TKA stands for total knee arthroplasty, the medical term for total knee replacement surgery. It is one of the most consistently successful procedures in orthopedic surgery, with over 90% of implants still functioning well at 20 years. The surgery replaces the damaged surfaces of your knee joint with metal and plastic components, and it’s typically reserved for people whose knee pain and stiffness haven’t improved with other treatments.
Why TKA Is Performed
The most common reason for a total knee replacement is end-stage osteoarthritis, where the cartilage cushioning the knee joint has worn away so severely that bone grinds against bone. This causes chronic pain, swelling, and stiffness that can make walking, climbing stairs, or even sitting comfortably difficult. Other conditions that can lead to TKA include inflammatory arthritis (such as rheumatoid arthritis), fractures that cause lasting joint damage, and structural abnormalities in the knee.
TKA is an elective procedure, meaning it’s scheduled rather than done in an emergency. Surgeons generally reserve it for patients who have already tried and exhausted conservative options: physical therapy, anti-inflammatory medications, injections, weight management, and activity modifications. When those approaches no longer control symptoms, replacement becomes a reasonable next step.
What Happens During the Surgery
During a total knee replacement, the surgeon removes the damaged cartilage and a thin layer of bone from three surfaces: the bottom end of the thighbone, the top of the shinbone, and the underside of the kneecap. These surfaces are then replaced with prosthetic components, typically made from metal alloys for the thighbone and shinbone caps, with a smooth plastic spacer between them that mimics the gliding function of healthy cartilage. The kneecap may also receive a plastic button on its underside.
Most TKAs use regional anesthesia, which numbs the lower body while you remain awake or lightly sedated. Compared to general anesthesia (being fully asleep), regional anesthesia is associated with about 40% fewer 30-day complications, lower rates of blood transfusion, and a hospital stay roughly half a day shorter. Your surgical team will recommend the best option based on your health history.
Robotic-Assisted TKA
A growing number of knee replacements now use robotic-assisted technology, where the surgeon operates with the help of a computer-guided robotic arm. The main advantage is precision in implant positioning. In studies comparing the two approaches, robotic-assisted surgery produced misaligned implants only about 16% of the time, compared to 76% with conventional manual techniques. Some studies found zero alignment errors in the robotic group versus roughly one in four with manual surgery.
Better alignment matters because a well-positioned implant distributes forces more evenly across the knee, which can reduce long-term wear. Robotic-assisted procedures also tend to involve less blood loss during surgery and less soft tissue swelling afterward, which can speed up early recovery and the return of full knee motion. Not every hospital offers robotic TKA, so availability varies.
Preparing for Surgery
Surgical teams now focus heavily on optimizing your health before the operation, because certain conditions significantly raise the risk of complications. If your body mass index is 40 or above, most programs will ask you to lose weight before scheduling surgery. If you have diabetes, your blood sugar control (measured by HbA1c) typically needs to be at or below 7.5%. Anemia is screened about four weeks before surgery and treated if found.
Smokers need to quit at least four weeks before and after the procedure, often confirmed with a blood test. If you’re taking opioid pain medications, you’ll be asked to reduce your dose by at least half in the month leading up to surgery. Nutritional status also matters: low protein levels in the blood are linked to poor wound healing and higher infection risk, so your team may order blood work and refer you to a nutritionist if levels are low.
Recovery Timeline
Recovery from TKA follows a fairly predictable path, though individual progress varies. In the first two weeks, the focus is on managing pain and swelling while starting gentle movement. Most people can bend the knee to about 90 degrees (a right angle) within two weeks and walk short distances using a walker or cane. Physical therapy begins almost immediately, often the day of or the day after surgery.
By six weeks, knee bend typically reaches around 110 degrees, and many people transition from a walker to a cane or walk unaided for short distances. The intermediate phase from six to twelve weeks is where more noticeable gains happen. Range of motion often reaches 120 degrees or more, and you can usually walk longer distances comfortably without an assistive device. Driving, light household tasks, and desk work are commonly resumed during this window.
Full recovery, meaning the point where the knee feels “normal” and strength is fully restored, generally takes six months to a year. Swelling can persist for several months even when function is good.
How Long a Knee Replacement Lasts
Modern knee implants are remarkably durable. Registry data and long-term studies show survival rates of about 93% at 15 years and 92% at 20 years, meaning fewer than 1 in 10 patients need a revision within two decades. Some registries report even tighter numbers, with revision rates around 8.8% at 19 years for commonly used implant systems.
When implants do fail, the reasons depend on timing. Early failures (within the first two years) are most often caused by infection, which accounts for about half of early revisions. Late failures, occurring after two years, are more varied. The leading causes are aseptic loosening (the implant gradually losing its bond with bone without infection), infection, and fractures around the implant. The average time from the original surgery to a first revision is about six years, though the range spans from a few months to over 20 years.
Cost of TKA in the United States
In the United States, total knee replacement is among the most expensive joint surgeries. The average cost is roughly $17,500 to $19,500, which includes the hospital stay, surgeon fees, implant, and anesthesia. Actual out-of-pocket costs vary widely depending on your insurance, whether the procedure is done as an inpatient or outpatient stay, and which facility performs it. Many TKAs are now performed with same-day or next-day discharge, which can lower the total bill compared to a multi-day hospital stay. By comparison, the same procedure costs a fraction of that price in other countries, averaging around $3,500 in India and roughly $7,000 to $13,000 in parts of Europe.