Rethinking Repeat Two-Stage Knee Exchange Arthroplasty: Outcomes, Risks, and Decision-Making.

Background: Chronic periprosthetic joint infection (PJI) presents a major challenge in knee arthroplasty, with varying success rates reported for two-stage exchange arthroplasty (EA) and a lack of consensus on managing failures from such procedures. This study evaluated repeat two-stage EA outcomes for knee PJI after initial treatment failure to identify the risk factors for reimplantation unsuitability and reinfection.

Methods: We analyzed 114 patients who underwent repeat EA for chronic knee PJI between 2010 and 2018. From an initial cohort of 1,351 patients, we excluded 231: 18 for incomplete records or protocol non-compliance and 213 for prior revisions. Among the remaining 1,119 patients, 150 experienced reinfection, and after excluding 36 who did not undergo repeat EA, the final cohort comprised 114 patients. Outcomes were evaluated using Delphi-based consensus success criteria: healed wounds, no further infection interventions, and no PJI-related mortality.

Results: In our study, 34.2% of the patients did not proceed with reimplantation due to reinfection or ongoing infection, which was influenced by factors such as high Charlson Comorbidity Index scores, recurrence of a microorganism, and shorter intervals between initial arthroplasty and reinfection. Among the reimplanted patients, 44.0% underwent further revision for re-reinfection. Kaplan-Meier analysis of 1,119 initial, 75 repeat, and 24 re-repeat two-stage cases revealed five-year infection-free survival rates of 93, 72, and 43%, respectively. This study identified significant reinfection risks in patients who have repeated infections by the same microorganisms, persistent PJI, or multiple spacer redo procedures. A 39.5% re-reinfection rate, including 12 amputations, and a 15.8% mortality rate was observed in this series.

Conclusion: This study underscores the effectiveness of first-time two-stage EA for knee PJI and notes the challenges and lower success rates of subsequent attempts. This emphasizes the importance of identifying high-risk patients for tailored treatment plans and setting realistic expectations of outcomes.