A study by the Insurance Institute for Highway Safety (IIHS) finds new designs of vehicle seats and head restraints are helping reduce the number of neck injuries in auto accidents, especially in rear-end crashes.

The IIHS study is the first to measure the effectiveness in real-world crashes of some of these new designs.

IIHS researchers claim for a long time, most of the head restraints in passenger vehicles weren't high enough or close enough to the backs of many occupants' heads to provide effective protection against neck injury in rear-end crashes. Many automakers have re-designed head restraints and seatbacks, to address the problem.

IIHS studied three approaches used to re-design seats and head restraints:

1. Some companies have designed their head restraints, so they are closer to the heads of many drivers. Among the manufacturers making this improvement is Ford. IIHS reports the design of the head restraints in 2000-2002 Ford Taurus and Mercury Sable models is improved compared with earlier models of the same cars.

2. Saab has introduced active head restraints. As an occupant's torso sinks back into the seat during a rear-end crash, a mechanism in the seatback pushes the head restraint up and toward the back of the head. In addition to Saabs, some General Motors and Nissan models are equipped with these restraints.

3. Volvo and Toyota focused on seatbacks. Volvo dubs its design a whiplash injury prevention system (WHIPS), which involves a specially designed hinge at the bottom of the seatback allowing it to move back to reduce the forward acceleration of the torso. This system includes head restraints that are high and close to the back of the head. Toyota's seat design, which the automaker calls a whiplash injury lessening (WIL) system, allows an occupant's body to sink into the seatback during a rear impact.

IIHS claims the key to reducing whiplash injury risk in rear-end crashes is to keep an occupant's head and torso moving together. IIHS researchers say the re-designed seats and head restraints are all intended to reduce the differential motion of the head and torso.

"There's evidence that many of the new designs are working. In some cases, the reductions in insurance claims for neck injuries are dramatic," says IIHS chief operating officer Adrian Lund.

“The results are encouraging, especially when we look at the even larger effects for women," Lund says.

New designs benefit women more than men

IIHS found the re-designed head restraints and seats tended to reduce the likelihood of neck injuries in women far more than in men.

IIHS found Saab's active head restraint design produced a 55 percent reduction in claim rates for women, compared with a 31 percent reduction for men. The effects of Ford's improved head restraint geometry were a 37 percent claims reduction for women and an 8 percent increase for men.

IIHS points out women are more likely to suffer neck injuries in rear-end crashes, than men are.

"Throughout whiplash injury research, the finding has been that women are at greater risk, so it's good that the women seem to be enjoying more of the benefits of the improved designs," Lund says.

Nationwide, Progressive, and State Farm supplied claims data for the study and participated in the research.