Kinematic Analysis and Simulation of Vertebral Motion Under Static Load—Part II: Simulation Study

Based on the earlier work by the author on the development of a theoretical motion simulation model of an open-loop, kinematic chain, the present paper examines the motion characteristics of a human spine motion-segment. Based on the experimental data collected from the human cadaver specimens of lumbar spine, a static simulation model of a lumbar segment is proposed. The equivalent motion characteristic of the intervertebral joint is described by a spherical pair which is located for an intervertebral joint by fitting in a least-square sense a cone to a set of motion data describing the axode characteristics of the joint. The intevertebral disk and the ligaments are represented by an equivalent stiffness matrix whose elements are assumed to be constant over the entire range of mobility. The proposed model showed a good agreement with the observed motion data of an intervertebral joint.