Biomechanical Analysis of Influence of Spinal Fixation on Intervertebral Joint Force by Using Musculoskeletal Model

Evaluation of the intervertebral joint force in vivo is very important for clinical spine problems, for example, spinal instability, disorder of intervertebral disc, compressive fracture of osteoporotic vertebra, etc. Direct measurement of the joint force is difficult to get permission, so computational method to calculate the force is expected. Spine structure is mainly constructed of many vertebrae and flexible intervertebral disks, and it is unstable by itself under standing condition. Supporting by erector muscles and ligaments keep the spine standing condition, so that loading condition of each vertebra depend on the muscle and ligament forces. Biomechanical analysis of musculoskeletal system taking into account of large number of muscle and ligament forces is necessary to determine the intervertebral joint force. Commercial software to deal with the musculoskeletal system is available nowadays, and it has been applied to clinical, ergonomic or sport biomechanics problem.