Abstract
Purpose: To compare the ten-year survivorship results of an established total and medial compartment knee replacement performed in a single centre over an eighteen year period.
Method: Since 1978 knee replacements have been prospectively recorded in Bristol on a database. Regular clinical and radiological review has been undertaken every two or three years up to twenty years. 408 medial St Georg Unicompartmental replacements and 531 Kinematic total knee replacements have been subject to survivorship analysis using three failure end points. One - revision or removal of the implant. Two – revision or removal and moderate or severe pain. Three – the worst case including all patients lost to follow-up.
Results: The follow-up rate was 97% in both groups. 212 patients (562 knees) died and 31 patients (35 knees) were lost to follow-up. At ten years 25 medial Sled and 20 Kinematic knee arthroplasties had been revised. There was no significant difference (p > 0.05) in the number of good and excellent results. The mean range of movement at the last follow-up was 109 degrees for the medial Sled and 100 degrees for the Kinematic (p< 0.01). 94% of the medial Sled patients obtained a range of movement equal to or greater than 90 degrees whereas only 84% of Kinematic patients obtained this range (p < 0.05).
The ten-year survivorship figures were similar for both groups. Revision as the end point was 87.5% for the medial Sled and 89.6% for the Kinematic knees. When moderate and severe pain was considered in addition to revision ten-year survivorship was 79.4% in both groups. The worst case survivorship was also 74% in both groups.
Conclusion: The ten-year survivorship results of a fixed bearing, non-congruous, Unicompartmental arthroplasty are as good as those of a total knee replacement when performed in a single centre by two consultant surgeons and a variety of trainees. The advantages of a more rapid recovery and better quality result are offset by an easier though slightly higher revision rate.
The abstracts were prepared by Mr Roger Smith. Correspondence should be addressed to him care of the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
