The leading rheumatology resource
for patients and physicians.

Commencez à lire en

Diseases > Osteoarthritis | OA > Diagnosis | Osteoarthritis | OA

What is Osteoarthritis?

There are about 100 different types of arthritis. Osteoarthritis (OA) is the most common type. It happens when a joint’s cartilage begins to break down. If you translate the name it makes sense: osteo refers to bone, arthr means the joint, and itis means inflammation. Putting it all together, osteoarthritis means inflammation of the joints that can result in delicate bones rubbing against each other. This causes pain, stiffness, and swelling of the joints.

What causes Osteoarthritis?

Osteoarthritis is a long-term (chronic) disease. It occurs when the cartilage at the ends of the bone wear down. The reason for this is not well understood. Cartilage helps protect the ends of the bones by working as a shock absorber for joints. It also keeps joints moving smoothly.

When cartilage starts to wear away, the ends of the bones in the joint may come into contact with one another (“bone on bone”). This can cause inflammation of the joint. The word inflammation comes from the Latin word “inflammare” which means to light on fire. In people with OA, inflammation causes the joints to become warm, swollen, and painful. In other words, the joints can feel like they’re “on fire.”

Joints that are commonly affected by OA include the knees and the hips. Other joints can also be affected by OA. These include:

  • Ends or middles of the fingers
  • Base of the thumb
  • Base of the big toe (this can form a bunion)
  • Neck
  • Low back (also known as “degenerative disc disease”)

The wearing down of the cartilage can cause inflammation. The body then tries to repair itself by growing new bone. It is thought that this is the body’s attempt to strengthen the damaged joint. Unfortunately, this part of the body’s healing process doesn’t work well. It can result in the formation of bumps or “nodes” of new bone growth around the joint. This occurs most commonly when joints in the hands are affected by OA. The inflammation and nodes can cause joint stiffness and pain.

Who gets Osteoarthritis?

Osteoarthritis is by far the most common type of arthritis. It is estimated to affect 1 in 10 adults. That means in a room full of 100 people, you could expect about 10 people to have OA. The condition can occur at any age, but it is more common as people get older (in their 50s or later). Ostearthritis is also more common in women than in men.

Age is not the only risk factor for OA. The disease can sometimes run in families, especially when it affects joints in the hands. You might hear someone with OA say “my mother had hands like this” when they have knobbly knuckles. The reason for this is not well understood. Experts think it may have something to do with the shape of bones and how they fit together. Or it may be related to the body’s ability to repair damaged joints.

People who are overweight also have a higher chance of developing OA, especially in the weight-bearing joints like the knees and hips. Even a little bit of weight loss (like 10 pounds) can make a big difference for people who have OA in their knees, hips or feet.

People who have had a serious injury to a joint have a higher chance of eventually getting OA in that joint. This is thought to be the result of damage to the cartilage itself or to the way the joint moves. That’s why OA is common among former professional athletes or people who may have injured their joints in their line of work. Some famous athletes who have or who had OA include Nolan Ryan (National Baseball Hall of Fame), Joe Namath (NFL Hall of Fame) and hockey great Wayne Gretzky.

How is Osteoarthritis diagnosed?

Osteoarthritis is diagnosed by a thorough assessment and physical examination by a physician familiar with the disease. Your family physician may be very comfortable making this diagnosis. Following the assessment you may be sent for x-rays and blood tests (see below).

What tests are done to diagnose Osteoarthritis?


X-rays are one of the best tests to diagnose osteoarthritis (OA). The x-ray changes of OA are very well described and easily recognizable.

Blood Tests

Your doctor may send you for blood tests to help rule out other conditions. Sometimes it can be difficult to distinguish OA from other forms of arthritis.  Blood tests can be useful in this regard.

Read more – Symptoms of Osteoarthritis