Fewster Kayla M, Guo Joyce R, Zehr Jackie D, Barrett Jeff M, Laing Andrew C, Callaghan Jack P
Department of Kinesiology, University of Waterloo, Waterloo, ON N2 L 3G1, Canada.
J Biomech Eng. 2022 May 1;144(5). doi: 10.1115/1.4053207.
Low back pain (LBP) is frequently reported following rear impact collisions. Knowledge of how the facet joint capsule (FJC) mechanically behaves before and after rear impact collisions may help explain LBP development despite negative radiographic evidence of gross tissue failure. This study quantified the Green strain tensor in the facet joint capsule during rotation and translation range-of-motion tests completed before and following an in vitro simulation of a rear impact collision. Eight FSUs (4 C3-C4, 4 C5-C6) were tested. Following a preload test, FSUs were flexed and extended at 0.5 deg/s until an ±8 N·m moment was achieved. Anterior and posterior joint translation was then applied at 0.2 mm/s until a target ±400 N shear load was imposed. Markers were drawn on the facet capsule surface and their coordinates were tracked during pre- and postimpact range-of-motion tests. Strain was defined as the change in point configuration relative to the determined neutral joint posture. There were no significant differences (p > 0.05) observed in all calculated FJC strain components in rotation and translation before and after the simulated impact. Our results suggest that LBP development resulting from the initiation of strain-induced mechanoreceptors and nociceptors with the facet joint capsule is unlikely following a severe rear impact collision within the boundaries of physiological joint motion.
在追尾碰撞后，经常会报告下背痛（LBP）。了解小关节囊（FJC）在追尾碰撞前后的力学行为，可能有助于解释尽管在X射线下没有明显的组织损伤证据，但仍会出现LBP的原因。本研究量化了在体外模拟追尾碰撞前后完成的旋转和平移运动范围测试中，小关节囊内的格林应变张量。测试了八个功能性脊柱单元（FSU，4个C3-C4，4个C5-C6）。在进行预加载测试后，FSU以0.5°/s的速度进行屈伸，直到达到±8 N·m的力矩。然后以0.2 mm/s的速度施加前后关节平移，直到施加目标±400 N的剪切力。在小关节囊表面绘制标记，并在碰撞前后的运动范围测试中跟踪其坐标。应变定义为相对于确定的关节中性姿势的点配置变化。在模拟碰撞前后的旋转和平移过程中，所有计算出的FJC应变分量均未观察到显著差异（p>0.05）。我们的结果表明，在生理关节运动范围内发生严重追尾碰撞后，由小关节囊内应变诱导的机械感受器和伤害感受器引发导致LBP的可能性不大。
