Systemic toxicity related to metal hip prostheses.

Area of Science:

• Orthopedic Surgery
• Toxicology
• Biomaterials Science

Background:

• Total hip replacements (THRs) have a high revision rate (1 in 8 within 10 years), primarily due to wear-related complications.
• Bearing surfaces of THRs, including cobalt/chromium, stainless steel, ceramic, or polyethylene, can release metal ions.
• Friction and corrosion in THR components can elevate local and systemic metal concentrations.

Purpose of the Study:

• To systematically review published reports on systemic toxicity linked to metals from hip implants.
• To establish criteria for assessing patients with suspected metal-induced systemic toxicity.

Main Methods:

• Searched Medline and Embase databases (1950-2014) for studies on chromium/cobalt toxicity in prostheses.
• Included PubMed searches for relevant MeSH terms and keywords.
• Analyzed 26 papers describing 18 individual cases of systemic toxicity.

Main Results:

• Systemic toxicity was observed in patients with revised ceramic-to-metal bearings (10 cases) and metal-on-metal prostheses (8 cases).
• Manifestations included neuro-ocular (14 patients), cardiotoxicity (11 patients), and thyroid toxicity (9 patients).
• Elevated blood cobalt concentrations were noted, particularly in patients with revised ceramic-to-metal implants.

Conclusions:

• High circulating cobalt concentrations from failed hip replacements can cause neurological damage, hypothyroidism, and cardiomyopathy.
• Accelerated wear in revised ceramic-to-metal implants presents a greater risk for systemic cobalt toxicity than primary metal-on-metal implants.