Although recently published results showed no dynamic superior humeral head migration among patients with well-compensated single or two-tendon rotator cuff tears, an unexpected inferior shift during active elevation was found.
Researchers used a custom biplane fluoroscopy system to measure the 3-D position and orientation of the scapula and humerus of 14 patients with full-thickness supraspinatus or supraspinatus and infraspinatus rotator cuff tears and 10 controls during shoulder abduction in a full range of motion. Researchers extracted the 3-D geometries of the scapula and humerus from a CT scan of each shoulder and estimated the 3-D bone position and orientation for each frame using a contour-based matching algorithm, while the 3-D position of the humeral head center was determined relative to the glenoid. The superior-inferior and anterior-posterior translation curves were determined for each patient from 20° through 150° of arm elevation, according to researchers.
Peter J. Millet
Compared with controls, results showed significantly inferior positioning in the humeral head in shoulders with rotator cuff tears, which led to higher elevation angles of 80° to 140°. However, the humeral head translated inferiorly during shoulder abduction from 80° up to 140° for both groups, according to results. Researchers found no significant translation in the anterior-posterior direction. – by Casey Tingle
Disclosures: Millett reports that he receives support from Arthrex, GameReady, VuMedi and Myos. Please see the full study for a list of all other authors’ relevant financial disclosures.