Fewer people may get joint replacement procedures in the future than previously thought. That’s according to research presented recently at the 2018 annual meeting of the American Association of Orthopaedic Surgeons (AAOS) in New Orleans. Lead author Matthew Sloan, MD, an orthopedic surgery resident at the University of Pennsylvania, says the number of procedures will continue to rise but at a slower rate.
Knee and hip replacements have been the standard treatment for end-stage arthritis for more than 40 years. During that time, the rate of surgeries has skyrocketed, more than doubling between 2000 and 2008 alone. There has also been an increase in so-called “revision surgeries” – do-over procedures to replace a failed or worn-out implant after the initial surgery.
Trends Behind the Numbers
Driving the increase in all procedures are better implants, the growing number of younger patients getting the surgery and an increasing obesity problem, says Geoffrey Westrich, MD, director of the Reconstruction and Joint Replacement Service at Hospital for Special Surgery in New York City, who was not involved in the study.
“[Joint replacement] procedures are now state of the art, with newer implant technology, excellent pain relief and return to function,” he says, adding that improved technology has also allowed “younger and younger patients to undergo joint replacement surgery.” Younger patients were typically considered poor candidates in the past.
The rising rate of joint replacement, especially for knee procedures, is also tied to obesity, which affects more than one-third of American adults.
“National data from the past 10 years shows that 47 percent of patients undergoing total hip replacement and 64 percent undergoing total knee replacement in the U.S. are obese [having a BMI greater than 30],” Dr. Sloan says.
Despite these factors and the historical upward trend, the rate of joint replacement surgeries actually plateaued in 2008, increasing only 10 percent over the next six years.
Dr. Sloan suspects rate of growth will slow even more in the future – limited by a lack of orthopedic surgeons to meet the demands of “an aging and more active population,” and reduced access to care.
Yet most mathematical models predict the opposite: unconstrained growth.
So Dr. Sloan and a colleague reviewed more than 116 million records of hospital discharges from 2000 to 2014 to determine the annual number of hip and knee replacements and revisions. They combined the number of procedures with census data based on sex, age, race and geographic location, and used a mathematical model to predict the number of procedures in each of these subgroups. They then combined the subgroup prevalence data with census projections to predict the volume of procedures for 2030 to 2060.
Parsing the Numbers
Here’s what they found:
- By 2030, hip replacements are expected to number 635,000 (171 percent increase), while knee replacements could reach 1.28 million, a 189 percent increase. Hip and knee revisions are expected to reach 72,000 (142 percent increase) and 120,000 (190 percent increase), respectively.
- In 2060, hip replacements are projected to reach 1.23 million (330 percent increase) and knee replacements 2.60 million (382 percent increase). Hip and knee revisions are expected to reach 110,000 (219 percent increase) and 253,000 (400 percent increase), respectively.
The increases sound huge, but Dr. Sloan says relatively speaking, they’re not.
“A big take-home from our projections paper is that we expect far fewer – about one-third – total knee replacement procedures by the year 2030 as had been predicted previously in the literature. The implications for future health care savings may be in the billions of dollars if current growth rate trends remain steady,” Dr. Sloan says.
Currently, there are few nonsurgical options for treating advanced arthritis, though that could change in the future. Dr. Sloan says people who can’t or don’t want to have surgery may get pain relief from medications or injections and in some cases from acupuncture, yoga, meditation or massage.
People of Color Still Underserved
The same researchers used the same data for a demographic study, also presented at the AAOS meeting. They looked at the types of patients having joint replacement or revision from 2000 to 2014 and found significant changes in the last decade. For one thing, the study confirmed that many younger adults are now having the procedures.
Dr. Westrich says younger patients historically were considered poor candidates for joint replacement because they put more stress on their implants and needed them to last longer. Now, he says, implants can hold up in more active patients and don’t wear out as fast.
But they do wear out eventually. Revision surgeries generally cost more and are less successful than the original procedure, and many younger patients are likely to need at least one.
The study also found that while white women still get the majority of hip and knee replacements, more white men are getting them, too.
The number of African-American patients also increased by about 0.1 to 0.2 percent a year –a significant gain, but not enough to make up for long-standing racial disparities. Also under-represented are Asians and Hispanics, whose numbers barely budged over the 14 years of the study.
Dr. Sloan doesn’t know why more men are getting joint replacements but says it could be “that they are living longer, are more obese or are increasingly interested in maintaining an active lifestyle at an older age.”
He also can’t explain the increase of joint replacement procedures among African-Americans but not among Asians or Hispanics, though it may be due to cultural differences or differences in access to care. The important thing, he says, is to identify underserved populations so those disparities can be addressed.
AUTHOR: Linda Rath