Synopsis
Recognise acute and indolent infection around joint replacement, separate septic instability from stable diagnostic sampling, protect deep-culture yield, classify evidence coherently, and select DAIR, staged exchange or salvage through a specialist implant-infection team.
- Classify the clinical syndrome before prescribing: acute postoperative, acute haematogenous, chronic indolent and septic presentations have different sampling and surgical opportunities.
- In sepsis, take blood cultures urgently and start parenteral protocol antibiotics, then drain emergently; current BOASt targets surgery within six hours for an acutely unwell patient when safe.
- Do not give antibiotics to a stable patient until diagnostic synovial or deep tissue samples are obtained, unless a documented competing infection requires treatment.
- Record index arthroplasty date, wound healing, later procedures, recent bacteraemia or infection, antibiotics, implant function and a cardiovascular assessment for endocarditis.
- Initial tests include FBC, CRP, renal function and plain radiographs, but normal inflammatory markers do not exclude PJI, particularly with immunosuppression or low-virulence organisms.
- A sinus communicating with the implant or visible prosthesis is confirmatory evidence; aspiration and tissue cultures are interpreted through EBJIS criteria rather than one cutoff alone.
- At indicated debridement, obtain five deep microbiology specimens with separate sterile instruments and no-touch technique; take two histology specimens when chronic infection or diagnostic doubt exists.
- DAIR is most useful for early or short-duration acute infection with stable components and viable soft tissue; exchange strategies address mature biofilm, loosening, poor tissue or unsuitable organisms.
Key red flags
Hypotension, confusion, lactate elevation, purulent drainage, rapidly spreading erythema or acute severe prosthetic-joint pain with bacteraemia requires immediate sepsis, orthopaedic and anaesthetic escalation.
A communicating sinus, visible prosthesis or persistent wound drainage is highly concerning and should not be repeatedly swabbed, probed or treated with short empirical oral courses.
Sudden joint pain during Staphylococcus aureus bacteraemia, skin infection or another septic focus suggests acute haematogenous seeding even years after uncomplicated implantation.
Normal CRP, white count or plain radiographs do not exclude low-grade infection, especially during immunosuppression or infection caused by low-virulence organisms.
Investigation priorities
Measure systemic inflammation, sepsis severity and treatment safety.
Assess component position, loosening, osteolysis, fracture and baseline bone stock.
Management branches
Suspected PJI accompanies sepsis, organ dysfunction or rapidly progressive local infection.
- Start the sepsis pathway, obtain urgent blood cultures and inform orthopaedics, anaesthesia and microbiology immediately.
- Give local parenteral protocol antibiotics after blood cultures and do not wait for planned aspiration in an unstable patient.
- Perform experienced emergency drainage as soon as safe and within six hours when acutely unwell unless a documented reason prevents it.
- Take five deep cultures at debridement and search for endocarditis and other metastatic or primary infection sources.
Pain, loosening or drainage suggests PJI without current sepsis.
- Withhold antibiotics, document index surgery, wound course, recent infection and agents and arrange consultant review within 48 hours.
- Obtain FBC, CRP, renal function, radiographs and image-guided synovial fluid with cultures, cell differential and crystals.
- Apply EBJIS evidence, treating a communicating sinus or exposed implant as confirmed and resolving discordance in the infection MDT.
- Plan five deep cultures and two histology samples at indicated surgery before any definitive organism-directed regimen.