Metal on Metal Hip Replacements

Metal-on-Metal (MoM) Hip Replacement devices are artificial joint products which are made entirely of metal. MoM devices are intended to be more durable and longer-lasting but grating of metal surfaces may result in the shedding and deposit of metal fragments into joint spaces, causing serious complications.

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metal on metal hipHip replacements are used to repair damaged hip joints by replacing bone or cartilage with a synthetic material. Common materials used to create the prosthetic joint include ceramic, polyethylene, and metal. Hip replacements can extend mobility and add range of motion for people that have chronic pain or limitations from arthritis or injuries.

Recently, metal-on-metal hip replacements have come under fire. In January of 2013, the FDA began to require companies selling metal-on-metal hip replacements to subject their products to clinical trials. These clinical trials must express the safety and effectiveness of the product for it to stay on the market.

This move was in reaction to the growing number of lawsuits and complaints about complications from the metal-on-metal hip replacements. A number of metal-on-metal hip replacements had been FDA approved through the 510(k) approval process. This process only requires that products show notable similarities to products currently used in similar surgeries.

Types of Metal-on-metal Hip Replacements

There are two common types of metal-metal hip replacements: total hip replacement and hip resurfacing. In a total hip replacement, there is a stem placed into the patient’s femur to support the artificial femoral head, the “ball”. The acetabulum, the “socket” is replaced as well.

In a hip resurfacing, the acetabulum is replaced, while the femoral head is resurfaced. There is then a covering cemented on the femur’s top with a stem inserted into the femur. With the newly-revised FDA approval process, there are only three metal-on-metal hip replacement systems currently available.

FDA-approved metal-on-metal hip replacement systems include:

  • Corin USA Limited-Cormet Hip Resurfacing System
  • Smith and Nephew Inc,-Birmingham Hip Resurfacing System
  • Wright Medical Technology, Inc-Conserve Plus Total Resurfacing System

Complications from Metal-on-Metal Hip Replacements

The most common complications that arise as a result of hip replacement surgeries in which metal is used are metallic debris, hip replacement failure, and osteolysis. Metallic debris comes from the constant rubbing together of the metal in the joint. Small pieces of metal may collect at the site of the replacement from the friction or because of corrosion. These pieces of metal can cause metallosis if the patient is sensitive to metal, or a number of other issues. These issues include infection, pain, inflammation, death of surrounding tissue, cysts, and weakening of surrounding bone.

Hip replacement failure occurs when the joint becomes dislocated or the components of the hip replacement start to loosen. Osteolysis is a condition where the body recognizes the hip replacement material as a foreign substance and attempts to remove it. Revision surgeries may be performed to try to fix problems with the prosthetics or to remove metallic debris.

Response to Complications with Metal-on-metal Systems

Due to the change in regulations and the growing number of complaints, many top manufacturers of hip replacements have had to revise the way they sell their products. DePuy Orthopedics, a division of Johnson and Johnson, will stop all sales on two of its hip replacement products that utilize metal. These are the Ultamet metal-on-metal articulation and Complete Ceramic-on-metal Acetabular Hip Systems.

DePuy will also discontinue the use of metal lining its hip replacement systems, including the Pinnacle Acetabular Cup System. In 2010, DePuy Orthopedics issued a voluntary recall on two of its products belonging to the articular surface replacement (ASR) line, the ASR Hip Resurfacing System, and the ASR XL Acetabular System.

In 2012, Stryker, another top manufacturer of metal-on-metal hip replacements, issued a voluntary recall on two of its products as well: the Rejuvenate and ABG II modular-neck hip stems. Stryker also encouraged patients that had received one of those products to get blood work done to test for complications. Three other top manufacturers-Zimmer, Wright, and Smith and Nephew Company, also issued voluntary recalls in 2012 for products or components that featured metal-on-metal.

A shift is being seen in the use of metal-on-metal hip replacements. In 2007, about 20 percent of all hip replacements were metal-on-metal. Metal-on-metal now accounts for only about two percent of hip replacement surgeries.

Lawsuits from Metal-on-metal Hip Replacement Complications

Roughly 17,000 complaints have been filed with the FDA about problems stemming from metal-on-metal hip replacements. To date, nearly 10,000 lawsuits have been filed against DePuy Orthopedics alone. In March 2013, the first trial involving the recalled DePuy ASR hip implant concluded. A jury awarded $8.3 million to a Montana patient that had to undergo revision surgery to correct his defective implant.

Lawsuits have also been filed against nearly every other manufacturer of metal-on-metal hip replacement systems for complications arising from the product. There is some concern that the shift in FDA regulation on metal-on-metal hip replacements may result in an infringement upon affected patients’ legal rights. The stronger regulation may provide immunity for companies that comply to lawsuits filed by patients who have suffered.

Notwithstanding claims relating to this product, the drug/medical device remains approved by the U.S. FDA. 

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