Prior Cellulitis as a Risk Factor for Periprosthetic Joint Infection in Total Knee Arthroplasty: Influence of Timing and Antibiotic Prophylaxis

Background Periprosthetic joint infection (PJI) is a leading cause of implant failure and revision surgery after total knee arthroplasty (TKA), occurring in 1 to 3% of patients. Despite the high incidence of cellulitis and shared causative organisms with PJI, little is known about its impact on PJI risk. This study aimed to assess whether a prior history of cellulitis is associated with an increased risk of PJI after TKA, with attention to timing, and to evaluate the role of extended oral antibiotic (EOA) prophylaxis in reducing PJI risk. Methods Patients who underwent elective TKA were identified in a large national database. Those who had cellulitis of the lower extremities before TKA were matched 1:1 to those who did not have a history of cellulitis based on age, sex, Charlson Comorbidity Index, obesity status, diabetes, and smoking status. Patients were stratified by timing of cellulitis and receipt of EOA prophylaxis. The 2-year PJI incidence and odds were calculated using Chi -square analyses and logistic regressions. A total of 105,926 patients were included. Results Patients who had prior cellulitis had a higher incidence of PJI than controls (7.2 versus 3.1%; odds ratio: 2.4, 95% confidence interval: 2.3 to 2.6, P < 0.001). Those who had cellulitis within one year of surgery had higher PJI incidence than patients who had more remote cellulitis (9.3 versus 4.7%; odds ratio: 2.0, 95% confidence interval: 1.9 to 2.2, P < 0.001). Although EOA prophylaxis was more common in the cellulitis group, these patients still had a higher incidence of PJI (10.4 versus 5.4%, P < 0.001). Conclusions Prior cellulitis is a risk factor for PJI after TKA, especially when it occurs within a year of surgery. Enhanced preoperative screening and postoperative surveillance are critical to identifying and managing high-risk patients. Although EOA prophylaxis is often used in this population, it does not appear to fully mitigate the elevated risk, highlighting the need for additional preventative strategies.