36 patients scheduled for total shoulder arthroplasty were randomized to to postoperative immobilization for 6 weeks in either a neutral rotation sling or an internal rotation sling. Patients were assessed for outcome in patient-reported measures of disability, function, and pain, as well as shoulder ranges of motion over 12-month follow-up. Results demonstrated no significant differences between groups in changes from baseline to 12 months in Disabilities of the Arm, Shoulder, and Hand (DASH) score, Western Ontario Osteoarthritis of the Shoulder (WOOS) score, and overall pain on a visual analog scale. For range of motion, significant difference was observed in favour of the neutral rotation sling group for external rotation when assessed while patients were standing, but not external rotation while patients were supine with the shoulder abducted. Differences between groups for range of motion in flexion and internal rotation were not significant.