腰骶部椎间盘髓核摘除对脊柱稳定性影响的生物力学研究

Biomechanical evaluation of stability of lumbosacrumal spine following resection of nucleus pulposus of intervertebral disc in vitro

目的：分析髓核摘除对腰骶部Ｌ４～Ｌ５和Ｌ５～Ｓ１节段稳定性的影响。方法：对６例成人新鲜腰骶部（Ｌ４～Ｓ１）标本髓核摘除前后进行三维运动范围和压缩、剪切刚度的测定。对标本施加最大为１０．０Ｎ．ｍ的力偶矩，使之产生前屈、后伸、左右侧屈和左右轴向旋转运动，并由双平面立体测量的计算机图像分析系统得到节段运动范围。分别在１３００Ｎ，６００Ｎ和６００Ｎ的载荷下测定压缩、前后剪切和左右剪切刚度。结果：髓核摘除后，Ｌ４～Ｌ５和Ｌ５～Ｓ１节段的三维运动范围明显增大，其中Ｌ４～Ｌ５节段的后伸、左右轴向旋转运动增大有显著性，Ｌ５～Ｓ１节段的前屈运动增大有非常显著性，左右轴向旋转增大有显著性；Ｌ４～Ｓ１节段压缩和剪切刚度降低，左右剪切刚度降低有显著性。结论：髓核摘除使腰骶椎节段性三维运动范围增大，压缩和剪切刚度下降，腰骶节段失稳，以致整个后部结构承受更大的负载，导致小关节和韧带的损伤和退行性改变。

Objective:The stability of lumbosacrumal spine was evaluated immediately after resection of nucleus pulposus of intervertebral disc(RNP).Methods:The ranges of motions,compression rigidity and shearing rigidity were analyzed before and after RNP at L 4 L 5 and L 5 S 1 levels respectively on six adult fresh human cadavers.Motions of flexion/extension,lateral bending and axial rotation were produced by six pure moments with maximum of 10.0N·m and measured with stereophotogrammetry.The compression rigidity and shearing rigidities in anterioposterior and lateral were measured under 1000N and 600N respectively.Results:The segmental motions in all directions increased after RNP.The motions increased significantly in extension and left/right axial rotation at L 4 L 5 level,and very significantly in flexion and significantly in left/right axial rotation at L 5 S 1 level.The compression rigidity and anteroposterior shearing righidity lowered and lateral shearing righidity lowered very significantly after RNP.Conclusions:The lumbosacrumal spine following RNP becomes instability because segmental motions increase and rigidities in compression and shearing lower,which increases loads on the posterior structures of spine and accelerates retrograde degeneration of lumbosacrumal spine.