34 patients with rotator cuff arthropathy were randomized to undergo either non-lateralized or bony increased offset lateralized reverse shoulder arthroplasty. The purpose of the study was to determine if rotational function differed between non-lateralized and lateralized arthroplasties up to 2 years post-operatively. Results found both surgical methods to be effective in restoring shoulder function, with no significant difference in external rotation or functional measures (CS, agCS, DASH, and ADLER tests). However, subgroup analysis removing patients with high fatty infiltration and atrophy of the teres minor revealed a significantly greater improvement to external rotation in the lateralized group compared to the non-lateralized group.