Among the proposed amendments to the US-NCAP announced on Dec. 2015, a new acetabulum injury evaluation along with the next-generation THOR dummy has been included [1]. In relation to this topic, numerous research tests and studies are already being conducted by NHTSA. However, 29% of those tests showed that acetabulum injury has occurred due to tensile load rather than a compressive load from the femur. Therefore, in this research, we investigated whether similar injury mechanism actually occurred in real world accidents using NASS-CDS (CY2000-10) data. It is observed that 95% of acetabulum injuries in real world accidents were injuries accompanied by fractures, and 82% of these injuries were related to interaction with the instrument panel. This suggests that most of the acetabulum injuries occur by a compressive load and they are far less likely to occur with tensile load.

In addition, by analyzing the mechanism of injury occurrence of the research tests, there are the two influential factors for the difference between the crash test results and real world accidents. They are i) the difference between the THOR dummy and the human body around the hip joint and ii) the problem of acetabulum injury criterion. In the future, further research is necessary in order to propose a more appropriate injury risk evaluation.