Thoracic Injury Mechanisms and Biomechanical Responses in Lateral Velocity Pulse Impacts

The purpose of this study is to help understand the thoracic response and injury mechanisms in high-energy, limited-stroke, lateral velocity pulse impacts to the human chest wall. To impart such impacts, a linear impactor was developed which had a limited stroke and minimally decreased velocity during impact. The peak impact velocity was 5.6 =/- 0.3 m/s. A series of BioSID and cadaver tests were conducted to measure biomechanical response and injury data. The conflicting effects of padding on increased deflection and decreased acceleration were demonstrated in tests with BioSID and cadavers. The results of tests conducted on six cadavers were used to test several proposed injury criteria for side impact. Linear regression was used to correlate each injury criterion to the number of rib fractures. This test methodology captured and supported a contrasting trend of increased chest deflection and decreased TTI when padding was introduced. This study suggested that chest deflection or the energy generated in a lateral velocity pulse impact, correlated with the number of rib fractures better than acceleration of the viscous response of the struck-side rib cage. Interestingly, Favg*Cmax, TTI*Cmax and peak spine acceleration also correlated well with the number of rib fractures. The hypothesis for injury assessment using energy concept, Maximum Stored Energy Criterion, also was supported by the BioSID and cadaver test results.