Two of the fastest-growing medical procedures in the United States are hip and knee replacement surgeries, which have been on the rise throughout this century and show no signs of slowing down. They did decline during the COVID-19 pandemic for obvious reasons, but as soon as the threat was lessened, they regained their earlier momentum. For baby boomers, replacements are as popular as TikTok is with teenagers.
Joint replacement involves removing parts of an arthritic or damaged joint and replacing them with metal, plastic or ceramic components that replicate the movements of a healthy joint.
Dr. Anthony McBride, an orthopedic surgeon with Owensboro Health, said joint replacement surgeries got off to a rocky start before rapidly gaining in popularity.
“(They) were developed as viable procedures in the 1960s,” he said. “Prior to this, attempts to resurface joints were met with many problems. Surgical techniques were not refined, and surgeons did not fully understand the complex balance between the anatomy and stability of our joints. In addition, the materials used to make artificial joints were inferior to those we use today. All of these factors made early joint replacement surgeries very difficult to recover from and prone to early failure.”
Since then, advances in the procedures and demand for them have certainly made up for lost time.
Despite the disruption during the initial impact of the pandemic (March through May 2020), procedures rebounded to historic averages by June 2020, according to The American Joint Replacement Registry (AJRR)—the cornerstone of the American Academy of Orthopaedic Surgeons (AAOS) Registry Program—in its 2021 annual report on hip and knee arthroplasty procedural trends and patient outcomes.
Even with the temporary decline in procedures, the report demonstrates an overall cumulative growth of 18.3% compared to the previous year and includes findings from 2,244,587 hip and knee arthroplasty procedures performed between 2012 and 2020. The 2022 report demonstrates an overall cumulative growth of 14% compared to the previous year and includes over 2.8 million hip and knee procedures since 2012 from over 1,250 hospitals, ambulatory surgery centers, and private practice groups submitting data. Although no figures are available for individual states, about 700,000 knee replacements and 400,000 hip replacements are performed in the U.S. each year.
“The growth in joint replacements has been accelerating ever since its inception,” said Dr. Evan Rhea of Ellis and Badenhausen Orthopedics in Louisville. “Over the past 20 years, improvements in patient optimization, surgical techniques and implant technology have allowed more advanced and more efficient surgeries to be performed on a larger percentage of the population with better long-term outcomes.”
As an indication of the demand for joint replacements, Ellis and Badenhausen has a staff of 11 surgeons, four medical/physical therapy offices and two facilities that are strictly for PT. They provide orthopedic and PT services for the University of Louisville, Bellarmine University, the Louisville Bats, and a number of high schools. And there are other providers in the area that are nearly as big or bigger, including Norton Healthcare, Baptist Health and UofL Health.
Earlier this year, OrthoCincy Orthopaedics & Sports Medicine announced a newly formed partnership with Ortho Louisville Orthopaedics & Sports Medicine, which has locations on Louisville’s southwest and southeast sides. OrthoCincy is the largest independent orthopedic practice in the tri-state area, with 13 locations across Northern Kentucky, southwestern Ohio and southeastern Indiana. The two practices are continuing to operate under their current names and at their same locations.
What’s driving the increase in surgeries?
A 2018 study in the Journal of Bone and Joint Surgery projected the number of total hip replacements to increase by 171% (635,000 procedures) and the number of total knee replacements to grow 189% (1.28 million procedures) by 2030. Similar gains are expected for revision, or “re-do” hip and knee replacement, growing by 142% (72,000 procedures) and 190% (120,00 procedures), respectively.
The baby boomer generation (generally defined as people born from 1946 to 1964) accounts for much of the growth, either to alleviate pain or the desire to regain or retain mobility because they want to maintain an active lifestyle into older age. In addition, one-third of American adults are obese, which is a risk factor for end-stage osteoarthritis.
Another factor is the increasing lifespan, according to Dr. Mathias Bostrom, an orthopedic surgeon at New York’s Hospital for Special Surgery, where total knee replacements were pioneered.
“A hundred years ago, we did more manual labor and worked our joints more, but we also didn’t live nearly as long,” Bostrom said in an interview with WebMD. “As our life expectancies increase, we’re putting more demands on our joints—and perhaps hitting their sell-by dates. Maybe our joints aren’t designed to last as long as we’re living these days. Many people aren’t willing to be sedentary or change their lifestyles. Their joints are beat up and they want joints that let them do the things they’re used to doing.”
Pain can certainly be a primary motivation as well, as was the case with Rod Cooper, a 72-year-old Louisvillian who underwent two hip replacements at age 60 at Baptist East Hospital in Louisville. He said he was having increasing problems on stairs, with his mobility and with pain in general.
