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INTRODUCTION — Total knee replacement, also known as total knee arthroplasty, is a surgical procedure in which parts of the knee joint are replaced with artificial (prosthetic) parts (image 1).
A normal knee functions as a hinge joint between the upper leg bone (femur) and the lower leg bones (tibia and fibula) (figure 1). The surfaces where these bones meet can become worn out over time, often due to arthritis or other conditions, which can cause pain and swelling. (See "Patient education: Osteoarthritis symptoms and diagnosis (Beyond the Basics)" and "Patient education: Osteoarthritis treatment (Beyond the Basics)".)
More detailed information about knee replacement is available by subscription. (See 'Professional level information' below.)
REASONS FOR KNEE REPLACEMENT — Total knee replacement is one option to relieve pain and to restore function to an arthritic knee. The most common reason for knee replacement is that other treatments (weight loss, exercise/physical therapy, medicines, injections, and bracing) have failed to relieve arthritis-associated knee pain.
The goal of knee replacement is to relieve pain, improve quality of life, and maintain or improve knee function. The procedure is performed on people of all ages, with the exception of children, whose bones are still growing. It is important to have significant pain and/or disability prior to considering this procedure. Because the replacement parts can break down over time, healthcare providers generally recommend delaying knee replacement until it is absolutely necessary.
Knee replacements are one of the most commonly performed joint replacement procedures.
ALTERNATIVES TO KNEE REPLACEMENT — While total knee replacement can be helpful under the right circumstances, you should discuss the risks, benefits, and alternatives with a doctor. Alternatives to total knee replacement include:
Nonsurgical treatment — Nonsurgical treatment methods are initially recommended for patients with osteoarthritis or inflammatory arthritis. This may include:
●Weight loss – The knee bears about four pounds of pressure for each pound of body weight, so even a small amount of weight loss (eg, 10 to 15 pounds) can reduce pain.
●Exercise/physical therapy – Strengthening the muscles around the knee help take pressure off the knee. Motion of the joint helps to keep it from getting stiff.
●Medications, including over-the-counter and prescription – These include pain relievers such as acetaminophen and antiinflammatory drugs such as ibuprofen or naproxen. Patients should discuss use of these medications with their primary care provider and pharmacist to be sure the risk of side effects is acceptably low. (See "Patient education: Nonsteroidal antiinflammatory drugs (NSAIDs) (Beyond the Basics)".)
●Knee bracing or shoe inserts – These may help align the knee and balance the weight on the joint.
●Injections – This might involve a cortisone-like drug or a hyaluronic acid derivative. (See "Patient education: Knee pain (Beyond the Basics)".)
Arthroscopy — Arthroscopy is a minimally invasive surgical procedure in which a doctor examines the inside of a joint with a device called an arthroscope. The doctor can repair any damage through small surgical incisions in the skin. Arthroscopy is only helpful for a certain type of knee problems. Arthroscopic surgery has not demonstrated significant benefit for patients with osteoarthritis.
Osteotomy — Osteotomy is a surgical procedure that involves cutting the leg bone, realigning it, and allowing it to heal. It is used to shift weight from a damaged part of the knee to a normal or less damaged one. Osteotomy is not recommended for patients older than 60 years of age or for those with inflammatory arthritis (such as rheumatoid arthritis).
Partial knee replacement — A "partial" or "unicompartmental" knee replacement involves replacing only one part of the knee joint. It may be an option for certain people whose osteoarthritis is limited to only one compartment of the knee. Your doctor can talk to you about whether you might be a candidate for this type of procedure, as well as the potential risks and benefits.
THE KNEE REPLACEMENT PROCEDURE — Knee replacement is performed in an operating room after you are given anesthesia. The surgery takes two to three hours. After surgery, you will be monitored in a recovery area for several hours, until the effects of the anesthesia wear off.
Most people stay in the hospital for one or two nights after surgery, although shorter stays are becoming more common and many procedures are even done on an outpatient basis (ie, not requiring a hospital stay).
After surgery, you will be given pain medicines to help control any discomfort from the procedure.
●Whenever possible, non-opioid medicines will be used to help minimize pain.
●Some opioid medicines may be needed for a few weeks, particularly before physical therapy and sleep.
Blood clots in the legs (called deep vein thromboses or "DVT") are a common concern after knee replacement surgery. To reduce the risk of blood clots, you can:
●Get up and moving as soon as possible – Work with your physical therapist to try and get up the day of surgery or the day after. Learn exercises to do while in bed.
●Take an anti-clotting medication – You will take an anticoagulant medicine ("blood thinner"), either as a pill or a shot. Most people continue to take this medicine for a few weeks after surgery.
