Information for Patients Considering a Metal-on-Metal Hip Implant System
- What types of questions should I ask my orthopaedic surgeon about metal-on-metal hip implants?
- Which patients should not have a metal-on-metal hip implant implanted?
- What personal information should I share with my orthopaedic surgeon if I am considering a metal-on-metal hip implant?
- What are the risks of having a metal-on-metal hip implant?
- Is there a way to determine ahead of time if I might have a reaction to the metal in the metal-on-metal hip implant?
- Are there any ways to prevent the metal from reaching the joint and bloodstream if I get a metal-on-metal hip implant?
- With the risk of adverse reactions to metal-on-metal hip implants, why are these devices still being offered to patients?
When discussing your options for hip surgery with your surgeon, some questions you should ask include:
- What are the benefits and risks of each type of hip implant system (metal-on-metal, metal-on-polyethylene, ceramic-on-polyethylene, ceramic-on-ceramic, and ceramic-on-metal total hip systems, as well as, resurfacing hip implants)?
- Why is a metal-on-metal hip implant the best for your situation?
- What are the surgeon’s outcomes and personal experience in performing surgical procedures with metal-on-metal hip implants? If the surgeon recommends a resurfacing hip system, what are the surgeon’s results and personal experiences with the recommended hip resurfacing system?
- What are the surgeon’s outcomes and personal experience in performing surgical procedures with other types of hip systems?
- What symptoms can you expect to experience after surgery and for how long?
- What types of activities, if any, should be limited or restricted with a metal-on-metal hip implant?
- What results can you expect after surgery with a metal-on-metal hip implant?
- Which specific symptoms should you report after the surgery?
- What types of reactions may occur due to the implant and/or metal ions and how would they be evaluated and treated?
- If you have a complication related to the metal-on-metal hip implant, how likely is it that the implant would need to be removed and what would be the consequences?
Each type of hip implant has its own set of benefits and risks. Metal-on-metal hip implants are not for everyone. You should discuss your situation with your orthopaedic surgeon to determine whether you are a candidate or not. In general, metal-on-metal hip systems are not meant to be implanted in patients:
- Who have kidney problems
- Who have a known allergy or sensitivity to metals
- Who have a suppressed immune system
- Who are currently receiving high doses of corticosteroids such as prednisone
- Who are women of childbearing age
What personal information should I share with my orthopaedic surgeon if I am considering a metal-on-metal hip implant?
It is critical that your orthopaedic surgeon know your complete medical history including any problems you may have with your kidneys and any known sensitivities or allergies to metal, for example, tell the surgeon if you have allergic reactions from wearing certain jewelry or from your skin contacting your belt buckle.
See the section above, called “Information for Patients who have Metal-on-Metal Hip Implants.”
Is there a way to determine ahead of time if I might have a reaction to the metal in the metal-on-metal hip implant?
Currently there is no widely accepted test to predict if you will develop a reaction to the metal from a hip system, and there is insufficient evidence to support using a skin patch test or any other type of test to determine your sensitivity to a metal-on-metal hip implant. If, however, you have a known sensitivity to metal, it is important to share that information with your surgeon.
Part of the difficulty in answering this question is that individuals vary in how they react to metal ions in their bodies. For example, one patient may develop a reaction in response to a very small amount of metal ions in their body, whereas a different patient may have a much larger amount of metal ions in their bodies before they develop a reaction.
Certain patients may have an increased risk of device wear or adverse local tissue reaction (ALTR) and should follow-up with their surgeon more frequently. They include:
- Patients with bilateral implants (hip replacements on both the right and left sides)
- Patients with resurfacing systems with small femoral heads (44mm or smaller)
- Female patients
- Patients receiving high doses of corticosteroids
- Patients with evidence of renal insufficiency (kidney problems)
- Patients with suppressed immune systems
- Patients with suboptimal alignment of device components (device components not placed in the ideal positions)
- Patients with suspected metal sensitivity (e.g. cobalt, chromium, nickel)
- Patients who are severely overweight
- Patients with high levels of physical activity
Are there any ways to prevent the metal from reaching the joint and bloodstream if I get a metal-on-metal hip implant?
No. All artificial hips require one component to slide against another component and it is inevitable that material at the surfaces will wear as they interact. In metal-on-metal hip implants, some tiny metal particles or metal ions are released into the joint space and the metal ions may enter the bloodstream. Certain characteristics outlined in the previous question may place patients at risk for increased wear and metal ion production and these patients will need closer follow-up after implantation. Patients will react differently to metal ion levels.
With the risk of adverse reactions to metal-on-metal hip implants, why are these devices still being offered to patients?
Every hip implant has a distinct set of benefits and risks and should be considered on its own merit. The key design features of each implant including size, material, and dimensions make each system unique. In addition, the same hip system will have different outcomes in different patients.
The FDA’s assessment of medical devices, including metal-on-metal (MoM) hip implants is based on the ratio of benefits to risk with the data available. MoM hip implants were designed to offer the following benefits:
- Less device material wear is generated when the ball and socket rub against each other in comparison to other hip implants
- Decreased chance of dislocation when the ball of the thighbone (femur) slips out of its socket in the hip bone (pelvis)
- Decreased chance of device fracture
Although the exact prevalence of adverse local tissue or systemic reactions ( link to local and systemic section) is not known, for many patients, currently available information supports a favorable benefit-risk ratio.
The orthopaedic surgeon should assess the patient’s individual needs and should avoid using MoM hip implants in patients where the risks outweigh the benefits.