后部结构对腰椎前屈／后伸稳定性的影响

目的：探讨小尾寒羊L5／6后部结构分级切除对腰椎前屈／后伸稳定性的影响。方法：利用改良的定位移生物力学测试方法，对L5／L6后部结构依次分级切除：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，Instron8874试验机依次测试标本前屈／后伸椎间运动的变化。结果：全椎板减压和左侧关节突的全部切除对于前屈／后伸的稳定性影响不大（P〉0．05）；当再切除右侧关节突1／2时，稳定性影响明显（P〈0.05）。结论：在保证手术视野的情况下，腰椎后路手术力求做到微创，尽量保留后部结构的完整性。

Effect of Sequential Section of Posterior Spinal Structures on Lumbar Flexion/extension Stability

Objective To study the effect of sequential section of L5/6 posterior spinal structure on lumbar mechanical stability. Methods Constant displacement testing method was used by measuring vertebral segmental motion on flexion and extension. Several sections of L5/6 posterior structures of experimental animal were cut in sequence. The procedure was as follows： Ⅰ normal→Ⅱ total laminectomy→Ⅲ half resection of left facet joint→Ⅳ full - resection of left facet joint→Ⅴ half - resection of right facet joint→Ⅵ full - resection of right facet joint. Corresponding changes of bending/torsional moment and angular displacement were measured using Instron 8874 dynamic biomechanical fatigue testing machine. Results The resection of posterior ligaments and the affiliated bone structures as well as the left facet joint had some effect on the stability of flexion/extension, but the mechanical instability did not occur（ P 〉 0.05）. In case of the additional half- resection of right facet joint, the mechanical instability appeared （ P 〈 0.05）. Conclusion On the basis of insuring the vision field , microinvasive trauma should be made to preserve the integrity of posterior spinal structures as far as possible during the operation procedures of posterior approach of lumbar vertebrae.