颈椎前路环锯法减压术后三种处理方法的生物力学评价

目的 研究环锯法减压后不植骨、自体柱状髂骨植骨及螺柱状颈椎内固定器植入后，三者的生物力学稳定性，为临床手术提供依据。方法 采用新鲜青年尸体标本，分别用三种方法处理C5－6段，测量其在1．53nm的纯力矩载荷条件下的稳定性并用相邻椎体间的空间位移和卡当角表示。结果 环锯法减术后，手术节段的稳定性明显减轻。自体髂骨植入后，椎间隙高度升高，伸屈活动度下降，但其稳定性仍比正常时差。螺柱状颈椎内固定器植入，前屈、侧屈和旋转的活动度明显较正常时小，但后伸范围无明显改变。结论 环锯减压后如不植骨有可能不融合或畸形愈合。椎间植骨能明显改善减压节段的稳定性，但手术后仍应采用辅助外固定。螺柱状颈椎内固定器不但能维持椎间隙高度，防止术后畸形，而且有足够的稳定性，术后不必应用外固定。

Biomechanical analysis ofthree types of treatment after loop-saw method anterior cervical decompression

：Objective　To study the biomechanical stability of three types of operation,after anterior cervical loop-saw method decompression and to provide biomechanical basis for clinical surgery. Methods　The fresh cervical spine speciman of young cadaver were used for biomechanical test.The anterior cervical loop-saw decompression were carried out at C5～6 and a autogenous bone graft taken from iliac bone were implanted into decmopressed intervertebral space.After test,the bone graft were removed and a threaded cervical intervertebral inner fixation device were implanted into C5～6.The stability of C5～6were tested respectively under anterior flexion,posterior extensive,lateral flexion and rotation when the speciman were loaded with 1.53 nm moment at normal,and three types of operative management diseribed as above.The spinal stability were expressed by space displacement and angular displacement between two neighbour vertebrae.Results　The stability of C5～6were significantly decreased after loop-saw decompression that exhibited as the increasing of range of motion(ROM).Bone graft results in a increasing of height of intervertebral space and decreasing of the ROM of the fusion segment,but its stability is inferior to that of normal segment.After implant the threaded intervertebral cervical device,the ROM of C5～6 in anterior flexion rotation and lateral bending are significantly decreased with no change of the range in extension.Conclusion　The stability of cervical spine were significantly decreased after anterior loop-saw decompression.Bone graft and fusion is essential for prevent the possible non-union or mal-union of decompressed segement.Though bone graft at intervertebral space can significantly improve the stability of the cervical spine,a postoperative assistant external fixation is still required.Threaded cervical intervertebral fusion device can provide a satisfactory stability of the fusion segment without require any external fixation.