Unexplained new pain after total hip or knee arthroplasty should raise concern for infection
Periprosthetic joint infection complicates 1% to 2% of primary arthroplasties. Risk is highest soon after surgery, but infection can occur years later from hematogenous seeding. Acute periprosthetic joint infection often presents with pain, swelling, erythema, and wound drainage. Indolent infections may present with unexplained joint pain or functional decline alone. Fever is inconsistently present. Persistent wound drainage or delayed postoperative recovery should raise concern for infection.
Suspected infection requires urgent referral
Patients should be referred to their surgeon or an arthroplasty centre with collaborative orthopedic surgery and infectious disease expertise. Patients with sepsis require assessment in the emergency department.
Initial investigations include radiography, arthrocentesis, and testing for inflammatory markers
Radiographs may demonstrate component loosening or osteolysis, although findings are often nonspecific. Diagnosis is guided by validated consensus criteria incorporating clinical, serologic, and synovial fluid findings.1 Arthrocentesis is often coordinated through the orthopedic surgeon or arthroplasty centre and should be performed using strict aseptic technique.2 Arthrocentesis of the hip may require image guidance. Synovial fluid samples should be tested for leukocyte count and neutrophil percentage, and sent for aerobic and anaerobic cultures. Molecular diagnostics (e.g., 16S rRNA gene sequencing) may be considered in select culture-negative or diagnostically challenging cases. Swab cultures are not advised because of poor diagnostic performance.3
Antibiotics should be withheld until samples are obtained for culture, except for patients with sepsis
Prior antibiotic exposure increases the risk of culture-negative periprosthetic joint infection and complicates antimicrobial therapy.4,5 In patients with sepsis, blood and synovial fluid samples should be promptly collected for cultures and empiric intravenous antibiotics started.
Treatment usually requires surgery with prolonged antibiotics
Antibiotic therapy alone, without surgery, fails in most cases. In select patients, early postoperative or acute hematogenous infections may be managed with débridement and antibiotics, allowing implant retention. Patients with chronic infections often require 1- or 2-stage exchange arthroplasty and prolonged antimicrobial therapy.
Acknowledgements
The authors thank D. William Cameron and Melissa T. Cammuso for their insights and fruitful discussions. They also thank their microbiology colleagues at the Eastern Ontario Regional Laboratory Association.
Footnotes
Competing interests: Marisa Azad reports funding from BioMérieux and The Ottawa Hospital. Dr. Azad is a consultant for BioMérieux Canada.
This article has been peer reviewed.
References
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