IIHS: Knee airbags increase injury risk in certain scenarios

A study could not find evidence that knee airbags reduce injuries.

Knee airbags may not provide much safety benefit and actually increase injury risk in some cases, according to a study conducted by the Insurance Institute for Highway Safety.

Analyzing data from real-world crashes in 14 states, there was not a statistically significant difference in the overall injury risk between cars equipped with knee airbags and those without.

The more concerning finding came to light after the IIHS looked at data crash dummy data from 400 front-impact tests. In the small-overlap test, head injury risk was slightly reduced but the airbags were associated with a higher likelihood of injuries to the lower leg and right femur.

The IIHS admits that knee airbags may provide a safety benefit for occupants not wearing seatbelts. Automakers are said to have implemented knee airbags to pass federally mandated tests with unbelted dummies, which is outside the scope of the IIHS test program.

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