Mid-Term Clinical Outcomes And Survivorship Of A Second-Generation Modular Revision Knee System

Introduction: Revision knee systems have adapted to the challenges of revision knee arthroplasty with offset stems, augments, cones, and various levels of constraint. The purpose of this study is to review the mid-term outcomes of a second-generation modular knee revision system.Materials and Methods: A retrospective review was conducted from 2011 through 2014 on all patients who underwent knee arthroplasty with the Vanguard (R) 360 revision knee system (Zimmer Biomet, Warsaw, Indiana). Patients were included in the study if they were eligible for five-year minimum follow up and had signed a general research consent. The initial query revealed 253 patients (267 knees) that met inclusion criteria. Complications assessed were manipulation under anesthesia (MUA) and revision of any component. Statistical analysis using paired t-test was performed to evaluate changes in clinical outcomes and Kaplan-Meier survival analysis.Results: Mean follow up was 6.6 years. The Vanguard (R) 360 knee system was used in four (1.5%) primary total knee arthroplasties (TKAs), 66 (24.7%) second-stage reimplantation TKAs after infection, and 197 ( 73.8%) aseptic revisions. There were significant improvements in knee range of motion and Knee Society Scores (all p<0.05). Manipulations under anesthesia were performed in 17 knees (6.4%). A total of 41 knees (15.4%) failed for any cause and required re-revision surgery. Of these, 11 (4.1%) failed due to aseptic loosening. Kaplan-Meier analysis revealed overall survival to endpoint of aseptic loosening to be 96.4% (95% CI: +/- 1.2%) at five years and 95.2% (95% CI: +/- 1.4%) at 9.5 years. When comparing survivorship in patients who underwent initial revision for aseptic indications compared with those whose underwent revision for second-stage reimplantation after infection, Kaplan-Meier survival to endpoint of revision for any cause at 9.5 years was higher for patients with aseptic than septic indication for TKA (87.0% [95% CI: +/- 2.4%] vs. 75.3% [95% CI: +/- 5.4%], p=0.0156).Conclusion: The findings of this study demonstrate greater than 95% aseptic survivorship with the use of the Vanguard (R) revision knee system at mid-term follow up.