Appendix A.tiff

BACKGROUND

This prospective study evaluates outcomes and reoperation rates for unicompartmental knee arthroplasty (UKA) from a single non-designer surgeon using relatively extended criteria of degenerative changes of grade 2 or above in either or both non-operated compartments.

METHODS

187 consecutive medial mobile bearing UKA implants were included after history, clinical assessment and radiological evaluation. 91 patients had extended clinical outcomes. Post-operative assessment included functional scoring with the Oxford Knee Score (OKS) and radiographic review. Survivorship curves were constructed using the life-table method, with 95% confidence intervals calculated using Rothman`s equation. Separate endpoints were examined: revision for any reason and revision for confirmed loosening.

RESULTS

The mean follow-up was 3.5 years. The pre-operative OKS improved from a mean of 21.2 to 38.9 (Mann-Whitney U Test, p=<0.001). Twelve Patients required further operations including 9 revisions. No patients developed deep infection and no surviving implants were loose radiographically. Survivorship at 7 years with endpoints of re-operation, revision and aseptic loosening at surgery or radiographically was 88.4% (95% CI 79.6-93.7), 93.1% (95% CI 85.5-96.9) and 97.3% (95% CI 91.2-99.2) respectively. The presence of pre-operative mild contralateral tibiofemoral or any extent of patellofemoral joint degeneration was of no consequence.

DISCUSSION

This study shows comparable clinical outcomes of UKA for extended indications from a high volume, high-usage non-designer unit.