Survivorship and patient satisfaction of a fixed bearing unicompartmental knee arthroplasty incorporating an all-polyethylene tibial component

We report the survivorship of 91 fixed bearing unicompartmental arthroplasties with all-polyethylene tibial components (Preservation DePuy UK), which were used for medial compartment osteoarthritis in 79 patients between 2004 and 2007. The satisfaction level of patients who had not undergone revision of the implant was also recorded. For comparison, we reviewed 49 mobile bearing unicompartmental arthroplasties (Oxford UKA Biomet UK Ltd), which had been used in 44 patients between 1998 and 2007. Mean length of follow-up of patients with the fixed bearing implant was 44.7 months (range 24–74 months) and for the mobile bearing replacement, the mean follow-up was 67.6 months (24–119). In the fixed bearing design, at maximum follow-up period of 74 months, eight implants (8.8%) had been revised (or were listed for revision) to Total Knee Replacement and in the mobile bearing design over the maximum follow-up period of 119 months there had been only one revision (2.0%). Patients who had not undergone revision were asked if they were satisfied with their knee following the unicompartmental arthroplasty. In the fixed bearing design, 83.5% said that they were satisfied with the outcome of the operation compared to 93.9% of the patients receiving the mobile bearing design. We conclude that there is a higher incidence of revision of this fixed bearing design using an all-polyethylene tibial component compared to the mobile bearing design. We found that those patients who had not required revision had a lower rate of satisfaction with the fixed bearing compared to the mobile bearing design.