Monday, February 7, 2011

Cobalt Toxicity in Two hip Replacement Patients

MoM hip replacement patients for whom revision surgeries are indicated due to pain often have implant malposition and metallosis.  Additionally, these patients often have high serum and cobalt levels despite normal renal function and are at risk for cobalt poisoning.  Patients with impaired renal function may experience cobalt poisoning without the presence of pain despite a well positioned implant because cobalt released by normal implant wear is not adequately cleared by their kidneys.

These two Alaska case reports underscore the importance of monitoring MoM implant patients for signs of cobalt toxicity.

(Stephen S Tower, MD, Anchorage Fracture and orthopedic Clinic, State of Alaska Epidemiology Bulletin, May 28, 2010.)
[unfortunately, there is not much in the way of literature on systemic cobalt toxicity with hip implants.]

connie

2 comments:

  1. Hi Connie,
    Since the Alaska Epi report our first two cases have been detailed in the 12/2010 American JBJS. A more general paper on identifying patients at risk for cobalt poisoning was publish in Alaska Medicine in Summer 2010. These paper are easily found on line. We now have about 25 patients that have required revision of metal-metal hips because of Adverse Reactions to Metal Debris (ARMD), of those six likely have cobaltism. There are now about 14 published case of arthroprosthetic cobaltism. So far the toxic patients have had blood cobalt levels > 14 mcg/Liter. Early symptoms can include mood changes and tinnitus (ringing in the ears), rashes, and being easily winded. Patients with cobalt levels in excess of 20 mcg/Liter have been noted to develop stiffening of the heart on echocardiogram and high frequency deafness, and cognitive decline. Patient with blood cobalt level > 100 have been reported to have developed deafness, blindness, overt heart failure, hypothyroidism or goiter (enlargement of the thyroid gland), and peripheral neuropathy (numbness and weakness in the extremities).

    Sincerely,
    Stephen Tower, M.D.
    stephentower@mac.com

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  2. Thanks for your comment. Interesting statistics and observations.

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