Jaumard Nicolas V, Bauman Joel A, Weisshaar Christine L, Guarino Benjamin B, Welch William C, Winkelstein Beth A
J Biomech Eng. 2011 Jul;133(7):071004. doi: 10.1115/1.4004409.
The facet joint contributes to the normal biomechanical function of the spine by transmitting loads and limiting motions via articular contact. However, little is known about the contact pressure response for this joint. Such information can provide a quantitative measure of the facet joint's local environment. The objective of this study was to measure facet pressure during physiologic bending in the cervical spine, using a joint capsule-sparing technique. Flexion and extension bending moments were applied to six human cadaveric cervical spines. Global motions (C2-T1) were defined using infra-red cameras to track markers on each vertebra. Contact pressure in the C5-C6 facet was also measured using a tip-mounted pressure transducer inserted into the joint space through a hole in the postero-inferior region of the C5 lateral mass. Facet contact pressure increased by 67.6 ± 26.9 kPa under a 2.4 Nm extension moment and decreased by 10.3 ± 9.7 kPa under a 2.7 Nm flexion moment. The mean rotation of the overall cervical specimen motion segments was 9.6 ± 0.8° and was 1.6 ± 0.7° for the C5-C6 joint, respectively, for extension. The change in pressure during extension was linearly related to both the change in moment (51.4 ± 42.6 kPa/Nm) and the change in C5-C6 angle (18.0 ± 108.9 kPa/deg). Contact pressure in the inferior region of the cervical facet joint increases during extension as the articular surfaces come in contact, and decreases in flexion as the joint opens, similar to reports in the lumbar spine despite the difference in facet orientation in those spinal regions. Joint contact pressure is linearly related to both sagittal moment and spinal rotation. Cartilage degeneration and the presence of meniscoids may account for the variation in the pressure profiles measured during physiologic sagittal bending. This study shows that cervical facet contact pressure can be directly measured with minimal disruption to the joint and is the first to provide local pressure values for the cervical joint in a cadaveric model.
小关节通过关节接触传递负荷和限制运动，从而对脊柱的正常生物力学功能发挥作用。然而，对于该关节的接触压力反应却知之甚少。此类信息可为小关节的局部环境提供定量测量。本研究的目的是采用保留关节囊技术测量颈椎生理弯曲过程中的小关节压力。对六个人类尸体颈椎施加屈伸弯矩。使用红外摄像机跟踪每个椎体上的标记来定义整体运动（C2-T1）。还通过一个插入C5侧块后下区域孔内的尖端安装压力传感器测量C5-C6小关节的接触压力。在2.4 Nm的伸展力矩下，小关节接触压力增加67.6±26.9 kPa，在2.7 Nm的屈曲力矩下，小关节接触压力降低10.3±9.7 kPa。伸展时，整个颈椎标本运动节段的平均旋转角度为9.6±0.8°，C5-C6关节为1.6±0.7°。伸展过程中压力的变化与力矩变化（51.4±42.6 kPa/Nm）和C5-C6角度变化（18.0±108.9 kPa/°）均呈线性相关。颈椎小关节下部区域的接触压力在伸展时随着关节面接触而增加，在屈曲时随着关节张开而降低，尽管这些脊柱区域的小关节方向不同，但与腰椎的报道相似。关节接触压力与矢状面力矩和脊柱旋转均呈线性相关。软骨退变和半月板样结构的存在可能解释了生理矢状面弯曲过程中测量的压力分布变化。本研究表明，可在对关节干扰最小的情况下直接测量颈椎小关节接触压力，并且首次在尸体模型中提供了颈椎关节的局部压力值。
