The categorization of people by social strata occurs in all societies, ranging from the complex, state-based societies to tribal and feudal societies, which are based upon socio-economic relations among classes of nobility and classes of peasants.
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,[1] and also for other knee diseases such as rheumatoid arthritis and psoriatic arthritis.
1 Osteoarthritis is the most common reason for knee replacement operation in the U.S. 2  Risks of total knee replacement surgery have been identified. 3  Physical therapy is an essential part of rehabilitation after total knee replacement. Risks of total knee replacement surgery have been identified. 2  Physical therapy is an essential part of rehabilitation after total knee replacement. 3  Patients with artificial joints are recommended to take antibiotics before, during, and after any elective invasive procedures (including dental work).