During a rotator cuff repair, it is ideal to reattach the torn edge of the cuff tendon back to the greater tuberosity. However, with massive tears where the torn edges are too retracted to be reattached to the greater tuberosity, they may have to be reattached somewhere more medial. It is clinically important to know how far medially one can shift the reattachment site without sacrificing function of the shoulder. Ten fresh, previously-frozen cadaveric shoulders were used. Medial shift of the supraspinatus tendon was simulated by placing the suture anchors along lines 3, 10, or 17 mm medial to the cuff attachment site. The ranges of glenohumeral motion were measured using a goniometer with a constant torque applied to the humerus. All motions, except for internal rotation at 60° of abduction, were significantly restricted by medial shift of 10 mm or more compared with that of the intact shoulder. We conclude that significant restriction of joint motion occurs when a bony trough is created more than 10 mm medial to the cuff attachment site.