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Evaluation of Prosthetic Implant Degradation

Orthopedic Prostheses



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Interpretive Values

Slide 10

December 2011

Our recommendations regarding interpretation of chromium and cobalt concentrations in various biological tissues are shown here. As noted previously, patients with functioning implants with no pain will have increased serum chromium and cobalt concentrations as compared to individuals with no implants. Patients with deteriorated implants typically have serum chromium in excess of 15 ng/mL and cobalt in excess of 10 ng/mL. The difference between synovial concentrations in patients with functioning implants compared to deteriorated implants is not as significant. We recommend serum chromium and cobalt tests for evaluation of these patients, rather than synovial fluid evaluation for chromium and cobalt.

It is important to point out at this time that some laboratories are offering tests for blood concentrations of chromium and cobalt for orthopedic evaluation. With 1 exception, all studies published in the peer-reviewed literature document an association between increased serum concentrations of chromium and cobalt and implant wear. One study by Liu, et al published in Tohoku Journal of Experimental Medicine in 1998 evaluated blood, but only correlated elevated blood chromium and cobalt with implant loosening. No peer-reviewed publications demonstrate that blood analysis correlates with implant wear. Despite this, the FDA has recommended blood analysis. Because CLIA rules require that all clinical laboratory tests be clinically validated, my interpretation is that the FDA implied evaluation of blood serum, since that specimen has been clinically validated.

Interpretive Values

 


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