Lee Kathryn E, Franklin Andrew N, Davis Martin B, Winkelstein Beth A
Department of Bioengineering, University of Pennsylvania, 120 Hayden Hall, 3320 Smith Walk, Philadelphia, PA 19104-6392, USA.
J Biomech. 2006;39(7):1256-64. doi: 10.1016/j.jbiomech.2005.03.018.
Clinical, epidemiological, and biomechanical studies suggest the involvement of the cervical facet joint in neck pain. Mechanical studies have suggested the facet capsular ligament to be at risk for subfailure tensile injury during whiplash kinematics of the neck. Ligament mechanical properties can be altered by subfailure injury and such loading can induce cellular damage. However, at present, there is no clear understanding of the physiologic context of subfailure facet capsular ligament injury and mechanical implications for whiplash-related pain. Therefore, this study aimed to define a relationship between mechanical properties at failure and a subfailure condition associated with pain for tension in the rat cervical facet capsular ligament. Tensile failure studies of the C6/C7 rat cervical facet capsular ligament were performed using a customized vertebral distraction device. Force and displacement at failure were measured and stiffness and energy to failure were calculated. Vertebral motions and ligament deformations were tracked and maximum principal strains and their directions were calculated. Mean tensile force at failure (2.96 +/- 0.69 N) was significantly greater (p < 0.005) than force at subfailure (1.17 +/- 0.48 N). Mean ligament stiffness to failure was 0.75 +/- 0.27 N/mm. Maximum principal strain at failure (41.3 +/- 20.0%) was significantly higher (p = 0.003) than the corresponding subfailure value (23.1 +/- 9.3%). This study determined that failure and a subfailure painful condition were significantly different in ligament mechanics and findings provide preliminary insight into the relationship between mechanics and pain physiology for this ligament. Together with existing studies, these findings offer additional considerations for defining mechanical thresholds for painful injuries.
临床、流行病学和生物力学研究表明，颈椎小关节与颈部疼痛有关。力学研究表明，在颈部挥鞭样运动过程中，小关节囊韧带存在亚失效拉伸损伤风险。亚失效损伤可改变韧带的力学性能，这种负荷可导致细胞损伤。然而，目前对于亚失效小关节囊韧带损伤的生理背景以及与挥鞭样损伤相关疼痛的力学影响尚无清晰认识。因此，本研究旨在确定大鼠颈椎小关节囊韧带拉伸时失效时的力学性能与与疼痛相关的亚失效状态之间的关系。使用定制的椎体撑开装置对C6/C7大鼠颈椎小关节囊韧带进行拉伸失效研究。测量失效时的力和位移，并计算刚度和失效能量。跟踪椎体运动和韧带变形，并计算最大主应变及其方向。失效时的平均拉伸力（2.96±0.69 N）显著大于（p<0.005）亚失效时的力（1.17±0.48 N）。失效时韧带的平均刚度为0.75±0.27 N/mm。失效时的最大主应变（41.3±20.0%）显著高于（p = 0.003）相应的亚失效值（23.1±9.3%）。本研究确定，失效状态和亚失效疼痛状态在韧带力学方面存在显著差异，研究结果为该韧带的力学与疼痛生理学之间的关系提供了初步见解。与现有研究一起，这些发现为定义疼痛性损伤的力学阈值提供了更多考虑因素。
