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目的：比较腰椎峡部裂滑脱和退变滑脱节段在生理载荷下的三维瞬时运动特征。方法选取同一时期有临床症状需手术治疗的L4峡部裂滑脱患者14例、L4退变滑脱患者15例，另招募健康志愿者15名作为正常对照。采用双X线透视和螺旋CT检查结合技术，从薄层CT扫描获取腰椎三维重建模型，依据每个椎体的解剖标记匹配到由双X线透视影像系统捕获的不同体位的腰椎双斜位X线透视图像上，在计算机内模拟生理载荷下腰椎节段的三维运动状态。在脊椎上建立三维坐标系，测量不同体位变换时L4与L5椎体间三个方向的位移和三个方向的旋转角度，及以L4峡部裂为界的峡部裂前部椎体和后部椎板之间的位移。结果峡部裂滑脱组从前屈到后伸位时，L4，5节段间沿矢状轴相对位移（2.5±1.1） mm，较正常对照组增加；沿垂直轴相对位移（2.0±1.1）mm，较退变滑脱组增加。左旋到右旋位，L4，5节段间沿矢状轴相对位移（1.6±0.7）mm，较正常对照组增加；沿垂直轴旋转6.1°±3.8°，较退变滑脱组和正常对照组均增大。左右侧弯时，L4，5节段间沿冠状轴相对位移（3.6±1.5）mm），较退变滑脱组和正常对照组均增加。站立位时峡部裂前后两部分沿冠状轴相对位移（2.3±1.7）mm，较平卧位增大；前屈位时峡部裂前后两部分沿矢状轴相对位移（42.9±4.3）mm，较站立位增大。结论有临床症状的L4退变滑脱节段与正常椎间节段活动度无差异。在某些腰椎活动体位，有临床症状的L4峡部裂滑脱节段较正常椎间活动度异常增加。峡部裂滑脱前部椎体和后部椎板之间从站立到前屈时沿矢状轴存在前后分离运动，从平卧到站立位时沿冠状轴存在左右错动现象。

Objective To observe and compare in vivo segmental lumbar motion between symptomatic L4 isthmic spondy?lolisthesis (IS) patients and L4 degenerative spondylolisthesis (DS) patients during functional weight?bearing activities. Methods Fifteen symptomatic L4 IS patients and fifteen symptomatic L4 DS patients were recruited. Fifteen asymptomatic volunteers were en?rolled as the control group. The L4,5 vertebral segment motion of each subject was reconstructed using three?dimensional computed tomography and a solid modeling software. In vivo, lumbar vertebral motion during functional postures (flexion?extension, left?right twisting and left?right bending) was observed using a dual fluoroscopic imaging technique. The spinal function unit was divided in?to anterior and posterior segments by the isthmic cleft. Local coordinate systems were established at the vertebral body, to obtain the 6 degree?of?freedom (DOF) intervertebral range of motion (ROM) at L4,5 and the ROM between the anterior and the posterior segments of L4 IS. Results The motion of IS at L4,5 was found to be increased. The migrations along both sagittal and vertical axis were significantly larger than control group (P<0.05). During left?right twisting, the migration along sagittal axis was significantly larger than control group (P<0.05);the rotation along vertical axis was significantly larger than DS and control group (P<0.05). During left?right bending, the migration along frontal axis was significantly larger than DS and control group ( P<0.05). The inter?vertebral ROM at L4,5 showed no significant difference between DS and control group. The migration between anterior and posteri?or segments of IS L4 was larger in standing than supine (P<0.05). The relative migration along sagittal axis between anterior and posterior segments of IS L4 was significantly larger in flexion than standing (P<0.05). Conclusion A spondylolytic defect does lead to detectable instability or hypermobility in the lumbar spine compared with degenerative spondylolisthesis and normal group. From supine to standing posture, migration at isthmic cleft along sagittal and coronal axis are identified in IS spondylolithesis.