Although osteoarthritis was long believed to be caused by the “wear and tear” of joints over time, scientists now view it as a disease of the joint. Here are some of the factors that contribute to the development of OA:
Genes: Various genetic traits can make a person more likely to develop OA. One possibility is a rare defect in the body’s production of collagen, the protein that makes up cartilage. This abnormality can cause osteoarthritis to occur as early as age 20. Other inherited traits may result in slight defects in the way the bones fit together so that cartilage wears away faster than usual. Researchers have found that a gene called FAAH, previously linked to increased pain sensitivity, is higher in people with knee OA than in people who don’t have the disease.
Weight: Being overweight puts additional pressure on hips and knees. Many years of carrying extra pounds can cause the cartilage that cushions joints to break down faster. Research has shown there is a link between being overweight and having an increased risk of osteoarthritis in the hands. These studies suggest that excess fat tissue produces inflammatory chemicals (cytokines) that can damage the joints.
Injury and overuse: Repetitive movements or injuries to joints (such as a fracture, surgery or ligament tears) can lead to osteoarthritis. Some athletes, for example, repeatedly damage joints, tendons and ligaments, which can speed cartilage breakdown. Certain careers that require standing for long periods of time, repetitive bending, heavy lifting or other movements can also make cartilage wear away more quickly. An imbalance or weakness of the muscles supporting a joint can also lead to altered movement and eventual cartilage breakdown in joints.
Others: Several other factors may contribute to osteoarthritis. These factors include bone and joint disorders like rheumatoid arthritis, certain metabolic disorders such as hemochromatosis, which causes the body to absorb too much iron, or acromegaly, which causes the body to make too much growth hormone.