The hip is a ball-and-socket joint. In traditional hip replacement, the artificial “ball” is made of metallic material and the “socket” is made of plastic. However, a number of years ago, manufacturers began producing and marketing metal sockets to go with the metal balls in an effort to increase joint durability. These prosthetic joints are called “metal-on-metal” hip implants. In recent years, these all-metal replacement hips have been linked to a number of serious complications, including cobalt toxicity.
Cobalt in Metal-on-Metal Replacement Hips
Cobalt is a particularly hard metal, and is one of the metals used in the manufacture of artificial hip joint components. Cobalt is also a key building block of vitamin B-12, so a small amount of cobalt in the human body is essential to good health. However, too much cobalt in the body can have severe negative health consequences.
Cobalt toxicity from hip replacement surgery involving metal-on-metal implants is becoming increasingly common. In metal-on-metal hip implants, the metal ball and metal socket slide against each other during walking, running, and other physical activities. The resulting friction can cause tiny metal particles called “ions” to wear off and enter the body. These cobalt ions can cause painful and dangerous reactions in the body.
Sometimes cobalt ions remain close to the hip, and only cause damage to tissues or bone surrounding the implant. In other cases, ions enter the bloodstream and are carried to other parts of the body. This can cause serious health problems, including kidney failure, thyroid disorders, heart disease, and perhaps even cancer. This condition is called “arthroprosthetic cobaltism.”
Symptoms of Cobalt Toxicity from Hip Replacement
Localized symptoms include:
- Persistent or worsening hip or groin pain
- Severe inflammation or swelling
- Evidence of tissue death
- Evidence of bone loss
- Asymptomatic masses
Non-localized symptoms include:
- Tinnitus (“ringing” or “buzzing” in the ears)
- Visual impairment
- Anxiety and irritability
Diagnosis and Treatment for Cobalt Toxicity
Blood tests can identify the levels of cobalt in a person’s system. If testing reveals dangerously elevated levels, the first line of treatment is usually to remove the metallic implant. In patients with normal kidney function, cobalt levels will rapidly decrease following removal of the metal hip. In some instances, all symptoms will eventually resolve. However, sometimes the damage caused by cobalt toxicity does not resolve simply because the implant is removed.
Treatment following removal of the artificial joint will depend upon the medical issues caused by the cobalt poisoning. The longer the person was exposed to elevated cobalt levels in his or her system, the worse the prognosis. Unfortunately, in some cases patients never fully recover and may require ongoing medical monitoring and treatment for the remainder of their lives.
Reducing the Risk of Cobalt Toxicity
A person with a metal-on-metal hip implant who is experiencing any possible symptom of cobalt toxicity should immediately seek medical attention. The sooner the condition is diagnosed and treated the better. Persons at heightened risk for cobalt toxicity are those with kidney disease and compromised immune systems.
Even if a person with a metal-on-metal implant is not having cobalt toxicity symptoms, it does not mean a potential problem is not looming. It can take years for cobalt toxicity to produce symptoms. Some doctors advocate that all patients with metal-on-metal hip implants have their blood-cobalt levels tested at least once per year to monitor for rising levels.
Cobalt toxicity from hip replacement is just one of many problems associated with metal-on-metal hip implants. As a result of these issues, a number of manufacturers have issued implant recalls, and thousands of product liability lawsuits have been filed on behalf of injured patients.
Manufacturers have a duty to ensure that all products introduced into the market are as safe as possible. A manufacturer may be liable in a product liability case simply upon a showing that the product was unreasonably dangerous; even if the manufacturer was unaware of the danger.
A person who develops cobalt toxicity from hip replacement surgery may have a case against the manufacturer. The patient shouldn’t delay in having his or her case evaluated by an attorney because a law called the statute of limitations restricts the time to bring a lawsuit against a manufacturer.