Biomedical Engineering, University of Minnesota, 312 Church St. SE, 7-105 Nils Hasselmo Hall, Minneapolis, MN, 55455, USA.
Divisions of Physical Therapy and Rehabilitation Science, Departments of Rehabilitation Medicine and Orthopedic Surgery, University of Minnesota, 426 Church St. SE, 366A Children's Rehab Ctr, Minneapolis, MN, 55455, USA.
Biomech Model Mechanobiol. 2021 Aug;20(4):1445-1457. doi: 10.1007/s10237-021-01455-3. Epub 2021 Mar 31.
The human lumbar facet capsule, with the facet capsular ligament (FCL) that forms its primary constituent, is a common source of lower back pain. Prior studies on the FCL were limited to in-plane tissue behavior, but due to the presence of two distinct yet mechanically different regions, a novel out-of-plane study was conducted to further characterize the roles of the collagen and elastin regions. An experimental technique, called stretch-and-bend, was developed to study the tension-compression asymmetry of the FCL due to varying collagen fiber density throughout the thickness of the tissue. Each healthy excised cadaveric FCL sample was tested in four conditions depending on primary collagen fiber alignment and regional loading. Our results indicate that the FCL is stiffest when the collagen fibers (1) are aligned in the direction of loading, (2) are in tension, and (3) are stretched - 16% from its off-the-bone, undeformed state. An optimization routine was used to fit a four-parameter anisotropic, hyperplastic model to the experimental data. The average elastin modulus, E, and the average collagen fiber modulus, ξ, were 13.15 ± 3.59 kPa and 18.68 ± 13.71 MPa (95% CI), respectively.
人腰椎小关节囊及其主要组成部分小关节囊韧带（FCL）是导致下腰痛的常见原因。先前对 FCL 的研究仅限于平面组织行为，但由于存在两个截然不同但机械性能不同的区域，因此进行了一项新的离面研究以进一步表征胶原和弹性蛋白区域的作用。一种名为拉伸弯曲的实验技术被开发出来，用于研究由于组织厚度中胶原纤维密度的变化而导致的 FCL 的拉伸压缩不对称性。根据主要胶原纤维取向和区域加载情况，将每个健康的离体 cadaveric FCL 样本在四种条件下进行测试。我们的结果表明，当胶原纤维（1）沿加载方向排列，（2）处于拉伸状态，以及（3）从离开骨骼的未变形状态拉伸 16%时，FCL 的刚度最大。优化例程用于将四参数各向异性、增生模型拟合到实验数据中。平均弹性模量 E 和平均胶原纤维模量 ξ 分别为 13.15 ± 3.59 kPa 和 18.68 ± 13.71 MPa（95%CI）。
