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Register studies

Higher revision risk for unicompartmental knee arthroplasty in low-volume hospitals

Data from 5,791 cases in the Norwegian Arthroplasty Register

, , , &
Pages 342-347 | Received 06 Nov 2013, Accepted 11 Mar 2014, Published online: 21 May 2014
 

Abstract

Background and purpose — Some studies have found high complication rates and others have found low complication rates after unicompartmental knee arthroplasty (UKA). We evaluated whether hospital procedure volume influences the risk of revision using data from the Norwegian Arthroplasty Register (NAR).

Materials and methods — 5,791 UKAs have been registered in the Norwegian Arthroplasty Register. We analyzed the 4,460 cemented medial Oxford III implants that were used from 1999 to 2012; this is the most commonly used UKA implant in Norway. Cox regression (adjusted for age, sex, and diagnosis) was used to estimate risk ratios (RRs) for revision. 4 different volume groups were compared: 1–10, 11–20, 21–40, and > 40 UKA procedures annually per hospital. We also analyzed the reasons for revision.

Results and interpretation — We found a lower risk of revision in hospitals performing more than 40 procedures a year than in those with less than 10 UKAs a year, with an unadjusted RR of 0.53 (95% CI: 0.35–0.81) and adjusted RR of 0.59 (95% CI: 0.39–0.90). Low-volume hospitals appeared to have a higher risk of revision due to dislocation, instability, malalignment, and fracture than high-volume hospitals.

MB: study design, data collection, and drafting of manuscript. BE: data acquisition, data analysis, and revision of manuscript. KI: revision of manuscript. LIH: data collection and revision of manuscript. OF: study design, collection and interpretation of data, statistics, and revision of manuscript.

There was no external funding. The NAR is financed by the Regional Health Board of Western Norway. We want to thank the Norwegian orthopedic surgeons for excellent reporting to the NAR.