Ⅱ°~Ⅲ°椎间隙完全塌陷峡部裂型滑脱不同术式的生物力学研究

Biomechanical characteristics of different surgical procedures for Ⅱ°~Ⅲ° isthmic spondylolisthesis with a fully collapsed intervertebral disk

目的探讨椎间隙完全塌陷峡部裂型腰椎滑脱不同术式的生物力学特性。方法利用2019年1月至2021年12月苏州大学附属第一医院就诊的Ⅱ°~Ⅲ°椎间隙完全塌陷L5峡部裂型滑脱的5名志愿者CT数据,构建有限元模型。以手术及邻近节段活动度验证有效性,构建原位后外侧融合(PLF-is)、完全复位后外侧融合(PLF-TR)、完全/部分复位后路椎体间融合(PLIF-TR/PR)及楔形融合器PLIF模型。500 N垂直预应力下,以10 Nm力矩进行活动,测试参数,组间比较采用方差分析。结果各模型前屈时活动度(ROM)最大,PLF-TR组最不稳定,其ROM最大值为(2.80±0.77)°,高于PLF-is组最大ROM(0.45±0.03)°(t=10.730,P<0.05),PLIF-PR组最大ROM(0.15±0.02)°(t=12.130,P<0.05),PLIF-TR组最大ROM(0.12±0.01)°(t=12.266,P<0.05)。各模型内固定最大负载均出现在前屈时;均集中于骶骨螺钉后段,其中PLF-TR组为(2008.60±556.61)MPa,高于PLF-is组[885.82±70.13)MPa,t=6.327,P<0.05],PLIF-PR组[(319.67±11.67)MPa,t=9.517,P<0.05],PLIF-TR组[(251.70±8.34)MPa,t=9.900,P<0.05]。邻近椎间隙最稳定的是楔形融合器PLIF组,其最大ROM出现在左旋时仅(5.66±0.02)°,低于PLIF-PR组[(6.22±0.07)°,t=-49.803,P<0.05],PLIF-TR组[5.85±0.04)°,t=-4.052,P<0.05]及PLF-is组[7.97±0.12)°,t=-12.079,P<0.05]。邻近椎间盘负荷最大值出现在PLF-is组的前屈活动中,其值为(4.08±0.20)MPa,同活动方向上高于PLIF-PR组[(1.49±0.04)MPa,t=39.307,P<0.05],PLIF-TR组[(1.33±0.04)MPa,t=41.742,P<0.05]和楔形融合器PLIF组[(1.08±0.04)MPa,t=45.485,P<0.05]。邻近关节突最大应力均出现在左旋时,PLF-is组应力最大为(412.34±4.08)MPa,高于PLIF-TR组[(291.26±0.86)MPa,t=65.667,P<0.05],PLIF-PR组[(309.12±4.02)MPa,t=55.977,P<0.05]和楔形融合器PLIF组[(294.42±0.67)MPa,t=63.954,P<0.05]。结论椎间融合治疗Ⅱ°~Ⅲ°椎间隙完全塌陷峡部裂型滑脱的力学特性优于后外侧融合,在避免邻近节段退变方面也更具有优势。

Objective To analyze the biomechanical characteristics of different surgical procedures for L5-Sl spondylolisthesis with fully collapsed intervertebral disk.Methods Data collected from 5 volun-teers were used to establish finite element(FE)models from 2019 to 2021.Range of motion(ROM)of the models was tested to verify the efficacy.FE models of posterolateral fusion in situ(PLF-is),posterolateral fusion with total reduction(PLF-TR),posterior lumbar interbody fusion with total/partial reduction(PLIF-TR/PR)and posterior lumbar interbody fusion(PLIF)with wedged cage were simulated.A vertical pressure of 500 N was applied at the top of the models,and movement of daily life was simulated with 10 Nm.Results The maximal ROM appeared at the motion of anteflexion.PLF-TR model was the most unstable with the ROM of(2.80±0.77)°,higher than the PLF-is group(0.45±0.03)°(t=10.730,P<0.05),PLIF-PR group(0.15±0.02)°(t=12.130,P<0.05)and PLIF-TR group(0.12±0.01)(t=12.266,P<0.05).The maximal load on the internal fixation also appeared at anteflexion movement in the PLF-TR group,which was(2008.60±556.61)MPa,higher than the PLF-is group[(885.82±70.13)MPa,t=6.327,P<0.05],PLIF-PR group[(319.67±11.67)MPa,t=9.517,P<0.05],PLIF-TR group[(251.70±8.34)MPa,t=9.900,P<0.05].The maximum ROM of the adjacent intervertebral disk in the PLIF with wedged cage group was(5.66±0.02)°,lower than that in the PLIF-PR group[(6.22±0.07)°,t=-49.803,P<0.05],PLIF-TR group[(5.85±0.04)°,t=-4.052,P<0.05]and PLF-is group[(7.97±0.12)°,t=-12.079,P<0.05].The maximum stress in adjacent intervertebral disc in PLF-is group was(4.08±0.20)MPa,higher than that in PLIF-PR group[(1.49±0.04)MPa,t=39.307,P<0.05],[(1.33±0.04)MPa,t=41.742,P<0.05]in PLIF-TR group and[(1.08±0.04)MPa,t=45.485,P<0.05]in PLIF with wedged cage group.The maximum load in the adjacent articular process appeared in PLF-is group at left rotation[(412.34±4.08)MPa],higher than that in PLIF-TR group[(291.26±0.86)MPa,t=65.667,P<0.05],PLIF-PR group[(309.12±4.02)MPa,t=55.977,P<0.05]and PLIF with wedged cage group[(294.42±0.67)MPa,t=63.954,P<0.05].Conclusion For L5-S1 isthmic spondylolisthesis with fully collapsed disk,interbody fusion provided better biomechanical performance than PLF and had less possibility to develop adjacent segmental disease.