Knee airbags, safety feature in some cars, don't do much: researchers

Car safety is a priority for automakers, so they are constantly introducing new features to make driving safer. This includes increasingly advanced technologies to help prevent accidents and overall improvements to reduce injuries when there is an accident. One such improvement is the addition of knee airbags, but the Insurance Institute for Highway Safety says they don’t offer much benefit.

While airbags are lifesaving devices that prevent deaths and reduce injuries, it appears not all airbags are created equal. They’re just about everywhere in today’s cars from the passenger and driver’s side dashboard to curtains between the passengers and sides of the vehicle. There are even airbags in some rear seatbelts.

More is better, at least that’s what you’d think, but the IIHS says knee airbags are the exception. These airbags are housed in the lower part of the dashboard and are designed to reduce injuries to your knees. They also help reduce body movement, which can further reduce injuries, in theory.

IIHS researchers decided to compare data to see if these airbags really do make a difference. First, they looked at data from over 400 frontal crash tests conducted as a part of their crash test ratings program to compare the results from vehicles with and without knee airbags. Next, they looked at actual crash reports collected from 14 states to compare real-world data.

The results in IIHS crash tests were mixed. The moderate overlap front crash tests saw no difference. The small overlap front crash tests showed an increased risk of injury for the lower leg and right femur, although head injury was slightly reduced. Those results were backed up by real-world data where knee airbags reduced overall injury by just half a percentage point from 7.9 to 7.4.

“There are many different design strategies for protecting against the kind of leg and foot injuries that knee airbags are meant to address,” says Becky Mueller, an IIHS senior research engineer. “Other options may be just as, if not more, effective.”

Knee airbags are also one way automakers pass federally mandated tests with unbelted dummies. The IIHS conducts all its tested with belted dummies and didn’t collect info specifically on crashes with unbelted occupants. It’s possible knee airbags offer more protection for those driving without a seatbelt.

Driving without a seatbelt, however, is an incredibly risky decision. Even if it’s not a law where you live, seatbelts are one of the best ways to protect yourself in the event of an accident. And while not all airbags are as effective as others at preventing injuries, the combination of airbags and seatbelts overall makes cars safer for everyone.