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.

人体腰椎小关节囊及其主要成分小关节囊韧带 (FCL) 是腰痛的常见来源。先前对 FCL 的研究仅限于平面内组织行为，但由于存在两个不同但机械上不同的区域，因此进行了一项新颖的平面外研究，以进一步表征胶原蛋白和弹性蛋白区域的作用。开发了一种称为拉伸和弯曲的实验技术来研究 FCL 由于整个组织厚度中胶原纤维密度不同而导致的拉压不对称性。每个健康的切除尸体 FCL 样本都在四种条件下进行测试，具体取决于初级胶原纤维排列和区域负载。我们的结果表明，当胶原纤维 (1) 沿载荷方向排列、(2) 处于拉伸状态、(3) 从离骨、未变形状态拉伸 16% 时，FCL 是最硬的。使用优化例程将四参数各向异性、超塑性模型拟合到实验数据。平均弹性蛋白模量E和平均胶原纤维模量xi分别为 13.15 ± 3.59 kPa 和 18.68 ± 13.71 MPa (95% CI)。