Muscle edema of the rotator cuff: a systematic review of characteristics and associated pathologies from the LaTour group

Objective: To systematically review the characteristics, diagnostic methods, and etiologies of rotator cuff (RC) muscle edema. Methods: A PRISMA-compliant review of clinical and laboratory studies from PubMed and Embase (PROSPERO ID: 626276); data on edema location, imaging features, and associated pathologies were qualitatively synthesized. Results: MRI is the most consistent tool for detecting muscle edema, typically showing T2 hyperintensity with variable patterns depending on etiology (traumatic, neurogenic, exertional, myopathic, or iatrogenic). Traumatic edema is associated with tendon retraction, bursal effusion, and fatty infiltration; neurogenic edema is diffuse and symmetric with atrophy; exertional edema appears 'fluffy' or 'feather-like'; myopathic and iatrogenic forms show peripheral or localized changes. Conclusion: The imaging appearance, location, and timing of RC muscle edema provide valuable diagnostic clues and should be considered in the context of the underlying pathology. Level of evidence: Systematic review, level 4.