triceps wet weight:After neurophysiologicalexamination, removing bilateral triceps from the beginning and ending points,weighing and recording the results by an analytical balance, calculating tricepswet weight recovery rate.5Statistical analysis: Apply statistical software SPSS13.0for statisticalanalysis. level of inspectionα=0.05.Results:1General observation：All experimental animals incision healedwell, no case of infection occurred, no autophagy and toe-off phenomenonoccurred. After two weeks’ entrapment, right lower extremity coat color of rats turned yellow, glossiness dropped, toes actively stretch limited mobility, thelimp phenomenon appeared, calf muscles shriveled obviously, but no footulcer appeared. After removing entrapment, entrapment segment nerve turnedpale, hard texture and significantly thinner, but outer membrane thicker. Bothfar and proximal sides of entrapment segment significantly enlarged andturned neuroma-like. With time prolonging, two groups of nerve thickeningsegment gradually thinning, entrapment segment nerve gradually thickeningand epineurial also gradually thinning until close to normal. When drawnamniotic soft tissue filler material absorption was not obvious, still persisted to8weeks. Compared with contral group, the experimental group in each timeperiod local tissue adhesions lighter, easy blunt dissection, less oozing whenseparated nerve and better neural activity (P <0.05, rank sum test)2Neurophysiological examination: Nerve conduction velocity.compound muscle action potential amplitude and peripheral latency of twogroups were both improved in the differential degree after the operation, butnot normally recovered. Experimental group recovered better than contralgroup （P<0.05， t-test）.Until8weeks, nerve conduction velocity ofexperimental group reached45.16±1.91m/s, while the contral group only32.60±3.57m/s. Compound muscle action potential amplitude recovery: theexperimental group is83.89±1.94(%), the contral group was only61.96±2.69(%). Peripheral incubation period of delay: the experimental group was1.30±0.06and the contral group1.48±0.06.3Histological observation: Under light microscope, compared withcontral group, the experimental group showed a large number of myelinatednerve fibers, a higher proportion of coarse nerve fibers, myelin was thickerand nerve fibers of degeneration in a relatively smaller number, connectivetissue hyperplasia lighter and blood supply richer. Eight weeks after operation,the number of nerve fibers of degeneration was28.6±1.4in contral group,and23.9±1.2in experimental group. The two groups difference wasstatistically significant (P<0.01).Electron microscopy: Eight weeks afteroperation, contral group showed many myelinated fibers of regeneration, smaller axonal, regular arrangement, thick myelin, obvious hyperplasiaconnective tissue. There were many newborn axons in myelin, a few empty.While experimental group showed a significant regeneration of myelinatedfibers，more regular arrangement and bundle growth, significantly thickermyelin, relatively clear lamellar structure, bigger axonal diameter, welldeveloped endoneurium. Connective tissue hyperplasia was not obvious.Schwann cells, mitochondria, microfilaments, microtubules, etc. occasionallycan be seen.4Recovery rate of triceps wet weight: Every stage after operation,recovery rate of triceps wet weight is better in experimental group than contralgroup（P<0.05,t-test）. Until8weeks, experimental group reached90.55±4.03(%), while the contral group only79.53±4.01(%).Conclusion:1Amniotic soft tissue filling material used in postoperativeof SD rat neurolysis, can be effective in preventing nerve and the surroundingtissue adhesions, and avoid allergic phenomenon caused by nerve bareness.2The application of the material made the nerve have a certain activity, andreduced the compression of nerve surface vascular caused by adhesions, whichin turn can promote the regeneration of nerve.