后部结构分级切除对下腰椎稳定性影响的实验研究

目的 探讨小尾寒羊L5,6后部结构分级切除对腰椎稳定性的影响.方法 选取14只小尾寒羊,截取L4～L7脊柱标本.实验前摄正、侧位X线片以排除脊柱疾患,CT定位关节突关节分级切除.对L5,6节段后部结构依次分级切除如下:Ⅰ正常→Ⅱ全椎板减压→Ⅲ左侧关节突切除1/2→Ⅳ左侧关节突全部切除→Ⅴ右侧关节突切除1/2→Ⅵ右侧关节突全部切除→结束.利用Instron 8874液压伺服动态生物力学测试系统依次测试标本六个自由度上椎间运动的变化,计算平均刚度.利用SPSS 11.5行单因素方差分析,检验水准α值取0.05.结果 全椎板减压和左侧关节突的全部切除对于前屈或后伸的稳定性影响不大;当再切除右侧关节突1/2时,前屈或后伸的平均刚度比正常时分别下降32.33%和30.83%.腰椎后路结构的切除对于腰椎侧弯的稳定性影响不大.全椎板减压即出现左和右扭转失稳,平均刚度分别比正常时下降26.13%和26.20%,关节突关节与扭转的稳定性亦具有重要意义,特别是对对侧扭转的稳定性.结论 行腰椎后路手术时,在保证手术视野的情况下,力求做到微创,尽量保留后部结构的完整性.

Study on the effect of sequential section of posterior spinal structures on low lumbar stability

Objective To study the effect of sequential section of L5.6 posterior spinal structures on lumbar mechanical stability using constant displacement testing method by measuring vertebral segmental motion on 6 degrees of freedom. Methods Forteen fresh segments of L4-L7 were selected as spinal speci-mens from healthy female Small-Tailed Han sheep. The sequences were procedured as follows: Ⅰnormal→Ⅱ total laminectomy→Ⅲ half-resection of left facet joint→Ⅳ fuU-resection of left facet joint→Ⅴ half-resection of right facet joint→Ⅵ full-resection of right facet joint. Instron 8874 was used for testing six sequences. Then the mean stiffness of every sequence were recorded and analyzed. SPSS 11.5 statistical package was used for ANOVA. Results The resection of posterior ligaments as well as left facet joint had some effect on the stability of flexion/extension, but the mechanical instability did not occur (P>0.05). Plus the half-resec-tion of right facet joint, the mechanical instability appeared (P<0.05). The mean stiffness of flexion/extension decreased 32.33% and 30.83% than normal respectively. However when both of facet joints were resected, the mean stiffness of flexion/extension decreased 35.59% and 34.80% than normal respectively. The resec-tion of posterior structures of lumbar had little effect on the stability of lateral bending (P>0.05). The resec-tion of posterior ligaments led to the mechanical instability of left/right axial torsion(P<0.05). The mean stiff-ness decreased 26.13% and 26.20% respectively. Facet joints had important sense on torsional stability, es-pecially on the opposite side. Conclusion Under conditions of insuring the field of vision, we must carry out microinvasive operation and preserve the integrity of posterior spinal structures as far as possible during performing posterior approach of lumbar.