American Medical Association Family Medical Guide - American Medical Association [698]
Osteoarthritis
Osteoarthritis, also called degenerative joint disease, occurs when cartilage (the tough, smooth tissue that covers the ends of bones in a joint) breaks down and gradually becomes rougher and thinner. Swelling can occur if the lining of the joint (called the synovial membrane) becomes irritated and produces excess fluid that collects inside the joint. As the cartilage wears away, growths of bone called bone spurs may form around the edges of the joint, making it look knobby and swollen. As the process continues, more cartilage wears away, causing the bones that meet at the joint to rub against each other. Because bone is very sensitive, this rubbing together can cause extreme pain and severely reduce movement in the joint. The joints that are most often affected by osteoarthritis include the knees, hips, back, neck, toes, and fingers.
Risk Factors
Osteoarthritis, which affects both women and men, is the most common joint disorder. Women usually develop it in their hands and knees, while men tend to develop it in their hips, knees, and back. The following factors can increase your risk of osteoarthritis:
• Age People age 45 and older are most often affected by osteoarthritis. Most people over age 60 have some degree of osteoarthritis. Although age is an important factor in osteoarthritis, the disease is not an inevitable result of aging.
• Heredity Some people inherit genes that make them more susceptible than other people to developing osteoarthritis.
• Being overweight People who are overweight are more likely to develop osteoarthritis because extra weight can strain the joints, especially the knee joints. If you already have osteoarthritis, being overweight can make your symptoms worse.
• Injury or overuse Osteoarthritis usually results from injury to a joint. A serious injury to a joint such as a fracture or an infection can damage the tissue in the joint, which can cause osteoarthritis in that joint. Overusing a joint can also lead to osteoarthritis.
• Lack of activity You are more likely to develop osteoarthritis if you rarely exercise. Inactivity can cause a joint to become stiff and painful and reduces flexibility.
Joint damaged by osteoarthritis
In a healthy joint (left), cartilage on the end of each bone cushions the bones and allows them to glide easily against each other. In a joint that has been damaged by osteoarthritis (right), the cartilage is damaged and the bones rub against each other, making movement painful.
Symptoms
In many people, osteoarthritis does not cause symptoms. (Osteoarthritis is often detected when X-rays are taken for some other reason.) When symptoms develop, they may be mild, with only one or two joints affected at first. Over time, symptoms may become severe and eventually make normal movement difficult. See your doctor if you have any of the following symptoms for longer than 2 weeks:
• Pain or stiffness in or near a joint The pain of osteoarthritis can be deep and aching in or near the affected joint. It can come and go and increase or decrease in severity, depending on the time of day or the type of activity. The pain may be worse at the end of the day or after extreme use such as exercise. The joint is often stiff in the morning and after other long periods of inactivity.
• Swelling in a joint Swelling occurs in the joint when the synovial membrane becomes irritated and produces fluid that collects inside the joint. As more cartilage wears away, growths may form on the ends of the bones and make the joint look knobby and swollen.
• Crackling and grating when you move a joint You may hear crackling and feel a grating sensation (called crepitation) when you move a joint that is affected by osteoarthritis. In most cases, crepitation results from swollen synovial membranes rubbing inside the joint. In severe cases, it can result from