Local Vancomycin Application Reduces Periprosthetic Joint Infections in Oncologic Megaprosthetic Reconstruction: A Retrospective Cohort Study

<b>Background/Objectives:</b> Periprosthetic joint infections (PJIs) represent a serious complication following musculoskeletal tumor resection and megaprosthetic reconstruction. Local antibiotic administration may reduce infection risk by achieving high local drug concentrations. The aim of this study was to evaluate whether local vancomycin powder reduces postoperative periprosthetic infections in bone tumor surgeries involving megaprostheses. <b>Methods:</b> This retrospective cohort study included 276 patients who underwent bone tumor resection and megaprosthetic reconstruction. Study subjects were divided into two groups: the control group (n = 142) that received standard perioperative intravenous antibiotics, and the vancomycin group (n = 134) that received an additional 1 g of vancomycin powder locally at wound closure. Periprosthetic joint infections were defined using the 2018 International Consensus Meeting (ICM) criteria and monitored for 2 years. A multivariable competing risks regression model was used to assess the independent effect of local vancomycin on infection risk. <b>Results:</b> Periprosthetic joint infections occurred in 28 patients in the control group (19.7%) vs. eight patients in the vancomycin group (5.9%, <i>p</i> = 0.001). The most frequently isolated pathogens were coagulase-negative staphylococci (52.7%), followed by <i>Staphylococcus aureus</i> (22.2%). Among infected patients in the vancomycin group, only two had Gram-positive infections, suggesting efficacy against staphylococcal PJIs. The multivariable regression confirmed a significantly lower risk of infection in the vancomycin group (hazard ratio [HR]: 0.40, 95% confidence interval [CI]: 0.16-0.95, <i>p</i> = 0.040), while pelvic tumors were associated with a higher infection risk (HR: 5.82, <i>p</i> < 0.001). <b>Conclusions:</b> Our results indicate that local vancomycin may reduce periprosthetic infection rates in oncologic megaprosthetic reconstruction without added complications. Randomized studies are warranted to confirm these findings and refine dosing strategies.