A FINITE ELEMENT STUDY OF THE EFFECTS OF MUSCLE DYSFUNCTION ON SPINE MECHANICS

摘要

A combined finite element and optimization approach was initiated to investigate the effects of muscle dysfunction on lumbar spine mechanics. An optimization based biomechanical model was used to predict the forces in the L3-4 disc and muscles spanning the L3-4 segment. The forces on the superior surface of the L3 vertebra and forces in muscles or fascicles attached to the L3-5 segments were then calculated appropriately, and applied to a finite element model of the ligamentous two motion segments lumbar spine (L3-5). The biomechanical parameters of the FE model under five quasi-static back lifting conditions (a subject flexed freely 30, 60 or 90 degrees, and flexed 30 degrees while holding weights of 90 or 180 N) were analyzed. The muscular "dysfunction" in the model was simulated by reducing the computed muscle forces to 90% of the normal values. The results showed that muscle dysfunction destabilized the lumbar spine, reduced the role of facet joints in transmitting load, and shifted loads to the intervertebral disc, ligaments and other spinal components.