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In February 2011, the Food and Drug Administration (FDA) issued a public health communication about Metal-on-Metal (MOM) hip replacement components”[1] and the possibility of adverse effects of the implants due to metal ions leaching into the body and circulatory system: “Because the metal ball and the metal cup slide against each other during walking or running, some tiny metal particles may wear off of the device and enter into the space around the implant. Some of the metal ions from the metal implant or from the metal particles may even get into the bloodstream.”[2]

May 6, 2011, the FDA issued orders to 21 companies that manufacture the MOM hip implant systems to conduct further research regarding the safety of their devices. Metal-on-metal hip replacement devices consist of a ball, stem and shell, all made of metal parts.[3] A postmarket surveillance study monitors adverse events after a device has been approved or cleared by the FDA. In particular, the FDA is concerned about the levels and effects of cobalt and chromium ions which may get into the blood stream, as well as other adverse effects possibly caused by the MOM hip implants.[4]

It is known that metal-on-metal and other types of hip implants involve risks and the possibility of adverse effects, such as infection, joint dislocation, an adverse local tissue reaction (ALTR) or an adverse reaction to metal debris (ARMD). The American Academy of Osteopathic Surgeons (AAOS) advises that metal particles may cause a reaction around the joint, which could lead to deterioration of surrounding tissue, or even loosening of the implant and failure of the device.

Regarding metal ions from the implant entering the bloodstream, there have been reports of people with metal-on-metal hip implants experiencing reactions to the metal ions and medical problems, including effects on the nervous system, heart, and thyroid gland, which may be associated with their implants. The increased concern over the adverse effects of metal ions to the body is the primary reason for FDA’s postmarket surveillance.

If you have had a MOM hip replacement, your surgeon may be contacting you to learn how you are doing. Reactions to the MOM hip replacement vary. If a person experiences pain or swelling in the groin, hip or leg following hip replacement surgery, they are advised to immediately check with their surgeon. Patients who receive a MOM hip replacement are also urged to pay attention to any other new symptoms their doctor could confirm that might involve their heart (chest pain, shortness of breath), nerves (numbness, weakness, change in vision), thyroid gland (fatigue, feeling cold, weight gain), or kidneys (change in urination habits).[5]


[1] American Academy of Orthopaedic Surgeons, Questions and Answers About Metal-on-Metal Hip Replacements,

[2] U.S. Department of Health & Human Services, Food and Drug Administration, Medical Devices: Concerns About Metal-on-Metal Hip Implant Systems, February 10, 2011,

[3] American Academy of Orthopaedic Surgeons, Questions and Answers, Op. Cit.

[4]“FDA Asks Metal Hip Makers for More Data”, Marissa Cevallos, Health Key, Los Angeles Times, May 11, 2011;,0,7767788.story

[5] Concerns About Metal-on-Metal Hip Implant Systems, DHHS, FDA, February 10, 2011.

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