腰椎终板骨折特点及相关因素的实验研究

目的 探讨腰椎椎体终板压迫骨折的特点及其影响因素。方法 19个尸体标本的腰椎运动节段（FSU）,根据X线检查来确定椎间盘的退变分级,在双能X线吸收仪器（DEXA）上测量椎体和椎体终板的骨密度（BMD）和骨矿含量（BMC）,然后分别承受过度负荷导致终板骨折,根据力-位移曲线来确定终板骨折和终板的极限负荷（FL）。终板骨折后,运动节段解剖为单独的椎体,观察终板骨折情况。结果 19个FSU标本中,16个发生肉眼可见的终板骨折,骨折仅仅发生在下位椎体的上终板,比率为84．2％,骨折均位于终板的中央部分或前部,表现为星形放射状、阶梯状、局部突入型等;终板的FL与椎体及终板的BMD、BMC呈正相关。同一个椎体内,上终板的BMD、BMC显著低于下终板,而同一个椎间盘周围,上终板的BMD高于下终板者,BMC却无差异。结论终板压迫骨折易发生于椎体的上终板;不同退变程度椎间盘邻近终板骨折的特点不同,但这种骨折在X线片上很难显现,终板的极限负荷与椎体终板的BMD、BMC呈正相关。

The feature of experimental endplate fracture in lumbar spine and its related factors

Objective To evaluate the feature of experimental endplate fracture in lumbar spine and its related factors. Methods Nineteen cadaveric lumbar motion segments aged 48-77 years were compressed by overload to fracture the endplate and dissected into isolated vertebrae to evaluate feature of their endplate failure. Before and after failure of endplate, radiographic tests were taken on every motion segment The bone mineral density ( BMD) , bone mineral content ( BMC ) of the vertebral body and endplate were tested respectively before endplate fracture. Results Among 19 motion segments, 16 were fractured and accounted for 84. 2% of all and fracture featured as stellate, step, depression and intrusion. Fracture concentrated on the center or anterior of superior endplate of the inferior vertebrae in one motion segment. Failure load of endplate was positively correlated with BMD, BMC of vertebral endplate. Within one vertebral body, the BMD and BMC of its superior endplate was markedly less than that of inferior endplate, on the other hand, the difference of BMD and BMC of endplate around one disc was opposite. Conclusions Fractures usually concentrate on the center or anterior part of superior endplate of one vertebrae and are hard to be identified by conventional radiographic examination. Failure load of endplate is positively correlated with BMD, BMC of vertebral body and endplate. There might be certain relationship between feature of fracture and severity of disc degeneration.