It also absorbs energy from the shock of physical movement. When cartilage in a joint deteriorates osteoarthritis occurs. There are two categories of osteoarthritis, primary and secondary. Primary osteoarthritis appears without any apparent cause, usually as a result of aging. Secondary osteoarthritis occurs in joints that have sustained injuries, experienced infections or fractures.
Obesity can also cause secondary osteoarthritis due to the added pressure on weight bearing joints.
Secondary osteoarthritis can also occur as the result of another type of arthritis, such as rheumatoid. As the cartilage in a joint deteriorates the bones begin to rub together, causing pain, swelling, and loss of motion of the joint. The joint may begin to lose shape. Small bone spurs called osteophytes may grow on the edges of the joint. Inflammation may or may not be present.