Total knee replacement is a surgical procedure that replaces some parts or the whole knee joint with artificial components. This operation is most often done to relieve pain and improve movement in people with advanced arthritis or injury. More than 90% of people who have a total knee replacement experience significant improvement in pain and daily function after surgery. While recovery takes time and effort, advances in surgical techniques and rehabilitation have made this procedure highly successful for many patients.

Total knee replacement, also called total knee arthroplasty, is a surgery in which worn or damaged surfaces of the knee joint are cut and replaced with artificial parts. The knee is a hinge joint formed by the thigh bone (femur), shin bone (tibia), and kneecap (patella). During surgery, the doctor takes out worn cartilage and a thin layer of bone from the thigh and shin bones, then fits metal pieces over these areas. A durable plastic insert is placed between them to help the knee move smoothly. The underside of the kneecap may also be resurfaced with a plastic part in some cases.

The artificial knee is designed to mimic the natural movement of a healthy joint. Most implants are made of metal and strong plastic, and some may use ceramic materials. The goal is to relieve pain, correct deformity, and restore function so people can return to daily activities with less discomfort. Total knee replacement is one of the most commonly performed and successful orthopedic procedures.

People may need total knee replacement when knee pain, stiffness, and functional limitations become severe and do not improve with other nonsurgical treatments. The most common reason is advanced arthritis, which causes the cartilage in the knee to wear away. This leads to pain, swelling, and difficulty moving the joint.

Common reasons for considering total knee replacement include:

• Persistent knee pain or stiffness that interferes with daily movement, such as walking or using stairs
• Pain that does not go away, even when resting
• Swelling and inflammation that remain despite rest or medication
• Changes in leg alignment, such as bowing inward or outward
• Trouble with routine tasks, including self-care or errands
• Lack of improvement after trying physical therapy, medication (including joint injections), weight management, or supportive devices

Other causes that may lead to secondary osteoarthritis (joint wear and tear caused by another condition or injury) and subsequent knee replacement are rheumatoid arthritis, posttraumatic arthritis from previous injury, or certain bone diseases. The decision to have surgery is usually made after careful discussion with a doctor, considering how much the knee problems affect quality of life.

A good candidate for total knee replacement is someone with significant knee pain and disability that has not improved with other treatments. Doctors consider several factors when deciding if surgery is appropriate:

• People who have not found relief with nonsurgical treatments
• Those whose knee symptoms make daily life difficult or reduce independence
• Individuals who have advanced arthritis or joint damage visible on imaging
• Patients who are medically able to have surgery and participate in recovery

There are no strict age limits for knee replacement. Most patients are between 50 and 80 years old, but the procedure can be done in younger or older adults if needed. However, younger, more active people may put more stress on the artificial joint, which can lead to earlier wear.

Certain conditions may make surgery unsafe or less successful, such as:

• Active infection in the natural knee (before replacement) or elsewhere in the body
• Poor blood flow to the leg
• Severe weakness or paralysis of the leg muscles
• Inability to participate in rehabilitation after surgery

Preparing for total knee replacement involves several steps to ensure the best possible outcome. Planning ahead can help make recovery smoother and reduce the risk of complications.

Key steps in preparation include:

• Complete a medical checkup: Assess overall health and address any medical issues before surgery.
• Review current medications and supplements with the healthcare team; some may need to be paused.
• Address dental and other infections ahead of time to lower infection risk after surgery.
• Quit smoking in advance to help with healing and reduce complications.
• Modify the home for safety and convenience, such as removing tripping hazards, adding support bars, and arranging a sleeping area on the main floor if needed.
• Plan for help with meals, chores, and personal care during early recovery; consider short-term rehab if living alone.
• Practice exercises or physical therapy before surgery to build strength and learn to use mobility aids.

Total knee replacement is performed in a hospital or surgical center. The procedure usually takes one to two hours but may be longer in complex cases.

