BACKGROUND: This retrospective study aimed to compare the clinical results of reverse total shoulder arthroplasty (rTSA) and combined anterior latissimus dorsi and teres major (aLDTM) tendon transfer in patients with non-arthritic anterosuperior irreparable rotator cuff tears (ASIRCTs) with loss of active internal rotation (aIR). METHODS: Using propensity score matching based on demographic variables, 29 patients were included in each group (rTSA and aLDTM) with a minimum follow-up period of two years. Clinical results were evaluated using the visual analog scale (VAS) score, Constant-Mueley score, American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, activities of daily living requiring active internal rotation (ADLIR), active range of motion (aROM), subscapularis (SSC)-specific examinations, rotational strength, and the ability to perform toileting activities. The progression of arthritic changes in the shoulder joint was evaluated by the acromiohumeral distance (AHD) and Hamada grade. RESULTS: Significant improvements of clinical results were confirmed in both groups. However, the Constant-Murley score (58.4±10.5 vs. 69.1±8.2, p<
.002), ASES score (64.5±12.3 vs. 78.5±10.9, p<
.002), UCLA shoulder score (22.9±5.3 vs. 28.2±4.1, p<
.002), forward elevation (134.1±35.7 vs. 162.4±15.5, p<
.002), and IR at the back (4.6±1.1 vs. 6.9±2.2, p<
.002) were significantly better in the aLDTM group compared with the rTSA group. The SSC-specific physical examination (p<
.002), IR strength (p<
.002), and the ability to perform toileting activities (p<
.002) were significantly better in the aLDTM group compared with the rTSA group. There was no significant change in the AHD (preoperative 8.3±1.3 to postoperative 8.5±1.8, p=0.367) and no significant progression of arthritic change (Hamada grade preoperative 1.4±0.5 to postoperative 1.5±0.6, p=0.458) in the aLDTM group. CONCLUSION: Both rTSA and aLDTM improved overall patient outcomes postoperatively. However, combined aLDTM tendon transfer was superior in terms of clinical scores, IR aROM, IR strength, and the ability to perform toileting activities in patients with ASIRCTs and loss of aIR. This study suggests that combined aLDTM tendon transfer could be a first-line joint-saving treatment for patients with non-arthritic ASIRCTs and loss of aIR, considering the longevity and related complications of arthroplasty.