Results of Two-Stage Exchange for Periprosthetic Joint Infection Following Total Knee Arthroplasty: Low Rates of Failure in 463 Knees at 10 years.

Abstract

Some recent data suggest similar reinfection rates between two- and one-stage exchange arthroplasties for infected total knee arthroplasties(TKAs). However, those data are limited by their short duration and cannot provide meaningful analysis of aseptic failure rates. The purpose of this study was to assess the 10-year results of two-stage exchange for TKAs in one of the largest series to date. We identified 463 infected TKAs treated with two-stage exchange from 1991-2021 at a single institution. The mean age at reimplantation was 68 years,49% were women; mean body mass index(BMI) was 32 (range,16 to 64). Diagnosis of periprosthetic joint infection (PJI) was based on the 2011 Musculoskeletal Infection Society(MSIS) criteria. Cumulative incidences of reinfection and revision with death as a competing risk were calculated. The mean follow-up was eight years(range,two to 30). The cumulative incidence of reinfection was 6% at one year,14% at five years,19% at 10 years. Factors predictive of reinfection included elevated body mass index (BMI) (hazard ratio(HR) 1.3 for every 5-point increase), McPherson host grade C(HR 2.3),previous revision surgery(HR 2.1) and Anderson Orthopaedic Research Institute(AORI) type-3 bone loss(HR 4.6). The cumulative incidence of aseptic revision was 1% at one year, 5% at five years, 9% at 10 years. The cumulative incidence of any revision was 7% at one year,18% at five years,26% at 10 years. The most common indications for revision were recurrent PJI(63%),aseptic loosening(22%),and instability(6%). The mean Knee Society Score (KSS) improved from 48 to 69 at two years. In this series of 463 two-stage exchanges for infected TKAs, the cumulative risk of reinfection was less than 20%, and the cumulative risk of aseptic revision was less than 10% at 10 years. Poor host status, obesity, and severe bone loss were predictive of reinfection. These outcomes provide a benchmark against which new management protocols may be compared.