目的  观察腰椎滑脱时椎体间接触面积变化的规律和临床意义。 方法  采集25套L4椎体下表面和L5椎体上表面的图像，在二维平面上均分为14步模拟腰椎滑脱过程，Image-ProPlus软件计算每一滑脱点（n）椎体间重叠面积Sn，取平均值后再换算成百分面积（Sn%=Sn/S*100%）。 结果  腰椎滑脱过程中，Sn%的变化是一双曲线：滑脱率0~23%阶段，Sn%降低较缓慢；23%~44%阶段，Sn%的变化明显加快；44%~100%阶段，Sn%的变化再次变缓，拐点分别出现在一维滑脱率的（23±2.02）％和（44±1.46）％处。结论  腰椎滑脱时椎体间接触面积的变化是非线性的，有助于腰椎稳定性评估和指导手术复位。

        Objective   To study the changes of intervertebral contact area during lumbar spondylolisthesis and discuss its clinical effects.   Methods   The images of superior surface of L5 vertebras and inferior surface of L4 vertebras from 25 cases were taken by a digital camera, and then spondylolisthesis procedure in 2D plane was simulated by computer with the step of  fourteen, while intervertebral contact area (Sn) of every step was measured by Image-Pro Plus software. Results  During lumbar spondylolisthesis procedure,  Sn% （Sn%=Sn/S*100%）showed a hyperbola changes. Sn% lost slowly during the rate of 0~23%, then lost quickly during 23%~44%, finally slowly once again after the rate of 44%. The inflection points appeared at the rates of (23±2.02)％ and (44±1.46)％.  Conclusions   The intervertebral contact area presents a non-linear change, which is helpful to judge the stability of lumbar spine and guide stable reduction during spondylolisthesis operation.