Disc Injury and Spine Loads in Low-to-Moderate-Severity Frontal Impacts.

Abstract

Determine the cervical and lumbar spine forces and moments generated in belted occupants in frontal impacts up to 40-km/h change in velocity ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Δ</mi> <mi>V</mi></mrow> </math> ) and assess their potential to cause spinal disc injury. Loads experienced by anthropomorphic test devices, human volunteers, and human cadavers were measured in 282 impact tests. Functions were developed to describe the expected loads as functions of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Δ</mi> <mi>V</mi></mrow> </math> for small females, mid-size males, and large males. Loads were contextualized by comparison to injury assessment reference values, manual lifting standards, the compressive loads that have caused spinal disc injuries in vitro, and the compressive spinal loads that occur in other situations. The functions confirm that the spinal loads are well below any established injury assessment reference value. Compressive loads are within the range of loads voluntarily tolerated during daily activities and well below the loads that have caused disc injuries in biomechanical studies. This study confirms the lack of a biomechanical foundation to assert specific causation when a belted occupant presents with isolated disc herniations, bulges, or extrusions through the annulus following a frontal impact under 40-km/h <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Δ</mi> <mi>V</mi></mrow> </math> .