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Dangers of Metal-On-Metal Hip Components Used In Total Hip Arthroplasty (THA)

Author: American Academy of Orthopaedic Surgeons

Published: 2011-02-13 : (Rev. 2017-06-06)

Synopsis and Key Points:

According to the AAOS patients have several options for hip replacement implants each with its own advantages and potential drawbacks.

Main Digest

The U.S. Food and Drug Administration (FDA) posted a public health communication about metal-on-metal hip components used in total hip arthroplasty (THA). The American Academy of Orthopaedic Surgeons (AAOS) appreciates this thorough and well-considered look at the concerns surrounding the use of these implants. The FDA's communication also keeps each of the key stakeholders in mind: patients, potential patients, orthopaedic surgeons and other medical practitioners.

With the patient's safety, health, and quality of life always in mind, the members of the AAOS will continue to work with device makers and agencies such as the FDA to share knowledge and communicate any potential concerns.

"The FDA is a partner in patient safety and education. We believe that a significant majority of metal-on-metal hip replacement implants have successfully relieved pain and improved function without any problems for the patients who have received them but there have been some concerning exceptions. We are working together to investigate and report these concerns and will continue to communicate with our 36,000 members, the medical community and the public," stated AAOS President John J. Callaghan, MD.

According to the AAOS patients have several options for hip replacement implants, each with its own advantages and potential drawbacks. For the vast majority of patients, hip replacements - no matter what type of bearing surface is used - dramatically improve overall quality of life. Metal-on-metal hip implants are made of a cobalt-chromium alloy.

What did the statement say?

The FDA's public health communication included an overview of the concerns and effectiveness of metal-on-metal hip implants, as well as information for orthopaedic surgeons, healthcare professionals, and patients who have these implants or are considering them.

What has the AAOS done to educate its members and help communicate the concerns raised in the FDA's message?

The AAOS has notified all members about the possible side effects of the metal-on-metal devices. We also have included this in our Headline News Now e-blast to all members. We have updated our existing patient-education page on metal-on-metal hip implants to include the FDA's comments at and will send an e-mail to more than a dozen national medical specialty societies, asking primary and specialty care physicians to work with us to identify patients who may have adverse reaction to the metal implants. We also are working closely with the Hip Society and the American Association of Hip and Knee Surgeons, whose members are specialists in joint replacement surgery.

Why would an orthopaedic surgeon suggest a metal-on-metal implant?

In general, metal-on-metal hip implants have been known to generate less wear debris, which can reduce the risk of osteolysis (loosening of the implant and weakening of the bone). They also use a larger ball/socket component, which can reduce the risk of a dislocated hip. MoM hip implants typically have been used in younger patients to treat osteoarthritis and pain in the joint.

To whom does this public health communication apply?

Patients who have had or are considering a metal-on-metal hip implant: According to data from the Nationwide Implant Sample database, in a one-year period from 2005-2006, approximately 39,200 MoM hip replacements were performed.

What should a patient do if he or she has had a metal-on-metal hip replacement?

Most patients have not had any problems with metal-on-metal implants. If the patient does not have any medical or health changes, and the hip is not painful, there is no reason to believe a problem exists. Periodic follow up with their orthopaedic surgeon is recommended. If, however, the patient notices new pains or medical concerns, he or she should talk to a doctor and orthopaedic surgeon. An open dialog with a physician is the best way for patients to protect their own health.

The members of the AAOS strongly feel that a patient understands his or her own body best.

A patient who notices any changes to his or her medical status, has any new symptoms develop or has pain that is new or gradually increasing, since the joint replacement surgery, must speak to an orthopaedic surgeon as any new symptom may be a symptom of an adverse reaction to an implant.

"We recommend all patients tell their physicians about their metal-on-metal implants, because if they are experiencing new symptoms or new pain, that can indicate a complication," stated Joshua Jacobs, MD, spokesperson for the AAOS and an orthopaedic surgeon and researcher in Chicago.

Total hip arthoplasty is one of the most successful surgeries of the past several decades.

This procedure has relieved pain and restored movement to hundreds of thousands of people. The decision to have hip replacement surgery should only be made after discussion between the patient and his or her orthopaedic surgeon. As with any surgery, joint replacement surgery has some risks, but is successful in more than nine out of ten people. If complications occur, most can be successfully treated.

As a way of identifying early problems that may arise from any joint replacement procedure, the Academy has helped to establish the American Joint Replacement Registry (AJRR). The AJRR will track data on outcomes and devices, just as joint registries in other countries do. This national database will serve as an early alert system for continued or new device problems. The data collection process has just begun and will allow orthopaedic surgeons to track the success and failures of any implant used nationwide.

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