Jaumard Nicolas V, Welch William C, Winkelstein Beth A
Dept. of Neurosurgery, University of Pennsylvania, Philadelphia, PA 19104, USA.
J Biomech Eng. 2011 Jul;133(7):071010. doi: 10.1115/1.4004493.
The facet joint is a crucial anatomic region of the spine owing to its biomechanical role in facilitating articulation of the vertebrae of the spinal column. It is a diarthrodial joint with opposing articular cartilage surfaces that provide a low friction environment and a ligamentous capsule that encloses the joint space. Together with the disc, the bilateral facet joints transfer loads and guide and constrain motions in the spine due to their geometry and mechanical function. Although a great deal of research has focused on defining the biomechanics of the spine and the form and function of the disc, the facet joint has only recently become the focus of experimental, computational and clinical studies. This mechanical behavior ensures the normal health and function of the spine during physiologic loading but can also lead to its dysfunction when the tissues of the facet joint are altered either by injury, degeneration or as a result of surgical modification of the spine. The anatomical, biomechanical and physiological characteristics of the facet joints in the cervical and lumbar spines have become the focus of increased attention recently with the advent of surgical procedures of the spine, such as disc repair and replacement, which may impact facet responses. Accordingly, this review summarizes the relevant anatomy and biomechanics of the facet joint and the individual tissues that comprise it. In order to better understand the physiological implications of tissue loading in all conditions, a review of mechanotransduction pathways in the cartilage, ligament and bone is also presented ranging from the tissue-level scale to cellular modifications. With this context, experimental studies are summarized as they relate to the most common modifications that alter the biomechanics and health of the spine-injury and degeneration. In addition, many computational and finite element models have been developed that enable more-detailed and specific investigations of the facet joint and its tissues than are provided by experimental approaches and also that expand their utility for the field of biomechanics. These are also reviewed to provide a more complete summary of the current knowledge of facet joint mechanics. Overall, the goal of this review is to present a comprehensive review of the breadth and depth of knowledge regarding the mechanical and adaptive responses of the facet joint and its tissues across a variety of relevant size scales.
小关节是脊柱的一个关键解剖区域，因为它在促进脊柱椎体的关节活动方面具有生物力学作用。它是一个双动关节，有相对的关节软骨表面，提供低摩擦环境，还有一个包围关节间隙的韧带囊。双侧小关节与椎间盘一起，由于其几何形状和机械功能，在脊柱中传递负荷、引导和限制运动。尽管大量研究集中在确定脊柱的生物力学以及椎间盘的形态和功能，但小关节直到最近才成为实验、计算和临床研究的焦点。这种力学行为在生理负荷期间确保脊柱的正常健康和功能，但当小关节组织因损伤、退变或脊柱手术改变而发生改变时，也可能导致其功能障碍。随着脊柱手术（如椎间盘修复和置换）的出现，颈椎和腰椎小关节的解剖、生物力学和生理特征最近成为人们日益关注的焦点，这些手术可能会影响小关节的反应。因此，本综述总结了小关节及其组成的各个组织的相关解剖学和生物力学。为了更好地理解在所有情况下组织负荷的生理影响，还从组织水平到细胞修饰层面介绍了软骨、韧带和骨中的机械转导途径。在此背景下，总结了与改变脊柱生物力学和健康的最常见改变——损伤和退变相关的实验研究。此外，已经开发了许多计算和有限元模型，与实验方法相比，这些模型能够对小关节及其组织进行更详细和具体的研究，并且还扩展了它们在生物力学领域的应用。这些也进行了综述，以更全面地总结当前关于小关节力学的知识。总的来说，本综述的目标是全面回顾关于小关节及其组织在各种相关大小尺度上的机械和适应性反应的知识广度和深度。
