Fixed Versus Mobile Bearing Knee Arthroplasty: A Randomized Trial with a Minimum of 10-Year Follow-Up.

Abstract

The mobile bearing knee arthroplasty features a highly congruent mobile meniscal bearing allowing both rotation and antero-posterior translation. At present, it remains unclear whether fixed bearing platforms are clinically advantageous over mobile bearings. In this randomized trial, we sought to compare patient-reported outcomes, complications, and revision rates in patients undergoing fixed versus mobile bearing total knee arthroplasty (TKA) for osteoarthrosis. In this randomized trial, data from 207 patients (105 patients who had mobile bearing TKA and 102 patients who had fixed bearing TKA) were gathered between 2001 and 2006. Overall, the mean age at surgery was 61 years (range, 42 to 71) with 104 men and 102 women. The primary outcome was the Oxford Knee Score (OKS) over a 10-year follow-up period. The secondary outcomes were the Western Ontario and McMaster Universities (WOMAC) arthritis index, Bristol Knee Score, and postoperative complications. Failure of an implant was defined as revision for any reason and/or removal of any implant for any reason and expressed as a risk ratio. For the primary outcome measure with OKS, there was a statistically significant difference in patient-reported outcome measure (PROM) in favor of the fixed bearing group at two-year follow-up (mean difference in OKS was 3.6; 95% confidence interval (CI): 0.51 to 6.69, P = 0.0226). There was no statistically significant effect demonstrated in the reoperation rate between the two intervention groups over a 19-year period (the risk ratio was found to be 1.51 (95% CI: 0.79 to 2.87, P = 0.2096)) or in PROMs at 10 years. At two-year follow-up, there was no clinically meaningful difference in patient-reported outcome measures (PROMs) between fixed-bearing and mobile-bearing total knee arthroplasty. In addition, no difference in reoperations was noted at any time point up to the 19-year follow-up.