Modelling clavicular and scapular kinematics: from measurement to simulation

Area of Science:

• Biomechanics
• Musculoskeletal modeling
• Orthopedics

Background:

• Musculoskeletal models aid in preventing and treating musculoskeletal disorders.
• Accurate simulation of clavicular and scapular movements is vital for understanding shoulder dysfunction.
• Individual anatomical variations necessitate personalized musculoskeletal models.

Purpose of the Study:

• To address the discrepancy between patient-specific measurements and cadaveric musculoskeletal models.
• To introduce and evaluate novel methods for improving the fit of musculoskeletal models to individual anatomy.
• To assess the impact of improved model fitting on shoulder kinematics and kinetics.

Main Methods:

• Developed two novel methods to decrease the discrepancy between experimental data and musculoskeletal simulations.
• Method 1: Scaling the musculoskeletal model to fit the subject's specific anatomy.
• Method 2: Increasing the range of possible joint rotations by allowing variations in motion constraints.

Main Results:

• Scaling the model resulted in a 34% better fit compared to existing methods.
• Allowing variation in motion constraints yielded a 42% better fit.
• Muscle forces for scapular stabilizers changed by up to 17%, while glenohumeral joint contact force showed a marginal change of 1.3%.

Conclusions:

• The presented methods significantly improve the accuracy of shoulder simulations by better fitting models to individual anatomy.
• These advancements represent a step towards more realistic shoulder simulations for clinical applications, particularly for scapular imbalance.
• Improved kinematic and kinetic predictions can enhance the understanding and treatment of shoulder pathologies.