During the surgery:

• Before surgery, anesthesia is given to block pain, either by putting the patient to sleep or numbing the lower body.
• The surgeon opens the front of the knee to reach the joint.
• Worn cartilage and a thin layer of bone are carefully removed from the thigh and shin bones.
• The remaining bone is shaped to fit the artificial parts.
• Metal components are secured to the bone, sometimes using cement (cemented implants) or allowing bone to grow into them (cementless implants).
• A plastic insert is placed between the metal pieces to help the knee move easily.
• The kneecap may also be resurfaced with a plastic part if needed.
• Before closing, the surgeon checks the fit and movement of the new joint.
• The incision is closed with stitches or staples, and a bandage is applied.

Recovery after total knee replacement takes time and effort, but most people can return to basic daily activities within a few days to weeks. The process involves several stages:

• Hospital stay: Some people go home the same day, while others stay one to two nights. Early movement is encouraged to reduce the risk of blood clots and speed healing.
• Pain management: Medicines, including non-opioid and sometimes opioid pain relievers, are used to control discomfort. Nerve blocks or local anesthetics may also be used.
• Physical therapy: Rehabilitation begins as soon as possible, often the day of or after surgery. A physical therapist will teach exercises to improve knee movement, strengthen muscles, and help with walking.
• People often rely on a walker, crutches, or a cane during the first weeks of recovery while they rebuild strength and stability.
• Care for the incision by keeping it dry and clean; stitches or staples are typically taken out a couple of weeks after surgery if needed.
• Patients should plan for assistance with meals, bathing, and errands during early recovery, and adjust their living space to reduce fall risks, such as by adding support bars or clearing clutter.
• Increase activity level step by step as the knee becomes stronger and more flexible.
• Many people return to their usual routines within a month or two, though it may take several months up to a year for complete healing and recovery.
• Most people are able to drive again once they can move their knee easily and have regained strength, which is often about a month after surgery.
• Attend scheduled appointments with the doctor to track recovery and check the artificial joint.

Total knee replacement is generally safe, but like any major surgery, it carries some risks and possible complications. Most people recover well, but it is important to know what to watch for and when to seek medical help.

Possible risks and complications include:

• Blood clots may develop in the legs after surgery, and in rare cases, can travel to the lungs, causing a pulmonary embolism.
• Infections can affect the wound or the area around the prosthetic knee joint, sometimes requiring further treatment.
• Some people experience slow or difficult healing of the incision site.
• Injury to nerves or blood vessels near the knee is uncommon but can cause numbness or weakness.
• Scar tissue may form, limiting knee movement and sometimes needing additional physical therapy or surgery.
• Artificial joint parts can loosen or wear out over time, especially in younger or very active individuals.
• The new knee may feel unstable if ligaments are weak or the parts are not aligned well.
• Broken bones around the implant can occur, particularly in those with weaker bones.
• Some patients continue to have knee pain even after surgery.
• Rarely, people may have allergic reactions to the materials in the implant.
• Other risks include heart or anesthesia problems, especially in those with other health issues.

Most people who have total knee replacement experience significant pain relief and improved ability to perform daily and specific sports activities. The majority can walk, climb stairs, and enjoy low-impact activities such as swimming, biking, and golfing. High-impact sports and heavy lifting are generally not recommended.

Most knee implants work well for at least 20 years, and many continue to function for 25 years or more. Younger and more active people may need a second surgery (revision) if the implant wears out over time. While most people are pleased with their new knee, up to one in 10 may still have pain or feel less satisfied after surgery.

“Yale Medicine, through the division of hip and knee joint reconstruction, distinguishes itself through a rare blend of historic surgical leadership and futuristic technology,” says Elie Mansour, MD, a Yale Medicine orthopaedic surgeon who specializes in hip and knee replacement and reconstruction. “All surgeons are fellowship trained to deal with any primary or revision knee replacement surgery. Furthermore, every surgery is tailored to the patient’s unique anatomy, using cutting-edge technology in the field of knee replacement, including navigation and robotic surgery. The increasing percentage of patients who are discharged to home the same day after total knee replacement is another proof of the commitment of Yale Medicine to improving patient experience and satisfaction.”