UNI-COMPARTMENTAL OR TOTAL KNEE REPLACEMENT? THE TEN-YEAR RESULTS OF A RANDOMISED STUDY

Abstract

Introduction and Aims: There has recently been an increase in the use of uni-compartmental knee replacement (UKR), but there are few studies comparing its long-term efficacy and survival with total knee replacement (TKR). We reported the five-year results of a randomised trial which showed that uni-compartmental replacement had a faster rehabilitation and better functional results than total replacement. We now report the 10-year results.

Method: After obtaining ethical approval, between 1989 and 1992, 102 cases judged suitable for UKR were randomly allocated to receive either a St Georg Sled UKR or a Kinematic Modular TKR. Both cohorts had a median age of 68 and a similar sex distribution and pre-operative knee scores. Regular follow-up has been maintained. All cases have now been assessed after a minimum of 10 years using modified the WOMAC, Pain, Oxford and Bristol Knee (BSK) scoring systems as well as radiographs.

Results: At 10 years, 29 cases had died with their knees known to be intact, two totals cases were untraceable. Thirty-two uni`s, and 34 totals were available for review. Three uni`s (6%) and two totals (4%) had been revised; there was one impending total failure on the radiographs.

The UKR group had better scores with Oxford: 38 v 34 /48 and WOMAC: 17 v 21 /60 and more excellent results (19 v 14) and fewer fair and poor results on the BKS (4 v 6). The range of movement improved in UKA`s from 107 degrees to 117 degrees, whereas the range decreased in TRK`s from 107 degrees to 104 degrees. Sixty-one percent of the UKR and only 16% of the TKR group had more than 120 degrees of flexion.

Conclusion: The St Georg Uni-compartmental arthroplasty continues to function well at 10 years, with better functional scores and a better range of movement than the Kinematic Total arthroplasty. There were similar failures in both groups.