Curriculum · Musculoskeletal / Orthopedic / Rheumatology
Osteoarthritis
What it is
Osteoarthritis is often described as wear and tear in the joints. It is not an inflammatory condition like rheumatoid arthritis, and the -itis ending is misleading. It occurs in the synovial joints and is thought to be the result of an imbalance between the cartilage being worn down and the chondrocytes repairing it, leading to structural issues in the joint.
Causes and risk
It is a result of a combination of genetic factors, overuse and injury. Risk factors include obesity, age, occupation, trauma, being female and family history. Overweight and obesity have consistently been found to approximately double the risk for developing knee osteoarthritis, and the other risk factors identified for the knee are female sex, advancing age (50-75 years of age), and previous trauma. Smoking, inactivity, moderate physical activity, and socioeconomic status have not been shown to affect the risk for developing knee osteoarthritis. In those aged 65-75 the frequency of osteoarthritis is 75% in the spine, 60% in the hand, 30% in the knee and 10% in the hip. The incidence in adults over age 20 is 88 per 100,000 person-years for the hip, 100 per 100,000 person-years for the hand, and 240 per 100,000 person-years for the knee.