March 5, 2010

2 Min Read
Metal-on-Metal Implants Experience (More) Backlash



Metal-on-metal hip implants are no stranger to bad press. Over the years, they have garnered attention for the debris they generate, which can damage soft tissue and bone around the implant. On the other hand, they have remained viable because of the exceptional mechanical strength that they offer, which is critical for such a load-bearing application. A resurgence in metal-on-metal skepticism has returned, however, according to a recent article in the New York Times.Employed in close to one-third of U.S. hip replacements, metal-on-metal implants can produce sizable amounts of metallic debris as a result of friction between the components of the ball-and-socket configuration. Released into the body, these metallic ions, which generally end up near the implant, stimulate an immune response from the body. Consequently, damage to surrounding bone, called osteolysis, can occur. In addition to inflammation in the area, this condition can cause loosening of the implant and, in turn, the need for revision surgery.Because of these issues, medical professionals are distancing themselves from metal-on-metal designs, according to the article. The Times cites a recent editorial in the Journal of Arthroplasty that discouraged the use of the implants as well as the 80% reduction of metal-on-metal implant use by the Mayo Clinic in the past year as evidence of this trend.While the issue is not new, there seems to be a renewed aversion and criticism of metal-on-metal implants. While this situation should be analyzed by device designers, metal-on-metal implants are not the only material with problems; they all have their drawbacks. Polyethylene has also been known to generate quite a bit of debris and cause osteolysis as well. And who can forget the squeaking ceramic hips a few years ago? Despite ceramics' wear resistance, they also are more vulnerable to fracture than some other materials.What do you think, readers? Will this backlash have repercussions in the device industry, or will it quiet down as it has before? What needs to be done? Sound off in the comments section and share your thoughts.Stay tuned for more information on materials for hip implant design in a related special feature in the April issue of MPMN. Plus, read about the companies behind the implants in our Regional Focus on Warsaw, Indiana, which is considered the orthopedics capital of the world.

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