Technical aspects of revision and functional outcome after revision of the Oxford unicompartmental knee arthroplasty.

BACKGROUND: This study analysed the technical aspects of revision of the Oxford unicompartmental knee arthroplasty (OUKA) and functional results after revision.

METHODS: In a historic cohort study we analysed all revised OUKAs that were primarily implanted at our clinic over a 10-year period (1998-2009). The primary aim was to investigate surgical difficulties encountered during revision surgery of the OUKA. Outcomes were the knee society score (KSS), WOMAC (Western Ontario and McMaster Universities), SF-36, VAS pain and VAS satisfaction after revision.

RESULTS: During the study period, 331 OUKAs were inserted. With an average follow-up of six years and five months (range one month to nine years and eight months), there were 44 (13.3%) OUKAs that needed one or more revision surgery procedures. The average time to revision was three years and eight months (range one month to nine years and five months). The main reasons for revision surgery were bearing dislocation, malpositioning or loosening of a component and progression of osteoarthritis. Most revisions, mainly conversion to primary total knee arthroplasty (TKA), gave few surgical problems. Minor bone loss that needed no augmentation was seen most frequently. The functional outcomes after revision surgery were moderate.

CONCLUSION: A limited amount of surgical difficulty during revision of OUKA was found; in all total revision cases a primary TKA was implanted. However, in most patients there were moderate functional results as well as disappointing pain and satisfaction scores after revision.