Seventy-three patients with full-thickness rotator cuff tears >2 cm were randomized to receive either an autologous dermal fibroblasts (ADF) injection during arthroscopic rotator cuff repair (n=36) or arthroscopic rotator cuff repair (ARCR) alone (n=37). The primary outcome was the retear rate at 6 months, assessed by MRI. Secondary outcomes included American Shoulder and Elbow Surgeons (ASES) score, Constant score, Simple Shoulder Test (SST), and range of motion at baseline, 6 months, and 12 months. Overall, the results of the study revealed that the ADF group had a significantly lower retear rate (5.6%) compared to the control group, although functional scores and ROM improved similarly in both groups over time. These findings suggest ADF injections may improve tendon healing but do not yield additional functional benefits in the short term.