Date Issued: Jan. 17, 2013
Medical Specialties: Orthopaedics, General Medicine, Family Practice, Radiology, Radiologic Technology, Clinical Laboratory Managers and Directors
Device: Metal-on-metal hip implants consist of a ball, stem and shell, all made from cobalt-chromium-molybdenum alloys.
There are two types of metal-on-metal hip implants1:
Purpose: In February 2011, the FDA launched a metal-on-metal hip implant webpage2. The FDA is providing updated safety information and recommendations to patients and health care providers. This new information is based on the FDA’s current assessment of metal-on-metal hip implants, including the benefits and risks, the evaluation of the published literature, and the results of the June 2012 Orthopaedic and Rehabilitation Devices Advisory Panel meeting. Summary of Problem and Scope: Metal-on-metal hip implants have unique risks in addition to the general risks of all hip implants3.
In metal-on-metal hip implants, the metal ball and the metal cup slide against each other during walking or running. Metal can also be released from other parts of the implant where two implant components connect. Metal release will cause some tiny metal particles to wear off of the device around the implant, which may cause damage to bone and/or soft tissue surrounding the implant and joint. This is sometimes referred to as an “adverse local tissue reaction (ALTR)” or an “adverse reaction to metal debris (ARMD).”
Soft tissue damage may lead to pain, implant loosening, device failure and the need for revision surgery (a surgical procedure where the implant is removed and another is put in its place). Some of the metal ions released will enter the bloodstream and travel to other parts of the body, where they may cause symptoms or illnesses elsewhere in the body (systemic reactions).
Presently, the FDA does not have enough scientific data to specify the concentration of metal ions in a patient’s body or blood necessary to produce adverse systemic effects. In addition, the reaction seems to be specific to individual patients, with different patients having different reactions to the metal wear particles.
Recommendations for Orthopaedic Surgeons:
Additional information on the FDA’s recommendations for orthopaedic surgeons before, during and immediately following metal-on-metal hip replacement surgery can be found in Information for Orthopaedic Surgeons4.
Additional information on the FDA’s recommendations for patient follow-up can be found in Information for Orthopaedic Surgeons6.
For additional information regarding soft tissue imaging or assessing metal ion levels, please review the FDA’s recommendations below.
Imaging For some symptomatic patients with metal-on-metal hip implants, additional diagnostic imaging is required to assess and diagnose soft tissue findings surrounding the implant. Please be aware of the FDA’s recommendations:
If you determine that an MRI of a metal-on-metal hip implant patient is appropriate, the FDA recommends the following:
For additional information on the FDA’s recommendations about imaging a patient with a metal-on-metal hip implant, please see Imaging Evaluation7.
Assessing Metal Ion Levels Some patients with a metal-on-metal hip implant may have elevated metal ion levels (e.g. cobalt and/or chromium) in their bloodstream. Several factors can impact the accuracy, reproducibility, and clinical interpretation of metal ion test results. Please be aware of the FDA’s recommendations:
For additional information on the FDA’s recommendations on metal ion test methods, selecting a test lab and interpreting test results, please see Metal Ion Testing8.
Device Revision The decision to revise a metal-on-metal hip implant should be made in response to the overall clinical scenario. In case of adverse local tissue reactions (ALTR), revision of a metal-on-metal hip implant may have a worse prognosis than revision of other types of bearing surfaces.
In selecting components for revision:
For additional information, please review the FDA’s considerations on device revisions9, which includes our recommendation for a retrieval analysis of every failed metal-on-metal hip implant.
Summary of FDA Recommendations for Orthopaedic Surgeons
*For chromium testing, a validated method that resolves potential interferences must be used. Please review FDA’s recommendations for chromium testing10.
Recommendations for Health Care Providers: Metal-on-metal implant patients with systemic symptoms are more likely to visit their primary care practitioner than their orthopaedic surgeon, which makes it important for all health care providers to be aware of metal ion adverse events that may occur in metal-on-metal hip implant patients. Based on case reports, these events may include:
Patients with systemic findings that are thought to be related to a metal-on-metal hip implant should be advised to follow-up with his or her orthopaedic surgeon to determine the appropriate course of action.
For additional information, please review the FDA’s considerations to Health Care Professionals11.
Recommendations for Patients Considering Hip Implants:
A list of some questions to ask your orthopaedic surgeon can be found in Patients Considering a Metal-on-Metal Hip Implant12.
Recommendations for Patients with Metal-on-Metal Hip Implants:
Additional information for patients with a metal-on-metal hip can be found in Patients who have a Metal-on-Metal Hip Implant13.
FDA Activities: The FDA is committed to providing reliable safety recommendations to patients and health care providers about the utilization of these devices. Recent activities include:
Additional information on FDA ongoing activities are provided in FDA’s Role and Activities17.
Other Resources: For additional resources, see Metal-on-Metal Hip Implants: Other Resources18.
Reporting Problems to the FDA: Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices. If you suspect a problem with a metal-on-metal device, we encourage you to file a voluntary report through MedWatch, the FDA Safety Information and Adverse Event Reporting program19. Health care personnel employed by facilities that are subject to the FDA’s user facility reporting requirements20 should follow the reporting procedures established by their facilities. Device manufacturers must comply with the Medical Device Reporting (MDR) regulations.21 Reports to the FDA about adverse events related to metal-on-metal hip systems include, but are not limited to: pain, malposition, adverse local tissue reaction, metallosis, hypersensitivity (allergy), loosening, and dislocation.
To help us learn as much as possible about the adverse events associated with metal-on-metal hip implants, please include the following information in your reports, if available:
Contact Information: If you have questions about this communication, please contact the Division of Small Manufacturers, International and Consumer Assistance (DSMICA) via e-mail at DSMICA@FDA.HHS.GOV or by phone: 800-638-2041 or 301-796-7100.
This document reflects the FDA’s current analysis of available information, in keeping with our commitment to inform the public about ongoing safety reviews of medical devices.