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The DePuy Hip Dead Zone

You hear a great deal about the "dead zone" these days.

 

In ecology, the term refers to areas of the ocean in which oxygen is absent and thus is devoid of life - something that is of great concern to environmentalists.  In communications technology, it describes areas in which cell phone service is unavailable. It was even an early novel by Steven King as he was making the transition between pulp fiction writer and serious literary figure.

 

Thanks to metal-on-metal hip implants, "dead zone" now describes areas of human tissues as well, resulting from metal poisoning caused by the shedding of small bits of metal.

 

In retrospect, one must wonder what the designers of these hip implants were thinking. Yes, the joint is lubricated and the pieces and parts are the product of precision engineering. However, consider a mechanical analogue, the automotive ball joint.

 

If you look at the picture above, you will see how an automotive ball joint resembles an artificial hip joint. Like a hip implant, most automotive ball joints are "sealed" and "permanently lubricated." However, automotive engineers will tell you that even when lubricated, any metal-on-metal surfaces are going to shed microscopic bits of metal over time. Generally, an automotive ball joint can be expected to fail within 80,000 miles.

 

Did the designers of hip implants think their device would be any different? Or did they not even care?

 

One interesting tidbit that was reported in Bloomberg in early October: Democrats in the U.S. House of Representatives called on their Republican counterparts to "investigate the safety of metal-on-metal hip implants."

 

Given the recent record of House Republicans, it is not surprising that there has been no further news on this front.

 

Sources

 

Edney, Anna. "Hip Implants Targeted for Probe by House Implants." Bloomberg, 12 October 2011

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