Two-Stage Treatment of Chronic Periprosthetic Knee Infections With the Use of Gentamicin-Articulated Spacers: Success Rate and Predictors of Failure at the Minimum Seven-Year Follow-Up

BACKGROUND: The purpose of this study was to assess the survivorship rates of 2-stage treatment with gentamicin-impregnated polymethylmethacrylate articulated knee spacer in patients with chronic periprosthetic joint infection and to identify risk factors associated with failure. METHODS: We conducted a retrospective study among 73 patients with chronic periprosthetic joint infection after primary total knee replacement with articulated polymethylmethacrylate gentamicin-impregnated spacers (Subiton, Medical Labs, Ind Argentina), performed in a single institution with a minimum follow-up of 7 years. Clinical and functional assessment was performed with Knee Society Score and Western and Ontario McMaster Universities Osteoarthritis Index. A univariate and multivariate analysis was performed to identify the variables that influenced the success and failure rates. RESULTS: We included 73 patients. There were 53 (71.3%) monomicrobial, 11 (15%) polymicrobial, and 10 (13.7%) negative cultures infections. The success and failure rates were 90.5% (n = 66) and 9.5% (n = 7), respectively. Multivariate analysis identified that age (odds ratio = 1.77; P = .039), greater erythrocyte sedimentation rate values prior to the first stage (odds ratio = 1.04; P = .006), and polymicrobial infections (odds ratio = 7.32; P = .0003) were independent variables associated with failure. CONCLUSIONS: Two-stage revision with polymethylmethacrylate gentamicin-impregnated knee spacers is an effective strategy for the treatment of chronic periprosthetic joint infection after total knee arthroplasty. Age, higher erythrocyte sedimentation rate values prior first stage, and polymicrobial infections were independent risk factors for treatment failure.