Disabling Muscles - Joint Reaction Force Analysis

[Hazimah Mahmud]

Hello,

I am using the Thoracoscapular Model (https://simtk.org/projects/thoracoscapular) to analyse the muscle forces/ joint reaction force (JRF) when a certain muscle is disabled. I am expecting large differences in the JRF considering when one muscle is dysfunctional, the forces of other muscles increase to produce the same motion/joint torque. However, this was not the case and JRF remains constant. There is also not much difference in the muscle forces. Is this expected?

I computed the muscle forces using CMC and the given IK results. The JRF is computed using Analyze Tool - the inputs were based on CMC results (control and states) and the same actuator file as used in CMC. The muscle was simply disabled from the GUI. Below is the Glenohumeral JRF_xyz for 3 difference shoulder conditions (1) normal - all muscles preserved (2) subscapularis disabled (3) supraspinatus disabled.

GH JRF normal and abnormal.png (115.79 KiB) Viewed 405 times

Thanks,
Hazimah

[Carmichael Ong]

You can take a look at a paper called "Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement" by Hicks et al. for some ideas for verifying and validating your simulations. A link to the paper can be found at https://nmbl.stanford.edu/publications/ ... ks2015.pdf