A nonlinear contact algorithm predicting facet joint contribution in the lumbar spine of a specific person

Abstract

The objective of this study was to realistically include the effect of facet loading in an EMG-assisted lumbar biomechanical model. Most biomechanical models lack detailed facet geometry, the inclusion of cartilage, and fail to model the full lumbar spine. Several new facet-specific components were added to an EMG-assisted biomechanical model, including realistic geometry and facet-specific contact algorithms. These algorithms defined nonlinear contact between each lumbar spine facet. Subject-specific data were applied to the model for assessment. As expected, resultant disc loads were generally lower in the model with facets. This information improves our understanding of how loads are distributed in the spine, and it can lead to a better understanding of causal pathways. If we understand those pathways, we then realise how to design better ergonomic interventions.

Keywords:

• facets
• low back pain
• spine modelling
• contact forces
• low back disorder

Acknowledgements

The authors are grateful to the assistance in model building by Gregory Knapik, and in data collection by Dynamic Medical Imaging.