Suezawa Y, Jacob H A, Bernoski F P
Int Orthop. 1980;4(3):205-9. doi: 10.1007/BF00268157.
To investigate the effect of mechanical stresses in the aetiology of spondylolisthesis a study of the behaviour of the lumbar spine under load has been carried out. The loading tests on the lumbo-sacral segment, both with and without the dorsal elements present, showed that generally the disc only transmitted axial loads whereas transverse loads are resisted by the dorsal processes. Only after simulating a spina bifida, by splitting the lamina, was it possible to initiate a fracture in the isthmus by means of force applied in the transverse direction. Measurement of the stress behaviour in the neural arch shows that with transverse loading alone the pedicle can be just as heavily stressed as the pars interarticularis. Strain gauge measurements were performed on a macerated fifth lumbar vertebra to determine the manner in which loading forces must act to provide the greatest effect upon the region of the pars interarticularis. This was found to occur with vertical loading of the hyperextended spine. The vulnerability of the vertebra under these conditions was confirmed with further tests upon fresh cadaver specimens when it was found that the pars interarticularis of the fifth lumbar vertebra, when impinged upon by the caudal joint edges of the fourth lumbar vertebra, could be fractured with a vertically applied load of about 200 kp.
为了研究机械应力在腰椎滑脱病因学中的作用，我们对腰椎在负荷下的行为进行了一项研究。对腰骶段进行的加载试验，无论有无后部结构，结果显示一般情况下椎间盘仅传递轴向负荷，而横向负荷则由后部突起抵抗。只有在模拟脊柱裂，即劈开椎板后，才有可能通过横向施加力在峡部引发骨折。对神经弓应力行为的测量表明，仅横向加载时，椎弓根所受应力与关节突间部一样大。对一个浸软的第五腰椎进行应变片测量，以确定加载力必须以何种方式作用才能对关节突间部区域产生最大影响。结果发现，在脊柱过伸时垂直加载会出现这种情况。当对新鲜尸体标本进行进一步测试时，证实了在这些条件下椎骨的脆弱性，结果发现，当第四腰椎的尾侧关节边缘撞击第五腰椎的关节突间部时，垂直施加约200千克力的负荷就可能导致骨折。
