[A CAE (computer aided engineering) approach to dynamic whole body modeling--the forces iin the lumbar spine in...

Biomechanical models of the human body play an important role in the analysis of the mechanical loading of the musculo-skeletal system. The whole-body model presented in this paper is based on a CAE (Computer Aided Engineering) program that permits the dynamic simulation of complex systems of rigid bodies. The model we developed on this basis consisted of 19 segments and 18 joints. The experimental data are derived from the 3D motion analysis system VICON, which is provided with 5 cameras, a force-plate and a 10-channel EMG recorder. The kinematic data are fed into the simulator after first being processed in a special manner to generate drivers for joint angles. The model was first used to calculate the compression forces generated within the lumbar spine during the asymmetric lifting and putting down of a 15 kg stone. The quasistatic calculation shows a dynamic contribution to the compression forces generated during the lifting of 11%. Increasing or decreasing the inertial moments of the segments by the factor 2 had an effect of less than 1% with the identical movement.