A hallmark of injury biomechanical investigation is the production of injury to human surrogates and derivation of variables that quantify or explain the mechanism of trauma. This study was based on the concept that motion and injury are interrelated. In the first phase, post mortem human subjects (PMHS) were subjected to single rear acceleration using a sled. These tests were done to determine soft tissue-related injuries. Cryomicrotomy techniques were used because x-rays cannot directly document these types of injuries. In the second phase, head-neck complexes were tested in rear impact using a mini-sled pendulum. Injuries determined from intact tests were evaluated with kinematic parameters obtained from head-neck complex tests. Injuries (first phase) were primarily confined to the facet joints of the lower cervical spine and anterior column trauma. A majority of trauma was concentrated at the C5-6 level. Mechanically supporting evidence was observed in the kinematics of the cervical joints (second phase), wherein the C5-6 level responded with higher magnitudes of motions (than at other levels) associated with sliding and facet capsule stretch. Accentuated motions at lower levels explain injuries to the lower cervical spine seen in the form of soft tissue injuries due to single rear impact. The investigation indicated that neck pain may arise due to abnormalities of the intervertebral joints at the lower spinal level, as these soft tissues are replete with nociceptors. (A)
Samenvatting