北京生物医学工程

新型腰椎后路动态内固定的生物力学评价及其对邻近节段的影响

Biomechanical evaluation of the posterior dynamic internal fixation of the lumbar spine and its effects on adjacent segments

作者：蒋帅刘洋陈元元冯勇袁文

单位：海军军医大学第三附属医院骨科（上海 200438）海军军医大学第二附属医院脊柱外科（上海 200003）微创医疗器械（上海）有限公司（上海 201203)

关键词：腰椎；动态系统；生物力学；内固定；运动范围；中性区

分类号：R318.01

出版年·卷·期（页码）：2021·40·3（295-302）

摘要：

目的应用新鲜人体标本，对新型腰椎后路动态内固定进行体外生物力学试验，进一步明确动态内固定对受试节段及邻近节段的活动度影响，最终为临床应用动态内固定治疗腰椎退行性疾病提供参考提供。方法选用6具腰椎尸体标本，固定于脊柱生物力学试验机上，测试的状态依次为完整腰椎状态、失稳腰椎状态、动态内固定状态及坚强内固定状态，分别在前(后)屈、左(右)侧弯和左(右)旋转3个运动平面上施加7.5 N·m的力矩，计算并比较腰3-腰4、腰4-腰5、腰5-骶1之间3个运动平面的脊柱运动范围(range?of?motion，ROM)及中性区(neutral zone, NZ)。结果在所有的3个运动平面上(侧弯、屈/伸、轴向旋转)，与完整腰椎状态对比，失稳腰椎状态增加了ROM和NZ (P＜0.05)。坚强内固定和动态内固定状态均使侧弯和屈曲ROM和NZ较正常腰椎减少1个数量级(P＜0.05)，屈/伸时，坚强内固定组ROM和NZ明显减小(P＜0.05)，动态固定组的ROM和NZ较完整腰椎状态无明显改变(P＞0.05)。轴向左右旋转时，坚强内固定状态ROM和NZ明显减小，动态内固定状态ROM则较正常腰椎状态有所增大，但差异无统计学意义(P＞0.05)。腰3-腰4及腰5-骶1邻近节段的3个运动平面上(侧弯、屈/伸、轴向旋转)的ROM和NZ均未明显受到固定节段的影响(P＞0.05)。结论相对坚强内固定，动态内固定能够稳定失稳的脊柱节段，允许更多的节段活动，可考虑将动态内固定作为坚强内固定的替代治疗方法。

Objective To use fresh human specimens to conduct biomechanical experiments on the new type of posterior dynamic internal fixation of the lumbar spine in vitro, to further clarify the procedure for dynamic internal fixation on the mobility of the tested segment and adjacent segments and provide reference for the clinical application of dynamic internal fixation in the treatment of lumbar degenerative diseases. Methods Six lumbar cadaver specimens were selected and fixed on the spine biomechanics testing machine. The tested states were intact lumbar spine state, unstable lumbar spine state, dynamic internal fixation state and rigid internal fixation state, respectively in front (rear) flexion and left (right) ?lateral bending and left (right) rotation exert a torque of 7.5 N·m on the 3 motion planes. The spine motions of the 3 motion like range of motion (ROM) and neutral zone (NZ) between L3- L4, L4- L5 and L5-S1. Results In all 3 motion planes (?lateral bending, flexion/extension and axial rotation), compared with the intact lumbar spine, the unstable lumbar spine increased ROM and NZ(P＜0.05). Both rigid internal fixation and dynamic internal fixation reduced ?lateral ending and flexion ROM and NZ by an order of magnitude compared with normal lumbar spine(P＜0.05). During flexion/extension, ROM and NZ of the rigid internal fixation group were significantly reduced(P＜0.05) , ROM and NZ of the dynamic fixation group were not significantly changed compared with the intact lumbar spine state (P＞0.05). When the axis rotates left and right, the ROM and NZ of the rigid internal fixation state are significantly reduced, and the ROM of the dynamic internal fixation state is increased compared with the normal lumbar state, but the difference is not statistically significant (P＞0.05). The ROM and NZ on the 3 motion planes of the adjacent segments of L3- L 4 and L 5-S1 were not significantly affected by the fixed segment(P＞0.05). Conclusions Compared with the internal fixation, the dynamic internal fixation can stabilize the unstable spinal segment and allow more segmental mobility. Dynamic internal fixation might be considered as an alternative treatment for rigid internal fixation.

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