颈椎后路单开门手术对颈椎三维运动及刚性的影响

The effect of the expansive open-door laminoplasty on the three-dimensional motion and stiffness of the cervical spine

目的研究颈椎后路单开门椎管扩大成形术对颈椎三维运动及刚性的影响。方法脊髓型颈椎病单开门手术后病例 55例，平均随访 35.9个月，对手术前后的颈部轴性症状、神经功能变化 (JOA评分 )和颈椎动态侧位片进行比较。运用 ZMS－ 1型人体颈椎三维运动及刚度测试仪对颈椎单开门术后组 (12例 )和术前对照组 (10例 )进行活体力学测试。测试内容包括 :(1)颈椎主动及被动运动范围； (2)载荷－位移关系和颈椎刚度； (3)颈椎伸、屈肌群主动等长收缩力矩。结果术后 JOA评分平均改善率 66.2％，优良率 78.2％。术后出现明显或严重颈部轴性症状的病例较术前增加 (P< 0.01)；术后颈部轴性症状明显者颈椎弧度较小 (P< 0.01)；颈部轴性症状分级与 JOA评分改善率两者差异无显著性意义 (P >0.05)。手术后颈椎区域主动及被动伸屈、旋转和侧屈运动范围减小 (P< 0.05)，主要影响中下颈椎。颈椎载荷－位移关系可拟合为指数方程 T=b0e。在颈椎各向运动中侧屈刚度最大，其次为后伸与前屈，旋转刚度最小。术后组颈椎刚度大于术前组。结论单开门手术损害颈椎矢状面的静态力学平衡，并使颈椎运动范围减小、柔韧性下降。颈椎弧度改变同颈部轴性症状轻重相关，而与 JOA评分改善率无关。

Objective To study the effect of the expansive open-door laminoplasty on the three-dimensional motion and stiffness of the cervical spine. Methods 55 cases after open-door laminoplasty of cervical spine due to myelopathy were follow-up for an average of 35.9 months. Cervical axial symptoms, neural functionality (JOA scoring system) and pre-and post-surgery dynamic cervical spine lateral X-ray films were evaluated. The Three-dimensional Motion and Stiffness of the Cervical Spine of Human Body Measuring Equipment was used in 12 post-operative open door laminoplasty cases and 10 pre-operative cases to measure the active and passive range of motion(ROM), load-displacement relationship, stiffness of cervical spine and torque caused by the isometric contraction of the extensors and flexors of the cervical spine. Results The average rate of improvement was 66.2％ . The excellent and good rate was 78.2％ . The number of cases with distinct or severe cervical axial symptoms increased after the surgery (P< 0.01). The patients who have severe axial symptoms tend to have less curved cervical spine (P< 0.01). There was no significant statistic difference between the severity of post-surgery cervical axial symptoms and JOA improvement level (P >0.05). The active and passive ROM of extension, rotation and lateral bending of cervical spine were decreased after the surgery (P< 0.05), and the main affection was on the middle and lower part of the cervical spine. The load-displacement figure of cervical spine can fit into an exponential equation T=b0e . In each direction, the lateral bending had the strongest stiffness, then the extension and flexion. The stiffness of rotation was the weakest. The stiffness of cervical spine of the post-surgery group was stronger than that of the contrast group. Conclusion The open-door laminoplasty of cervical spine damages the static mechanic balance on the sagittal plane and decreases the ROM and the flexibility of cervical spine. The curvature of the cervical spine is related to the severity of the axial symptoms and seems not to be related to the JOA score improvement.