The Airbag You Don't Want? IIHS Cuts a Popular Safety Device Off at the Knees

Steph Willems
by Steph Willems

It’s likely your average new car buyer can’t come close to guessing the number of airbags poised to deploy in their new ride. Gone are the days when Lee Iacocca would hit the airwaves, bragging about his company’s standard driver’s side airbags. New vehicles are festooned with then.

However, one particular airbag could be doing more harm than good, according to a study by the Insurance Institute for Highway Safety.

After looking at recorded “injuries” in more than 400 small- and moderate-overlap front crash tests, researchers at the institute turned the spotlight on a seldom-thought-of safety device: the knee airbag. While these types of crashes are most likely to lead to lower-leg injuries (read up on the Dodge Challenger if walking away from a crash is something you value), the presence of a cushion for that all-important leg joint didn’t do much to alleviate the risk of injury.

Surprisingly, the presence of knee airbags in some cases actually upped the risk of leg injury. The IIHS researchers then pored over real-world data to see if the same outcomes showed up in actual crashes.

From the IIHS:

Knee airbags had only a small effect on injury measures recorded by dummies in IIHS driver-side small overlap front and moderate overlap front crash tests. In the small overlap test, knee airbags were associated with increased injury risk for lower leg injuries and right femur injuries, though head injury risk was slightly reduced. The airbags had no effect on injury measures in the moderate overlap test.

In the analysis of real-world crashes, knee airbags reduced overall injury risk by half a percentage point, from 7.9 percent to 7.4 percent, but this result wasn’t statistically significant.

The institute suggests the proliferation of knee airbags is primarily aimed at helping manufacturers pass tests conducted with unbelted crash test dummies. In collisions where the occupant is not restrained, such an airbag might provale valuable. When you’re a loose pebble in a tin can, everything helps.

For secure front seat occupants, the value in having a knee airbag is much less clear.

“There are many different design strategies for protecting against the kind of leg and foot injuries that knee airbags are meant to address,” said Becky Mueller, IIHS senior research engineer and the study’s co-author, in a statement. “Other options may be just as, if not more, effective.”

[Image: IIHS]

Steph Willems
Steph Willems

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  • NeilM NeilM on Aug 08, 2019

    Never mind the knee airbag effectiveness; what I can get out of my head is where the left front wheel is ending up in the Lincoln pic at the top of this article. No airbag is going to save you from that.

    • -Nate -Nate on Aug 09, 2019

      -THIS- It looks like that 1959 Chevy crash video...... -Nate

  • Tankinbeans Tankinbeans on Aug 08, 2019

    What kinds of injuries can occur when occupants have had knee replacement surgery? Does the force profile create its own possibility für injury? I know traditional airbags can cause issues for young children and people of short stature.

  • Lou_BC Maybe if I ever buy a new car or CUV
  • Lou_BC How about telling China and Mexico, we'll accept 1 EV for every illegal you take off our hands ;)
  • Analoggrotto The original Tassos was likely conceived in one of these.
  • Lorenzo The unspoken killer is that batteries can't be repaired after a fender-bender and the cars are totaled by insurance companies. Very quickly, insurance premiums will be bigger than the the monthly payment, killing all sales. People will be snapping up all the clunkers Tim Healey can find.
  • Lorenzo Massachusetts - with the start/finish line at the tip of Cape Cod.