The Effect of Coupled Motions and Lifting Tasks on Human Lumbar Nucleus Pressures and Annulus Fibrosus Stresses in a Muscle-loaded Finite Element Model

INTRODUCTION Approximately one-fifth of occupational injuries are related to low back problems. Coupled motions involving a combination of flexion, lateral bending, and axial rotation have been linked to increased incidence of low back disorders [1]. The role of lifting in low back injuries has been well established, but many of the underlying mechanisms behind low back pain remain unclear. Until recently, the inability to accurately determine musculature recruitment patterns with respect to force magnitude and timing has hindered advancement in this area. New musculoskeletal modeling techniques have provided insight into these details, which are especially important in determining the role of the spinal musculature on the mechanical parameters of the relevant osseous and soft tissues. The aim of the current study was to evaluate the effect of muscle-driven coupled rotations and lifting on key mechanical parameters such as annulus fibrosus stresses and intradiscal pressures of the human lumbar spine.