What happens when a joint replacement fails?

Total knee and hip replacements are among the most successful surgeries, easing pain and restoring mobility for millions of Americans with severe arthritis. They involve removing cartilage and some bone in the joint and inserting an implant made of some combination of metal, ceramic, and plastic parts. The implant functions like a natural joint.

Even though they’re remarkably durable, implants occasionally fail, or complications develop. If this happens, the solution might be another procedure, known as revision surgery.

Why do knee and hip replacements fail?

Knee and hip replacement failure can happen for a variety of reasons, including the following:

Infection. Although rare, infections can develop soon after surgery or years later. “The risk is highest in the first year or two,” says Dr. Hany S. Bedair, chief of the Hip and Knee Replacement Service at Harvard-affiliated Massachusetts General Hospital, who is an expert in complex revision hip and knee replacements.

People with diabetes or obesity are at a higher risk of infection. “Losing weight and getting blood sugar under control around the time of surgery can lower the risk,” says Dr. Bedair.

Implant loosening. Implants must be firmly attached to the bone. This can be done with bone cement, or with a “cementless” method that uses implants with a porous surface. Bone grows into and around the implant, providing a secure attachment.

If one or more implant components become loose, revision surgery may be needed. With cemented implants, loosening tends to occur years after surgery. “The cement is sort of like grout between tiles,” says Dr. Bedair. “Once it starts to loosen, it continues to loosen.”

If a cementless implant loosens, it’s because the bone was not successfully incorporated into the implant. If this happens, it will be soon after surgery. “Once bone grows into the implant, which happens within a few months of surgery, it’s generally there for good,” says Dr. Bedair.

Dislocation. A hip replacement may require revision if the new joint dislocates (the ball part comes out of the socket) or becomes unstable. “If this occurs, it’s usually within the first few months after surgery, before tissues have fully healed and muscle strength has returned,” says Dr. Bedair.

Dislocation or instability can also result from trauma such as a fall, which can happen at any time, even years later.

Fractures around the implants. Fracturing a bone near an implant usually requires surgical repair. In some cases, the implants must be replaced.

Signs your joint replacement may be failing

Some knee and hip replacement failures are dramatic and unmistakable. “If you fall and break the bones around a hip implant or there’s a dislocation, there’s no mystery,” says Dr. Bedair.

Other problems, such as infections or loosening, can develop slowly and may be less obvious. Troubling signs include persistent pain, swelling, and a sense that the joint feels unstable. “If you have any changes from your baseline status, and it persists or worsens over a few weeks or months, that’s a reason to see your surgeon,” says Dr. Bedair.

Keep in mind that mild discomfort doesn’t necessarily mean that something’s wrong. “Some people think their new knee or hip will feel like it did when they were 20 years old,” says Dr. Bedair. “If they don’t get that, they may perceive it as a failure. It’s not really a failure, but rather reflects that these implants are not perfect replicas of natural joints.”

How is it fixed?

If caught early, infections may be treated with intravenous antibiotics and surgery to clean the joint and possibly replace the components of the implant. Chronic infections, which may be deep in the bone and tissues around the hip or knee, often require the removal of the implant and replacement with a specialized revision-style implant.

In cases of hip replacement loosening, the affected part (such as the socket in the hip or the stem in the thighbone) can often be replaced while keeping the stable component. If a knee replacement loosens, it’s common to replace all the parts of the implant.

If a bone fracture causes an implant to loosen from the bone, the implant will be replaced.

A tougher recovery

Revision surgery is complex and challenging. Recovery tends to take one-and-a-half to two times longer than it did for the original surgery. There’s also a higher risk of complications, including infections, fractures, and loosening.

Not all orthopedic surgeons perform revision surgeries. If you are considering revision joint replacement, look for a surgeon who performs this type of surgery often and is skilled in the techniques. “Outcomes for joint replacement are better with high-volume surgeons,” says Dr. Bedair. “The difference is magnified for revision surgery.”

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