Influence Of RhBMP12on The Healing Of Achilles Tendon Rupture Of SD Rats After Surgery

【Objective】To observe the changes of biological and mechanical properties of recombinanthuman bone morphogenetic protein12(rhBMP12) on the healing of Achilles tendonrupture of Sprague Dawley(SD) rats after surgery.To investigate the influence andpossible mechanisms involved and provides experimental foundation for clinictherapy.【Methods】In this experiment, adopting60male SD rats10-12weeks old and350(±50)grandomly, every left hind limb of rats as experimental group(A group),and right hindlimb as control group(B group). All rats manage an anastomosis on the bilateralAchilles tendon, Group A with2μg/ml rhBMP12processing Achilles tendon endbefore Kessler3/0nylon wire suture, Group B with normal saline instead. Bilateralhind legs were not fixed.12rats were executed randomly on postoperative1,2,4,6and8weeks(marked as subgroups A1、B1, A2、B2, A4、B4, A6、B6, A8、B8).Toobservated rats Achilles tendon in general, under the light microscope; to measurecollagen content, stiffness, maximum load and strains under maximum load of theachilles tendon.【Results】1. gross appearanceThe same point in time, the Achilles tendon in experimental group was white, luster,strong but pliable in texture, fibrous structure of neat; while was gruy, vascularizationon the surface, tendon sheath adhesion and poor flexibility in the control group.2. the degree of adhesionThe adhesion of Achilles tendon in the experimental group was lighter than in thecontrol group, P <0.05, and the difference was statistically significant. 3. Count the fibroblastFibroblasts in the experiment gruop was less than the control group in number, P<0.05, and the difference was statistically significant.4. mechanical propertiesThe stiffness, maximum load,strains under maximum load of the Achilles tendonincreased gradually from the1st week to the6th week post operation, with no obviouschange between A6and A8, B6and B8subgroup. Except the maximum load betweenA8and B8, compared with the control group, the mechanical properties of theAchilles tendon in the corresponding experimental group were higher, withstatistically significant difference（P<0.05）.5. collagen content5.1PⅠNPThe PⅠNP content increased gradually from the1st week to the8th week postoperation. P<0.05, and the difference was statistically significant (1st,2nd,4th,6thweek post operation); P=0.18, with no statistically significance (8th week postoperation).5.2PⅢNPThe PⅢNP content is to increase after the fall. P<0.05, and the difference wasstatistically significant(1st,2nd,4th,6th week post operation); P=0.62, with nostatistically significance(8th week post operation).【Conclusion】1. The rhBMP12can promote achilles tendon healing in SD rats.2. The rhBMP12promote the expression of collagen, enhance the strength andhardness of the Achilles tendon,which may play an role in the tendon healingmechanism.