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Background and purpose — Although common in medical research, meta-analysis has not been widely adopted in registry collaborations. A meta-analytic approach in which each registry conducts a standardized analysis on its own data followed by a meta-analysis to calculate a weighted average of the estimates allows collaboration without sharing patient-level data. The value of meta-analysis as an alternative to individual patient data analysis is illustrated in this study by comparing the risk of revision of porous tantalum cups versus other uncemented cups in primary total hip arthroplasties from Sweden, Australia, and a US registry (2003-2015). Patients and methods — For both individual patient data analysis and meta-analysis approaches a Cox proportional hazard model was fit for time to revision, comparing porous tantalum (n = 23,201) with other uncemented cups (n = 128,321). Covariates included age, sex, diagnosis, head size, and stem fixation. In the meta-analysis approach, treatment effect size (i.e., Cox model hazard ratio) was calculated within each registry and a weighted average for the individual registries’ estimates was calculated. Results — Patient-level data analysis and meta-analytic approaches yielded the same results with the porous tantalum cups having a higher risk of revision than other uncemented cups (HR (95% CI) 1.6 (1.4-1.7) and HR (95% CI) 1.5 (1.4-1.7), respectively). Adding the US cohort to the meta-analysis led to greater generalizability, increased precision of the treatment effect, and similar findings (HR (95% CI) 1.6 (1.4-1.7)) with increased risk of porous tantalum cups. Interpretation — The meta-analytic technique is a viable option to address privacy, security, and data ownership concerns allowing more expansive registry collaboration, greater generalizability, and increased precision of treatment effects. [ABSTRACT FROM AUTHOR]

Background: Earlier results with porous tantalum acetabular cups in revision THA generally have been favorable. Recently there has been some evidence presented that porous tantalum cups might decrease the risk of rerevision in the setting of revision hip surgery performed owing to prosthetic joint infection (PJI). As the data supporting this assertion come from a study with a limited study population, examining this issue with a large registry approach may be enlightening.Questions/purposes: By combining results from two large, national registries, we asked: (1) Do porous tantalum cups show improved survival after revision THA compared with other cementless designs? (2) Does the use of porous tantalum cups influence survivorship when rerevision for PJI is the endpoint?Methods: A total of 2442 first-time THA revisions with porous tantalum cups and 4401 first-time revisions with other uncemented cups were included in this collaborative study between the Australian and Swedish national joint registries. The mean age of the patients was 69 years (range, 19-97 years), 3754 (55%) of the patients were women, and the mean followup for the porous tantalum and uncemented control groups were 3.0 years (SD, ± 2.1 years) and 3.4 years (SD, ± 2.3 years), respectively. Concomitant stem revision was more common in the porous tantalum group (43% versus 36%). The use of porous tantalum augments also was analyzed as a proxy for more complex acetabular reconstructions. In an attempt to further reduce selection bias, we performed subgroup analysis for primary operations attributable to osteoarthritis and first revision attributable to aseptic loosening.Results: Kaplan-Meier survivorship with rerevisison for any reason up to 7 years was comparable between the porous tantalum cup group and the uncemented cup control group (86% [95% CI, 85%-89%] and 87% [95% CI, 85%-89%], respectively; p = 0.85) and the overall survivorship up to 7 years with a second revision for PJI as the endpoint (97% [95% CI, 95%-98%] and 97% [95% CI, 96%-98%], respectively; p = 0.64). Excluding procedures where augments had been used or studying primary osteoarthritis and first revision owing to aseptic loosening subgroups did not change this result.Conclusions: Implant survival for a porous tantalum cup in first-time THA revision was similar to the survival of the uncemented cup control group. With the numbers available, no benefit in survival with rerevision for infection as the endpoint could be ascribed to the porous tantalum cup group, as has been suggested by earlier work. Further studies with acetabular bone deficiency data, greater insight into host comorbidity factors, and a longer followup are needed to corroborate or refute these results.Level Of Evidence: Level III, therapeutic study. [ABSTRACT FROM AUTHOR]