Hip replacement surgery using artificial hip components can give a person with pain and immobility in the hip joint a chance to enjoy life again. But when these artificial hips fail, they instead cause more pain and often additional surgeries. Zimmer Biomet is an orthopedic company that manufactures a huge portion of the artificial components used in surgeries, including hip replacements.
One of those hip components in particular has caused a number of serious complications in the people who had them implanted. Instead of better mobility and less pain, these patients often suffered dislocations, painful movement, and a later need for revision surgery. The Durom Acetabular Component, also known as the Durom Cup, is not used as often as it once was, but it is still causing problems for many patients. Some of these have filed lawsuits and Zimmer has had to pay up.
Zimmer Biomet is an orthopedic and medical device manufacturer based in Warsaw, Indiana. Originally called just Zimmer, the company has its beginnings in the 1920s when it made aluminum splints for medical use. Over the years, Zimmer has been owned by Bristol-Myers Squibb and has acquired other smaller companies. In 2015 the name officially became Zimmer Biomet after the company bought another medical device company called Biomet for over $13 billion. Zimmer takes in close to $5 billion each year in revenues for its medical devices.
Hip Replacement and Resurfacing Surgery
Hip surgery is used to replace all or some of a damaged hip joint with artificial components like those made by Zimmer Biomet. Conditions like osteoarthritis, rheumatoid arthritis, bone cancer, and osteonecrosis, as well as injuries, can cause the hip joint to become damaged and to deteriorate. This can cause a significant amount of pain, as well as a lack of mobility. Replacing damaged parts of the joint with artificial components can relieve pain and restore mobility.
Total hip replacement is done when the entire hip is damaged and is changed out for all artificial components. This means that the head or ball, the top of the leg bone, as well as the cup or socket attached to the pelvis, are removed and replaced. There is also usually some type of stem that connects the two artificial parts. If some of the hip can be saved, a surgeon may do resurfacing surgery. This entails removing the parts of the joint that are damaged and replacing them as needed.
Complications of Hip Surgery
As with any major surgery, hip surgery puts patients at risk for infections, excessive bleeding, blood clot formation, and bad reactions to general anesthesia. There are also more specific risks and possible complications with hip replacement. For instance, the surgery may lead to an infection deep in the joint. It may cause later pain or immobility, legs of different lengths, bone loss, or nerve damage. The artificial hip may not seat well and could come loose or dislocate, which can cause serious pain, inflammation, and usually requires revision surgery to correct the hip.
The Durom Acetabular Cup
Zimmer makes several different high-tech hips and hip components, which the company claims are more advanced than older hip systems, more durable, and give surgeons more choices when fitting in patients. One of their hip systems, the Durom hip system, came with a component called the acetabular cup, which caused a lot of problems in patients and was eventually recalled.
The acetabulum is the cup, or socket, that holds the ball or head of the femur. The acetabular cup is the synthetic version of this part of the hip joint. The Durom cup is made of a cobalt chromium alloy and is a single, forged piece of metal. Several thousand patients had the Durom cup implanted during hip replacement surgery.
Zimmer designed the Durom cup to correct problems that older hip systems had: poor durability and a lack of range of motion in the joint. With older hip systems, durability was a problem and hip replacement surgery was mostly reserved for older patients who would be less active and wouldn’t need the hips to last very long.
Companies like Zimmer started designing more durable hips that could be used in younger, active patients. As a forged metal hip, the Durom system was supposed to last longer than other hips. It was also designed with a large diameter head and cup, to give patients greater ranges of motion in the hip joint.
Problems with the Durom Cup
Unfortunately the design of the Durom cup did not work as Zimmer hoped it would. Although it was approved by the U.S. Food and Drug Administration (FDA) in 2006, it wasn’t long before surgeons and patients realized there were some serious problems with the hip. One study compared patients with the Durom system to those with more traditional hips and found that the revision rate—the need for additional surgeries to correct problems—was unacceptably high for the Durom system.
One major issue was that the acetabular cup tended to fail and slip out of position. This caused a huge amount of pain for patients. Most of these failures occurred within just two years of the first surgery and required revision. Many patients in the study needed revision surgery within the first year for the implanted hip becoming loose.
The study authors concluded that the hip was poorly constructed. The fixation surface, the place at which the natural bone was to fix to the artificial hip, was inadequate and caused the joint to come loose. The authors also suggested that better testing of the hip and more clinical data could have found these issues before thousands of patients had the hip components implanted.
The Durom Acetabular Cup was recalled briefly in 2008, but only because of inadequate instructions for surgeons. Zimmer removed the component from the market in Australia, but not in the U.S., although surgeons rarely choose to use the cup now with the proven high revision rates. One problem that may have caused such issues with the cup was that Zimmer changed a coating on the hip without testing it thoroughly. This could prove to be a costly mistake as lawsuits and settlements pile up.
Many patients have filed lawsuits against the company, claiming that the hip component wasn’t tested adequately and that risks about it were not communicated. Money is already coming in to patients who have suffered. In one case a jury determined that Zimmer owed the plaintiff over $9 million. If you have had a Zimmer hip implanted and suffered complications, you too may have a case to win compensation.
- http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/MetalonMetalHipImplants/ucm241770.htm - 3