Osteoarthritis (OA) is not a single disease but rather the end result of a variety of disorders leading to the structural or functional failure of one or more of your joints. Osteoarthritis is the most common cause of chronic joint pain, affecting millions of people in the world. Osteoarthritis involves the entire joint, including the nearby muscles, underlying bone, ligaments, joint lining (synovium), and the joint cover (capsule). A diagnosis of osteoarthritis may be suspected after a medical history and physical examination is done. Blood tests are usually not helpful in making a diagnosis. However, the following tests may help confirm it:

X-ray
X-rays can show damage and other changes related to osteoarthritis to confirm the diagnosis.

MRI
Magnetic resonance imaging (MRI) does not use radiation. It is more expensive than X-rays, but will provide a view that offers better images of cartilage and other structures to detect early abnormalities typical of osteoarthritis.

Joint aspiration.
The doctor will numb the affected area and insert a needle into the joint to withdraw fluid. The fluid will be examined for evidence of crystals or joint deterioration. This test can help rule out other medical conditions or other forms of arthritis.