Treatment of Partial Knee Replacement Infection

Surgical Management Algorithm

• The American Academy of Orthopaedic Surgeons recommends a two-stage revision with complete removal of all prosthetic components, thorough debridement of infected tissue, placement of an antibiotic-loaded cement spacer, followed by prolonged targeted antimicrobial therapy (minimum 6 weeks) and delayed reimplantation after confirmed infection eradication 1, 2
• Complete removal of all components and infected material is essential for treatment success, as recommended by the American Academy of Orthopaedic Surgeons 1, 2
• The first stage of two-stage revision involves removing all prosthetic components, infected cement, and performing complete excision of infected bone and soft tissues, as suggested by the American Academy of Orthopaedic Surgeons 1, 2
• Collecting a minimum of three intraoperative tissue specimens for culture, including specific mycobacterial cultures if initial cultures are negative, is recommended by the American Academy of Orthopaedic Surgeons and Clinical Microbiology and Infection 1, 2, 3
• Delayed reimplantation timing should be a minimum of 6 weeks after the first stage, with some protocols recommending up to 6 months for difficult infections, as recommended by the American Academy of Orthopaedic Surgeons 1, 2
• Confirming infection eradication through multiple preoperative joint aspirations and normalized inflammatory markers (ESR and CRP) is critical before reimplantation, as recommended by the American Academy of Orthopaedic Surgeons and Clinical Infectious Diseases 1, 2, 4

Antimicrobial Therapy

• The American Academy of Orthopaedic Surgeons and Clinical Infectious Diseases recommend 6 months of antimicrobial therapy following two-stage revision for total knee arthroplasty infections 4
• Initial phase antimicrobial therapy should consist of 2-6 weeks of pathogen-specific intravenous antimicrobial therapy, as recommended by Clinical Infectious Diseases 4
• Continuation phase antimicrobial therapy should consist of oral antimicrobials to complete a total 6-month course, as recommended by Clinical Infectious Diseases 4
• For staphylococcal PJI, rifampin-based combination therapy is recommended by Clinical Infectious Diseases 4
• Rifampin 300-450 mg orally twice daily PLUS a companion drug is recommended for staphylococcal PJI, as suggested by Clinical Infectious Diseases 4

Special Considerations

• Nontuberculous mycobacterial (NTM) infections can present indolently and mimic aseptic loosening, with negative cultures in up to 61.5% of cases, as reported by the American Academy of Orthopaedic Surgeons 1, 2
• Suspecting NTM when initial cultures are negative despite clinical suspicion of infection is crucial, as recommended by the American Academy of Orthopaedic Surgeons 1, 2
• Sending multiple tissue and implant specimens specifically for mycobacterial culture is recommended for NTM infections, as suggested by the American Academy of Orthopaedic Surgeons 1, 2

Alternative Approaches

• Permanent resection arthroplasty may be considered in patients with nonambulatory status, limited bone stock or poor soft tissue coverage, highly resistant organisms with limited treatment options, medical conditions precluding multiple surgeries, or failed previous two-stage exchange with unacceptable reinfection risk, as recommended by Clinical Infectious Diseases 4
• Arthrodesis may be considered for total knee arthroplasty infections when functional benefit exists over resection arthroplasty, as suggested by Clinical Infectious Diseases 4
• Amputation should be the last resort but may be necessary for necrotizing fasciitis, severe bone loss preventing reconstruction, inability to achieve soft tissue coverage, or no available medical therapy for resistant organisms, as recommended by Clinical Infectious Diseases and the American Academy of Orthopaedic Surgeons 2, 4

Multidisciplinary Approach

• 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 patient adherence, as recommended by the American Academy of Orthopaedic Surgeons and Clinical Microbiology and Infection 1, 3, 5, 6