定量外固定器刚度对骨折愈合影响的组织学研究

Histological Study of the Effect of Quantitative External Fixator Stiffness on Fracture Healing

目的:探讨不同刚度外固定对骨折愈合的影响。方法:18只健康雄性SD大鼠随机分为低刚度组和高刚度组,均行股骨干中段横行截骨,分别以自行设计的18.5N/mm(低刚度组)和60.6N/mm(高刚度组)刚度的外固定支架固定。术后6周一次性处死大鼠,对骨折愈合情况进行组织学观察。结果:高刚度组骨折愈合,新生骨痂连接骨折断端,骨痂中可见大量活跃的骨细胞;低刚度组大鼠股骨干均表现肥大性骨不连。1)在股骨干增粗处均是新生骨,骨细胞较多且活跃,表现膜内成骨;2)骨折端软骨内成骨为主;3)软骨成骨活跃,形成了明显的肥大区和成骨区,在与正常骨组织接触处形成了软骨成骨的骨痂组织。结论:肢体负荷与固定器刚度是调节骨折端稳定性的两个重要因素,稳定性决定着骨折愈合的形式和性质。因此,在固定器刚度不变的情况下,可以通过控制肢体负荷来调节骨折端的稳定性,从而调节骨折愈合过程。

Objective： To explore the effect of different external fixation stiffness on fracture healing. Methods： All 18 healthy male SD rats were randomly divided into low stiffness and high stiffness group. Two groups were performed the middle femoral bone cutting. And they were fixed by different support of the self-designed 18. 5 N/mm（low stiffness group）and 60.6 N/mm（high stiffness group） stiffness of external fixations respectively. Six weeks after the operation all rats were killed at once. To observe the histology of the fracture healing. Results： In the high stiffness group, new bone scabs link of fracture broken end,and bone scabs were visible in a large number of active bone cells,with the fracture healing. In the low stiffness group, the femoral shaft of rats were characterized by hypertrophic nonunion：1）In the femoral enlargement were new bone,bone cells were more and active, and they were showed intramembranous ossification; 2）Fracture end was given priority to endochondral ossification; 3）The osteogenesis of cartilage was active, hypertrophy and ossification were formed obviously. The bone scab formed from the cartilage in contact with normal bone tissue. Conclusion： The physical load and stiffness of the fixator are two important factors which can regulate the stability of fracture end. Stability decided the modality and nature of fracture healing. Therefore,in the case of the same stiffness, we can regulate the stability of fracture site by controlling the body load,and we can regulate the process of fracture healing eventually.