Resolvin E1 as a Potential Biomarker of Tendon Retraction Severity in Rotator Cuff Tears

Background/Objectives: Specialized pro-resolving lipid mediators (SPMs), such as Resolvin E1 (RvE1) and Resolvin D1 (RvD1), play a critical role in the resolution phase of inflammation. However, their relevance to tendon pathology and tissue-specific degeneration in rotator cuff tears remains unclear. This study aimed to investigate the relation between serum RvE1 and RvD1 levels and the morphological severity of tendon retraction and muscle fatty degeneration in patients with full-thickness rotator cuff tears. Methods: A total of 70 participants were included: 35 patients with full-thickness rotator cuff tears determined by magnetic resonance imaging (MRI) and 35 healthy controls. Tendon retraction and muscle fatty degeneration were graded using Patte and Goutallier classifications, respectively. Serum RvE1 and RvD1 levels were measured using enzyme-linked immunosorbent assay (ELISA). Group comparisons were performed using Welch's t-test, and correlations were analyzed with Spearman's coefficient. Results: RvE1 and RvD1 levels were significantly lower in patients compared to controls (p < 0.001). RvE1 showed a moderate positive correlation with Patte score (ρ = 0.37, p = 0.027), while no significant correlation was observed with Goutallier classification (ρ = 0.19, p = 0.27). RvD1 levels demonstrated no significant relationship with either morphological parameter. Conclusions: These findings suggest that decreased serum RvE1 levels are associated with the severity of tendon retraction but not with muscle fatty degeneration. Therefore, RvE1 may serve as a potential biochemical biomarker reflecting tendon damage severity and the impaired resolution of inflammation in rotator cuff tears.