Structural analysis for the forces in the human spinal column and its musculature.

A method of structural analysis is proposed for a model of the thoracic and lumbar spine which involves body weight, external load, muscle forces, intervertebral reactions and disc and ligament elasticity. The procedure consists of three phases: (i) for an initial position the equations of equilibrium are solved using a linear programming technique which minimizes the total force in the system and produces intervertebral reactions and muscle forces, (ii) for an incremental change in configuration a structural analysis is performed to obtain a further set of intervertebral reactions, (iii) with the net values of intervertebral reactions, from combining the results of the previous two phases, a further application of the linear programming technique is made to obtain the muscle forces in the deformed positions. The results are presented for a subject, in a single step of forward flexion.