Modeling Glenohumeral Stability in Musculoskeletal Simulations: A Validation Study With In Vivo Contact Forces

Area of Science:

• Biomechanics
• Musculoskeletal modeling
• Orthopedics

Background:

• Muscle redundancy in simulations often leads to inaccurate shoulder contact force predictions.
• Existing models struggle to maintain glenohumeral joint stability, with forces exiting the glenoid cavity.

Purpose of the Study:

• To evaluate various glenohumeral stability formulations for musculoskeletal simulations.
• To compare predicted contact forces against in vivo measurements.

Main Methods:

• Tested constraint and penalty-based stability formulations against the Orthoload dataset.
• Utilized in vivo glenohumeral contact force data from dumbbell raises.
• Assessed force direction accuracy relative to the glenoid cavity.

Main Results:

• Most formulations showed good agreement in contact force magnitude.
• Strictest constraint models predicted forces outside the glenoid.
• Continuous penalty models yielded more accurate force directions within the glenoid cavity.

Conclusions:

• Penalty formulations offer a more accurate and reasonable approach for predicting glenohumeral contact forces.
• Continuous penalty models improve simulation fidelity for shoulder joint stability.