Periprosthetic joint infection (PJI) is the most devastating complication following hip and knee arthroplasty, driven by resilient bacterial biofilms. Learn the complete framework for recognising, classifyingand managing this challenging condition using MSIS and EBJIS criteria. ⏱ Chapters 0:00 Intro 0:21 Essentials 0:49 Classification 1:14 Msis 1:43 Ebjis 2:08 DAIR Indications 2:31 Algorithm 3:00 Markers 3:28 Imaging 3:52 Numbers 4:16 Clinical reasoning — Manage 4:40 Clinical reasoning — Pearls This Orthovellum masterclass provides an in-depth exploration of periprosthetic joint infection, from pathophysiology and biofilm formation to acute versus chronic classification. We break down the 2018 MSIS and EBJIS diagnostic criteria, serum and synovial fluid laboratory thresholdsand imaging roles. The video outlines a clear, evidence-based treatment paradigm, including the FIXED mnemonic for DAIR (debridement, antibioticsand implant retention), single-stage revisionand two-stage revision protocols. 🦴 IN THIS VIDEO YOU'LL LEARN • How to differentiate acute, haematogenous, chronicand low-grade periprosthetic joint infections • How to apply the 2018 MSIS and EBJIS diagnostic criteria using major and minor thresholds • How to interpret serum inflammatory markers and synovial fluid tests including alpha-defensin • The indications and contraindications for debridement, antibioticsand implant retention (DAIR) • The decision-making process between single-stage and two-stage revision arthroplasty • Why bacterial biofilm formation dictates surgical strategy and limits antibiotic efficacy • How to correct synovial white blood cell counts in bloody aspirates • The role of nuclear medicine scans and sonication in culture-negative PJI cases ⏱️ CHAPTERS 📌 KEY TAKEAWAYS ✔️ A symptom duration of three weeks is the critical threshold separating acute infection (amenable to DAIR) from chronic infection (requiring revision). ✔️ MSIS major criteria include a sinus tract or two identical positive cultures, instantly confirming infection. ✔️ CRP and ESR together have a negative predictive value exceeding ninety percent when both are normal. ✔️ Use the FIXED mnemonic for DAIR: Fixed implant, Infection short, X-rays stable, Exchange modular parts, Debridement thorough. ✔️ Up to thirty percent of chronic infections present with normal blood markers, so always aspirate if clinically suspicious. 👩⚕️ WHO THIS IS FOR This masterclass is designed for orthopaedic trainees, junior doctorsand medical students seeking a comprehensive understanding of arthroplasty complications. It is also highly valuable for allied clinicians and curious patients wanting to understand the complexity of prosthetic joint infections. 📚 RELATED TOPICS: Aseptic loosening and osteolysis in total hip arthroplasty · Antibiotic spacers in two-stage revision knee replacement · Alpha-defensin and leukocyte esterase in synovial fluid analysis · Cutibacterium acnes infections in shoulder arthroplasty · Management of culture-negative periprosthetic joint infection 🔗 More free orthopaedic teaching at Orthovellum.com — subscribe for weekly videos. 🎨 CREDITS • Original Orthovellum production. ⚠️ DISCLAIMER: Educational only — not individual medical advice. Always consult a qualified clinician for diagnosis and treatment. #orthopaedics #arthroplasty #periprostheticjointinfection #PJI #jointreplacement #orthosurgery #kneereplacement #hipreplacement #MSIS #EBJIS #DAIR #medicaleducation