1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

Metal-on-Metal Hip Replacement Problems

By

Updated June 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

metal hip replacement

A hip replacement implant can be made of different materials including metal.

Image © Medical Multimedia Group

Hip Replacement Surgery:

Hip replacement surgery is a procedure performed for the treatment of severe hip arthritis. For patients who have hip arthritis that is interfering with their normal activities and has not been adequately treated with non-surgical treatments, a hip replacement surgery may be a good option.

All patients want their hip replacement to relieve their symptoms. However, they also want their implant to last a long time--hopefully the rest of their life. Over the past several decades, new hip replacement implants have come and gone, in hopes of finding improvements in implant design. While implants have improved, they still wear out, making doctors and patients interested in new designs that may lead to a better, longer lasting hip replacement implant.

Hip Replacement Implants:

Hip replacements are performed using artificially designed prosthetic implants. Implant designs date back to the 1960s, but have evolved over time. Some implant designs have been used for decades, with long track records, others are brand new and have no track record.

Most patients have a tendency to want the newest type of implant, thinking that newer is likely better. However, one advantage of using an implant that has been around is that more is known about long-term results with the implant.

Metal-on-Metal Hip Replacements:

Metal-on-metal hip replacements have been done for many years, but became more popular over this past decade. Metal-on-metal implants use a similar design to standard hip replacements, but the surfaces of both the ball and the socket are made of metal. These metal surfaces are highly polished and smooth. In addition, the surfaces are much harder than the traditional artificial plastic hip socket, making it less susceptible to wearing out. Metal-on-metal implants are also used for hip resurfacing implants.

Advantages:

Metal-on-metal hip replacements were designed with two specific potential advantages. First, the size of the ball of the ball-and-socket implant can be larger. In a traditional metal-and-plastic hip replacement, the socket is made of plastic that takes up space. With metal-on-metal implants, there is no plastic taking up space, and the metal ball can be larger. This larger metal ball is more stable and less prone to hip dislocation. This is often a significant concern for active patients.

The second issue is concern about wear rates. All materials used for joint replacements wear out over time, some faster than others. One concern about standard metal-and-plastic hip implants is wearing out of the plastic over time. New materials have been investigated to find materials that don't wear out as easily. New plastics, ceramics, and metal are all materials used to address this concern.

Problems:

The concern about some metal-on-metal hip replacements, specifically one implant made by a Johnson & Johnson Company called DePuy Orthopaedics, is that implants were causing problems within the first few years after replacement. The problem found is that while the materials don't wear out quickly, they do create microscopic particles of metallic debris. The body seems to react to this microscopic debris with an immune response. This can lead to soft-tissue and bone damage around the hip joint. In some patients, this tissue damage has been severe causing permanent injury and requiring additional surgery. Patients with this particular implant are much more likely to need their hip replacement repeated.

Patients with these metal-on-metal implants have also been found to have high levels of metal ions in their blood stream, evidence of the microscopic wear particles escaping into the body. The effect of these metal ions in the bloodstream is not fully understood, although there is no evidence of problems in other parts of the body, just the effects on the hip itself.

What You Should Do Now:

If you have this specific type of metal-on-metal hip replacement implant, you should regularly see your doctor for routine evaluation of the hip joint. There are specific recommendations for patients with this implant about what surveillance tests should be done, and if further surgery should be considered.

Patients with other types of metal-on-metal hip replacement implants should also been seen regularly by their surgeon for continued evaluation. Only a limited number of metal-on-metal implants have been recalled, and even those recalled implants may not need to be removed. However, because of these concerns, these implants should be closely monitored to watch for potential problems.

Why Did This Happen?:

How can it happen that tens of thousands of patients received an implant that was ultimately determined to be a failure? This is an excellent question, and this issue is shining a bright light on the process by which medical devices are reviewed and approved for implantation.

Surgeons need to be mindful of companies touting a new system that may lack clinical data. Patients need to be educated about potential risks of different types of implants. It is important to understand that all implant types have specific concerns, and determining which is best can be a challenge for doctors and patients.

Sources:

Smith AJ, et al. "Failure rates of stemmed metal-on-metal hip replacements The Lancet, V. 379, Is. 9822, Pg. 1199 - 1204, 31 March 2012.

Depuy Orthopaedics: ASR Hip Replacement Recall Guide Updated: April 2012.

Meier B "Hip Device Phaseout Followed F.D.A. Data Request" New York Times, March 22, 2012.

  1. About.com
  2. Health
  3. Orthopedics
  4. Hip & Knee
  5. Hip & Knee Replacement
  6. Hip & Knee Implants
  7. Metal-On-Metal Hip Replacement Recalls and Problems

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.