Comparative Effects of Acellular Dermal Matrix and Atelocollagen Injections in Intratendinous Partial-Thickness Rotator Cuff Tears: A Retrospective Cohort Study.

BACKGROUND

The purpose was to compare the functional and structural outcomes between injectable acellular dermal matrix (ADM) and atelocollagen in patients with intratendinous partial-thickness rotator cuff tears.

METHODS

From January 2020 to May 2021, 115 consecutive patients with magnetic resonance imaging (MRI)-confirmed intratendinous partial-thickness supraspinatus tears who met the inclusion criteria were retrospectively identified. After applying predefined exclusion criteria, 85 patients remained for final analysis and were categorized into 2 groups: intratendinous injection with 1 mL ADM (group A, n = 40) and 1 mL type I atelocollagen (group B, n = 45). The visual analog scale (VAS) score for pain, American Shoulder and Elbow Surgeons (ASES) score, Constant Shoulder score (CSS), and range of motion (ROM) were evaluated before injection and at 1, 3, 6, and 9 months and the last follow-up after injection. MRI was performed at 6 months after injection to evaluate rotator cuff integrity and healing response.

RESULTS

The mean follow-up period was 14.1 months. Both groups demonstrated significant improvements in pain, functional outcomes, and ROM from baseline to final follow-up. ASES scores increased from 60.3 to 88.4 in group A and from 67.4 to 90.2 in group B (both p < 0.001). CSS improved from 58.3 to 73.2 in group A and from 61.1 to 71.9 in group B (both p < 0.001). External rotation at the side improved significantly in both groups (group A: 73.7° to 80.5°, p = 0.035; group B: 74.2° to 79.5°, p = 0.011), and other ROM parameters demonstrated similar longitudinal improvement. Activity VAS decreased from 5.1 to 1.5 in group A and from 5.8 to 1.5 in group B. However, no statistically significant differences were observed between the 2 treatment groups in any clinical outcome measures at final follow-up. MRI demonstrated tendon improvement in 32.5% of ADM-treated and 35.6% of atelocollagen-treated patients (p = 0.821).

CONCLUSIONS

Both ADM and atelocollagen injections were associated with clinically meaningful improvement in patients with intratendinous partial-thickness rotator cuff tears, with generally maintained MRI-based structural outcomes at follow-up.