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Muscle moment-arms: a key element in muscle-force estimation
David Ingram1, Christoph Engelhardt, Alain Farron
1a Labortatoire d'Automatique, Ecole Polytechnique Fédérale de Lausanne , Station 9, 1015 Lausanne , Switzerland.
Computer Methods in Biomechanics and Biomedical Engineering
|September 4, 2013
Summary
This study defines muscle moment-arms using classical mechanics, offering a coordinate-independent alternative to the tendon excursion method for musculoskeletal modeling. This new definition improves accuracy in muscle-force estimation, reducing errors significantly.
Area of Science:
- Biomechanics
- Musculoskeletal System Modeling
- Computational Mechanics
Background:
- Accurate muscle moment-arm calculation is crucial for musculoskeletal system modeling.
- The tendon excursion method can yield inaccurate moment-arms due to coordinate system dependencies.
- A robust definition is needed for rigid body, ideal joint, and cable-modeled muscle systems.
Purpose of the Study:
- To present a rigorous, coordinate-independent definition of muscle moment-arms.
- To offer an alternative to the potentially inaccurate tendon excursion method.
- To validate the new definition in a muscle-force estimation problem.
Main Methods:
- Application of classical mechanics and screw theory for definition.
- Development of a construction method for moment-arms.
- Modeling bones as rigid bodies, joints as ideal, and muscles as wrapping cables.
- Solving a 2D muscle-force estimation problem using the new definition.
Main Results:
- A novel, coordinate-independent definition of muscle moment-arms was established.
- The new method was applied to a 2D musculoskeletal model.
- Comparison with the tendon excursion method showed relative errors ranging from 0% to 100%.
Conclusions:
- The proposed definition of muscle moment-arms is rigorous and applicable to standard musculoskeletal models.
- This coordinate-independent approach offers a significant improvement over the tendon excursion method.
- The method enhances the accuracy of muscle-force estimation in biomechanical simulations.
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