This study1 documented the head restraint position of 1,915 vehicles at an intersection. Researchers found that only 10% of the occupants had the head restraint in the proper position to avoid hyperextension. Only 1/4 of the adjustable head restraints were in the "up" position.
The authors estimate that if all of the adjustable head restraints had been in the up position, it would result in a 28% reduction of whiplash injury risk.
This study confirms what others have found, including a report released by the Insurance Institute of Highway Safety2 that found that less than 10% of 1995 vehicles had good or acceptable head restraint design. (For more information, see our new book, The Guide to Low Velocity Whiplash Biomechanics.)