Proceedings from the 2025 International Consensus Meeting on Orthopedic Infections: the definition of Shoulder Periprosthetic Joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) remains one of the greatest diagnostic and treatment challenges facing shoulder surgeons and their patients. A definition for shoulder PJI was established by the 2018 International Consensus Meeting (ICM) on Orthopedic Infections, but the selection and weighting of its minor criteria relied largely on expert opinion. The purpose of this study was to present an updated, evidence-based definition of shoulder PJI generated by the 2025 ICM Shoulder Group.

METHODS: The 2025 ICM Shoulder Group, an international panel of shoulder surgeons and infectious disease specialists, used a modified Delphi process informed by 86 systematic reviews and by a predictive statistical model derived from the American Shoulder and Elbow Surgeons (ASES) Multicenter Revision Arthroplasty and PJI Group dataset to reconsider the 2018 ICM definition of shoulder PJI, including its major criteria, minor criteria, and diagnostic categories.

RESULTS: The delegates voted to eliminate organism virulence from the definition and to retain gross intra-articular purulence and presence of a sinus tract as the two criteria defining Definite PJI. The Minor Criteria were revised to include erythema, unexpected wound drainage, elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), elevated synovial neutrophil percentage, positive frozen section, radiographic humeral osteolysis, intraoperative humeral loosening, and positive culture, each statistically weighted using the predictive model. Non-definite PJI was categorized by summed minor criteria score as High likelihood (≥13 points), Moderate likelihood (7-12 points), Unknown (1-6 points), or No PJI (0 points). The final definition achieved unanimous delegate consensus (51 of 51 delegates; 100% agreement; super majority, strong consensus).

CONCLUSIONS: The 2025 ICM definition of shoulder PJI represents an evidence-informed evolution of the 2018 definition, combining statistical modeling of prospective multicenter data with structured expert consensus. The definition is expected to continue to evolve as further shoulder-specific data become available.