Patient discomfort following all-metal hip implants (metal-on-metal) has become a focus of the U.S. Food and Drug Administration (FDA), especially discomfort caused by the ball and cup of the implants when they “slide against each other during walking or running.” Another lingering health concern about these hip implants is that friction from the metal-on-metal (ball and socket) can cause the implant to shed metal in the body where the two parts connect. Release of metal in the body can damage bone and the soft tissue surrounding the implanted joint.
Alternatives to the metal-on-metal implants are a combination of a ceramic or metal ball and a plastic socket. The FDA is advising surgeons to “select a metal-on-metal hip implant for their patient only after determining that its benefits outweigh that of an alternative hip system.” (Reuters, 1/17/2013)
Various manufacturers of the metal-on-metal devices have recalled their products in the recent past due to safety concerns, including the Johnson & Johnson ASR hip implant (2010) and Smith & Nephew’s all-metal artificial hip system (2012), in addition to Stryker Corp’s recall of some of their implant components “due to risks associated with corrosion.” (Reuters, 1/17/2013)
The FDA stated however, that the agency hasn’t enough data to be able to indicate the maximum concentration of metal ions that could occur in a patient’s body (or blood) without producing negative effects. The FDA’s website noted that adverse reactions seemed to be patient-specific. A wide variety of medical conditions have been suggested to be related to high metal concentrations, including neurological problems, eye problems, pain, swelling, skin rashes and symptoms mimicking local site infection. The medical research is ongoing in these areas, however.