60 patients with primary glenohumeral osteoarthritis and scheduled for a total shoulder arthroplasty (TSA) were randomized to receive sub-scapularis repair via a sub-scapularis tenotomy (ST) or a lesser tuberosity osteotomy (LTO). Outcomes of interest included range of motion and strength measurements on forward elevation, internal rotation and external rotation, pain on a Visual Analog Scale (VAS), the Simple Shoulder Test (SST), the Short-Form 36 (SF-36) questionnaire and American Shoulder and Elbow Surgeons (ASES) score. Follow up was performed up to 1 year post-operation. Results revealed no significant differences between the LTO and ST groups in range of motion or strength om forward elevation, internal rotation, or external rotation, as well as no significant differences in VAS pain scores, ASES scores and SF-36 scores. At 3 months, SST score was significantly higher in the LTO group compared to the ST group, however at 1 year no significant difference in SST score was observed between the two groups. Additionally, mean case duration and the time for sub-scapularis repair was significantly longer in the LTO group compared to the ST group. No cases of component loosening or instability were reported in either group.