All hip replacement surgeries carry risks and the potential for problems. But metal-on-metal hip replacements carry an extra burden: patients need to watch out for hip replacement poisoning symptoms.
Hip replacements have become more popular over the years. According to the U.S. Centers for Disease Control and Prevention, the number of hip replacements increased significantly in the early 2000s. The government agency reported that during that time the number of hip replacements per year in the United States went from 138,700 in 2000 to 310,800 in 2010, a 125 percent increase.
The study did not indicate how many patients opt for metal-on-metal hip replacements each year.
The U.S. Food and Drug Administration has noted that in metal-on-metal hip replacements, the metal ball and metal socket will slide against one another during walking or running and tiny pieces of metal can be released into the bloodstream. When metal debris build-up in soft tissue, it can lead to a toxic condition known as metallosis.
Symptoms of Hip Replacement Poisoning
It’s difficult to predict how the body will react to the metal particles breaking off from the device but the agency has reported several types of adverse events associated with metal-on-metal hip replacements including:
- Soft tissue damage that may become painful
- A loosening of the implant
- Failure of the implant
- Needing to remove the old device in order to replace it with another one.
Besides the above adverse events, here are the hip replacement poisoning symptoms that the FDA recommends patients watch out for in terms of overall health:
- General hypersensitivity reaction (skin rash)
- Cardiomyopathy, or heart muscle disease. Symptoms of cardiomyopathy include shortness of breath, swollen legs and feet and a bloated belly.
- Neurological changes, including sensory changes (auditory, or visual impairments)
- Psychological status changes, including depression or cognitive impairment
- Renal function impairment
- Thyroid dysfunction, including neck discomfort, fatigue, weight gain or feeling cold
FDA Actions: Metal-on-Metal Hip Implants
The FDA classifies metal-on-metal hip replacements as class III, high-risk devices. The agency has taken action to investigate the safety of hip replacements by reviewing adverse event reports and requiring manufacturers conduct postmarket surveillance studies, in addition to issuing a safety communication.
The FDA has also created the Orthopaedic and Rehabilitation Devices Panel of the Medical Devices Advisory Committee to discuss risks, complications and failure rates.
Canada and Australia both issued safety recommendations for healthcare professionals considering using the metal-on-metal implants and the United Kingdom has recommended blood tests and imaging for patients with painful metal-on-metal hip replacements.
At the moment, the FDA does not recommend that asymptomatic metal-on-metal hip replacement patients need to visit their doctor. Instead, the agency suggests that patients follow up with their orthopedic surgeon every one to two years to monitor for early signs of problems.