Knee Replacement and Revision Surgeries on the Rise
Having knee surgery too soon could send you back into the operating room.
More Americans are choosing to have knee replacement surgery, and at increasingly younger ages. As more knees damaged by arthritis are replaced with titanium and plastic, the number of revision surgeries — procedures to correct a failed joint replacement — is also soaring. Although knee replacement surgeries have a good track record, new knees don’t last forever.
A study presented at the 2014 American Academy of Orthopaedic Surgeons (AAOS) meeting highlighted the rising numbers of knee replacement surgeries. When researchers reviewed hospital discharge data for more than 2 million people undergoing this procedure, they found the rate of knee replacements jumped 120 percent over a 10-year period.
The overall increase was steep, but it was even more pronounced in younger age groups. While the number of surgeries increased by 89 percent among those ages 65 to 84, they increased by 188 percent in 45- to 64-year-olds.
Studies have found that 85 percent of knees last 20 years, and the AAOS estimates 10 percent of patients will need a revision at some point. The younger patients are when they have the first surgery and the longer they live afterward, the more likely they will be to need revision surgery.
“We had some theoretical concerns about how young is too young,” says lead study author Jacob Drew, MD, of the Medical University of South Carolina in Charleston.. The study’s findings seemed to support his concerns: The number of revision surgeries increased 133 percent during the study period, particularly among younger patients.
Some revision surgeries are relatively minor – for instance, when one component of the implant is exchanged for another. But many entail removing and replacing the entire implant device, the ends of which are affixed to the thigh and shin bones. Revisions are long and complex, require special surgical skills and are rarely as successful as the first operation at restoring normal function and range of motion.
“It appears that revision rates are growing in a younger age group, but the value is to focus on understanding why these patients are at increased risk,” says William Robb, MD, director of the Illinois Bone and Joint Institute, a Chicago-area orthopaedic practice.
Why Have Revision Rates Risen?
Researchers at the University of California, San Francisco (UCSF) evaluated the reasons for revision surgery in nearly 302,000 procedures performed over a five-year period. The most frequent causes of revisions were joint infections and implant loosening (when the bond between implant and bone fails). Far less common were fractures in the bones around the implant and osteolysis (when debris from the implant damages or destroys surrounding tissue).
Although improvements in implants and surgical techniques have reduced rates of implant loosening, infection rates haven’t improved in decades. This is, in part, due to changing patient characteristics. “We know that smoking, diabetes, obesity and [poor] nutrition increase the risk of infection. In fact, the risk of all complications increases exponentially in patients with a body mass index [BMI] of 40, and even those with a BMI of 30 to 40 are at increased risk,” says lead study author Kevin Bozic, MD, a professor of orthopaedic surgery and vice-chair of the department of orthopaedic surgery at UCSF.
Younger knee replacement candidates are more likely to be obese and have health issues than those over 65, says David Ayers, MD, chair of the department of orthopaedics and physical rehabilitation at the University of Massachusetts Medical School. “People assume that most knee replacement patients are young, active baby boomers who have damaged their knees through sports and other activities. But when we look at the representative set of patients age 45 to 64, they aren’t like that.”
The Right Time for a Knee Replacement
The rising numbers of younger adults interested in a total knee replacement creates a dilemma for doctors. “If a patient has debilitating pain and loss of function at age 47, do we ask him to wait as long as possible before undergoing total knee replacement so the need for revision is less likely? Or do we perform the procedure, relieve the pain and get the person back in the workforce, knowing that he may need a revision 20 years down the road?” asks Dr. Drew. "That question is very difficult to answer.”
Instead of rushing into surgery, younger people can try other treatments to manage knee pain—including corticosteroid injections and over-the-counter pain relievers. Losing weight can also help take pressure off damaged joints, and improve outcomes in people who do undertake knee replacement surgery.
Once the decision to have surgery has been made, surgeons and patients need to work together to ensure the best outcome.