Wilke Hans-Joachim, Mehnert Ulrich, Claes Lutz E, Bierschneider Michael M, Jaksche Hans, Boszczyk Bronek M
Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany.
Spine (Phila Pa 1976). 2006 Dec 1;31(25):2934-41. doi: 10.1097/01.brs.0000248423.28511.44.
We developed a new method to simulating in vivo dynamic loading as closely as possible, which allows comparison of kyphoplasty and vertebroplasty, as well as augmentation materials.
Special interest was given to calcium phosphate cement, which might fail due to its brittleness.
Vertebroplasty and kyphoplasty are, with limitations, 2 promising alternative techniques to augment osteoporotic vertebrae with polymethyl methacrylate or calcium phosphate cements. However, little is known about the fatigue characteristics of the treated vertebrae under cyclic loading.
Twenty-four intact, osteoporotic bi-segmental human specimens were divided into 4 groups: (1) vertebroplasty with polymethyl methacrylate, (2) kyphoplasty with polymethyl methacrylate, (3) kyphoplasty with calcium phosphate cement, and (4) untreated control group. After augmentation of the middle vertebrae, all specimens underwent 100,000 cycles of eccentric loading during which the specimen revolved around its longitudinal axis. Pre-loading and post-loading radiographs, and subsidence measurements at different sites of the vertebrae were taken. The overall height was additionally determined every 20,000 cycles in the material testing machine. Finally, the specimens were cryosectioned to examine the cements.
Loss of height progressed with strong individual differences in all groups, with an increasing number of load cycles up to median values of 2.8 mm for both augmented groups and 4.2 mm for the nonaugmented group. At the center of the upper endplate, subsidence in kyphoplasty was greater than in vertebroplasty, with little differences with respect to the kind of cement. The cryosections did not show any signs of fatigue in the polymethyl methacrylate, but small cracks were in the calcium phosphate.
Vertebroplasty and kyphoplasty seem to be equivalent methods in strengthening osteoporotic vertebrae. However, these results cannot be transferred to the treatment of fractures with these methods. A "physiologic" loading situation was achieved by complex motion, including all combinations of flexion/extension with lateral bending during eccentric cyclic loading.
我们开发了一种新方法，尽可能逼真地模拟体内动态负荷，这使得椎体后凸成形术和椎体成形术以及增强材料之间的比较成为可能。
特别关注磷酸钙骨水泥，因其脆性可能导致失效。
椎体成形术和椎体后凸成形术是用聚甲基丙烯酸甲酯或磷酸钙骨水泥增强骨质疏松椎体的两种有前景的替代技术，但存在一定局限性。然而，对于经治疗的椎体在循环负荷下的疲劳特性知之甚少。
将24个完整的骨质疏松双节段人体标本分为4组：（1）聚甲基丙烯酸甲酯椎体成形术组，（2）聚甲基丙烯酸甲酯椎体后凸成形术组，（3）磷酸钙骨水泥椎体后凸成形术组，（4）未治疗对照组。在对中间椎体进行增强后，所有标本均接受100,000次偏心负荷循环，在此期间标本绕其纵轴旋转。拍摄加载前和加载后的X线片，并测量椎体不同部位的下沉情况。在材料试验机中每20,000次循环额外测定一次总体高度。最后，将标本冷冻切片以检查骨水泥。
所有组的高度丢失均有明显个体差异，随着负荷循环次数增加，增强组的中位数为2.8 mm，未增强组为4.2 mm。在上终板中心，椎体后凸成形术的下沉大于椎体成形术，不同类型骨水泥之间差异不大。冷冻切片显示聚甲基丙烯酸甲酯未出现任何疲劳迹象，但磷酸钙中有小裂纹。
椎体成形术和椎体后凸成形术在增强骨质疏松椎体方面似乎是等效方法。然而，这些结果不能直接应用于用这些方法治疗骨折。通过复杂运动实现了“生理”负荷情况，包括偏心循环负荷期间屈伸与侧弯的所有组合。
Zotero 插件