经伤椎单侧椎弓根螺钉内固定术治疗急性脊柱创伤中的生物力学评价

Biomechanical evaluation of unilateral pedicle screw fixation through injured vertebrae in the treatment of acute spinal trauma

目的通过生物力学评价的方法比较不同内固定术式治疗急性脊柱创伤的稳定性。方法选取成都中医药大学医学院解剖教研室提供的成人尸体胸腰段标本(T11-L3)共10具,经锯条横断其2/3椎体后制备成胸腰段椎体骨折标本。将标本随机等分为经伤椎单侧固定组和跨伤椎固定组各5具。前组行经伤椎单侧椎弓根固定联合四钉固定临近椎体,后组给予跨伤椎四钉固定临近椎体,观察并比较两组标本的强度、扭转力、拔出力、轴向刚度、载荷与应变及位移的关系。结果500 N作用力下,经伤椎单侧固定组应变及位移均小于跨伤椎固定组(P<0.05);以L1椎体为例,在500 N作用力下,经伤椎单侧固定组强度、轴向刚度、扭转强度和扭转刚度均高于跨伤椎固定组(P<0.05),在拔出力方面两组无显著差异(P>0.05)。结论经伤椎单侧椎弓根螺钉内固定在治疗急性脊柱损伤时较跨伤椎内固定体现出更稳定的生物力学特性,值得临床推广。

Objective To compare the stability of different internal fixation methods in the treatment of acute spinal trauma by biomechanical evaluation.Methods A total of 10 fresh adult cadaveric thoracolumbar specimens(T11-L3)provided by the Department of Anatomy,Chengdu University of Traditional Chinese Medicine were selected to prepare thoracolumbar vertebral fracture specimens after 2/3 vertebral bodies were transected by saw blade.The specimens were randomly divided into unilateral fixation through injured vertebrae group and cross injury fixation group,5 in each.In the former group,the adjacent vertebrae were fixed by unilateral pedicle fixation combined with four screws,while in the latter group,the adjacent vertebrae were fixed by four screws.The relationship between the strength,torsion force,pull-out force,axial stiffness,load,strain and displacement was observed and compared between the two groups.Results Under the action of 500 N,the strain and displacement of the unilateral fixation through injured vertebrae group were less than that of the cross injury fixation group(P<0.05);taking L1 as an example,under the action of 500 N,the strength,axial stiffness,torsional strength and torsional stiffness of the unilateral fixation through injured vertebrae group were higher than those of the cross injury fixation group(P<0.05),and there was no significant difference between the two groups(P>0.05).Conclusion Compared with the traditional cross injury internal fixation,the unilateral fixation through injured vertebrae has more stable biomechanical characteristics in the treatment of acute spinal injury,and the operation is more convenient,which is worthy of clinical promotion.