Hip joint deterioration can lead to pain, stiffness or difficulty walking. When these symptoms do not respond to conservative treatment, such as physical therapy, patients may be advised to undergo total hip replacement or hip resurfacing. As part of this treatment, they may receive a “metal-on-metal” hip implant in which the “ball and socket” of the device are both made from metal. This webpage provides information on: hip implants, how metal-on-metal implants differ from other hip implants and recommendations for patients and health care providers about the benefits and risks of these products. The information provided on this webpage is not meant to replace a discussion with your health care provider.
Metal-on-Metal (MoM) Devices
In metal-on-metal devices both the ball and socket components are made of metal. These metal implants have been used in total hip replacement surgeries and hip resurfacing procedures.
Because of metal’s durability, metal-on-metal devices were expected to last longer than other hip implants. In addition, the ball in a metal-on-metal device is larger, making the hip joint more stable and less likely to dislocate.
MoM implants have also been used because they avoid the complication of debris wear from implants made of plastic/polyethylene. However, recent information about the wear of certain metal-on-metal devices has raised concerns about their use. Like polyethylene, metal surfaces give off small particles of debris. In addition, metal surfaces can corrode, giving off metal ions. Metal debris (ions and particles) can enter the space around the implant, as well as enter the bloodstream. This can cause a reaction in some patients, such as pain or swelling around the hip, osteolysis, and very rarely symptoms in other parts of the body.
Although the vast majority of patients have not had any problems with MoM implants, orthopaedic surgeons and the U.S. Food and Drug Administration (FDA) are concerned because cases have been reported in the peer-reviewed literature and through a British database in which patients have local hip symptoms (pain and swelling). In addition, there have been a very small number of cases that have had other medical concerns seemingly unrelated to the hip.