Abstract
Introduction
There is conflicting evidence about the merits of using mobile bearings at total knee replacement (TKR), partly because most randomised controlled trials (RCTs) have not been adequately powered.
Methods
A pragmatic multicentre RCT involving 116 surgeons in 34 UK centres was begun in 1999. Within a partial factorial design, 539 patients were randomly allocated to mobile or fixed bearings. The primary outcome measure was the Oxford Knee Score (OKS); secondary measures included SF-12, EQ-5D, costs, cost-effectiveness and need for further surgery.
Results
There was no significant difference between the groups preoperatively. At five years the mean OKS was approximately 33 in both groups. There was no significant difference between trial groups in OKS at five years (-1.21 95%CI -3.20, 0.96) or any of the other outcome measures. There was no significant difference in the proportion of patients with knee-related re-operations.
Discussion and Conclusion
In this appropriately powered RCT over the first five years after TKR, functional outcomes and re-operation rates appear to be the same whether mobile of fixed bearings are used.