●Wear compression boots (devices that go around the legs and inflate periodically) while you are lying down – Once you are able to get up and walk, your doctor may suggest wearing antiembolism stockings. These stockings fit snugly around the foot, ankle, lower leg, and knee to help prevent blood clots.
Infection is another major concern, and you will be given antibiotics within an hour of the procedure and for up to 24 hours after. Eating a healthy diet, avoiding obesity, controlling blood sugars if diabetic, and smoking cessation all are helpful for minimizing infection risk.
Rehabilitation — You will be encouraged to start moving your feet and ankles immediately after surgery. It is common to begin physical therapy the day of or the day after surgery. Active motion of the knee is encouraged.
Physical therapy is an important part of the recovery process. After leaving the hospital, some people have physical therapy in their home or at a clinic, while others stay in a rehabilitation facility or nursing home for a few days.
The rehabilitation program generally includes exercises to improve range of motion (how far you can bend and straighten your knee) and to strengthen your leg muscles. Your surgeon and physical therapist will help to set goals as you progress through rehabilitation. It is important to avoid overworking or straining the knee during the recovery period. You can usually resume your normal daily activities within three to six weeks after surgery. After several months of rehabilitation, you will be able to have a more active lifestyle. High-impact sports such as running and sports that involve heavy contact (football) are not recommended, but you should be able to participate in activities like walking, bicycling, and swimming.
Potential complications — Serious complications are not common after knee replacement. However, any surgery comes with risks, and it is important to be aware of this. Your doctor will discuss the potential complications with you in detail.
Studies have shown that a successful joint replacement partially depends upon the experience of the surgeon and the hospital. Finding an experienced surgeon and a hospital where joint replacements are routinely done will likely improve your chances of a successful procedure with improved knee function and minimal complications.
The following are some of the more common complications that may occur after total knee replacement:
Blood clot — Having total knee replacement increases the risk of a blood clot forming in a vein. The most common place for a clot to develop after knee surgery is in the deep veins of the leg (called a deep vein thrombosis or DVT). This is a concern because a clot can be deadly if it travels to the lungs (doctors call this a pulmonary embolism). Call your doctor's office if you have symptoms that could indicate a DVT, such as leg pain or swelling. (See "Patient education: Deep vein thrombosis (DVT) (Beyond the Basics)".)
Infection — Infection following knee replacement is a relatively uncommon but serious complication. Signs of infection include fever, chills, pain in the knee that gets worse suddenly, increasing redness, or swelling. Call your doctor's office if you are worried that you could have an infection.
Wound infections are treated with antibiotics and occasionally by draining excess fluid from the joint. If an infection becomes deep or extensive, the prosthetic joint may need to be removed and reimplanted later, after the infection has cleared. (See "Patient education: Joint infection (Beyond the Basics)".)
Stiffness — Occasionally, despite physical therapy, a patient's knee may get stiff and may not bend or straighten properly. If this occurs, then the patient may return to the operating room in order to bend and/or straighten the knee under anesthesia.
Early failure — The majority of knee replacements will last between 15 to 20 years. However, early failures may occur due to a variety of reasons. These include loosening of the implants, infection, fractures of the bone around the implants, and instability. When early failures occur, revision surgery may be necessary.
Because knee implants typically do not last much longer than 20 years, people who get a knee replacement at a younger age are more likely to require revision surgery. Younger people are more likely to live for longer than the lifespan of their implant; they may also have a more active lifestyle, which can put strain on the implant, contributing to failure over time. For these reasons, doctors are cautious about recommending knee replacement in people younger than 50.
Persistent pain/dissatisfaction — Approximately 15 percent of patients who undergo total knee replacement may have persistent pain or will not be satisfied with the outcome of the procedure. However, most people experience significant reduction or elimination of pain.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient education: Knee replacement (The Basics)
Patient education: Osteoarthritis (The Basics)
Patient education: Paget disease of bone (The Basics)
Patient education: Using crutches (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient education: Knee pain (Beyond the Basics)
Patient education: Deep vein thrombosis (DVT) (Beyond the Basics)
Patient education: Joint infection (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Complications of total knee arthroplasty
Prevention of venous thromboembolism in adults undergoing hip fracture repair or hip or knee replacement
Prosthetic joint infection: Epidemiology, microbiology, clinical manifestations, and diagnosis
Prevention of prosthetic joint and other types of orthopedic hardware infection
Prevention of venous thromboembolic disease in acutely ill hospitalized medical adults
Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients
Overview of surgical therapy of knee and hip osteoarthritis
Total joint replacement for severe rheumatoid arthritis
Total knee arthroplasty
Prosthetic joint infection: Treatment
The following organizations also provide reliable health information.
●National Library of Medicine
(https://medlineplus.gov/healthtopics.html)
●The Arthritis Foundation
(800) 283-7800
●American Academy of Orthopaedic Surgeons
