Stabilization of the lumbar spine by spinal muscle forces producing compressive follower loads: 3-dimensional computational study.

Axial compressive loads whose direction changes along the spinal curvature (so called compressive follower loads (CFLs)) was postulated as a normal physiological load in the lumbar spine in the literature. Computational analyses were conducted in this study using finite element and optimization models of the spinal system incorporating 244 fascicles of back muscles. It was feasible to find optimum solutions for spinal muscle forces generating CFLs in the lumbar spine in 3-D postures of neutral standing, flexion 40°, extension 10°, axial rotation 10°, or lateral bending 30°.