计算机辅助设计腰椎融合器的生物力学评价

The biomechanical study of computer aided design lumbar interbody fusion cage

目的探讨新型计算机辅助设计腰椎椎间融合器和2种常用的椎间融合器在PLIF附加椎弓根螺钉术后的生物力学稳定性。方法选用经过检查无损伤（肿瘤、外伤、手术）的10具成人新鲜冰冻尸体脊柱标本（L4-S1）进行实验分组：①完整标本组；②行腰椎后路L4,5全椎板切除减压合并椎间隙单纯植骨组；③行腰椎后路L4,5全椎板切除减压、椎间隙单纯植骨合并L4，5椎弓根螺钉组；④行腰椎后路L4，5全椎板切除减压、椎间隙植骨CAPSTONE融合器植入合并L4，5椎弓根螺钉组；⑤行腰椎后路L4，5全椎板切除减压、椎间隙植骨OIC融合器植入合并L4，5椎弓根螺钉组；⑥行腰椎后路L4，5全椎板切除减压、椎间隙植骨CAD-CAGE融合器植入合并L4，5椎弓根螺钉组。各组随机顺序进行7项非损伤性加载，运用数字相关法对不同处理组术后腰椎即刻生物力学指标进行测定，并运用统计学方法分析。结果腰椎后路L4，5全椎板切除术后，与完整标本组和其他固定组相比，在屈曲、左右侧弯、左右旋转6个方向的动态加载下角位移和运动范围显著增大（P〈0．01）；行PLIF附加椎弓根螺钉固定术后各组，与完整标本和不附加椎弓根螺钉固定组相比，6个方向的动态加载下角位移和运动范围显著减小（P〈0．01）；使用椎弓根螺钉各个固定组之间比较，单纯椎间隙植骨组仅在屈曲方向的动态加载下角位移和运动范围显著增大（P〈0．01），其他各个方向的动态加载下角位移和运动范围差异无统计学意义（P〉0．05）。使用椎间融合器的3组之间比较，6个方向的动态加载下角位移和运动范围差异无统计学意义（P〉0．05）。结论①腰椎全椎板切除后，腰椎稳定性显著降低。②附加椎弓根螺钉固定可以得到比完整状态更好的腰椎稳定性。③PLIF术式中，采用椎间融合器比不采用融合器，能够使腰椎得到更可靠的稳定性。④融合器外形设计的区别对稳定性影响甚微。

Object To study the lumbar stability after posterior lumbar interbody fusion （PLIF） with CAD-cage and 2 other lumbar interbody fusion cages followed by bilateral transpedicular screws fixation. Methods Ten fresh-frozen human cadaveric lumbar spines（ L4 -S1） were inspected by plain radiographs to ensure specimens the absence of structural spinal disorders, previous neoplastic disease, or spinal surgery. After intact specimen （ group Ⅰ ） analysis, posterior laminectomy and intervertebral fusion（ L4.5 ） with autologous bone was performed（ group F1）, then added pedicle screw instrumentation from L4.5 （group F2 ）. After group I and F1, F2 analysis, 3 different lumbar fusion cage were implanted once a time. Capstone was named group F3. OIC was named group F4. CAD-cage was named group F5. The order of testing these nondestructive loads was randomized in each of the reconstruction stages and in each individual specimen. Data was collected through DICT （ Digit- al-Image-Correlation Technique） before analyzed by SASS. 2. Results Posterior laminectomy can provide less stability than intact specimen in all loading modes （ P 〈 0.01 ）. All group with transpedical screws fixation provided more stability to the specimen than intact spine in all loading modes （ P 〈 0.01 ）. No statistical difference was found among all lumbar fusion cages group （ P 〉 0.05 ）, though no cage group （ group F2 ） provided less stability than other lumbar fusion cage groups in flexion loading modes （ P 〈 0.05 ）. Conclusion ① Posterior laminectomy can cause serious lumbar instability. ② Transpedicle screws fixation play an important role in lumbar stability after PLIF surgery. ③ Lumbar interbody fusion cage can provide stability in lumbar flexion. ④ The geometry design of the cage has little influence on lumbar stability.