Spinal posture helps crash response evaluation of reclined occupant

OBJECTIVE: The growing adoption of self-driving vehicles and zero-gravity seats presents emerging challenges for occupant safety. With lumbar spine injury of reclined occupants receiving increasing research attention, the influence of spinal postures on crash response warrants further investigation. METHODS: A precise adjustment method was employed to generate THUMS models in several specific reclined postures. Crash responses were evaluated against subjects in postmortem human subject (PMHS) tests in both average and subject levels. RESULTS: The average model aligned by angular spinal posture more accurately predicted the occupant kinematics than the model aligned by average vertebral location, yielding an average 47% improvement in predicting peak X-displacement (except at L3). Regarding injury response, the spine-specific models accurately predicted the lumbar and iliac injury locations observed in the PMHS tests. CONCLUSIONS: THUMS models incorporating subject-specific spinal postures provide improved prediction of Z-direction kinematics compared to generic models and enable preliminary evaluation of spinal injury risk. Additionally, correlations established between thoracolumbar spine kinematic and kinetic responses offer new insights into lumbar injury mechanisms for reclined occupants.