Prosthetic-joint infection

Establish timing relative to arthroplasty and symptom duration. Acute postoperative infection may present with persistent drainage, increasing pain, fever or wound breakdown; acute haematogenous infection produces sudden pain in a previously well implant during or after bacteraemia; chronic infection causes progressive pain, stiffness, loosening, sinus or unexplained functional decline. Ask about every antibiotic course, aspiration and operation because these change culture interpretation and the chance of implant retention.

Examine the patient and the implant environment. Record sepsis physiology, gait or limb use, wound edges, drainage, sinus, erythema, effusion, passive range, stability and distal neurovascular function. Do not probe a sinus or repeatedly swab drainage. Search for skin, urinary, respiratory and dental infection and perform cardiovascular assessment for endocarditis, particularly with S. aureus bacteraemia. Examine other painful joints and spine for metastatic infection.

Separate unstable treatment from stable diagnosis. A septic patient needs immediate sepsis care, urgent blood cultures and parenteral antibiotics followed by emergency drainage by an experienced surgical team. BOASt states that surgery in an acutely unwell person should occur as soon as safe and within six hours unless a specific documented reason prevents it. A stable patient should not receive antibiotics until appropriate deep samples are secured and should have consultant orthopaedic review within forty-eight hours.

Initial tests are FBC, CRP, renal function and plain radiographs. Look for migration, radiolucency, osteolysis, periosteal response, fracture and component position, recognising that early infection may show no change. Ultrasound detects and guides aspiration of effusion. Synovial cell count, differential, Gram stain and aerobic and anaerobic cultures support diagnosis; crystals are sent because they can coexist. Alpha-defensin, leukocyte esterase, molecular tests and nuclear imaging answer selected specialist questions rather than replacing culture and operative evidence.

Use a definition that integrates evidence. EBJIS groups findings as infection unlikely, likely or confirmed. A sinus communicating with the joint or exposed prosthesis is confirmatory. Multiple cultures of the same organism, histological neutrophils and sufficiently high synovial biomarkers add weight, while one low-virulence isolate needs contamination context. Recent surgery, inflammatory arthritis and prior antibiotics shift thresholds. A normal CRP cannot exclude infection, and an isolated superficial swab should not select definitive therapy.

Surgical sampling is disciplined. Before irrigation and antibiotics where stability permits, take five deep tissue or fluid specimens from distinct representative sites, using a new sterile instrument and no-touch technique for each. For chronic infection or doubt in an acute case, take two histology samples. Label sites precisely and tell microbiology about implants, prior agents and suspected slow-growing organisms. Sonication of removed components may increase biofilm yield under the revision-centre protocol.

Choose the operation from symptom duration, component fixation, soft tissue, organism, host and reconstructive feasibility. DAIR means open debridement, synovectomy, multiple samples and exchange of accessible modular components while retaining well-fixed major implants; it suits carefully selected early postoperative or short-duration haematogenous infection. Mature chronic biofilm, component loosening, sinus, difficult organisms or damaged tissue generally requires one-stage or two-stage exchange. Resection, fusion, suppressive antibiotics or amputation are salvage choices made through a specialist multidisciplinary process.

Antibiotics follow specimens and surgery. Empiric parenteral cover is selected from local resistance, allergy, renal function and sepsis risk, then narrowed. Biofilm-active combinations such as rifampicin-containing therapy for susceptible staphylococci require microbiology leadership and should not begin as rifampicin monotherapy or before the wound and bacterial burden are controlled. Rifampicin has major interactions with warfarin, direct oral anticoagulants, contraception and many other medicines. Duration and route depend on operation, organism and response.

Follow wounds, CRP trajectory, pain, function, cultures, renal and liver tests and drug adverse effects. Continued drainage, recurrent bacteraemia, rising pain or failure of markers to improve prompts renewed source-control assessment rather than automatic prolonged antibiotics. Rehabilitation respects fixation, soft tissue and loading while preventing deconditioning. Explain recurrence risk, red flags, dental and skin infection care and which team to contact directly if pain or drainage returns.