Comparison of 2D-pose with 3D motion capture methods for assessment of active shoulder range of motion.
Smartphone-based 2D-pose estimation can be a valid method for measuring shoulder ROM, but it should not replace 3D motion capture due to potential overestimations and anatomical considerations.
Where it sits
this study against the rest of the selank corpusSummary and findings
This study compared smartphone-based 2D-pose estimation to 3D motion capture for assessing shoulder range of motion (ROM) in seventeen participants without shoulder issues. High consistency was observed between the two methods, particularly for abduction and flexion, but 2D-pose overestimated ROM at greater ranges. The study highlights the need for careful interpretation of shoulder ROM assessments using these methods.
Abstract
<h4>Background</h4>Smartphone-based 2D-pose estimation offers a convenient method for assessing shoulder range-of-motion (ROM), but its accuracy compared to 3D motion capture (3D-mocap) needs to be determined.<h4>Methods</h4>Shoulder ROM was recorded in seventeen participants without shoulder issues using 3D-mocap and 2D-pose concurrently. Movements included abduction, flexion, extension, external, and functional internal rotation (IR). 2D-pose ROM estimates (mymobility's<sup>®</sup> Skeletal Tracking Shoulder Range of Motion Assessments feature (Apple Vision framework, Apple Inc., Cupertino, CA, USA) were compared to 3D-mocap using linear mixed-models and Bland-Altman analysis. The influence of thoracic compensation and anatomical frame definitions on shoulder ROM estimates was examined.<h4>Results</h4>High consistency was observed between 2D-pose and 3D-mocap (<i>R</i> <sup>2</sup> > 0.98), especially for abduction and flexion. Differences in ROM were linked to anatomical frame variations and thoracic contributions, with 2D-pose overestimating ROM at greater ranges (2°-25°). Internal rotation zone identification showed high consistency, but 2D-pose-based extension and external rotation showed more variability due to thoracic compensation.<h4>Conclusions</h4>Smartphone-based 2D-pose estimation provides a valid alternative for shoulder ROM measurement but should not be used interchangeably with 3D-mocap due to discrepancies arising from anatomical frame definitions and thoracic movements. Shoulder ROM assessment requires consideration of these limitations to ensure appropriate clinical interpretation.