Knee arthroplasty system with medialized keel: Seven-year follow-up of a pioneer cohort

Background: In this clinical investigation, a new design with a progressive increased keel medialization according to the size was implanted. The cohort of patients was followed up for seven years. Methods: From May 2012 to November 2012, we implanted 70 total knee arthroplasties in 69 patients. The mean age of the patients was 76.2 years. We followed up 56 patients for seven years; we evaluated the patients at six and 60 months after surgery by Patient Reported Outcome Measures score. During the seven-year follow-up, all patients were clinically re-evaluated using the Knee Society Score and the Forgotten Joint Score. All patients underwent a preoperative and postoperative radiographic investigation. At the last follow-up the presence of any radiolucency lines was checked using the Knee Society Total Knee Arthroplasty Radiographic Evaluation and Scoring System. Results: The patients defined the surgical results as excellent in 66% of the cases, very good in 23%, good in five percent. The analysis of the functional data at seven years, performed by administering the Forgotten Joint Score, showed average values of 70.4. The clinical analysis, performed through the Knee Society Score at the same follow-up, showed average values of 90.4. The seven-year radiological analysis revealed the presence of radiolucency lines in 20 implants. The sum of the line widths never exceeded the critical value of nine millimeters, always remaining below four millimeters. Only one patient was revised. Conclusions: The results showed an excellent outcome of this design. The medialization of the tibial keel showed good bone fixation and component alignment at seven-year follow-up.