“I probably waited longer than I should have to have it repaired,” he said. “I finally had X-rays and it was bone-on-bone,” Cooper said. “Once I got it diagnosed, I wanted to have the surgery as soon as possible. Actually, the recovery was very quick. I was walking smoothly and jogging in 30 or 40 days.”
Less than one year later, he had his hip on the other side replaced.
Carol Kolb of New Albany, Ind., a 66-year-old middle school teacher, had both knees replaced five months apart and, like Cooper, said she had “zero problems.”
“Two days after the second one, I babysat two grandkids, 4 and 2, and held them,” said Kolb. “Did it hurt a little bit? Yeah, but nothing compared to how bad it was before. I’d do it again tomorrow.
“Now I have other parts I’d like to have replaced,” she added with a laugh.
While baby boomers make up the majority of replacement patients, Dr. Kevin J. Himschoot of Norton Orthopedic Institute said more and more younger people are opting for the procedure.
“Years ago, the parts would wear out in 10 or 15 years if you were lucky,” he explained. “Now the replacement can last 20 years or more, depending on the person and their activity level. This has opened up the window for patients to have a joint replacement at younger ages. We also have even better options and techniques for revisions—patients who need to have a second joint replacement.”
Success rates
Success rates in both knee and hip replacements are very high and complications are rare. But as with any surgery, there are risks, such as infection, poor healing, an allergic reaction to the metal parts, and blood clots. According to the Mayo Clinic, serious problems occur in less than 2% of patients.
Dr. Frank Taddeo, who is a member of the orthopedic team at CHI Saint Joseph Medical Group in Lexington, is involved in working with alternatives to surgery, or what he refers to as a bridge between surgery and nonsteroidal anti-inflammatory drugs (NSAIDs), which are medications that relieve or reduce pain.
“Most of the time, we start with a diagnostic ultrasound to determine the cause of pain,” Taddeo said. “Then, once we determine whether it’s soft tissue (tendon, ligament, muscle, or even nerve entrapment) or bony, we can tailor the treatment specifically to the patient.”
Taddeo said that in most cases he can offer treatment using minimally invasive procedures with the help of ultrasound, which allows him to see the patient’s anatomy in real time.
“This allows me to place a needle in an exact location or if necessary, make precise smaller incisions for some of the procedures that traditionally require longer incisions. With this technology we are able to avoid putting people to sleep while also avoiding stitches so patients go home with a small bandage rather than stitches.”
Another cutting-edge advancement used for orthopedic surgery involves several different varieties of robotic assistance. A computerized tomography (CT) scan before the surgery is used to plan exactly how much bone should be removed and to maximize the accuracy of the alignment and placement of the implant. During the surgery, the robotic arm ensures that this plan is followed exactly so that just enough but not too much bone is removed.
According to the Mayo Clinic website, one of the most difficult aspects of joint replacement surgery is placing the individual components of the artificial joint in the best possible alignment so they will mesh together and work smoothly. The robotic arm provides tactile, visual and auditory feedback to assist the surgeon in achieving the desired orientation, which can enhance stability and mobility.
“The use of robotics in surgery started in the ’80s and has grown exponentially, particularly in joint replacement,” said Dr. Thomas Schlierf, an orthopedic surgeon with Baptist Health Medical Group. “Robotics in orthopedics is still in its infancy. I am not saying it is not good, safe or effective, but it is young and will continue to grow and improve. So as we move forward, robotics will become smaller, better and cheaper, which should improve patient outcomes and lessen the financial burden in healthcare.”
In addition to the rise in knee and hip replacements, there has been a corresponding increase in shoulder replacement surgery, which continues to evolve with custom implants and components, as well as surgical techniques. Rhea noted that hip and knee replacement had about a 20-year “head start” on shoulder replacement, but that the number has increased exponentially over the past 15-20 years.
National statistics show the prevalence of shoulder arthroplasty has increased by approximately 730% since 1995 and by 210% since 2005. More than two of every 10 people over the age of 80 has a shoulder replacement.
Millions per year
“An aging population combined with improvements in the implants and pain control following surgery has made it a better procedure for patients,” said McBride. “We also have the reverse total 
shoulder replacement, which has greatly expanded the (number of patients) getting surgery. Although it is not needed for most patients, it does provide an option for patients with severe problems who had no other options before.”
As orthopedic surgeons point out, there is every reason to believe the pace of replacement surgeries will continue to rise.
Studies predict that by 2060, 1.23 million hip replacements will be performed per year (a 330% increase) and 2.60 million knee replacements (382%). Advances in anesthesia and multiple methods to control pain following surgery has made them essentially an outpatient procedure.
“In the past 10 years I’ve continued to get busier,” said Himschoot. “I have also seen an increase in the number of orthopedic surgeons coming to town. Practices seem to be adding physicians specific to joint replacements. With so many options for activity later in life and a cultural shift to focus on exercise and activity, I see continued growth in replacements.”
