Sensitivity analysis of intervertebral disc parameters: MBS model of the lumbar spine

Sabine Bauer, Eva Keller, Dietrich Paulus

The range of possibilities to investigate the biomechanical behavior of human biological structures is manifold. The classical investigation methods such as e.g. experimental studies and image processing are complemented by the biomechanical computer modeling. These different investigation methods represent their own fields of research, but a comparison of the results can be used to validate the applied method. Also explored material properties of different structures can be used, for example in the computer modeling, as input parameters. In order to ensure a realistic modeling, the knowledge of the influence of the structure-specific parameters on the biomechanical behavior of the entire model system is required. Especially the biomechanics of the intervertebral discs is seen in the literature as a central component of a spine model. Therefore, a detailed analysis of the impact of an input parameter variation is necessary. By means of a multibody simulation (MBS) model of the human lumbar spine, the impact of modified disc stiffness onto the spinal structures has been investigated. The used stiffness values ​​are obtained from published literature. The model takes the biomechanical properties of the spinal structures such as the intervertebral discs, the fact joint and the ligamental structures into account and has been validated by comparing the results with results from appropriate literature. To analyze the effects of different input parameters variations on the biomechanical behavior of spinal structures, the upright standing is simulated.