Luo J, Pollintine P, Annesley-Williams D J, Dolan P, Adams M A
University of Roehampton, London, UK.
Centre for Comparative and Clinical Anatomy, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
J Biomech. 2016 Apr 11;49(6):869-874. doi: 10.1016/j.jbiomech.2015.09.006. Epub 2015 Sep 25.
Elderly vertebrae frequently develop an "anterior wedge" deformity as a result of fracture and creep mechanisms. Injecting cement into a damaged vertebral body (vertebroplasty) is known to help restore its shape and stiffness. We now hypothesise that vertebroplasty is also effective in reducing subsequent creep deformations. Twenty-eight spine specimens, comprising three complete vertebrae and the intervening discs, were obtained from cadavers aged 67-92 years. Each specimen was subjected to increasingly-severe compressive loading until one of its vertebrae was fractured, and the damaged vertebral body was then treated by vertebroplasty. Before and after fracture, and again after vertebroplasty, each specimen was subjected to a static compressive force of 1kN for 1h while elastic and creep deformations were measured in the anterior, middle and posterior regions of each adjacent vertebral body cortex, using a 2D MacReflex optical tracking system. After fracture, creep in the anterior and central regions of the vertebral body cortex increased from an average 4513 and 885 microstrains, respectively, to 54,107 and 34,378 microstrains (both increases: P<0.001). Elastic strains increased by a comparable amount. Vertebroplasty reduced creep in the anterior and central cortex by 61% (P=0.006) and 66% (P=0.017) respectively. Elastic strains were reduced by less than half this amount. Results suggest that the beneficial effects of vertebroplasty on the vertebral body continue long after the post-operative radiographs. Injected cement not only helps to restore vertebral shape and elastic properties, but also reduces subsequent creep deformation of the damaged vertebra.
由于骨折和蠕变机制，老年椎骨经常会出现“前楔形”畸形。向受损椎体注射骨水泥（椎体成形术）有助于恢复其形状和刚度。我们现在假设椎体成形术在减少后续蠕变变形方面也有效。从67 - 92岁的尸体上获取了28个脊柱标本，每个标本包含三个完整的椎骨及其间的椎间盘。对每个标本施加逐渐增加的压缩载荷，直到其中一个椎骨骨折，然后对受损椎体进行椎体成形术治疗。在骨折前后以及椎体成形术后，使用二维MacReflex光学跟踪系统，对每个标本施加1kN的静态压缩力1小时，同时测量每个相邻椎体皮质的前部、中部和后部区域的弹性和蠕变变形。骨折后，椎体皮质前部和中部区域的蠕变分别从平均4513和885微应变增加到54107和34378微应变（两者均增加：P<0.001）。弹性应变也有类似程度的增加。椎体成形术使前部和中部皮质的蠕变分别降低了61%（P = 0.006）和66%（P = 0.017）。弹性应变的降低幅度不到此值的一半。结果表明，椎体成形术对椎体的有益作用在术后X光片显示后仍持续很长时间。注入的骨水泥不仅有助于恢复椎体形状和弹性特性，还能减少受损椎体的后续蠕变变形。
