CoCrMo implants

Metikos-Hukovic, M., Pilic, Z., Babie, R., Omanovic, D. Influence of alloying elements on the corrosion stability of CoCrMo implant alloy in Hank s solution. Acta Biomater. 2, 693-700 (2006)... 

However, nanostructured CoCrMo implants still possess a potential risk of longterm toxicity caused by nanoscale wear debris from the articulating surfaces [30], especially in the case of metal-on-metal implants. In a recent study, cytotoxic and genotoxic effects of nanoparticles and micron-sized particles of CoCr alloy were... 

Metal CoCrMo alloy Femoral balls, shafts, knee implants Bioinert Fathi, Ahmadian and Bahrami (2012)... 

Several implants are commercially available for total or partial disk replacements. For instance, currently, two polymer-based cervical and two lumbar disk prostheses approved by the FDA are being widely used for disk replacement applications [103]. The first artificial disk (DePuy Inc.), approved by the FDA in 2004, was based on a hard-on-soft technology, which employed a CoCrMo alloy in conjunction with UHMWPE. Alternatively, ProDisc-C (Eigure 19.3b,i), approved in 2006 and 2007 for both lumbar and cervical replacements, respectively, was based on similar types of polymer composites. More recently, Medtronic developed Bryan prosthesis using titanium alloys and PU polymer (Figure 19.3b,ii) [104]. 

Nanoscale debris from CoCrMo, which is also a widely used orthopedic implant material, may also induce DNA and chromosome damage as well as cytotoxicity. For instance, CoCr nanoparticles demonstrated more severe DNA damage, chromosomal damage, and toxic effects compared to micron-sized CoCr particles [8,9]. For orthopedic implants made of stainless steels, Fe or Ni nanoparticles are also possible sources for triggering toxicity and adverse effects at local or systemic levels. For example, Ni particles implanted in rat soft tissues were found to cause just allergic reactions when... 

Crockett R. Roba H Naka M, Gasser B. Delfosse D. Frauchiger V. et al. Friction, lubrication, and po rmer transfer between UHMWPE and CoCrMo hip-implant materials a fluores( n( microscopy study. Journal of Biomedical Materials Research 2008. doi 10.1002/jbm.a.32036. 

Friction, lubrication, and polymer transfer between UHMWPE and CoCrMo hip-implant materials ... 

The adsorption of albumin, the most abundant protein in synovial fluid, on implant materials was studied in detail by means of XPS and I -labeUed albumin. These techniques showed the formation of a monolayer of albumin on alumina but multilayered islands of protein on the CoCrMo surface. No PE transfer was observed in AFM images of the surface of CoCrMo after tribological tests when an albumin solution was used as the lubricant. However, contrary to the studies described earlier, the addition of albumin to a solution of Hank s balanced salt solution caused a dramatic drop in the friction coefficient for UHMWPE sliding against CoCrMo. ... 

Friction, Lubrication, and Polymer Transfer Between UHMWPE and CoCrMo Hip-Implant Materials A Fluorescence Microscopy Study Rowena Crockett, Marcella Roba, Marco Naka, Beat Gasser, Daniel Delfosse, Vinzenz Frauchiger, Nicholas D. Spencer J. Biomed. Mat. Res. A] 2009 89A(4) pp 1011-1018... 

The ASTM lists four types of CoCr alloys which are recommended for surgical implant apphcations (1) cast CoCrMo alloy (F75), (2) wrought CoCrWNi alloy (F90), (3) wrought CoNiCrMo alloy (F562), and (4) wrought CoNiCrMoWFe alloy (F563). The chemical compositions of each are summarized in Table 38.3. At the present time only two of the four alloys are used extensively in implant fabrications, the castable CoCrMo and the wrought CoNiCrMo alloy. As can be noticed from Table 38.3, the compositions are quite different from each other. 

Attempts to use titanium for implant fabrication dates to the late 1930s. It was found that titanium was tolerated in cat femurs, as was stainless steel and VitaUium (CoCrMo alloy). Titanium s lightness (4.5 g/cm, see Table 38.5) and good mechanochemical properties are salient features for implant application. 

Yan, Y, Neville, A. and Dowson, D. (2007), Biotiibocorrosion of CoCrMo orthopaedic implant materials - Assessing the formation and effect of the biofilm . Tribology International, 40,1492-9. 

Eight MM implants (Table 1) were tested in an orbital bearing hip simulator (Fig. 4) for a total of 4 Me. All components were manufactured from medical grade CoCrMo alloy (ASTM FI537) and had high carbon (HC) content, except for the Ultima heads that had low carbon (LC) content. 

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