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 ( P < .001). The American Shoulder and Elbow Surgeons score improved from 47.3 at baseline to 68.5 at 3 months and 82.2 at 12 months. The Simple Shoulder Test improved from 8.8 to 9.7 at 3 months and 11.3 at 12 months. Pain scores decreased from 5.8 at baseline to 3.5 at 3 months and 2.1 at 12 months. Magnetic resonance imaging at 12 months showed improved tendon quality in 7 out of 20 evaluated patients (35%). 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.