Dynamic In-Vivo Scapular Motion in Abduction and Adduction

Preserving scapular function following total shoulder arthroplasty (TSA) is essential for maintaining the normal range of dynamic motion of the shoulder joint complex. However, the ability to accurately measure in-vivo glenohumeral and scapular motion remains a challenge in the field of bioengineering. Single plane radiography was used to explore scapular rotation, but is limited to motion parallel to the imaging plane [1]. Bi-plane x-ray systems have been developed to overcome this limitation; however, these systems can suffer from relatively high radiation dosages [2, 3]. To minimize these effects, 6DOF electromagnetic tracking devices have been attached to the shoulder joint complex to measure scapulothoracic kinematics; except at large humeral abduction angles they can suffer skin motion artifacts [4, 5]. The purpose of this study was to investigate the feasibility and repeatability of using dual orthogonal cine fluoroscopy to quantify the dynamic scapular motions of living subjects after anatomic TSA, simulating an arm raise/lower cycle of drinking from a coffee mug.