Risk of injury of the cervical spine in sled tests in female volunteers

BackgroundThe description of cervical spine motion and the risk to sustain a cervical spine injury is mainly based on cadaver studies. As the active influence of soft tissue is neglected in cadaver studies, our understanding of the kinematic model for whiplash is limited. Therefore the objective of this study was, to describe the in vivo cervical spine motion and acceleration during rear-end sled collisions to identify sequences of motion in which the risk of injury to the cervical spine is increased.MethodsA rear-end collision with a speed change (ΔV) of 6.3 km/h was simulated in a sled test with eight female subjects with no history of prior injury or pain of the cervical spine. A high-speed camera was used to document motion data. Acceleration data were recorded using accelerometers. Acceleration input to the cervical spine was assessed by the simultaneous analysis of the head angle and angular head acceleration as well as the simultaneous analysis of the relative motion and the relative acceleration between the head and T1 to define intervals of increased risk of cervical spine injuries during rear-end collision.FindingsThe motion sequence is characterized by the same phases that have already been described for male volunteers. Increasing angular head acceleration can explain facet joint injuries during the extension movement (100–120 ms) and hence occur about 50 ms later than shown in cadaver models. In the late rebound the combination of maximal ventral head acceleration and head movement is underestimated and can be responsible for soft tissue injuries.InterpretationThe study shows that during the extension phase and the late rebound phase, acceleration and movement pattern occur that could lead to cervical spine injuries.