Acute tear versus chronic-degenerated rotator cuff pathologies are associated with divergent tendon metabolite profiles.

Purpose/aim: Metabolic disorders are risk factors for rotator cuff injuries, which suggests that the rotator cuff is sensitive to local metabolic fluctuations. However, the link between the metabolic microenvironment and pathologic features of acute tear versus chronic degeneration is currently unknown. The overarching goal of this study was to evaluate alterations in tendon metabolite profiles following acute tear or chronic degeneration of the rotator cuff. We hypothesized that injury types (acute tear vs. chronic degeneration) would result in distinct metabolite profiles relative to clinically unaffected tendon controls.

Materials And Methods: We utilized untargeted metabolomics to identify pathways that were altered at the time of rotator cuff repair (RCR; acute tear) or reverse total shoulder arthroplasty (rTSA; chronic degeneration) relative to total shoulder arthroplasty controls (TSA; tendon clinically unaffected).

Results: Acute tears to the rotator cuff were associated with an overall decrease in tendon metabolites. This global decrease was primarily associated with glycolic acid and decreased tricarboxylic acid (TCA) cycle activity. Conversely, chronic tendon specimens from patients undergoing rTSA showed an overall increase in metabolites. Most notably, chronic injury was associated with increased levels of multiple amino acids including alanine, aspartate, lysine, and proline.

Conclusions: Overall, this study demonstrates that distinct metabolite profiles are associated with injury types, and that therapeutic strategies should address both cellular and matrix components regardless of injury induction. The specific pathways identified paired with validated, established, treatment methods may serve as novel therapeutic targets for patients who suffer from rotator cuff injuries.