This project provides a modified version of the Upper Extremity Kinematic Model designed by Saul et al. that can be found on the following pages:
Holzbaur et al., 2005: https://simtk.org/projects/up-ext-model/
Saul et al., 2015: https://simtk.org/projects/upexdyn/

The modifications are:
- Coordinate systems are updated to closely follow the recommendations of the ISB
- The CoordinateCouplerConstraints defining the scapulohumeral rhythm are rewritten as LinearFunctions instead of SimmSplines
- A bivariate dependency of the sternoclavicular and acromioclavicular angles on both the humeral elevation plane angle and the humeral elevation angle is implemented. The linear dependencies are based on the findings of De Groot et al. (2001)

We publish data of a study with ten healthy participants that perform a variation of high range-of motion arm movements. In each static trial the scapula orientation is palpated and measured.

The python code to scale the model and personalize the scapulohumeral rhythm based on five calibration measurements per shoulder is provided on https://github.com/stanfordnmbl/shoulder-personalization.

A preprint of the manuscript describing the personalization method in detail can be found on bioRxiv:
https://www.biorxiv.org/content/10.1101/2024.06.12.598739v1