[Purpose] To provide experimental evidence for mechanism of action and clinical application of the lever positioning manipulation. [Methods] Biomechanical modeling with simulation manipulation was applied. In order to observe the changes in morphology and density of the lumbar intervertebral disc of three orthostatic, real-time scanning focusing to 4~5 lumbar of healthy volunteers with CT was engaged when loading force. [Result] From the comparison of real-time data from middle layer between 4~5 lumbar at three different positions(lying down, extension and afterburning extension), we found that vertical and horizontal distance between 4~5 lumbers got smal er at the afterburning extension position(p value was less than 0.05), i.e. the cross-section of the disc was reduced; and that the density of back, left and right edges of lumbar discs raised, and core density got smal er simultaneously, indicating that inside the disc nucleus pulposus was displaced forward at afterburning extending position. [Conclusion] The lever positioning manipulation affected the normal stress-strain of lumbar intervertebral disc significantly. During the manipulation loading process, the hydrostatic pressure of the nucleoid dropped and negative pressure rose. Intradiscal nucleoid displaced forward, and a low pressure maintained inside the nucleoid. It il ustrated that lever posi-tioning manipulation was safe and effective.%[目的]为杠杆定位手法的作用机理与临床应用提供实验学依据。[方法]应用模拟手法的生物力学建模，当力的加载时用CT对健康志愿者的腰椎4-5进行实时扫描，观察三种体位的腰椎间盘形态与密度的变化。[结果]平躺位、后伸位、加力后伸位分别实时测试取腰椎4-5最中间层数据比较，发现后伸加力位的腰椎间盘纵、横向距离均变小，即椎间盘的横截面减小；腰椎间盘后缘、左、右缘密度均变大，中间密度均变小，即加力后伸体位时椎间盘内髓核向前发生位移。[结论]杠杆定位手法对正常的腰椎间盘应力应变发生明显的影响，在手法载荷过程中髓核的静水压下降，负压增加，椎间盘内髓核发生向前位移，髓核内压保持较低压力，说明杠杆定位手法安全而有效。
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