A recent study published in The Journal of Arthroplasty has concluded that metal-on-metal (“MoM”) hip replacements undergo more severe corrosion than comparable metal-on-polyethylene (“MoP”) replacement devices.
The study, published under the title Metal-on-Metal Local Tissue Reaction Is Associated With Corrosion of the Head Taper Junction, was conducted partially in response to increasing reports of adverse health events resulting from the ‘shedding’ of the cobalt and chrome ions in MoM devices. Such debris shedding can lead to elevated ion levels, tissue masses, pseudotumors and other forms of adverse local tissue reactions (“ALTR”).
The study examined 33 components that were recently removed from patients, 19 of which were MoM and 14 of which were MoP. Of the 33 devices, 21% had no visible corrosion, 31% had mild corrosion, 12% had moderate corrosion and 36% suffered severe and/or extreme corrosion. Notably, only 1 of the 19 MoM devices showed no visible corrosion; by contrast, 6 of the 14 MoP devices showed no corrosion.
The disparity of corrosion between MoM and MoP devices is alarming, and there is an appreciable relationship between MoM corrosion and adverse health implications. Moreover, the data suggests that, not surprisingly, the risk of device corrosion rises the longer the device is implanted. Unfortunately, for years MoM devices were implanted in younger patients because of a perceived ability to provide better longevity and function. Instead, younger patients with MoM devices are now the class most at risk of developing ALTR.