Mid-term results of two-stage revision of total knee arthroplasty using a mobile (dynamic) cement spacer in the treatment of periprosthetic infections

Introduction: Infection of the knee joint after primary total knee arthroplasty is a serious complication. In this work, we would like to evaluate the mid-term results after two-stage revision of total knee replacement in periprosthetic infection using dynamic spacer, in particular with regard to the function of the knee joint after reimplantation. Patients and methods: In this retrospective study, we included patients who were treated in our clinic between 2005 and 2013 due to infection of the knee after total knee arthroplasty. All patients included have had a mobile antibiotic-coated cement spacer implanted after surgical debridement and removal of the components of total knee replacement. Subsequently, reimplantation of total knee replacement was performed when no clinical or paraclinical signs of infection were found. We analyzed all included cases for potential reinfection, examined the range of motion of the knee joint and evaluated the Merle d'Aubigne-Postel score. Statistical evaluation was performed with SPSS 24.0. Results: This study group contains 16 patients (9 women and 7 men) with an average age of 72.0 +/- 8.3 years. All patients were followed up for at least 6 months with an average follow-up of 22.5 +/- 16.6 months. In all patients a pathogen was isolated intraoperatively during the first-stage surgery (explantation of the knee). Staphylococci were detected in 94% of the cases, streptococci in only one patient. Reimplantation was carried out after 6.2 +/- 5.2 months. The average knee flexion in the group of patients without relapse of infection was 103.3 degrees +/- 17.1 degrees. Only 3 patients showed extension deficit of max. 20 degrees. The Merle d'Aubigne-Postel Score was 14.4 +/- 1.9. Conclusion: Two-stage surgery of total knee replacement with the use of a mobile spacer has its high value in the treatment of periprosthetic infections. The mobile spacers contribute to an advantageous range of motion of the knee joint after reimplantation of a total knee endoprosthesis. However, further studies are required that compare the results after using mobile or static spacer, but with the inclusion of homogeneous patient collective.