Mid-term to long-term outcome of two-stage revision for knee chronic periprosthetic joint infection: an arthroplasty unit experience of 78 knees

Introduction: Knee periprosthetic joint infection (PJI) is a catastrophic complication with annual increase in overall prevalence.The aim of this study is to report the result of two-stage revision surgery of chronic knee PJI and its related outcomes.Methods: Retrospective analysis of 78 knees (78 patients) who received two-stage revision surgery for chronic knee PJI in an arthroplasty unit between 2001 and 2021.Their infection-free survival, re-operation rate, mortality, risk factors, complications and functional scores were presented.Results: The mean follow-up time was 7 (2 to 22) years, and nine knees (11.5%) were reinfected.The infection-free survival was 91.8% at 2 years, and 86.8% at 5, 10, 15 and 20 years.Five knees were re-operated on for aseptic causes.The cumulative survival for re-operation for aseptic causes was 97.3% at 2 and 5 years, 93.1% at 10 years, and 79.9% at 15 and 20 years.The cumulative survival for all-cause revision was 89% at 2 years, 86% at 5 years, 79.8% at 10 years and 76.3% at 15 and 20 years.Five knees did not complete the treatment (no 2nd stage) and they were excluded from survival analysis.The mean WOMAC knee score has improved from 69.3 15.3 pre-operative to 40.5 20.8 at 2.2 (2-5) years (P < 0.001) and remained relatively constant until latest follow-up.The most common microorganism was coagulase-negative staphylococci (42.3%) and 20.5% of cases were culture-negative.No risk factors were identified as predictors of failure.Conclusion: Our protocol of two-stage revision for knee PJI was successful and reproduced the best reported outcomes.