Objective:To compare the clinical and imaging outcomes of fascia lata autograft bridging repair reinforecd with an artificial ligament as the internal brace with the autograft bridging repair for the treatment of irreparable massive rotator cuff tears (IMRCTs).Methods:The data of 26 patients with IMRCT who underwent fascia lata autograft bridging repair augmented with artificial ligament as the internal brace (internal brace group) and of 24 patients with IMRCT who underwent bridging autograft repair alone (control group) were retrospectively evaluated preoperatively and at 2-year follow-up. Clinical outcomes were assessed using shoulder activity, the American Shoulder and Elbow Surgeons (ASES) Score, University of California Los Angeles (UCLA) Score, and visual analogue scale (VAS) for pain. Imaging outcomes were evaluated using acromiohumeral distance (AHD), Goutallier grade, and status of fascia lata grafts according to radiographs or magnetic resonance imaging results.Results:All 50 cases were followed up for 34.2±7.2 months (range 24-45 months). Compared to the control group, the internal brace group showed better ASES score (93.5±5.3 vs. 89.5±5.7, P<0.05), UCLA score (31.7±3.8 vs. 28.5±5.6, P<0.05), improvement in UCLA score (19.6±4.2 vs. 15.9±5.7, P<0.05), active elevation (167.3°±8.4° vs. 159.4°±13.6°, P<0.05), abduction strength (8.9±1.2 vs. 8.2±1.2, P<0.05), improvement in abduction strength (4.1±1.2 vs. 3.3± 1.0, P<0.05), AHD (7.0±1.4 mm vs. 5.9±1.0 mm, P<0.05), improvement in AHD (3.3±1.5 mm vs. 2.0±0.6 mm, P<0.05), and healing rate of fascia lata autografts (92% vs. 54%, P<0.05) at 2-year follow-up. Conclusion:Fascia lata autograft bridging repair reinforced with an artificial ligament as the internal brace improves healing rate of bridging graft and postoperatively short-term clinical outcomes of patients with IMRCT.