腰椎后部结构逐级切除稳定性时间变化的实验研究

[目的]探讨腰椎不同程度后部结构切除在术后不同时间脊柱稳定性的变化,分析机体对腰椎稳定性修复的动态表现.[方法]通过绵羊动物实验制备不同的腰椎后部结构损伤模型,分别为单纯椎板切除组、椎板切除并单侧下关节突全切除组及椎板切除并双侧下关节突全切除组,经过0、6、12、24、36周的术后修复,对腰椎标本进行生物力学测试,计算并比较屈伸活动的中性区、屈曲(伸)展活动的最大刚度及中性区刚度、侧弯(扭)转活动的各向刚度等生物力学指标,评价腰椎在结构损伤后稳定性的表现.[结果]去除后部结构会对腰椎被动性稳定系统造成破坏,主要表现在屈伸和扭转四个自由度上,屈曲稳定性受损程度与手术损伤程度有关；6周后,受到破坏的腰椎稳定性能得到不同程度的恢复；在12周时各力学指标可以达到完整标本的水平；在24周及36周的恢复时间内各力学指标均超过完整标本的水平.[结论]腰椎后部结构受损后机械稳定性即刻有所下降,随时间逐渐恢复,甚至超过完整腰椎标本.损伤程度的加重使术后恢复速度减慢,减小损伤程度有利于组织愈合和稳定性恢复,机体在一定程度上具有修复腰椎机械稳定性的能力.

Temporal changes of lumbar spine stability after posterior structure resection

[Objective]To study the performance of lumbar spine stability after posterior structure resection in different time points.[Methods]The injury models included 3 groups: laminectomy only,laminectomy and left total facetectomy,laminectomy and both facetectomy.After 0,6,12,24,and 36 weeks,the treated lumbar spine samples were harvested for mechanical test.The neutral zone stiffness and elastic zone stiffness in flexion/extention,and stiffnesses in lateral bending and axial rotation were analyzed and compared.[Results]The lumbar stabilities(mainly flexion/extention and axial rotation) were destroyed by the 3 types of injuries.The decreases of flexion/extension stabilities were related to the injury degrees.After 6 weeks,the mechanical stabilities of lumbar spine recovered partially,and recovered to intact levels by the 12th week and even exceeded the intact level after 24 and 36 weeks.[Conclusion]The experiments showed that the immediate stabilities of lumbar spine had decreased after injuries and recovered gradually until greatly exceeded the intact specimens.The degree of stability recovery is correlated with healing time.The more severe the injury is,the more slowly the stability can be repaired.Less injury is benefit to the tissue healing and stability regaining.Injuried lumbar spines have the abilities of self-repairing.