离体安装活动式椎间融合器的生物力学研究

Biomechanical evaluation of a new intervertebral disc implant in vitro

目的 :评价一种新型椎间融合器植入人体后对整个脊柱力学环境的影响。方法 :8例成人新鲜尸体脊柱 (C2 ～T1)标本 ,保留韧带、关节囊及椎间盘 ,低温 ( - 2 0℃ )保存。测试前解冻 ,将C2 和T1用牙托材料包埋。分 4组进行测试 :正常组 ;椎间盘摘除组 ;试验组 ;TFC组。通过施加最大载荷为 2 .34Nm的纯扭矩 ,使颈椎产生三维运动。结果 :在椎间盘摘除后 ,颈椎明显不稳 ;安装TFC后 ,颈椎在各个运动方向上运动范围呈减小趋势 ,手术节段的活动基本丧失 ,而邻近节段的活动呈增大趋势 ;安装新型椎间融合器后 ,颈椎的运动同正常状态近似 ,邻近椎节亦无明显变化。结论 :椎间盘摘除后 ,颈椎在各个方向上运动加大 ,刚度减小 ,脊柱已失稳。安装TFC后 ,脊柱的刚度增大 ,且邻近椎节的运动呈增加趋势 ,将引起力学性能的改变。安装新型椎间融合器后 ,对脊柱的力学性能影响较小 ,说明它能较好地与脊柱的力学环境相匹配。

Objective:To evaluate the biomechanical property of cervical spine following the insertion of a new intervertebral disc implant.Methods:The inflexion,extension,lateral bending and rotation were biomechanically tested on 8 fresh human cadaveric cervical spines specimens(C 2～T 1).Each specimen underwent four conditions:intact condition,simulated vertebral disc removal,insertions of the new intervertebral disc implant and TFC(Ray TFC).Results:The cervical spine became unstable and the ROM (range of motion)increased significantly after the removal of vertebral disc.The motion of the segment following insertion of TFC almost lost and the ROM of the adjacent segment increased.The ROM of cervical spine after the insertion of the new intervertebral disc implant was similar to that of intact condition.Conclusions:The biomechanics of the cervical spine can be changed after the simulated vertebral disc removal or insertion of TFC.The new intervertebral disc implant might have little effect on the biomechanical property of the spine and could match the biomechanical environment.