Whiplash

Nearly one third of all motor vehicle accidents are rear end collisions, and it is this type of accident that is responsible for most whiplash injuries.

Biomechanics, the study of how mechanical forces affect living organisms, is useful in explaining how even a "minor" rear end collision can result in a serious injury. The biomechanics of a common rear end collision can be understood as a sequence of events, one following the other.

Newton's First Law of Motion states that, "An object remains at rest or in a state of motion in a straight line unless it is acted upon by an outside force." To put this into practical terms, if you are sitting in your car at a stop light ("at rest") and are then struck by another vehicle from behind, ("acted upon by an outside force"), you will immediately not be ("at rest") anymore.

In this common scenario of whiplash-type injuries, your car is propelled forward, and as you sit in your seat with your torso supported by the car seat, it too goes forward. What doesn't go forward in that split second is your head. It generally stays where it is, but relative to your torso, it travels backward as your car travels forward.

Have you ever had someone come from behind you and push you between your shoulder blades, and felt your head go backwards? Whiplash biomechanics are just like that, only much more severe.

Hyperextension, or the abrupt movement of the head backwards, usually causes the most damage in a whiplash injury, since there are no anatomical restrictions to the range of motion. As a result of this sudden forceful movement of the head backward, numerous types of injuries can occur.

Tearing of the front muscles and ligaments of the neck is common. (Muscles move bones, and ligaments hold bones together.) Disc herniations are also possible, and fractures are also of great concern.

When the vehicle finally stops as a result of braking or hitting another object, your body is propelled forward, sometimes hitting the steering wheel, windshield, or airbag. If you are wearing a shoulder restraint, your head will fly forward, with a twisting motion, resulting in hyperflexion of the neck.