Thirty-four patients with partial-thickness supraspinatus tears were randomized to ultrasound-guided prolotherapy with 20% dextrose (n=17) or atelocollagen injections (n=17), each delivered in three weekly sessions. The primary outcome was change in pain (VAS) to 3 months. Secondary outcomes were K-SPADI and SCSS at 1 and 3 months, and MRI-based changes in tear status from baseline to 3 months. Overall, the results of the study revealed greater 3-month pain reduction with atelocollagen and superior structural healing on MRI (improvement in 26.7% vs 0%; fewer aggravations) with no between-group difference in functional gains; no complications were reported. These findings suggest atelocollagen confers added structural benefit beyond symptomatic improvement observed with both injections.