RÉSUMÉ
BACKGROUND:Achilles tendon adhesion after Achilles tendon injury can lead to decreased biomechanical properties,weakened healing ability,and ultrastructural changes of Achilles tendon,which further affects patients'daily life and work ability.Therefore,how to effectively deal with and prevent Achilles tendon adhesion has become a hot and difficult problem in clinical treatment. OBJECTIVE:To analyze the effects of biological amniotic membranes on postoperative Achilles tendon adhesion,biomechanics,and ultrastructural changes in rats with Achilles tendon rupture. METHODS:Sixty 6-week-old SD rats were selected to establish bilateral Achilles tendon rupture models and divided into two groups(n=30 per group)by the random number table method.In the model group,the severed end of the tendon was sutured directly.In the amniotic membrane group,the biological amniotic membrane was wrapped around the broken anastomosis and fixed by a suture.The adhesion,biomechanics,morphology,and structure of the Achilles tendon and the expression of p38 and ERK1/2 protein were evaluated 1,2,and 4 weeks after surgery. RESULTS AND CONCLUSION:(1)1 week after operation,the Achilles tendon and peritendinous tissues of the two groups were mildly edema,and the adhesion of the Achilles tendon tissues in the model group was more obvious.2 weeks after the intervention,the Achilles tendon and peritendinous tissues of the model group still had edema,and the adhesion degree between the Achilles tendon and the surrounding tissues was heavier than that of the amniotic membrane group.4 weeks after operation,there was no edema around the Achilles tendon in both groups,and the healing was well.The adhesion degree of the Achilles tendon in the amniotic membrane group was less than that in the model group.The maximum tension of Achilles tendons in the amniotic membrane group was higher than that in the model group at 2 and 4 weeks after operation(P<0.001).(2)Hematoxylin-eosin staining and transmission electron microscopy revealed that 1 week after operation,the tendon structure of rats of the two groups was disordered and the collagen fibers were sparsely arranged,in which the model group demonstrated obvious inflammatory reaction and adhesion to the Achilles tendon.Two weeks after operation,the model group still demonstrated obvious inflammatory response,adhesion of Achilles tendon,and irregular ordering of collagen fibers.The amniotic membrane group exhibited an orderly arrangement of collagen fibers and expansion of the endoplasmic reticulum of fibroblasts.At 4 weeks after operation,the collagen fibers of the Achilles tendon in the model group were thickened and disordered,and the rough endoplasmic reticulum was less in the fibroblasts,while the collagen fibers in the amniotic membrane group were ordered and thin,and the fibroblasts contained a large number of rough endoplasmic reticulum.(3)Four weeks after operation,western blot assay exhibited that the expressions of p38 and ERK1/2 protein in the Achilles tendon tissue of rats in the amniotic membrane group were lower than those in the model group(P<0.05).(4)The results confirm that the biologic amniotic membrane can promote the healing and inhibit the adhesion of Achilles tendon after the operation of the ruptured Achilles tendon,which may be associated with the regulation of the MAPK/ERK signaling pathway.