Traditionally, hip implants were made of ceramic and metal parts. More recently, some devices began using metal-on-metal components for increased durability. Although the vast majority of patients have not had any problems with metal-on-metal implants, there has been some concern that, when the metal parts rub on each other, small bits of metal are shed into the joint space and bloodstream, causing inflammation and other problems.
This concern, along with an increased failure rate for the DePuy metal-on-metal implant, caused a recall of that device in 2010. The 12% failure rate for that particular device was twice the expected failure rate and was related to loosening of the artificial joint and dislocation.
Recalls occur when a medical device is defective, when it could be a risk to health, or when it is both defective and a risk to health. A medical device recall does not always require removal and replacement. A recall sometimes means that the medical device needs to be checked, monitored, adjusted, or fixed. Patients with a recalled implants should discuss the reasons for the recall with their orthopedic surgeon and consider the risks of removing the device compared to the risks of leaving it in place.
After the initiation of substantial litigation and media attention, in May 2011, the U.S. Food and Drug Administration (FDA) asked for increased monitoring of all 22 commercially available metal-on-metal hip implant replacement systems. The purpose of this post-market surveillance is to determine the true likelihood of loosening of the joint, local inflammation caused by the implant, and the dangers of the release of metal ions into the bloodstream.
The FDA encourages every patient with a metal-on-metal implant to contact their orthopedic surgeon, and whether symptomatic or not, to participate in the FDA surveillance program. This will allow as much balanced information as possible can be obtained.
What Should Patients with Metal-on-Metal Implants Do?
The FDA’s patient health communication, issued in February 2011, suggests that hip replacement patients determine what type of implant they received and follow-up with their surgeon for monitoring to keep tabs on any symptoms or changes in your health which may occur.
The same communication indicates that a small number of metal-on-metal hip implant patients have observed symptoms such as hip/groin pain, local swelling, numbness or changes in the ability to walk and even changes to their general health including heart, nervous system and thyroid issues.
You and your surgeons may consider a device revision (removal of the metal-on-metal implant and replacement with another device). This is not necessarily called for in every case. Your surgeon will consider symptoms and problems such as infection, dislocation or fracture before revising your implant.
Many patients wonder why metal-on-metal hip implants are still offered despite the FDA communication and surveillance. Metal-on-metal hip implants overall have been shown to provide significant benefit (in terms of durability) in many, many patients of the years. The FDA’s risk-benefit assessment for these devices, at this time, suggests that metal-on-metal remains a viable option for most, as adverse outcomes are relatively infrequent (and do not appear to be any higher relative to other types of implants).
Your orthopedic surgeon should assess your individual needs and will not likely recommend metal-on-metal implants for those with metal allergies or existing kidney problems.
image credit: floeschie