LBD Risk Factors and the Structural Stability Tolerance of the Lumbar Spine

Abstract

A model of low-back injury is presented suggesting structural instability is a risk factor in occupation injury. The purpose of this research was to document the potential for spinal buckling as a function of asymmetric and sagittal trunk angle during lifting. A biomechanical model was developed to compute the Euler stability and determine the structural tolerance of the lumbar spine in work-related postures. When applied load and associated spinal compression exceeds the structural tolerance, i.e. buckling load, the spinal column fails. Analyses demonstrate the structural tolerance is often less than material tolerance estimates, particularly in flexed and asymmetric postures. Furthermore, the structural tolerance is reduced in sagittally flexed and asymmetric lifting postures. Hence, the relation between stability and trunk posture correlated with low-back disorder (LBD) risk factors. Results suggest musculoskeletal instability may help explain the relation between LBD risk and lifting posture.