Scapular and clavicular kinematics during humeral elevation: a study with cadavers.

A combination of kinematic testing and graphic reconstruction of cadaveric shoulders was used to characterize shoulder kinematics during a simulated passive clinical range-of-motion examination. Cadaveric shoulders were elevated in the coronal, scapular, and sagittal planes while the scapula, clavicle, and humerus were kinematically tracked. Graphic models of each shoulder were created from computed tomography data. The models were animated to display the experimental motions. Shoulder kinematics varied between elevation planes. The scapular and clavicular rotations were relatively small until the humerus reached approximately 90 degrees of elevation. Clavicular and scapular rotations that occurred at low humeral elevation angles for elevation in the coronal plane were significantly larger than for the other two planes. The glenohumeral to scapulothoracic ratio was approximately equal to 2 for the entire range of elevation for each elevation plane, but it was dramatically larger during early elevation than during late elevation.