Ultrasound localization of the humeral head in the glenoid cavity for motion capture

The shoulder joint most often is modelled as a spherical joint that requires accurate localization of the glenohumeral joint center (GHJC) with many clinical, biomedical, and biomimicry implications from injury evaluation to arthroplasty to robotics. We used ultrasound (US) imaging to locate the center of the humeral head, representing the GHJC, and compared its location to predictive and functional methods as related to digitized scapular landmarks. We tracked the US probe while producing multi-planar scans of the humeral head and related those locations to surface-marker clusters affixed to the humerus and acromion. The GHJC location determined by the proposed US imaging produced comparable results and appears to be a viable, cost-effective, non-invasive, subject-specific method with potential for broader research at this level of detail.