Intratendinous Porcine-Derived Type I Collagen Injections Result in Clinical and Radiographic Improvement of Rotator Cuff Tendinopathy 1 Year After Treatment.

Purpose: To evaluate the clinical and radiological effectiveness of porcine-derived type I collagen injections in patients with symptomatic rotator cuff tendinopathy. Methods: In this monocentric pilot study conducted between 2022 and 2025, adults with clinically and radiologically confirmed rotator cuff tendinopathy received 3 ultrasound-guided intratendinous injections at 2-week intervals and were followed for 12 months. A power analysis determined that 24 patients were required to detect a 13-point improvement in the Constant-Murley Score (CMS) at 3 months. The primary outcome was the achievement of a ≥13-point increase in the CMS at 3 months. Secondary outcomes included functional scores, pain intensity, magnetic resonance imaging findings, and analgesic consumption. Results: Twenty-four patients were enrolled, and 22 completed 12-month follow-up. At 3 months, 8 out of 23 patients (35%) achieved the predefined 13-point CMS as minimal clinically important difference. Mean CMS improved from 62.4 at baseline to 72.2 at 3 months and 78.7 at 12 months ( Conclusions: Intratendinous porcine-derived type I collagen injections were associated with progressive improvements in shoulder function and pain over 12 months in this single-arm pilot study. Although the predefined minimal clinically important difference at 3 months was reached by a proportion of patients, functional scores showed continued improvement throughout follow-up. Magnetic resonance imaging findings showed improved tendon quality in part of the cohort, and no serious adverse events were recorded. Level of Evidence: Level IV, prospective therapeutic case series.