Nationwide review of mixed and non-mixed components from different manufacturers in total hip arthroplasty: A Dutch Arthroplasty Register study

Background and purpose — Combining components from different 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 population-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 manufacturers (n = 12,960), and mixed stem-head-cup THAs with different femoral stem, head, and cup manufacturers (n = 1,773). Mixed prostheses were defined 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

Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty

Methods We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk. Results Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and by a possible antibiotic resistance and heavy metal co-selection mechanism. Interpretation Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future

Metal-on-metal bearings in total hip arthroplasties: Influence of cobalt chromium ions on bacterial growth and biofilm formation

Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm formation has never been studied. Therefore, the aim Of this Study was to evaluate how Co-Cr ions affect bacterial growth, biofilm formation, and architecture. A collection of clinically isolated and commercially available bacterial strains were exposed to Co-Cr concentrations as found in serum and above as found in adjacent tissue. Planktonic growth of bacteria was inhibited by concentrations of 200,000/93,000 mu g/L Co-Cr. Co-Cr concentrations Lip to 20/9.3 mu g/L as reported to occur in serum revealed no consistent influence on biofilm formation, but higher concentrations of 200,000/93,000 mu g/L significantly reduced Staphylococcus aureus and CNS biofilm formation. As indicated by confocal laser scanning microscopy, no dead bacteria were encountered in the biofilms, and the metal ion concentrations used must be classified as growth-inhibiting and not bactericidal. Long-term clinical data on infection rates for Co-Cr MOM-bearings are not yet available, but the current results suggest that Co-Cr ions may yield these prostheses less prone to biofilm formation and subsequent infection. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 88A: 711-716, 200

Influence of Co-Cr particles and Co-Cr ions on the growth of staphylococcal biofilms

Purpose: In the last decades, hip prostheses with a metal-on-metal (MOM) bearing have been implanted by orthopedic surgeons worldwide. However, concerns are now raised towards the metal particles and degradation products released by MOM-bearings into surrounding tissue, although effects of Co-Cr wear on infection are also unknown. Therefore, we here determine the viable volumes of staphylococcal biofilms formed on polystyrene in the absence and presence of Co-Cr particles and Co-Cr ions. Methods: Three clinically derived and two commercially available staphylococcal strains were grown in the presence of 2 mg/mL Co-Cr particles or 1000/500 mu g/L Co-Cr ions derived from Co-Cr salts or from particle supernatant, under static and dynamic growth conditions. A dynamic model simulates the conditions that apply for biofilm formation in the human body, as synovial fluid in mobile patients with hip prostheses is in constant motion with accompanying shear rates. Images of 24 h old biofilms were made with con focal laser scanning microscopy and analyzed with the mathematical computer program COMSTAT, yielding the biovolume of a biofilm. X-ray photoelectron spectroscopy was performed on the particles to study their elemental surface composition. Results: Most isolates showed a tendency of reduced biofilm growth in the presence of Co-Cr particles compared to growth during exposure to metal ions, but this was only significant in one strain under the dynamic growth condition (Staphylococcus aureus 7388). Characterization of the outer surface of the particles revealed a Co-Cr oxide layer enriched by Mo relative to the bulk concentration. Conclusions: MOM bearings produce metal particles which were found to possess antibacterial characteristics under dynamic growth conditions. Further research is needed towards the clinical relevance of this finding

The influence of Co-Cr and UHMWPE particles on infection persistence: An in vivo study in mice

Wear of metal-on-metal (cobaltchromium, CoCr particles) and metal-on-polyethylene (ultra-high-molecular-weight polyethylene, UHMWPE particles) bearing surfaces in hip prostheses is a major problem in orthopedics. This study aimed to compare the influence of CoCr and UHMWPE particles on the persistence of infection. Bioluminescent Staphylococcus aureus Xen36 were injected in air pouches prepared in subcutaneous tissue of immuno-competent BALB/c mice (control), as a model for the joint space, in the absence or presence of CoCr or UHMWPE particles. Bioluminescence was monitored longitudinally up to 21 days, corrected for absorption and reflection by the particles and expressed relative to the bioluminescence found in the presence of staphylococci only. After termination, air pouch fluid and air pouch membrane were cultured and histologically analyzed. Bioluminescence was initially lower in mice exposed to UHMWPE particles with staphylococci than in mice injected with staphylococci only, possibly because UHMWPE particles initially stimulated a higher macrophage presence in murine air pouch membranes. For mice exposed to CoCr particles with staphylococci, bioluminescence was observed to be higher in two out of six animals compared to the presence of staphylococci alone. In the majority of mice, infection risk in the absence or presence of CoCr and UHMWPE particles appeared similar, assuming that the longevity of an elevated bioluminescence is indicative of a higher infection risk. However, the presence of CoCr particles yielded a higher bioluminescence in two out of six mice, possibly because the macrophage degradative function was hampered by the presence of CoCr particles. (C) 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:341347, 201

Comparison of Techniques for Correction of Magnification of Pelvic X-rays for Hip Surgery Planning

The aim of this study was to develop an accurate method for correction of magnification of pelvic x-rays to enhance accuracy of hip surgery planning