Objectives: The results of knee arthroplasty are commonly assessed by survival analysis using revision as the endpoint. We have used the assessment of pain by a patient based questionnaire as an alternative after the Oxford Phase 3 UKA implanted by a minimally invasive technique.

Materials and Methods: Between January 1999 and May 2007, 223 consecutive Oxford arthroplasties were implanted by a single surgeon in a county hospital. Mean followup period was 35 months. Patients were assessed prospectively pre-operatively and after UKA in each year subsequently by a questionnaire. Survival analysis was undertaken.

Results: Preoperatively 85.8% had moderate or severe pain. Postoperatively, of five patients(2.6%) with persisting pain due to failure of using proper patient selection three were revised to TKA and two are still being followed. Three patients(1.6%) with moderate pain after using proper indication criteria accepted their complaints. Ten other patients (5.2%) experiencing moderate pain some time during the eight year period were successfully treated by arthroscopy. If after surgery patients experienced pain which had spontaneous improved by the second year, the initial pain was ignored. Totally 9.6% of patients experienced moderate or severe pain at some stage, and the failure rate was 4.2% in this period of 8 years’ experience.

Conclusion: When strict indications are followed the failure rate of the procedure can be minimised till 1.6% when moderate pain is considered the endpoint. As relief of pain is the primary reason for joint replacement, this is likely to be the most important factor in determining the long-term outcome for the patient.