Likelihood of Lumbar Spine Injuries for Far-side Occupants in Low to Moderate Speed Lateral Impacts

Previous studies have shown that occupant kinematics in lateral impacts are different for near- and far-side occupants. Additionally, injuries to far-side occupants in high-speed lateral impacts have been better documented in the scientific literature; few studies have looked at low-speed far-side occupants. The purpose of this study was to determine the risk of lumbar spine injury for restrained and unrestrained far-side occupants in low- to moderate- speed lateral impacts. The NASS/CDS database was queried for far-side occupants in lateral impacts for different levels of impact severity (categorized by Delta-V): 0 to 8 km/h, 8 to 16 km/h, 16 to 24 km/h and 24 to 32 km/h. To further understand the lumbar spine injuries sustained by occupants in real-world impacts, far-side lateral impact tests with ATDs from the NHTSA Biomechanics Test Database were used to estimate lumbar loads in generic far-side sled tests. From the NASS-CDS data, the risk of an AIS2+ lumbar spine injury was less than 0.2% for lateral impacts with Delta-V's less than 32 km/h. Lumbar spine lateral shear forces increased with impact severity, but were less than 1,000 N at the greatest impact severity studied. The likelihood of sustaining an AIS2+ lumbar spine injury in a low-to moderate- speed far-side lateral impact is low.