经皮椎体后凸成形术后邻近椎体再骨折的病理机制研究

Pathomechanism research of osteoporosis vertebral compression fractures after percutaneous kyphoplasty

目的探讨经皮椎体后凸成形术后邻近椎体再骨折的病理机制。方法新鲜成年羊,摄X线正侧位片排除先天性畸形、肿瘤、骨折等,应用双能X线骨密度仪测定每具标本的骨密度。用乙二胺四乙酸二钠盐体外脱钙模拟椎体骨质疏松,短期制造骨质疏松性椎体压缩骨折模型,清除椎体标本两旁的肌肉、软组织以及与胸椎相连的肋骨,T3~T9、T10~L4各为一组,各制备16组实验标本。每组中间一位椎体(T6或L1)造成压缩性骨折,行经皮椎体后凸成形术(percutaneous kyphoplasty,PKP)处理恢复压缩骨折椎体的高度。标本两端椎体固定,采用人工脊柱测试系统(Mini Bionix)和多通道脊柱测试系统,进行标本的屈曲、伸展、轴向载荷、旋转等运动,以及疲劳试验,获得静态和动态试验数据,进行统计分析。并观察椎体再骨折发生与强化椎体的关系。结果T10~L4组椎体再骨折发生率、松质骨最大von Mises应力和椎体皮质骨最大von Mises应力明显高于T3~T9组,差异具有统计学意义(P<0.05);为了保持直立状态,T10~L4组的竖脊肌力会明显高于T3~T9组,差异具有统计学意义(P<0.05);而且T10~L4组的椎间盘压力、终板最大von Mises应力与T3~T9组差异有统计学意义(P<0.05)。结论胸腰椎T10~L4比T3~T9更容易发生骨质疏松性椎体压缩骨折,椎体再发骨折与承受的应力能力有关,可以指导临床预防和治疗。

Objective:To study the pathomechanism of osteoporosis vertebral compression fractures after percutaneous kyphoplasty.Methods:Living adult sheep were purchased(4 male and female in each,40~50 kg in weight,all sacrificed on the same day),an anterioposterior and lateral X-ray was taken to rule out congenital malformation,tumor/fracture,etc.,and dual-energy X-ray absorptiometry(dexa)was used to determine the bone density of each specimen.Ethylenediamine tetraacetic acid disodium salt decalcified in vitro was used to simulate vertebral osteoporosis,short-term manufacturing model of osteoporotic vertebral compression fractures,and the muscle and soft tissue on both sides of the vertebrae specimen connected to the thoracic spine specimen were removed and ribs.T3~T9,and T10~L4 were the two groups,and preparation of 16 specimens of the experiments was made.In each group of a vertebral compression fractures(T6 or L1),line PKP was used to restore the height of vertebral compression fractures.The artificial spinal vertebrae of the specimen were fixed at both ends.The test system(Mini Bionix)and spinal multi-channel test system were used for flexion/extension,axial load,rotation movement,as well as fatigue test of the specimens to obtain static and dynamic test data for statistical analysis.The recurrence of vertebral fractures and the relationship with strengthened vertebrae were observed.Results:The vertebrae fracture incidence,cancellous bone maximum von Mises stress and the maximum von Mises stress of cortical bone vertebrae of T10~L4 group were higher significantly than those in T3~T9 groups,which were statistically significant(P<0.05);In order to remain upright,vertical ridge strength of T10~L4 group was obviously higher than that of T3~T9 group,which was statistically significant(P<0.05);The difference in intervertebral disc pressure,the maximum von Mises stress and endplate between T10~L4 group and T3~T9 groups was significant(P<0.05).Conclusion:The thoracolumbar osteoporotic vertebral compression fracture is more likely in T10~L4 than that in T3~T9,and the recurrence of vertebral fracture is associated with the ability to withstand stress,which can guide the clinical prevention and treatment.