Collagen Fiber Organization in the Cervical Facet Capsular Ligament Following Painful Facet Joint Distraction in the Rat

Chronic neck pain following whiplash is a substantial problem, affecting as many as 42% of whiplash patients [1]. The cervical facet joint is a common candidate for producing neck pain because it sustains altered kinematics during whiplash, with tensile stretch of its capsular ligament exceeding that during normal motions [2,3]. Altered facet capsule mechanics have been documented for loading conditions below structural failure [4,5]; evidence of both decreased linear stiffness and minor ruptures of the capsule suggest ligament injury prior to failure. In vivo studies have also implicated subfailure capsule injury as a potential source of pain. Capsule nociceptive pain fiber activation and saturation [6], as well as sustained pain symptoms [7], can be produced for facet joint distraction below gross failure.