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Background and purpose Joint Replacement Registries play a significant role in monitoring arthroplasty outcomes by publishing data on survivorship of individual prostheses or combinations of prostheses. The difference in outcomes can be device- or non-device-related, and these factors can be analyzed separately. Although registry data indicate that most prostheses have similar outcomes, some have a higher than anticipated rate of revision when compared to all other prostheses in their class. This report outlines how the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) has developed a method to report prostheses with a higher than expected rate of revision. These are referred to as 'outlier' prostheses. Material and methods Since 2004, the AOANJRR has developed a standardized process for identifying outliers. This is based on a 3-stage process consisting of an automated algorithm, an extensive analysis of individual prostheses or combinations by registry staff, and finally a meeting involving a panel from the Australian Orthopaedic Association Arthroplasty Society. Outlier prostheses are listed in the Annual Report as (1) identified but no longer used in Australia, (2) those that have been re-identified and that are still used, and (3) those that are being identified for the first time. Results 78 prostheses or prosthesis combinations have been identified as being outliers using this approach (AOANJRR 2011 Annual Report). In addition, 5 conventional hip prostheses were initially identified, but after further analysis no longer met the defined criteria. 1 resurfacing hip prosthesis was initially identified, subsequently removed from the list, and then re-identified the following year when further data were available. All unicompartmental and primary total knee prostheses identified as having a higher than expected rate of revision have continued to be re-identified. Interpretation It is important that registries use a transparent and accountable process to identify an outlier prosthesis. This paper describes the development, implementation, assessment, and impact of the approach used by the Australian Registry. [ABSTRACT FROM AUTHOR]

Background: Articular Surface Replacement (ASR) hip prostheses, which have metal-on-metal bearing surfaces, were manufactured by DePuy Orthopaedics (Warsaw, Indiana) for use in both conventional total hip arthroplasty and hip resurfacing. Both the ASR XL Acetabular System and the ASR Hip Resurfacing System were recently recalled worldwide by the manufacturer. This report summarizes an analysis by the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) of the outcome of arthroplasties involving the ASR prostheses. Methods: The first recorded use of the ASR XL Acetabular System in Australia occurred in 2004, and the Registry recorded 4406 procedures involving this system through December 31, 2009. The first recorded use of the ASR Hip Resurfacing System in Australia occurred in 2003, and the Registry recorded 1167 procedures through December 31, 2009. The Kaplan-Meier method and proportional-hazard modeling were used to compare the revision rate of primary total hip arthroplasties involving the ASR XL Acetabular System with that of arthroplasties involving all other conventional prostheses as well as with that of arthroplasties involving all other conventional prostheses with a metal-on-metal-articulation. In addition, the revision rate of primary arthroplasties involving the ASR Hip Resurfacing System was compared with that of arthroplasties involving all other hip resurfacing prostheses. Patient demographics, prosthesis characteristics, and information regarding the type of revision and the reason for revision were also compared. Results: Arthroplasties involving both ASR designs had a significantly greater revision rate compared with those involving all other prostheses. The cumulative revision rate of arthroplasties involving the ASR XL Acetabular System at five years postoperatively was 9.3% (95% confidence interval [CI], 7.3% to 11.9%) compared with 3.4% (95% CI, 3.3% to 3.5%) for total hip arthroplasties involving all other conventional prostheses. The cumulative revision rate of arthroplasties involving the ASR Hip Resurfacing System at five years postoperatively was 10.9% (95% CI, 8.7% to 13.6%) compared with 4.0% (95% Cl, 3.7% to 4.5%) for arthroplasties involving all other resurfacing prostheses. Arthroplasties involving the ASR XL Acetabular System had a greater rate of revision due to implant loosening and/or osteolysis and due to metal sensitivity compared with total hip arthroplasties involving all other conventional prostheses. Arthroplasties involving the ASR XL Acetabular System also had a significantly greater revision rate compared with total hip arthroplasties involving all other conventional metal-on-metal prostheses. Arthroplasties involving the ASR Hip Resurfacing System had a greater rate of revision due to metal sensitivity compared with total hip arthroplasties involving all other resurfacing prostheses. Conclusions: ASR prostheses used in conventional hip arthroplasty and in hip resurfacing exhibited a greater revision rate compared with other prostheses in the AOANJRR. These results are consistent with those derived from other registries and from published studies of individual cohorts. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]