Microbiological Characteristics and Clinical Outcomes of Periprosthetic Infections Following Oncologic Megaprosthetic Reconstruction: A Retrospective Cohort Study.

BACKGROUND

Periprosthetic joint infection (PJI) is a severe complication following megaprosthetic reconstruction in musculoskeletal oncology. This study aimed to evaluate outcomes of different surgical strategies for PJI in lower-limb megaprostheses and identify factors associated with treatment failure.

METHODS

We performed a retrospective cohort study of 29 consecutive patients treated for PJI after oncologic megaprosthetic reconstruction. Reinfection was analyzed using cumulative incidence functions (CIFs) with death treated as a competing event. Overall survival was assessed using Kaplan-Meier analysis. Univariable cause-specific Cox regression was performed for exploratory risk-factor analysis.

RESULTS

Among 29 patients, coagulase-negative staphylococci and Staphylococcus aureus were the most frequently isolated pathogens, and difficult-to-treat organisms were identified in a substantial proportion of cases. In patients managed with two-stage revision, the cumulative incidence of reinfection was 15% (95% CI: 0-30%) at 1 year and 30% (95% CI: 10-50%) at 2 and 5 years. In the DAIR cohort, the cumulative incidence of reinfection was 25% (95% CI: 0-62.5%) at 1 and 2 years and 37.5% (95% CI: 12.2-75%) at 3 years. Positive reimplantation cultures occurred in 38% of cases and were strongly associated with subsequent treatment failure. Polymicrobial infections were present in 27.5% of cases. Amputation was required in 17.2% of patients, often due to multidrug-resistant organisms or poor soft tissue.

CONCLUSIONS

Two-stage revision remains the most effective strategy for PJI management in megaprostheses. DAIR may control acute infection but is suboptimal for definitive treatment. Individualized, multidisciplinary approaches are essential to improve outcomes in this high-risk population.