椎管重建对腰椎活动度影响的有限元分析

Impact of internal fixations for lumbar canal reconstruction on segmental range of motion: a finite element analysis

[目的]比较椎板回植椎管重建内固定术对腰椎活动度范围(range of motion, ROM)的影响。[方法]分别建立腰椎L2~4三维有限元模型,包括正常模型组、椎板切除组、椎板回植H形钛板固定组(H形钛板组)、椎板回植L形钛板固定组(L形钛板组)和椎板回植两孔钛板固定组(两孔钛板组)。在L2椎体上施加10 N·m的应力,测量6种自由度下L_(2/3)和L_(3/4)节段ROM。[结果]总体方面,5组模型的6种自由度比较,L_(2/3)ROM由大至小均依次为:左侧弯>前屈>右侧变>后伸>右旋>左旋,L_(3/4)为:前屈>左侧弯>右侧变>后伸>右旋>左旋,总体差异均有统计学意义(P<0.05)。6种自由度的五组模型比较,L_(2/3)和L_(3/4)的ROM由大至小均依次为:椎板切除组>两孔钛板组> L形钛板组> H形钛板组>正常模型组,总体差异均有统计学意义(P<0.05)。左弯、右弯、左旋和右旋状态下,H形钛板的ROM显著小于L形钛板组和两孔钛板组(P<0.05)。[结论]椎管重建可有效减少椎板切除所致的异常节段的活动度增加,且H形钛板固定重建椎管在抗弯曲和旋转时,其生物力学稳定性要优于L型和两孔钛板。

[Objective] To compare the influence of lamina replantation with different internal fixations for spinal canal reconstruction on segmental range of motion(ROM) of the lumbar spine. [Methods] The lumbar L2~4three-dimensional finite element models were established respectively, including normal model group(NM group), laminectomy group(LE group), laminectomy and H-shaped titanium plate fixation group(H-plate group), laminectomy and L-shaped titanium plate fixation group(L-plate group) and laminectomy and two-hole titanium plate fixation group(TH plate group). A 10 Nm loading was applied to the L2vertebral body, the ROMs of L_(2/3)and L_(3/4)segments in six degrees of freedom were measured. [Results] In terms of overall comparison among the 6 degrees of freedom, the ROMs of L_(2/3)were ranked in descending order: left bending > forward flexion > right bending > extension > right rotation > left rotation, with statistically significant overall difference in all the 5 model groups(P<0.05). The ROMs of L_(3/4)were ranked in descending order: forward flexion > left bending >right bending > extension > right rotation > left rotation, with statistically significant overall difference in all the 5 model groups(P<0.05).However, in terms of overall comparison among the 5 model groups, the ROM of L_(2/3)and L_(3/4)were arranged in descending order of: LE group > TH plate group > L-plate group > H-plate group > NM group, which all were statistically significant in 6 degrees of freedom(P<0.05). In the left bending, right bending, left and right rotations, the ROM of H-plate group had significantly lower ROMs than that of Lplate group and TH plate group(P<0.05). [Conclusion] The lamina replantation with different internal fixations for spinal canal reconstruction does effectively reduce the abnormal increase of segmental ROMs caused by laminectomy. Of them, H-shaped titanium plate fixation achieves better stability than L-shaped plate and two-hole titanium plate in terms of resistance of bending and rotation.