Modern knee replacement surgery began in the early 1970s. Over the last 30 years, the procedure has been refined and improved and is now one of the most successful surgical procedures for the treatment of knee arthritis. Assuming there are no breakthrough preventive treatments for the conditions that lead to total knee arthroplasty, by the year 2030 the American Academy of Orthopaedic Surgeons estimates that about 450,000 total knee arthroplasty procedures will be performed every year. This is a large increase from the 245,000 total knee replacements performed in 1996 and reflects the aging of our active and mobile culture.
Knee replacement surgery is performed to treat advanced or end-stage arthritis. When arthritis in the knee joint or joints has increased to the point where medical management is not effective, or deformity has become severe and debilitating (reduces the person’s strength), knee replacement surgery might be indicated.
Arthritis is a general term that describes inflammation (swelling) and deterioration in joints. In the knee, arthritis results from damage to the coating or gliding surface called the articular cartilage. Depending on the amount of damage, ordinary activities such as walking and climbing stairs might become difficult.
Damage to the knee joint cartilage and underlying bone might also result in deformity. Knock-knee or bow-legged deformities and unusual knee sounds (crepitus) might become more obvious as the degeneration (deterioration) worsens.
Mechanical "wear and tear" on a person's knees over a lifetime seems to be an obvious explanation for the increase of arthritis with age, but the answer is not that simple. The current view is that a number of factors act together to cause knee deterioration. Some of these factors include heredity, developmental abnormalities of knee formation, genetic tendency to abnormal cartilage metabolism, major or minor repetitive injuries, and certain occupations. While being overweight does not necessarily cause arthritis, it certainly contributes to early and more rapid development of knee problems.
People with painful knee deformities, severe degenerative X-ray changes, or advanced symptoms of arthritis are candidates for knee replacement surgery. Symptoms of advanced end-stage knee arthritis include:
Family physicians, internists, rheumatologists, physiatrists, and orthopaedic surgeons are all trained to manage knee arthritis and can perform an initial evaluation. When medications (oral and injectable), diet, and physical therapy fail to manage these symptoms, knee replacement surgery may be indicated and performed by an orthopaedic surgeon.
Total knee replacement surgery provides relief for patients with severe pain caused by degeneration of the cartilage in the knee, advanced arthritis, or serious knee injuries. Approximately 85 to 90 percent of all total knee replacement operations performed are successful for approximately 10 to 15 years, depending on the patient's level of activity, after which time revision surgery may be recommended by your doctor.
Degenerative changes or injury can cause damage to some of the structures in the knee, causing pain and discomfort, and limiting normal activities. One of these conditions, called osteoarthritis, causes the cartilage that normally helps to cushion the bones to wear down, making the bones rub together, which causes pain. Other conditions that may lead to total knee replacement surgery are rheumatoid arthritis and post-traumatic arthritis. Your doctor may try to reduce your discomfort with pain medication, weight management, and physical therapy, but total knee replacement may be recommended if these remedies are unsuccessful.
Knee replacement surgery is designed to replace the damaged articular cartilage or gliding surface and any related loss of bone structure or ligament support. The procedure itself is a resurfacing of the damaged knee, and relies on the patient's muscles and ligaments for support and function. The prostheses (replacement knees) come in several different configurations designed for replacement of specific patterns of advanced arthritis.
Knee replacements are not all the same. There are different types of knee replacements, such as:
These different prostheses can be made of cobalt chrome, titanium, and polyethylene (plastic). They can be fixed to the bone with acrylic cement or can be press-fit, which allows bone to grow into the implant. The use of a particular implant design, material, and fixation method depends on many factors related to each patient. The orthopaedic surgeon selects the type of knee replacement that best suits the patient, based on the amount of arthritis bone loss and the quality of the ligaments supporting the knee.
The surgery involves removing a small portion of the bone in the knee, and covering it with a combination of metal and plastic to form a new surface of the joint and to repair loss of bone structure or ligament support.
Medicines may be prescribed by your surgeon to help prevent blood clots after surgery. Your surgeon and physical therapist will also discuss movement guidelines for you following surgery.
Knee conditions limit patients' activities of daily living due to pain and limited mobility. A benefit of knee replacement surgery is that it may be able to help patients resume a normal lifestyle. However, depending on the patient's underlying condition and overlying health, the patient may never be without pain, even after knee replacement surgery.
While knee replacement surgery is a safe treatment, there are risks that are possible with any surgery. For total knee replacement, they include:
Knee replacement surgery is nearly always a successful procedure, but patients should carefully consider any risks and weigh them carefully before deciding to have surgery.
The vast majority of patients who undergo total knee surgery have dramatic improvement within weeks of the surgery. The pain caused by the damaged knee is relieved when a new gliding surface is constructed. Patients who have knee replacement surgery are standing and moving the joint the day after surgery. After about six weeks, most patients are walking comfortably with only a little support. After muscle strength is restored, patients who have knee replacement surgery can enjoy most activities (except running and jumping).
When knee replacement procedures were first performed in the early 1970s, it was thought that the average total knee implant would last approximately 10 years. We now know that approximately 85 percent of the knee implants will last 20 years. Improvements in surgical technique, prosthetic designs, bearing surfaces, and fixation methods might increase the survival rate of these implants even longer.
Depending on the individual patient and their specific condition and needs, it may take from six months to a year to fully recover from knee replacement surgery. After total knee replacement surgery, patients can lead healthy and active lives. Some activities, such as high-impact sports, should be avoided, and a leg brace is required for any athletic sports.
Rehabilitation begins immediately following surgery and may include a machine to help move your leg in the first few days after surgery. The success of the replacement and recovery is contingent on the patient and their participation in the rehabilitation process. This process requires a lot of time, effort, and a positive attitude to ensure success.
Before you leave the hospital, a physical therapist will provide goals and instructions for you to complete while in the hospital and at home. It is recommended that you follow the instructions for a minimum of two months following surgery. At that time, you should ask your physician when you may resume your previous activities.
There are several basic rules about positioning that you should be aware of following surgery. Make sure that you do not kneel, squat or jump, and do not twist or pivot your operated knee. Do not place weights on top of your knee, and do not allow anyone to push on your knee or ankle while sitting or lying down. Do not use ankle weights, and do not lie in bed with a roll or pillow under your knee for prolonged periods of time. While sitting, make sure that you use a straight back chair with arm rests, and do not sit in chairs or sofas lower than knee height since they require excessive bending at the knees when sitting down and getting up. Also remember not to cross your legs while sitting and place a stool under your feet for support while lifting weights. Since most toilet seats are lower than knee height, patients are recommended to use a toilet seat extension, which are available for purchase in the hospital or a medical supply store. Based on your individual treatment plan, your physical therapist will determine your need for this item.
© Copyright 1995-2020 The Cleveland Clinic Foundation. All rights reserved.
This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 07/14/2016