DePuy Hip Implants The Sordid Details

Believe it or not, trace amounts of cobalt is necessary for one's health. This element is a key component in Vitamin B-12. So – why is it that when microscopic bits of cobalt metal from faulty implants get embedded in living tissue, the results include metallosis, synovitis and other health problems?

Notice the key term "trace amounts." Many elements that are necessary for proper biological function in extremely small amounts can be toxic in larger amounts. One case in point is potassium: an average sized male human weighing in at around 180 lbs may have up to 120 grams of potassium in his system; potassium (found in bananas, potatoes and avocados) is necessary to maintain neuron function and maintaining certain balances among bodily fluids inside and outside of cellular membranes. Some doctors even believe that hypertension may partially result from an imbalance between sodium and potassium in which levels of the latter are lower. On the other hand, excessive amounts of potassium can result in heart failure.

The optimal amount of cobalt in the human body is between 150 and 500 milligrams per kilo of body weight (a maximum of around 200 mg per pound). So, our average 180 pound male should have no more than about 15-17 grams of cobalt in his system.

The amount of cobalt fragments shed as hip implants fail is minute – but still more than is healthy. And here is the other factor. The cobalt metal that is used for joint replacements is not the same as naturally-occurring cobalt. That metal is actually an alloy; cobalt is combined with titanium, molybdenum and other metals. Such alloys are frequently used for high-precision machinery; it was apparently believed that its hardness and durability would be ideal for joint replacements.

Unfortunately, any metal-on-metal movement is going to result in some small amount of wear and tear. Medical scientists are not in complete agreement as to exactly what happens. The prevalent theory is that antibodies mistake metal ions for biological  pathogens, but some researchers say that the metal ions are too small for this to occur. 

What is not in doubt is that complications that include painful swelling due to inflammation (synovitus) and tissue necrosis are experienced by as many as eight out of every one hundred patients who receive metal-on-metal joint replacements. 

Sources

Metherell, Mark. "Faulty Hip Implants: Senate Inquiry Wants Action on 'Ticking Time Bomb."Sydney Morning Herald, 23 November 2011.

Romesburg, et. al. "Metallosis and Metal-Induced Synovitus Following Total Knee Arthroplasty: Review of Radiographic and CT Findings." Journal of Radiology Case Reports, vol. 4 no. 9 (Sept 2010).

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