Shirazi-Adl A
Department of Mechanical Engineering, Ecole Polytechnique, Montreal, Quebec, Canada.
Spine (Phila Pa 1976). 1994 Nov 1;19(21):2407-14. doi: 10.1097/00007632-199411000-00007.
The nonlinear stress analysis of the entire ligamentous lumbar spine (L1-S1) in single flexion, extension, right lateral, and left lateral moments of up to 15 Nm was performed. In sagittal moments, both disc fiber angles of 27 degrees and 30 degrees were considered. Moreover, in extension moment, the effects of larger gap limit (the distance at which the contact initiates) at all facet joints and of removal of left or left/right L4-L5 facet joints also were studied.
The overall and intersegmental biomechanics of the lumbar spine under sagittal moments with particular emphasis on the role facets were studied.
The analysis was performed using a nonlinear three-dimensional finite element model.
Intersegmental results were nonlinear and varied from one level to the next. Overall, the lumbar flexibility and disc pressures were larger in flexion. Conversely, larger facet forces were computed in extension whereas flexion caused negligible contact forces. Unilateral and bilateral removal of L4-L5 facets in extension reduced the stiffness and increased the disc pressure at the same level while the remaining levels were nearly unaffected. In contrast, larger gap limit for articulation increased stiffness, reduced disc pressure, and increased loads on facets at all segmental levels. Disc fiber layers are most loaded in flexion and least loaded in extension. Large tensile strains occur in disc fibers under flexion and lateral moments. This suggests the vulnerability of disc fibers to failure under movements involving large flexion and lateral rotations.
对整个腰椎韧带结构（L1 - S1）在单方向最大达15 Nm的前屈、后伸、右侧弯和左侧弯力矩作用下进行非线性应力分析。在矢状面力矩分析中，考虑了椎间盘纤维角度分别为27度和30度的情况。此外，在后伸力矩分析中，还研究了所有小关节处更大的间隙极限（接触开始时的距离）以及去除左侧或双侧L4 - L5小关节的影响。
研究腰椎在矢状面力矩作用下的整体和节段间生物力学，特别强调小关节的作用。
使用非线性三维有限元模型进行分析。
节段间结果是非线性的，且各节段不同。总体而言，腰椎在前屈时的柔韧性和椎间盘压力更大。相反，后伸时计算得出的小关节力更大，而前屈时产生的接触力可忽略不计。后伸时单侧和双侧去除L4 - L5小关节会降低同一节段的刚度并增加椎间盘压力，而其余节段几乎不受影响。相比之下，关节的更大间隙极限会增加刚度、降低椎间盘压力，并增加所有节段水平小关节上的负荷。椎间盘纤维层在前屈时负荷最大，后伸时负荷最小。在屈曲和侧弯力矩作用下，椎间盘纤维会出现较大的拉伸应变。这表明在涉及大角度前屈和侧方旋转的运动中，椎间盘纤维易发生破坏。
