Hip Replacement Surgery & Defective Hip Devices
Hip replacement surgery is the most common orthopedic surgery performed in the United States. In hip replacement surgery, the patient’s natural hip joint is replaced with an artificial joint. Artificial hip joints are most commonly implanted to relieve pain caused by osteoarthritis or rheumatoid arthritis or to restore mobility after a hip fracture. It is estimated that more than 400,000 people receive artificial hips each year in the United States.
Hip implants typically consist of three components. The stem component is fitted into the patient’s femur (thigh bone), the femoral ball or head is attached to the stem and the acetabular cup is attached to the patient’s pelvis. The components are generally made of metal, polyethylene plastic, or ceramic.
The articular surface is the area where the femoral head and the acetabular cup fit together to form the ball-and-socket joint. Some implants are made with a polyethylene liner in the acetabular cup. However, many implants are made with metal-on-metal (MOM) articular surfaces. Most of the problems from hip implants have been linked to MOM designs.
Hip Revision Surgery
A hip revision is a corrective surgery which is performed when an artificial hip either malfunctions or causes complications. The complications caused by hip implants include Adverse Local Tissue Reactions (ALTR)(damage to surrounding tissues), metallosis, chronic pain and metal toxicity.
FDA Regulation of MOM Hip Implants
In June of 2012 the FDA held a meeting of a panel of scientists and physicians regarding the safety of MOM implants. At the meeting, the FDA examined failure rates and mechanisms of failure of MOM implants. The FDA panel also discussed complications suffered by patients with MOM hip implants. These problems include damage to surrounding soft tissues, pseudotumors (an encapsulated collection of fluid), and metal toxicity.
As a result of the June 2012 meeting, the FDA issued a proposed regulation in January 2013 which would require pre-market clinical testing of MOM hip implant products sold in the United States. The proposed regulation is currently pending.