Osteoarthritis
(Degenerative Joint Disease)
In this condition factsheet:
The Facts on Osteoarthritis
Osteoarthritis (OA) is a joint disease that causes the cartilage to break down and bone to overgrow or form cysts. Cartilage is a smooth, shiny material that lines the joints – allowing them to glide easily as you move. It is a type of resilient connective tissue that covers and protects the ends of bones in joints. Although OA can affect any joint in the body, it most frequently affects the hips, knees, hands, feet, and spine.
Arthritis is among one of the leading causes of disability in Canada. OA is the most common form of arthritis. It affects 1 out of every 7 people in this country. Statistics show that women are more likely to be affected.
After menopause, women tend to have more severe and complicated problems. OA usually occurs after the age of 45, but it can occur earlier in life, and even be seen in the spines of teenagers. It is present, even if not causing symptoms, in virtually all people over the age of 80.
Risk factors for developing OA include:
- increasing age
- having a family member with the condition
- repeated injury to the joint through sports or work
- being overweight
- having another form of arthritis
There's no cure for OA, although research is beginning to unravel the mechanisms of the disease, which should lead to new treatments. Treatments currently focus on managing pain, reducing the load on the joints, and improving the strength of the muscles supporting the joints. Experimental therapies try to slow the progression of the disease and increase the mobility and flexibility of the joints.
Causes of Osteoarthritis
As you move or put pressure on a joint, cartilage allows bones to slide over one another and acts as a shock absorber.
Cartilage itself does not have any nerve cells and therefore cannot sense pain. OA results when the cartilage becomes worn out, allowing the bones underneath to rub against each other and cause pain and swelling. It is not simple wear-and-tear but a process involving the cells and proteins of bone and cartilage.
As the condition progresses, the joint may become disfigured and small growths called osteophytes begin to grow inside the joints. Osteophytes are small, irregular, bony growths that are also called bone spurs. Bits of broken-off cartilage or bone are also found floating inside the joint. This causes even more pain, swelling, and immobility of the joint.
The exact cause of these changes is unknown. Scientists believe that the following factors play a role:
- increasing age: The cartilage wears down with time. By age 65, 80% to 90% of people have OA, as shown on X-ray, though a much smaller percentage has symptoms.
- family genes: Scientists believe that OA may be passed on through families, with the symptoms appearing in middle age.
- being overweight: Excess weight puts stress on weight-bearing joints such as hips and knees, and increases the risk of cartilage breakdown. This is the most important risk factor for OA affecting hips, and leg and foot joints.
- injury: Trauma to the joint, such as overuse, can damage the cartilage and lead to OA. This is often the cause of OA in younger people.
- infection: Infection of the joint may lead to arthritis
- other types of arthritis: For example, rheumatoid arthritis can also damage joints and lead to OA.
Symptoms and Complications of Osteoarthritis
The following are symptoms of osteoarthritis (OA):
- deep, aching joint pain, sometimes sharp, with activity; the pain can persist at rest
- transient joint stiffness after a period of rest (such as getting up in the morning or after a long time spent sitting)
- swelling and stiffness in one or more joints
- enlarged middle- or end-joints of the fingers or the base of thumb
- a crunching feeling or sound when moving joints
- loss of joint flexibility
- back and neck pain and stiffness
Weight-bearing joints such as hips, knees, and feet are more prone to OA. It is important to note that many people have OA but don't experience any symptoms. Often, the onset is gradual with only one or a few joints. The symptoms of OA can be made worse by overusing the joints.
