Nationwide review of mixed and non-mixed components from different manufacturers in total hip arthroplasty

Background and purpose — Combining components from dif- ferent manufacturers in total hip arthroplasty (THA) is common practice worldwide. We determined the proportion of THAs used in the Netherlands that consist of components from different manufacturers, and compared the revision rates of these mixed THAs with those of non-mixed THAs. Patients and methods — Data on primary and revision hip arthroplasty are recorded in the LROI, the nationwide popula- tion-based arthroplasty register in the Netherlands. We selected all 163,360 primary THAs that were performed in the period 2007–2014. Based on the manufacturers of the components, 4 groups were discerned: non-mixed THAs with components from the same manufacturer (n = 142,964); mixed stem-head THAs with different manufacturers for the femoral stem and head (n = 3,663); mixed head-cup THAs with different head and cup manu- facturers (n = 12,960), and mixed stem-head-cup THAs with dif- ferent femoral stem, head, and cup manufacturers (n = 1,773). Mixed prostheses were defi ned as THAs (stem, head, and cup) composed of components made by different manufacturers. Results — 11% of THAs had mixed components (n = 18,396). The 6-year revision rates were similar for mixed and non-mixed THAs: 3.4% (95% CI: 3.1w–3.7) for mixed THAs and 3.5% (95% CI: 3.4–3.7) for non-mixed THAs. Revision of primary THAs due to loosening of the acetabulum was more common in mixed THAs (16% vs. 12%). Interpretation — Over an 8-year period in the Netherlands, 11% of THAs had mixed components—with similar medium- term revision rates to those of non-mixed THAs.