Chronic Infections of Knee Megaprostheses: Is "Off-Label" DAIR-Plus an Option?

Introduction Two-stage revision for chronic periprosthetic joint infections (PJI) of knee megaprostheses is complex and often results in significant bone loss. The DAIR-plus (DP) procedure, involving debridement with partial prosthesis removal but retaining stems, is typically used for acute PJI but may benefit select chronic cases. This study aimed to: i) assess DP outcomes in chronic megaprosthesis infections; and ii) identify prognostic factors to guide its use versus full component removal. Material and Methods Twenty-three patients underwent DP procedures for chronic knee megaprosthetic PJI between 2000 and 2022. Nineteen patients, were included. Targeted antibiotics were administered based on Infectious Disease Specialist recommendations. Infection eradication was evaluated using clinical and serologic parameters. Results The study involved 12 females and 7 males aged 18–87 (mean 53); twelve had oncological conditions. DP was performed as a one-stage procedure in 13 cases and two-stage in 6. Eight patients (42%) achieved infection resolution with DP alone, and four required additional procedures, yielding an overall success rate of 63%. Some required amputation or chronic antibiotics. Outcomes did not significantly differ by age (p = 0,85), gender (p = 0.31), oncology status (p = 0,95), radiotherapy (p = 0,43), previous revisions (p = 0,43), or revision type (p = 0,44). Staphylococcus spp infections had worse outcomes (25% vs. 62%, p = 0.048). Conclusions The DAIR-plus procedure is a viable option for selected patients, though it carries a high failure risk (over 50%). When successful, it offers notable advantages such as bone stock preservation and faster recovery. Infections caused by Staphylococcus spp. present greater challenges for eradication in this series.