Osteoarthritis

Overview

Risk Factors

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Osteoarthritis is an extremely common and potentially debilitating progressive condition. In fact, it's the most common joint condition throughout the world. Researchers believe that there are more than 20 million people with osteoarthritis in the United States alone. More than half of all people over the age of 65 has arthritis in at least one joint; researchers think that nearly everyone over the age of 75 has some degree of osteoarthritis. If you've had an injury to a joint, you may develop osteoarthritis at a younger age.

In osteoarthritis, the cartilage (the tissue located at the end of bones) deteriorates over time.
Normally, cartilage is the "shock absorber" in a joint. It absorbs energy from jarring movement, protecting the bone and other tissue in the area. Cartilage is naturally a slippery material, and helps the joint glide smoothly. When the cartilage begins to show "wear and tear," the joint becomes inflamed, painful, and stiff.

Osteoarthritis is usually a condition of aging. The exact cause is unclear, but it appears to be related to:

• Degeneration of cartilage, which can lead to a total loss of the cartilage cushion between the joints
  
• Bone spurs that form around the joints
  
• Muscle weakness
  
• Trauma to or near a joint
  

Risk Factors
It is possible to develop osteoarthritis with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing osteoarthritis. If you have a number of risk factors, ask your health care provider what you can do to reduce your risk.

Specific lifestyle factor

• Weakness of the thigh muscle may increase your risk of osteoarthritis; exercises that strengthen the thigh may provide some protection against osteoarthritis.
  

Medical condition
You have an increased risk of developing osteoarthritis if you have or have had:

• past injury to a joint
  
• history of infection in a joint
  
• congenital defect or weakness in a joint
  
• acromegaly (a pituitary disorder)
  
• Paget's disease of bone
  
• hemochromatosis (iron overload disease)
  
• gout or pseudogout
  
• bleeding into the joint (as occurs with hemophilia)
  

Age

• 50 percent of people over the age 65 have arthritis in at least one joint
  
• More than 80 percent of people over the age of 75 have arthritis in at least one joint
  

Gender

• Under age 45, more men than women have osteoarthritis.
  
• Over age 55, more women than men have osteoarthritis.
  

Genetic factors

• The tendency to develop osteoarthritis frequently runs in families.
  

Ethnic background
Risk factors for developing osteoarthritis in specific joints are different for different ethnic backgrounds. For example:

• Caucasians have a higher overall risk of developing osteoarthritis than Asians.
  
• Osteoarthritis of the hip is less common in Chinese, Jamaican and South African people of color, and Asian Indians; hip osteoarthritis is more common among the Japanese.
  
• African-American women have more osteoarthritis of the knee and less osteoarthritis of the hand than do Caucasian women in the United States.
  

Other
You are more likely to develop osteoarthritis if you:

• are overweight or obese
  
• work at a job or participate intensely in an athletic pursuit that requires a lot of lifting, squatting, and/or repetitive joint use