Cardiac Assessment of Patients With Hip Implants

BACKGROUND

Metal-on-metal (MOM) hip implants have a risk of releasing metal ions upon wear of the component material. Some of the metal ions (e.g. cobalt and chromium) from the metal implant or from the metal particles will enter the bloodstream.

The Food and Drug Administration (FDA, USA) recently highlighted systemic toxicity from metal on metal hip implants as a cause for concern and recommended that patients with systemic symptoms are assessed with a particular focus on cardiovascular, neurological, endocrinological (especially thyroid), and renal systems.

A number of cases of suspected toxicity to circulating cobalt and chromium from MOM hip implants, including cardiac toxicity, have been reported recently. The most profound case involves a patient who died from cardiac failure secondary to cardiomyopathy and cobalt deposition within the cardiac tissues. A recent cross sectional health screen and isolated case reports, suggest that raised metal ion levels have the potential to cause cardiomyopathy and cardiac failure. Such cases have raised public anxiety in the process.

Blood metal ions released from metal hip implants are increasingly recognized as a potential cause of local and distant abnormal tissue responses, since cobalt and chromium is released into the peri-prosthetic tissues and transported systemically throughout the body. Component design and positioning are associated with increased wear and as a result raised metal ion levels. However, a definitive causal link to systemic symptoms still remains to be established.