What is the best course of treatment for an older adult with a history of joint disease who develops a post joint replacement infection, presenting with symptoms such as fever, redness, swelling, and pain at the surgical site?

Management of Post Joint Replacement Infection

For an older adult with post-joint replacement infection presenting with fever, redness, swelling, and pain at the surgical site, the treatment approach depends critically on symptom duration and implant stability: perform debridement with implant retention (DAIR) if symptoms are <4 weeks and the prosthesis is stable, or proceed with two-stage exchange arthroplasty for chronic infections or when DAIR criteria are not met. 1

Initial Assessment and Classification

The first critical decision point is determining infection timing and characteristics:

• Early postoperative infection occurs within the first month after surgery 1
• Acute hematogenous infection presents with sudden onset of pain, swelling, and fever in a previously well-functioning joint 1
• Chronic infection develops insidiously over months to years, often with the complaint that "the joint has never been quite right" 1

Your patient's presentation with fever, redness, swelling, and pain suggests either early postoperative or acute hematogenous infection, which fundamentally alters the surgical approach 1.

Diagnostic Workup Before Treatment

Before initiating therapy, obtain:

• Joint aspiration for culture and synovial fluid analysis (cell count with differential) 1, 2
• ESR and CRP - when both are negative, infection is unlikely; CRP >13.5 mg/L has 73-91% sensitivity for prosthetic infection 3, 2
• Blood cultures if fever is present or acute symptom onset 1
• Plain radiographs to assess for implant loosening, osteolysis, or component migration 3, 2

Critical pitfall: Withhold antimicrobials for at least 2 weeks prior to obtaining cultures if the patient is medically stable, as this significantly increases organism recovery 1, 2.

Surgical Management Algorithm

DAIR (Debridement, Antibiotics, and Implant Retention)

DAIR is appropriate when ALL of the following criteria are met:

• Symptom duration <4 weeks 1
• Implant age <6-13 weeks (for early postoperative) OR well-fixed prosthesis (for acute hematogenous) 1
• Stable prosthesis with no loosening 1
• Biofilm-active antimicrobials available for the identified organism 1

The success rate for DAIR in ideal situations exceeds 80% 1.

Two-Stage Exchange Arthroplasty

Two-stage exchange is the gold standard for chronic infections or when DAIR criteria are not met:

• Stage 1: Complete removal of all prosthetic components, infected cement, thorough debridement of infected bone and soft tissue, placement of antibiotic-loaded cement spacer 4
• Collect minimum of 3-5 intraoperative tissue specimens for aerobic and anaerobic culture 1, 4
• Interval period: Minimum 6 weeks of pathogen-specific antimicrobial therapy, up to 6 months for difficult infections 4
• Stage 2: Delayed reimplantation only after confirmed infection eradication through normalized ESR/CRP and negative repeat aspirations 4

Two-stage exchange is recommended by the American Academy of Orthopaedic Surgeons as the definitive approach for established prosthetic joint infections 4.

Antimicrobial Therapy

For DAIR or Two-Stage Exchange:

Initial phase (2-6 weeks):

• Pathogen-specific intravenous antimicrobial therapy 1, 4
• For staphylococcal infections: rifampin 300-450 mg orally twice daily PLUS a companion drug (such as a fluoroquinolone or cephalosporin based on susceptibilities) 1, 4

Continuation phase:

• Switch to oral antimicrobials to complete total 6-month course for two-stage exchange 4
• For DAIR: 3-6 months total duration depending on organism and clinical response 1

Critical evidence: A high-quality trial demonstrated that oral antibiotics are non-inferior to 6 weeks of intravenous therapy, with fewer catheter-related complications 1. Early switch to oral therapy is appropriate when highly bioavailable agents are available 1.

Rifampin Use - Essential Details:

Rifampin combination therapy is specifically recommended for staphylococcal PJI because of its biofilm-penetrating properties 1, 4. Never use rifampin monotherapy due to rapid resistance development 1. One important caveat: rifampin interacts with selective serotonin reuptake inhibitors, increasing serotonin syndrome risk 1.

Alternative Surgical Options

When curative approaches are not feasible:

• Permanent resection arthroplasty: For nonambulatory patients, limited bone stock, highly resistant organisms, or medical conditions precluding multiple surgeries 1, 4
• Arthrodesis: When functional benefit exists over resection arthroplasty 4
• Amputation: Last resort for necrotizing fasciitis, severe bone loss preventing reconstruction, or no available medical therapy 1, 4

Chronic Antimicrobial Suppression

Indefinite oral suppression is reserved for patients who:

• Are unsuitable for or refuse further surgery 1
• Have completed initial antimicrobial course but cannot undergo definitive surgical management 1

Suppressive agents include cephalexin, dicloxacillin, co-trimoxazole, or minocycline/doxycycline based on susceptibilities 1. Rifampin alone should never be used for chronic suppression 1.

Multidisciplinary Coordination

All prosthetic joint infections require coordination between orthopedic surgery, infectious disease specialists, and pharmacists to optimize antimicrobial regimens, monitor for adverse reactions and drug interactions, and ensure adherence 4, 5. Shared decision-making with the patient about treatment goals (cure vs. suppression vs. resection) is essential, particularly when ideal curative approaches are not possible 1.

Monitoring and Follow-up

• Monitor inflammatory markers (ESR/CRP) every 1-3 months for minimum 12 months following antimicrobial cessation 1
• Counsel patients about symptoms suggesting infection recurrence requiring prompt reassessment 1
• Monitor for antimicrobial adverse effects with appropriate blood tests (e.g., liver function tests) 1