Introduction and Aims: Uni-compartmental knee arthroplasty has become a frequently performed procedure in patients with medial compartment osteoarthritis. There has been very little reported in the literature on lateral uni-compartmental knee arthroplasty results.

Method: One hundred and twenty-three consecutive patients undergoing an elective lateral uni-compartmental arthroplasty were identified from our database between November 1998 and November 2003. Prospective data collection included patient demographics, prosthesis type and radiological evaluation. Clinical outcome measures were assessed using the Oxford Knee Score. All adverse outcomes were analysed.

Results: One hundred and twenty-three patients (28% male and 72% female) with a mean age of 68 years and a mean body mass index of 28 were identified. The average pre-operative Oxford Knee Score was 19/48. The average post-operative improvement was 20 points. There were seven complications which have been analysed. These include one infection and six dislocated bearings in the Oxford Knee group.

Conclusion: The Oxford mobile bearing lateral prosthesis has a significantly higher complication rate than the fixed bearing implants in lateral uni-compartmental arthroplasty.