The following is a summary of “Incidence, Microbiological Studies, and Factors Associated With Prosthetic Joint Infection After Total Knee Arthroplasty,” published in the October 2023 issue of Infectious Disease by Weinstein et al. 

Despite total knee arthroplasty (TKA) frequency and clinical implications of prosthetic joint infections (PJIs), knowledge gaps remain on incidence, microbiology, and associated factors. Researchers performed a retrospective study to determine the incidence, microbiology, and patient/surgical factors of early, delayed, and late PJI after TKA. 

The study utilized US Department of Veterans Affairs (VA) Corporate Data Warehouse data. They focused on patients who underwent elective primary TKA within the VA system between October 1, 1999, and September 30, 2019, with at least 1 year of prior VA care. The overall cohort included all patients meeting these criteria, and the Veterans Affairs Surgical Quality Improvement Program (VASQIP) cohort consisted of those with linked VASQIP data.  

This study examined the incidence of prosthetic joint infection (PJI) at different time points after surgery. It also identified the most common organisms causing PJI and analyzed demographic and clinical factors associated with PJI.

The overall cohort comprised 79,367 patients (median (IQR) age of 65 (60-71) years) and primarily comprised 75,274 males (94.8%). Among them, 1,599 PJIs (2.0%) were identified. The incidence rate of PJI was notably higher in the early (26.8 [95% CI, 24.8-29.0] events per 10,000 person-months; IRR, 20.7 [95% CI, 18.5-23.1]) and delayed periods (5.4 [95% CI, 4.9-6.0] events per 10,000 person-months; IRR, 4.2 [95% CI, 3.7-4.8]) compared to the late postoperative period (1.3 events per 10,000 person-months). Staphylococcus aureus was the most common isolated organism (489 [33.2%]); however, early PJIs showed 15.4% (86 cases) of gram-negative infections. Hepatitis C virus infection, peripheral artery disease, and autoimmune inflammatory arthritis were associated with PJI across all postoperative periods in multivariable analyses. Diabetes, chronic kidney disease, and obesity (body mass index ≥30) were not associated factors. Additionally, other period-specific factors were identified. 

The study found that early and delayed post-TKA PJIs had higher incidence rates, different microbiology, and distinct risk factors, with implications for antibiotic use, risk stratification, and prevention. 

Source: jamanetwork.com/journals/jamanetworkopen/fullarticle/2811143