| Objective: Tendon injury is a common diseases among the field of handsurgery, mostly of which are multiple traumas and often need tendontransplant to repair defects. Allogeneic tendon is an ideal transplant choicebecause of adequate source and no cause vice damage for patients. Howeverallograft tendon transplantation prone to adhesions, thereby affecting thefunctional recovery, thus solving the problem of postoperative adhesions afterallograft tendon transplantation is very urgent.Amnion is smooth, transparent,soft and good plasticity, without blood vessels and lymphatic vessels, does notproduce rejection; after transplantation, Amnion can form a continuouscollagen thin pad grafts become mechanical barrier inhibiting adhesions;Amnion also enable inflammation apoptosis, having a good permeability tonutrients, can reduce the inflammatory response promoting tendon healing.This experiment use of amniotic membrane wrapped around the Achillestendon allograft,transplant to repair the New Zealand white rabbit Achillestendon defect, evaluation of prevention of tendon adhesion and promote theeffectiveness of the tendon, and provide a theoretical basis for clinical tendonallograft transplantation and adhesion prevention.Methods: Thirty New Zealand white rabbits, which were3-month-old atthe average weight of2.25±0.05kg,were randomly divided into2groups: thetransplanted Achilles’s tendons were covered with acellular amnion as theexperimental group,the transplanted Achilles’s tendons were covered withnothing as the control group. Selection of30male New Zealand whiterabbitswere randomly divided into experimental group (the amniotic wrappedtendon allograft group) and control group (tendon allograft group). Theexperimental animals were intramuscularly injected Sumianxin (2ml/kg) for anesthesia, routine disinfection and band a beam rubber tourniquet atmid-thigh. Longitudinally incision skin and subcutaneous tissue in eachAchilles tendon margo medialis, dissecting Achilles tendon and cut1.5cmlong Achilles tendon from1.0cm top of the attachment point of calcaneus toprepare of the Achilles tendon defect model.The two sets of cutting Achillestendonable were interchanged by modified Kessler suture, used3-0tendonlines in the surgical microscope. The transplanted Achilles tendon of the15animals from the experimental group implanted by small pieces of amnionwhich covered its upper and lower anastomosis, finally sutured the skin. TheAchilles tendon is not wrapped by the amnion in the control group, the rest ofthe processing is as the same as the experimental group. wrap incision bysterile dressing, fix knees flexor bit by gypsum, disinfect incision by75%alcohol every three days, give the active motion of the knee and ankle joints toprevent joint stiffness. remove the stitches after12days, except the fixedgypsum after21days for free activities. After the operation, daily to injectpenicillin (4ug/kg)intramuscularly last5days to prevent infection.The general observation: choose2animals respectively from the twogroup at2weeks and4weeks after surgical operation. Kill the New Zealandwhite rabbits and incise along original operation incision and observe thepathological changes of tendon tissues, anastomosis fracture, color oftransplanted tendon, sliding tendon, tendon healing, adhesion of tendon, etc.Histological observation: at2and4weeks after the general observation,cut the Achilles tendon centered by tendon coincidence with a length of1cm.Fixation, dehydration, embedding, slice thickness of5μm, performed HE andMasson staining before observation with light microscope. In HE stainingobserved Achilles tendon tissue hyperemia, edema, the degree of healing andadhesion with the surrounding tissue; Masson stained sections observed thesituation of collagen fibers arranging.TEM observations: At2and4weeks after the general observation, cut a1mm×1mm×1mm tissue blocks from the Achilles tendon the anastomosis, embedded, sliced, observed under electron microscopy to observe the changesin the nucleus and cytoplasm.Flow cytometric detection: One ml blood was harvested to EDTA-K2anticoagulant tube from the ear vein of5experimental animals in each groupat2,4, and6weeks after surgery, peripheral blood CD4+and CD8+Tlymphocytes were counted To reflect the degree of immune rejection.Determination of biomechanics: At2,4, and6weeks after surgery,4animals were choosed from each group and cut The bilateral leg and foot forbiomechanical testing.①Power dissipation of breaking down tendonadhesion (W0): Achilles tendon and the tibia are fixed on the testing machinefixture, drag with a speed15mm/min, the full load range is set to100N. Thetendon shall be stopped after a sliding of16.00mm, and get the force-displacement curve, the area under the curve of power (W1). Stretch16.00mmagain after resumption, get-power (W2). Power to break the tendon adhesions(W0): W0=W1－W2.②Determination of Achilles tendon maximum tensilebreaking strength (Pmax): Remove the Achilles tendon and fixed on thebiomechanical testing machine, The full-load range is set to100N, the tendonis dragged to the rupture of the tendon with a speed of15mm/min andconnected to the testing machine, run the computer program, simultaneouslymeasure and record the tensile breaking strength data. Data shall bestatistically analyzed.The determination of hydroxyproline: The transplanted Achilles’stendons were harvested at2,4,6weeks after biomechanical testing. The freshAchilles tendon specimens cleaned by saline and determinated hydroxyproline(Hyp) content in the process of Achilles tendon healing by ELISA assay.Results:①General observation: congestion and edema were foundaround the Achilles tendon at the two groups and eased with time. The surfaceof Achilles tendon of the experimental group was smooth,and had visibleloose adhesions; but in the control group, Achilles tendon surface is notsmooth for a wide range of dense fibrous tissue adhesions.②Histologicalobservation showed that the inflammatory response and infiltration range of the experimental group were slighter than those of the control group, andcollagen fibers were arranged in order.③TEM observations showed that at2and4weeks, fibroblasts had big cell nucleus, more euchromatin, and l ittleheterochromatin in experimental group; however, there were small amount ofrough endocytoplasmic reticulums with gentle expanded capsular space incontrol group, which contained sparse content.④Flow cytometric detectionat2,4, and6weeks, peripheral blood contained less CD4+、CD8+Tlymphocytes in experimental group than in control group, and the ratio ofCD4+/CD8+T lymphocyte significantly decreased in experimental group whencompared with control group (P <0.05).⑤Biomechanical measurement: at2,4, and6weeks, the maximum tensile strength in experimental group wasbigger than that in control group, and tensile adhesion power in experimentalgroup was smaller than that in control group(P<0.05).⑥hydroxyproline(Hyp) Determination: Hyp Content in experimental group was higher than thatin control group. There was significant difference in the indexes between2groups (P <0.05).Conclusion: Amnion as a graft material can not only effectively preventintrusive tendon peripheral connective tissue, suppressing the occurrence ofexogenous healing, to achieve the purpose of the prevention of adhesions; butalso have a good permeability of nutrients, secrete cell growth factor andimmune inhibitory factor, which can reduce the inflammatory response graftand promote endogenous healing of the tendon itself. Furthermore, amnionwithout blood vessels, nerves, and lymphatic, does not produce immunerejection, and can be absorbed in the body, provides a new direction for thethe clinical tendon graft to prevent postoperative adhesions. |
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