Skip to content

8 Key Facts About Knee Replacement Surgery

Will these new knees hold up?

En español | Lloyd Emanuel, a 62-year-old tennis pro from Rye, N.Y., had been playing competitively for 50 years — and hoped to keep going. Six years ago, however, the pain started in his right knee. The diagnosis: osteoarthritis, the breakdown of joint cartilage. An orthopedic surgeon repaired the torn cartilage, and — despite the doctor's warnings to slow down — Emanuel kept playing tennis full out. Three years later, he was back on the operating table, being prepped for a total knee replacement.

knee replacement

Mirko Ilic

More and more baby boomers are opting for knee replacement surgery earlier in life. The reason? Boomers like Emanuel are more active than any previous generation — and want to run, dance and play basketball and, yes, tennis at the same level of intensity as they did in their 20s.

Previously, knee replacement surgeries were reserved for very old patients who were severely crippled by osteoarthritis. "Now patients in their 40s and 50s are experiencing an earlier onset of osteoarthritis that affects their daily lives," says J. David Blaha, M.D., an orthopedic surgeon at the University of Michigan Health System. In fact, the number of boomers opting for early knee replacement is growing at a dramatic rate.

According to the American Academy of Orthopaedic Surgeons (AAOS), the total number of knee replacements performed each year, both total and partial, rose 30 percent from 2004 to 2008. In that same period, there was a whopping 61 percent increase in these surgeries among men and women ages 45 to 64. And that increase is expected to continue and even grow as boomers age. In 10 years, experts estimate, there could be as many as 3.2 million knee replacement surgeries each year, says Blaha.

What concerns orthopedic surgeons is that because joint replacements have been performed primarily on older patients, there isn't a lot of data to show how these implants hold up in younger people who will have them over longer periods of time.

"We use new and better materials and techniques, so we think there is an improvement in the longevity, but we still don't know. The new plastics have only been out there for three years," says Rafael J. Sierra, M.D., an orthopedic surgeon at the Mayo Clinic. The AAOS has announced the creation of the American Joint Replacement Registry to monitor replacement outcomes.

Younger knee replacement patients may need to get a new replacement in as little as five to 10 years, which is a concern. "It gets more complicated with each revision," says Michael R. Baumgaertner, M.D., professor of orthopedic surgery at Yale University School of Medicine. "Every time it has to be redone, there is more bone loss."

Still, researchers at the Center for Hip and Knee Surgery at St. Francis Hospital in Mooresville, Ind., report that total knee replacement patients demonstrated "remarkable" use of their knees 20 years after the surgery. The findings were presented last month at the annual convention of the AAOS.

"There is no free lunch," says Baumgaertner. "When it is successful, it is a powerful change in your life, but when it goes bad, it can be catastrophic." Any lower extremity surgery, he adds, "can lead to blood clots, and infections occur in about 2 percent [of cases]." The patients' symptoms, he says, "should be severe enough that they are willing to accept these risks. I find that patients tend to be very good at deciding when they've reached that point."

Most orthopedic surgeons recommend knee replacements only after all other options have been explored. These options include rest, pain medication, cortisone shots, physical therapy, weight loss and arthroscopic surgery. And some, mostly younger patients, may see good results with an osteotomy, surgery that shifts the alignment of the knees so that the weight-bearing part of the knee is moved away from diseased cartilage and onto healthier tissue.

Lloyd Emanuel knew he had reached the point where he needed a replacement when even standing became painful. He's glad he finally had the surgery. "I don't know if I'll get back to 100 percent on the court, but I do know my quality of life is back 100 percent. There is no throbbing pain, I can sleep and I can play and teach tennis. And I am getting better every day."

Eight Key Facts About Knee Replacement

1. What it is. Surgery to replace weight-bearing surfaces of a knee joint. The surgeon cuts away damaged bone, cartilage and one ligament, and replaces them with an artificial joint made of an alloy of cobalt, chrome or titanium, and a plastic compound called polyethylene. A total knee replacement replaces the entire joint; a partial knee replacement replaces only the damaged area. While a partial replacement can be done with minimally invasive surgery and has a speedier recovery time, only about 6 to 10 percent of patients are suitable candidates for this operation. Partial knee replacements work best where damage to the knees is only in a small area [see "What to Expect After Surgery"].

2. Why have it. To improve mobility and decrease pain caused by degenerative arthritis or injury to the knee joint. "I liken it to replacing a car tire when the treads wear out and getting a wheel realignment," says Yale's Baumgaertner.

3. Ballpark cost. Knee replacements are covered by Medicare and most private insurance. Hospital and surgeon costs vary widely, depending on the area of the country and the facility. According to the federal Agency for Healthcare Research and Quality, however, in 2008 hospitals charged an average of $45,783 for a patient stay of three to five days for a total knee replacement. But experts say few hospitals actually get that much. Medicare pays about $11,000, and some hospitals and insurance companies can negotiate reduced rates. Hospital costs include the implant, which runs from $5,000 to $10,000, surgical fees and hospital physical therapy. Partial knee replacement surgery costs about half that of total knee replacement.

4. Choose your surgeon and hospital wisely. A 2004 study reported in the Journal of Bone and Joint Surgery found that patients operated on by surgeons who performed 50 or more knee replacements a year had a lower risk of complications than those whose surgeons performed 12 or fewer a year. Patients who went to hospitals where more than 200 procedures were performed a year also fared better than those who went to hospitals that did 25 or fewer a year.

5. Beware marketing. In 2008, 63 percent of all knee replacement operations were performed on women. That may be because women over the age of 50 are more likely to develop osteoarthritis of the knee than men, experts say. Capitalizing on this, some manufacturers are promoting "gender specific" knee replacement devices they claim are tailored to a woman's unique physiology. However, Sierra of the Mayo Clinic says that while there are some subtle differences in structure between men and women, "it really is size-specific, not gender-specific. Your surgeon," he says, "will measure you to get the right size" device.

6. Recovery. The hospital stay is usually about three days after a total knee replacement operation; one day with a partial replacement. There is no cast, just a dressing covering the incision. After a total replacement you may need a short stay in a rehabilitation facility. And once at home you are going to need help. While recovery differs for everyone, expect to be uncomfortable for a week. When the discomfort subsides, start physical therapy. You'll probably need about two months of physical therapy, and it's critical — if you don't do the work right away, you can't catch up because the knee stiffens. After a partial replacement, expect two to four weeks of physical therapy.

7. Return to work. Those with a desk job may be able to return in as little as two weeks. If your job involves heavy labor, you could be out for several months.

8. Be realistic about outcome. "A knee replacement improves quality of life by reducing pain and improving mobility. It is not designed to make you younger or allow you to do activities that add stress to the joint or risk added injury," says Baumgaertner.

Beth Levine is a freelance writer who lives in Stamford, Conn.