WHAT IS A MOMENT ARM? CALCULATING MUSCLE EFFECTIVENESS IN BIOMECHANICAL MODELS USING GENERALIZED COORDINATES

Area of Science:

• Biomechanics
• Computational Biology
• Musculoskeletal Modeling

Background:

• Biomechanics research frequently employs multibody models to represent biological systems.
• The translation between biological structures and mechanical representations can be challenging.
• OpenSim is an open-source tool that facilitates this mapping using the Simbody system.

Purpose of the Study:

• To address challenges in calculating muscle moment arms for complex biological systems.
• To present a generalized definition of muscle moment arm applicable to biomedical research.
• To demonstrate how OpenSim and Simbody resolve these challenges.

Main Methods:

• Utilizing the OpenSim software and its underlying Simbody generalized coordinate multibody system.
• Developing and applying a generalized definition for muscle moment arm calculations.
• Modeling complex biological joints and multi-joint muscle paths.

Main Results:

• OpenSim can automatically compute muscle moment arms for any muscle in a built model.
• The generalized definition extends the conventional mechanical engineering concept to complex biological scenarios.
• Biologically meaningful muscle moment arms are yielded for intricate musculoskeletal models.

Conclusions:

• The generalized muscle moment arm calculation in OpenSim/Simbody is crucial for accurate biomechanical analysis.
• This methodology enhances the understanding of muscle function in complex biological movements.
• OpenSim and Simbody offer robust solutions for biomechanical modeling challenges.