Over the past twenty years, the Low Contact Stress Rotating Platform (LCS RP) showed good results. Buechel and Pappas invented the Buechel-Pappas Knee (B-P Knee) system that is a modified version of the LCS system with different material (titanium), axial rotation limiting bar and improved conformity. The purpose of this prospective randomized study was to compare the 2-year clinical outcomes between two implants in the same patients who had been operated with bilateral TKAs. We prospectively enrolled 107 patients and 18 patients were lost to follow-up. Therefore, 89 patients (178 knees; mean age, 69.8±6.0years) were included in the study. The range of motion and clinical scores such as Knee Society score (KSS), Hospital for Special Surgery score (HSS) and Western Ontario and McMaster University (WOMAC) scores were measured preoperatively and postoperatively. At each follow-up, patients also complete a Likert scale questionnaire regarding subjective pain, lightness, left-right side preference (naturalness and satisfaction) and subjective instability. There were no significant differences in all preoperative variables between the two groups(