Updated on September 24, 2024.
If you’ve been living with knee pain for some time and find it increasingly difficult to navigate the basic movements of daily life, you may be a candidate for knee replacement.
The knee has three compartments: the inner side of the knee (medial), the outer side (lateral), and under the kneecap (patellofemoral). A partial knee replacement involves surgery on one of the compartments. Total knee replacement addresses all three compartments.
Each year, more than 700,000 total knee replacements are performed in the United States, according to the American Academy of Orthopaedic Surgeons (AAOS). More than 1 in 10 Americans will have a knee replacement by the time they reach 80 years old.
Meanwhile, the average age of people getting knee replacement surgery has decreased over time. The AAOS estimates it’s about 66 years old.
“Total knee replacements are one of the most common procedures performed by orthopedic surgeons in the United States,” says Thomas Carrell, MD, an orthopedic surgeon in North Richland Hills, Texas. Partial knee replacements are becoming more common as well, he adds.
Is a knee replacement right for you?
Surgery may be an option when you haven't had success relieving pain through exercise, physical therapy, or pain medication. This can include people with osteoarthritis, as well as people with a knee deformity or injury. Your healthcare provider (HCP) will work with you to determine if a knee replacement makes sense for you.
Knee replacement is not for everyone. There are some conditions that may disqualify you from having the procedure, including:
- Deep vein thrombosis or other blood problems
- An ongoing infection
- Immunosuppression, such as chronic kidney disease
- Extreme obesity
- Unhealthy skin around the joint or a weak quadriceps muscle
Some people may need additional medical evaluation before surgery, such as a urologic test (for people with a history of urinary tract infections) or cardiovascular tests (for people with heart disease). People who need to have major dental work done, such as tooth extractions or gum surgery, may be advised to complete these procedures before knee replacement, to reduce the risk of infection.
How to prepare for a knee replacement
You should expect to do some preoperative physical therapy designed to get you ready for the procedure. “Prehab” often involves working on improving your knee function, as well as preparing your home to make it easier to navigate while you recover.
A study published in 2019 in the Journal of Rehabilitation Medicine found that patients who participated in preoperative therapy were able to leave the hospital faster after surgery. They were also more likely to be able to rehab without the need for a care facility or home-health services.
Surgical techniques have advanced
The surgery itself has come a long way since the first knee replacement was performed in 1968. “Surgeons have been refining their ability to be minimally invasive,” says Dr. Carrell. “Where once there was a lengthy incision, now it’s a short incision.”
Knee replacements don’t last forever, but they last longer than they used to. In 85 to 90 percent of people, the knee implant will last 15 to 20 years, meaning a knee replacement may eventually have to be refixed. In those cases, a surgeon can perform a knee revision surgery to correct it.
“The revision products are now as good as the initial knee replacement,” Carrell says. “What that means to patients is if you have a revision, you may be able to count on 20 or 30 more years. In the past, the revision products wore down quicker than the original.”
In revision surgery, the original prosthetic implant is removed and a new one is put in place. Although a knee replacement may last for the life of an older patient, in younger people who have active lifestyles, a knee prosthetic may eventually fail due to wear and tear, instability, or stiffness around the knee. In rare cases, a knee prosthetic may have to be replaced because of infection.
Recovering from surgery
It may take 6 to 12 months to fully recover from a knee replacement. You'll likely use a walker for a few weeks after surgery, then crutches, followed by a cane. It's likely you'll be walking on your own in four to eight weeks. It’s best not to plan on returning to your pre-operation levels of activity right away.
“A total knee replacement is not an automatic jump-up-and-go,” Carrell says. “It does take several months to do certain endeavors.” You can probably do some walking or other light exercise by six weeks, but high impact exercise may be off the table for months—or it may be best to abstain from it altogether on your new knee.
To help prevent blood clots and decrease swelling, your surgeon may prescribe blood-thinning medications, as well as support hose or compression boots. Even if you’re not up and running, you’ll be advised to move your feet and ankles regularly to increase blood flow and help avoid swelling and clots.
Managing pain after knee replacement surgery
Pain will likely be a factor for up to three months after the surgery. Your surgeon may prescribe a combination of pain relievers, including nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, local anesthetics, or opioids, with a goal toward reducing the need for opioids as much as possible. Pain control helps you stay active and engaged during your physical therapy and recovery.
“If patients manage pain properly with the advice of their healthcare provider, they’ll have less scar tissue formation,” Carrell adds. This helps prevent your knee from getting too stiff, which can impact your range of motion.
Physical therapy is an important part of your recovery from knee surgery and offers several benefits. A 2021 study published in JAMA Network Open found that among people who had a total knee replacement, those who underwent physical therapy had lower long-term use of opioid use for pain.
