Arthritis refers to biomechanical changes within a joint. Osteoarthritis (OA) is the most common kind of arthritis. There are a number of contributing factors to osteoarthritis, including age.
There are two main types of osteoarthritis:
What is cartilage?
Cartilage is a firm, rubbery, flexible connective tissue covering the ends of bones in normal joints. It is primarily made up of water and proteins whose primary function is to reduce friction in the joints and serve as a "shock absorber." The shock-absorbing quality of normal cartilage comes from its ability to change shape when compressed, because of its high water content. Although cartilage may undergo some repair when damaged, the body does not grow new cartilage after injury. Cartilage is avascular, meaning there are no blood vessels in it. Therefore, healing is a slow process.
Cartilage is made up of two main elements: cells within it known as chondrocytes and a gel-like substance called matrix, composed mostly of water and two types of proteins (collagen and proteoglycans).
Who is affected by osteoarthritis?
Approximately 80% of older adults, ages 55 years and older, have evidence of osteoarthritis on X-ray. Of these, an estimated 60% experience symptoms. It is estimated that 240 million adults worldwide have symptomatic osteoarthritis, including more than 30 million U.S. adults. Post-menopausal women have an increased incidence of knee osteoarthritis compared to men.
What are the risk factors for osteoarthritis?
In addition to age and secondary causes such as inflammatory arthritis and prior injury/ trauma, several other risk factors increase the chance of developing osteoarthritis including obesity, diabetes, elevated cholesterol, sex, and genetics.