Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability. It is most commonly performed for osteoarthritis, but it can also be used for other knee diseases, such as rheumatoid arthritis and psoriatic arthritis. In people with severe deformity from advanced rheumatoid arthritis, trauma, or long-standing osteoarthritis, the surgery may be more complicated and carry a higher risk. Osteoporosis does not typically cause knee pain, deformity, or inflammation and is not a reason to perform knee replacement. Knee replacement surgery can be performed as a partial or a total knee replacement. In general, the surgery consists of replacing the diseased or damaged joint surfaces of the knee with metal and plastic components shaped to allow continued motion of the knee. The operation typically involves substantial postoperative pain and includes vigorous physical rehabilitation. The recovery period may be 12 weeks or longer and may involve the use of mobility aids (e.g., walking frames, canes, crutches) to enable the person's return to preoperative mobility. It is estimated that approximately 82% of total knee replacements will last 25 years.
History The first documented artificial knee replacement was a device using ivory knee components fixed together with plaster of Paris, reported in 1890. In the 1950s, a cobalt-chrome hinged knee was used to replace both the femur and tibia, although this device had high failure rates due to an inability to accommodate the knee's natural rotational movement. In 1970, a knee replacement that featured metal runners with polyethylene components was applied, although this device was limited in design and instrumentation. The total condylar knee replacement was used to accommodate all three knee components (femur, tibia, and patella), with the first successful total condylar surgery performed at Hospital for Special Surgery in New York City in 1974. The first smart knee replacement, called Persona IQ smart implant, enabled remote daily monitoring for one year, as reported in 2021.
Medical uses
Knee replacement surgery is most commonly performed in people with advanced osteoarthritis and should be considered when conservative treatments have been exhausted. Total knee replacement is also an option to correct significant knee joint or bone trauma in young patients, treat complex fractures in the elderly, either due to previous symptomatic osteoarthritis or situations where internal fixation with plates and screws is deemed too hazardous. Similarly, total knee replacement can be performed to correct mild valgus or varus deformity. Severe valgus or varus deformity should be corrected by osteotomy. Physical therapy has been shown to improve function and may delay or prevent the need for knee replacement. Pain is often noted when performing physical activities requiring a wide range of motion in the knee joint.
Outcomes Knee replacement provides significantly better results than exercise training in terms of reducing pain 6 months to 2 years afterwards. People who have had knee replacements have lower death rates than the matched population for 10 years after surgery, but increased rates from 11 years onwards. For this reason, it is sometimes argued that the age group 65-75 is the best time to consider having a knee replacement if activity is being severely curtailed by knee pain. Although knee replacement has superior 24-month results in terms of pain relief than exercise treatment, it may not be cost-effective compared to the option of initial exercise treatment followed by crossover to knee replacement if results are unsatisfactory.
Pre-operative preparation
To indicate knee replacement in case of osteoarthritis, its radiographic classification and severity of symptoms both should be substantial. Such radiography should consist of weightbearing X-rays of both knees: AP, lateral, and 30 degrees of flexion. AP and lateral views may not show joint space narrowing, but the 30-degree flexion view is most sensitive for narrowing. Full-length projections are also used in order to adjust the prosthesis to provide a neutral angle for the distal lower extremity.
… excerpt ends here. Continue reading the full article.
