Comparison of Pelvis Injury Patterns and Loading Mechanisms in Postmortem Human Subject Tests and Real-World Side-Impact Collisions

Pelvis fractures can be complex and occur in many different regions of the bone. Loading due to side impact can transfer anteriorly through the pubic symphysis and posteriorly through the sacroiliac joint. Virtual testing with human body models (HBMs) has the potential to capture the complex loading mechanisms that contribute to pelvis fractures, but injury prediction with HBMs must be refined and validated using physical test data. Most postmortem human subject (PMHS) studies testing side-impact and pelvic injuries use simplified test modes rather than simulating realistic boundary conditions. It is important to understand the differences between pelvis fractures resulting from in-lab tests and those sustained in real-world collisions, particularly for when these PMHS tests are used in injury risk function development to predict injuries caused by collisions in the real world. This study seeks to compare injury types and loading mechanisms from existing PMHS tests to those observed in real-world side-impact collisions from Crash Injury Research and Engineering Network (CIREN) to examine their suitability for refining HBM injury prediction for the pelvis. Seventy-seven percent of PMHS tests with injuries had fractures in the anterior region of the pelvis, 23% in the iliac wing, 30% in the sacroiliac region, and 16% in the acetabulum, where a PMHS test could have fractures in multiple regions. Fractures were divided into primary- and secondary-side fractures, where the primary side was defined as the side impacted in a PMHS test and the side closest to the crash in a CIREN case. A higher proportion of cases with secondary-side acetabulum and sacroiliac pelvis fractures was observed in CIREN compared to PMHS tests, which may be related to interaction with structures in a vehicle environment. A pattern of “squeezing” the pelvis between the intruding door and the center console in near-side crashes was observed.