组合式可变应力接骨板固定对实验性山羊股骨骨折愈合影响的研究

Study on therapeutic effects of combined variable stress plate fixation on femoral fracture healing in experimental sheep model

目的探讨组合式可变应力接骨板固定对实验性山羊股骨骨折愈合的影响。方法健康成年山羊30只,普通环境下饲养,制作山羊右下肢股骨骨折动物模型,随机分为组合式可变应力接骨板组(实验组)、普通直型接骨板组(对照组),每组15只。分别于手术后4周、8周、12周处死山羊,取股骨断端组织进行组织病理学观察。测量2组钢板下面骨皮质厚度及髓腔直径的变化,评估钢板的应力遮挡效应;测量2组骨折断端骨痂中骨小梁密度,评估骨折愈合情况;通过2组的破骨细胞计数,评估骨折愈合过程中骨痂改建情况。结果4周时,2组的骨皮质厚度与髓腔直径比较差异无统计学意义,实验组4周、8周、12周骨皮质及髓腔直径无明显变化。对照组在治疗8周、12周骨髓腔直径大于实验组,而骨皮质厚度值低于实验组,提示对照组钢板存在应力遮挡效应,实验组钢板未见明显的应力遮挡效应造成的骨质厚度丢失。与对照组相比,实验组4周、8周的骨痂中骨小梁密度较高,差异有统计学意义,实验组较对照组成骨快;与对照组相比,实验组8周的骨小梁周边的破骨细胞计数增多,12周时实验组破骨细胞计数明显低于对照组,差异均有统计学意义。实验组的骨痂改建出现较早,12周时实验组骨痂改建基本结束。结论组合式可变应力接骨板可促进骨痂的生成,加快骨痂的改建,促进骨折愈合。

Objective To investigate the therapeutic effects of combined variable stress plate fixation on experimental sheep femoral fracture healing. Methods Thirty healthy adult goats were successfully constructed with the model of right lower limb femur fracture, and model animals were equally divided into the experimental group (given the combined variable stress plate fixation) and the control group (given the common straight steel plate fixation). The goats were sacrificed at 4 weeks, 8 weeks and 12 weeks after operation, and the broken end tissues of femur were taken for observation in imaging and histopathologic changes. The changes of thickness of cortical bone and diameter of medullary cavity were measured in two groups. The stress shielding effect of the plate was evaluated. The changes of bone trabecular density in callus of fracture end were measured to evaluate fracture healing in two groups. The number of osteoclasts was used to evaluate bone callus remodeling in the process of fracture healing in the two groups. Results There were no significant differences in the thickness of cortical bone and diameter of medullary cavity at 4 weeks between two groups. There were no significant differences in the thickness of cortical bone and diameter of medullary cavity between 4, 8 and 12 weeks in the experimental group. The diameter of bone medullary cavity was significantly higher in the control group than that of the experimental group at 8 and 12 weeks after treatment. The bone cortical thickness was significantly lower in the control group than that of the experimental group, which indicated that there was stress shielding effect in the control group, and there was no obvious stress shielding effect in the experimental group resulted in the loss of bone thickness. The bone trabecular density in callus of fracture was significantly higher in the experimental group than that in the control group at 4 and 8 weeks after treatment, suggesting that the rapidly bone formation in experimental group. The osteoclasts surrounding bone trabecular were significantly more at 8 weeks in the experimental group than those in the control group, but osteoclasts were significantly lower in the experimental group than those in the control group at 12 weeks, suggesting that the callus remodeling appeared earlier in the experimental group, and bone callus remodeling was basically over at 12 weeks in the experimental group. Conclusion Combined variable stress plate fixation can promote callus formation, accelerate callus reconstruction and promote fracture healing.