The dynamic behaviour of the head and cervical spine during ‘whiplash’

Whiplash injuries and the potential for mechanical instability

“…This was not simulated in our model, and its consequences are presently unknown. It should be noted, however, that several important findings from our study closely match the observations made by recent in vivo studies using volunteers [22]. The maximum head rotation, which varied between 18°for 10.5 g to 31°for 2.5 g in our study [6] is within the range (18°-51°) observed by others [21].…”

“…In these subfailure injuries, the soft tissues are not completely torn, but become stretched beyond their elastic limit [27]. Subsequent increases in flexibility have been correlated to soft tissue injuries of the spine [7,[22][23][24]27]. Thus, increased flexibility implies yielding of the soft tissue structure, and constitutes functional injury to the spine.…”

Whiplash injuries

“…McKenzie [6] described the dynamic aspects of the head and cervical spine at the time of the injury. The classic description is of a driver, or passenger, sitting in a stationary vehicle that is hit from behind.…”

“…The chin hitting the sternum limits the degree of hyperflexion. It is well-established that the degree of damage to the vehicle bears little relationship to the size of force applied, both to the neck and also to the head [6]. Hyperextension injuries usually result in more neck trauma than hyperflexion injuries.…”

Case study: Acceleration/deceleration injury with angular kyphosis

“…1 In a rear-end collision, the head and neck are acted on with 2 to 2 1 ⁄2 times the acceleration force as the vehicle itself. 2,3 The acceleration rates are significantly more by comparison, and the deceleration rates reflect more force to the head and neck. According to the law of linear conservation of energy, 4,5 the increase of energy on impact must be transferred until completely dissipated.…”