L5/S1和骶髂关节对腰-髂固定稳定性影响的生物力学分析

Biomechanical analysis of L5/S1 complex and sacroiliac joints on the stability of lumbo-iliac fixation

中文关键词:  腰骶部失稳  骶髂关节切除  髂骨钉固定  腰-髂固定  生物力学

英文关键词:Lumbo-sacral instability  Sacroiliac joint resection  Iliac screw fixation  Lumbo-iliac fixation  Biomechanics

中文摘要:

  【摘要】 目的：探讨L5/S1和骶髂关节对腰-髂固定稳定性的影响，为腰-髂稳定性理想重建提供生物力学依据。方法：7具成年新鲜尸体L2-骨盆标本，先行L3~L5椎弓根螺钉固定，并将此结构定义为腰-髂部稳定初始状态。初始状态测试后，在同一标本上实施连续性操作如下：使用髂骨钉的L3-髂骨固定（A组）、L5/S1双侧关节突关节切除（B组）、L5/S1椎间盘切除（C组）、左侧骶髂关节切除（D组）。在MTS材料实验机上，给标本头侧分别施加600N轴向压缩和7Nm轴向扭转载荷，计算并比较各组结构压缩和扭转刚度。结果：初始状态组的压缩刚度值为（332±103）N/mm，A～D组腰-髂固定结构的压缩刚度分别为初始状态组的（122±15.5）%、（118.3±10.5）%、（81.1±7.7）%和（59.2±8.6）%。A和B组间无显著性差异（P>0.05），两组的压缩刚度均显著高于初始状态组（P<0.05）；C组和D组的压缩刚度均显著低于A、B组及初始状态组（P<0.05），C组和D组间的差异也具有显著性（P<0.05）。初始状态组的扭转刚度值为（2.47±0.88）Nm/deg，A～D组固定结构的扭转刚度分别为初始状态组的（128±14.3）%、（120±12.6）%、（78.4±13.2）%和（62.9±11.3）%，A组和B组获得同等的扭转刚度（P>0.05），而且此两组的扭转刚度均显著高于初始状态、C组和D组（P<0.05），C、D组和初始状态三组彼此间的差异均具有显著性（P<0.05）。结论：L5/S1椎间盘切除和单侧骶髂关节切除均显著降低腰-髂固定结构的稳定性，在腰-髂稳定性重建中，获得脊柱前方支撑和恢复骨盆环完整性是提高腰-髂固定结构稳定性的关键。

英文摘要:

  【Abstract】 Objectives: To explore the biomechanical effects of L5/S1 complex and sacroiliac joints on the stability of lumbo-iliac fixation construct, and to provide evidences for the rational reconstruction. Methods: Seven fresh L2-pelvic specimens harvested from donated adult cadavers were used in this study. After testing the initial state simulated by L3-L5 pedicle screw fixation, L3-iliac fixation and sequential joint resections were performed on the same specimen as follows: group A, L3-iliac fixation using bilateral iliac screws; group B, bilateral L5/S1 facetectomy; group C, L5/S1 discectomy; group D, left side sacroiliac joint resection. Biomechanical testing was performed on a material testing machine under 600N compression and 7Nm torsion loading modes for construct stiffness evaluation. Results: The compressive stiffness of initial state was (332±103)N/mm, group A-D obtained(122±15.5)%, (118.3±10.5)%, (81.1±7.7)% and (59.2±8.6)% of the initial compressive stiffness, respectively. No significant difference was detected between group A and B(P>0.05); furthermore, the two groups showed significantly higher compressive stiffness than the initial state(P<0.05); group C and D exhibited lower compressive stiffness than group A, B and the initial state(P<0.05); there was significant difference between group C and D(P<0.05). The torsional stiffness of initial state was (2.47±0.88)Nm/deg. Group A-D acquired (128±14.3)%, (120±12.6)%, (78.4±13.2)% and (62.9±11.3)% of the initial torsional stiffness, respectively. Group B obtained sufficient torsional stiffness compared to group A(P>0.05); both group A and B exhibited notably higher torsional stiffness than all the other three groups(P<0.05). Significant differences were demonstrated among group C, D and initial state(P<0.05). Conclusions: L5/S1 discectomy and one-side sacroiliac joint resection significantly decrease the stability of lumbo-iliac fixation construct. Therefore, anterior support of spine and pelvic continuity reconstruction is important in the lumbo-iliac stability.