Fig. 4.

Shoulder segment anatomic coordinate frames and testing degrees of freedom from an oblique view (left) and lateral-to-medial view (right) are shown. The scapular coordinate system was based on bony landmarks (left): acromion angle, root of spine, and inferior angle. Glenohumeral kinematics were calculated as the translational motion of the humeral head center of rotation (COR; dotted circle) with respect to the scapula (right) offset to the glenoid COR. Dotted line indicates the superoinferior axis of the glenoid. ABD = abduction; POST = posterior; ANT = anterior; INF = inferior.