Abstract
Introduction
Kozinn and Scott have made recommendations about contra-indications for unicompartmental knee replacement (UKR). They suggest that patients younger than 60, weight > 82 kilograms, patients with exposed bone in patella-femoral compartment or patients who are physically active/perform heavy labour should not be offered a UKR. In addition, chondrocalcinosis is a contra-indication. These strict selection criteria are based on the experience with fixed bearing UKAs and are more intuitive than evidence based. The Oxford UKR has a fully congruous mobile bearing and has been shown to have minimal wear. Over the past 25 years, the Oxford Group has followed a standardised protocol for patient selection for UKR. We ignore patella-femoral joint pathology, chondrocalcinosis, patient's age, weight and activity level when deciding the suitability for UKR.
Methods
Using the standardised indications, more than 1100 Oxford UKRs have been performed to date over the last 10 years. These patients are assessed pre-operatively and at regular intervals post-operatively in a dedicated research clinic. We present the results of these consecutive cases. Patients were classified into two groups: group I (satisfy Kozinn-Scott recommendations) and group II (outside recommendations).
Results
Overall 70% of patients were outside Kozinn and Scott's indications (27% < 60 years, 47% > 82 kg, 12% chondrocalcinosis and 21% with patellofemoral damage with exposed bone as an inter-operative finding, 10% Tegner score 5 or more). No significant difference was noted either in 10 year survivorship or in 5-year clinical outcome (mean 5 year Oxford Knee Score [range 0 -48] for group I is 41 and 40.5 for group II).
Discussion and Conclusion
These results suggest that the indications for UKR proposed by Kozinn and Scott are too narrow. Probably four times as many patients are appropriate for the mobile bearing Oxford Unicompartmental Knee Replacement than suggested.
