Clinical Pearls & Morning Reports
Published January 18, 2023
Periprosthetic joint infection is associated with extended hospitalizations, less-than-ideal success rates, high rates of disability, decreased quality of life, and high mortality, as compared with noninfected arthroplasties. Read the NEJM Review Article here.
Q: What is the impact of the biofilm that forms on arthroscopy surfaces in cases of periprosthetic joint infection (PJI)?
A: Arthroplasty-associated infection, or PJI, is clinically distinct from native bone or joint infection. PJI involves interactions between microorganisms, on the one hand, and the implant and host immune system, on the other. A small quantity of microorganisms can cause PJI; bacteria (and in rare cases, fungi) adhere to, and form biofilms on, arthroplasty surfaces. Biofilms tend to be refractory to many antimicrobial agents and the host immune system.
Q: Name some of the risk factors for PJI.
A: Numerous risk factors for PJI have been identified, only some of which, including anemia, injection drug use, malnutrition, obesity, poor glycemic control (with diabetes), and tobacco use, are potentially modifiable. Many surgeons attempt to address these factors before performing arthroplasty.
A: Although the risk of PJI is highest in the early postoperative period, the risk persists for the lifetime of the joint, with a significant proportion of infections manifested after 1 year. The most common symptom is joint pain. In some cases, local signs of infection (e.g., erythema, swelling, and warmth of the joint) may be present. Fever is often absent. With chronic infection, there may be pain alone, sometimes in conjunction with prosthetic loosening and a draining sinus tract. Although the presence of a draining sinus is pathognomonic for PJI, many cases are not associated with draining sinuses. In some cases, it may be challenging to differentiate PJI from noninfectious causes of arthroplasty failure, a distinction that informs surgical and medical management.
A: Arthrocentesis is a highly recommended mainstay of PJI diagnosis. Gram’s staining is not recommended. Synovial fluid should be submitted for assessment of the leukocyte count and neutrophil percentage and for culture. Normal laboratory-reported values and those for septic arthritis of a native joint do not apply to the leukocyte count and neutrophil percentage. PJI-specific interpretive criteria are used, which vary according to the definition used and the interval between arthroplasty and the development of infection. The aim of treatment is to ensure functional, pain-free joints and, ideally, to cure infection. Antibiotic therapy alone, without surgical intervention, fails in most cases; meticulous surgical débridement is important. For acute PJI of the hip or knee, débridement, antibiotics, and implant retention (DAIR) may be used, unless a sinus tract is present, the prosthesis is loose, or the wound cannot be closed. Chronic infections require resection arthroplasty, either one-stage or two-stage revisions. Prolonged antimicrobial therapy, guided by the results of antimicrobial susceptibility testing, is used to treat PJI. The preferred antibiotics, routes of administration, and durations of therapy are incompletely defined.