The term 'whiplash' was initially used to describe injuries to the neck cau
sed by the head being forced backwards during a rear-end collision in cars
without head restraints. The addition of head restraints in the 1970s was e
xpected to solve this problem by preventing excessive extension of the neck
but experience suggests the problem still exists. This paper reviews avail
able experimental studies of whiplash and uses the data to construct a fini
te element model which is capable of dynamically simulating whiplash collis
ions and predicting the forces in all the relevant neck ligaments. For the
first time, it is shown that trauma occurs long before the head hits the he
ad restraint as a result of displacement between the head and the torso cau
sed by the head's inertia leading to markedly different acceleration histor
ies. It is concluded that experimental and computational studies must be us
ed together to produce progress in biomechanical studies.