A metal hip replacement may not last as long as expected due to complications that could require revision surgery to resolve.

Hip replacement surgeries are fairly common and often aim to handle damage from injury, arthritis, and other degenerative bone conditions that cause damage to joints.

During the surgery, the damaged part of the femur and where it articulates with the hip is removed and replaced with an implant to mimic the movement of the natural joint.

Hip replacements may last over 20 years, and studies have shown that 80 percent of implants were functioning well after 15 years in younger patients. In patients over 65 years of age, 94 percent of hip replacements were functioning well after 15 years.

The longevity of hip replacements reportedly depends on a variety of factors including:

• Patient age: Younger patients tend to be more active so their hip implants may not last as long.
• Patient activities: High-intensity activities may place undue stress on hip replacements.
• Patient weight: High weight can be hard on a hip implant.
• Complications: Issues such as infections and injuries can lead to the failure of a hip implant.

Most modern hip implants are made of plastic materials, although metal on metal hip replacement implants were more common in the past. These implants fell from popularity when it was revealed that they may be prone to early failure.

According to the American Academy of Orthopedic Surgeons, metal on metal hip replacements have components made entirely of metal – usually cobalt-chromium. Because metal wears down slower than plastic, it was thought that metal on metal hip implants would last longer.

However, the wear of metal on metal may cause the implant to release small debris. When metallic debris enters the surrounding tissue or bloodstream, they may cause complications such as metal poisoning, inflammation, fluid buildup, and more.

Certain complications may require revision surgery to correct. Revision surgery can be hard on the patient and, unfortunately, doesn’t guarantee the success of any further implants. In fact, implants after revision surgery may actually be less likely to succeed.

Studies of national joint registry data have shown that metal on metal hip replacement patients are at a higher risk for revision surgery, with 1 in 5 implants needing revision 10 to 13 years after implantation. A 2015 study aimed to assess the risk and summarize potential complications associated with metal on metal hip implants.

A variety of complications were identified, most of which stemmed from the release of metal debris from device wear. Tissue complications reportedly include an adverse tissue reaction, metallosis, and inflammatory pseudotumor. Most complications reportedly start with pain that eventually progresses to instability, clicking, stiffness, and reduced range of motion.

The researchers noted that the number of individuals needing revision surgery due to complications was relatively small. However, this does not mean that patients and doctors should dismiss the idea of complications when it comes to metal on metal hip replacements.

“Even with this knowledge, however, clinicians must remain vigilant and be thorough with their assessment and investigation of patients with these types of implants, regardless of whether or not a patient is symptomatic,” the study concluded.