From various studies and researchers:

The degree of patient/passenger injury from automobile collisions is not related to the size, speed, or magnitude of damage of the involved vehicles.

Neck extension became almost 60 degrees which is the potential danger limit of whiplash, at collision speed as low as 2.5 km/h.

It is false reasoning and a misconception to claim that vehicle crash damage offers a correlation to the degree of occupant injury.

A number of authors have made the observation that vehicle damage is not an indicator of occupant injury. Dr. Ruth Jackson M.D. is quoted as saying, “The forces which are imposed on the cervical spines of the passengers of colliding vehicles are tremendous, and if one attempts to calculate mathematically the amount of such forces, the results are unbelievable.” “The damage to the vehicles involved in collisions is no indication of the extent of the injuries imposed on the passengers.” “The extent of damage to the vehicles is in no way proportional to the extent of damage imposed upon the cervical spines of the passengers.”

From Dr. Rene Cailliet, M.D.

“Simulated impacts have been studied extensively and essentially confirm that at low-speed impact with minimal or no damage to the impacted vehicle can and does cause significant musculoskeletal injury to the driver’s or occupant’s head and neck.”

“I have been shown that high speeds are not specifically pertinent in determining the extent of the whiplash injuries sustained.”

“Numerous injuries result from vehicular accidents even when the impacts are not very big and there is minimal damage to both vehicles.”

Headrests are the best protection in rear-end collisions. However, if the headrest is set too low, the head is able to roll over the top of the headrest, producing even more hyperextension.

“A variety of factors, including the occupant’s awareness or head position in a colliding vehicle, defines the risk of neck injury to passengers in colliding vehicles. One can only conclude that the threshold of injury is a complex dynamic relying on velocity, force, head position, head-torso angles, restraint placement, anticipation, tissue elasticity, tissue strength, and any multitude of variables that evade accurate determination.”

“Disability appears unrelated to the severity of the collision.”

“The degree of damage to the vehicle was not a predictor of outcome.”

“If the passenger is aware of and anticipates a collision, and makes his neck muscles tense, he can tolerate more severe impact.”

Dr. Cailliet (1981) indicates that if the head is turned at the moment of impact, there is increased injury on the side to which the head is turned, as: “not only will the already narrowed foramen be compressed more, but the torque effect on the facets, capsules, and ligaments will be far more damaging.”

“Rotated as well as inclined head position showed a significantly higher incidence in the symptomatic group.”

Research by Ryan et. al. (1994) states:

“Subjects who were unaware of the impending collision were 15 times more likely to have a persisting condition than those who were aware.”

…subjects who were unaware of the impending collision had a greatly increased likelihood of experiencing persisting symptoms and/or signs of neck strain, compared to those who were aware.

Primary research by Brault and Wheeler (1998) indicates that if the patient is caught by surprise during a rear-end collision, the threshold for injury begins at a change in velocity of only 2.5 mph.