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How is osteoarthritis diagnosed?

Debra Fulghum Bruce PhD
Healthcare Specialist

Blood tests can help eliminate other types of arthritis and other medical problems, while a sample of the joint fluid from the knee can also show typical changes of osteoarthritis.

Usually by the time a person seeks treatment for osteoarthritis, there are changes visible on x-ray of the joint. There may be a narrowing of the cartilage on the x-ray, but no destruction as with rheumatoid arthritis.

Generally, it is not difficult to tell if a person has osteoarthritis. The signs and symptoms that you describe and your test results will enable your doctor to make a diagnosis. Be aware that no single test can diagnose osteoarthritis.

It is more difficult to determine if the disease is actually the cause of the symptoms. The doctor will try to rule out other disorders, such as joint infection, fracture, injury, gout, bursitis and other conditions, that may cause the same symptoms as osteoarthritis or make these symptoms worse.

Most likely, your doctor will begin by asking you to describe the pain, stiffness and joint function (including when and how these symptoms started) and to explain how your symptoms have changed over time. It also is important for the doctor to know how your symptoms are affecting your work and daily life, what other medical conditions you have and whether you are taking any medications or nutritional supplements.

Your doctor will check your general health, including reflexes and muscle strength and your ability to walk, bend and carry out daily activities. When examining your joints, your doctor can feel the bony swelling and hear the creaking of the joint. Your doctor will look for tenderness, any thinning of muscles, excess fluid or instability in the joints. You will be asked to move your limbs as far as you can, to see if your joints restrict movements. Your doctor also will move your limbs to check for any restricted movement.

X rays may be used to confirm that the joint problems are caused by osteoarthritis and not some other form of arthritis. In affected joints, x rays will show how much joint and bone damage has been done. For example, the spaces between the bones affected by osteoarthritis may be narrower than in normal joints because of thinning of the cartilage and extra bone growth such as bone spurs.

There may be a big difference between the severity of osteoarthritis that the x rays show and the degree of pain and disability that you experience. X rays help the doctor make a diagnosis but do not indicate how much the osteoarthritis will bother you. Also, x rays may not show early osteoarthritis damage.

There is no blood test for osteoarthritis. However, blood tests are sometimes done to make sure that your symptoms are not caused by another type of arthritis.

In some cases, the doctor may draw fluid from inside the affected joint, for example, to check for particles that may cause pain.

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The diagnosis of osteoarthritis is usually based on multiple factors, including your doctor's evaluation and X-rays. There is not a specific test that can tell you whether or not you have osteoarthritis. The diagnosis is primarily based on the history you provide to the doctor. In osteoarthritis, it is typical to have a slow onset of symptoms that gradually worsen over time. X-rays can be helpful by showing that the joint space is becoming smaller, and sometimes finds evidence of bone spurs. Occasionally, a small sample of the joint fluid can be obtained, which can suggest that osteoarthritis is more likely than other types of arthritis.

Your doctor will often clinically diagnose knee osteoarthritis during a physical exam. This is suspected when your doctor notes popping, clicking or grinding with movement of your knee, which is called crepitus. However, the definitive diagnosis of osteoarthritis often requires an x-ray that shows irregularities of the bony surfaces of the knee.

Osteoarthritis is diagnosed with a physical examination but may require imaging or laboratory tests to confirm the diagnosis. Your doctor may order an x-ray or MRI (magnetic resonance imaging). Both tests can determine if there is cartilage loss or bone spurs. Blood tests may be ordered to test for other possible causes for your symptoms. And, a sample of your joint fluid may be taken to check for inflammation and rule out the possibility of other infection or disease.

Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

To a great extent, a doctor uses his or her eyes and ears to diagnose osteoarthritis. A doctor will first consider the symptoms a patient describes. Osteoarthritis will be the prime suspect if a patient complains of joints that are:

  • painful
  • stiff
  • tender to the touch
  • swollen
  • difficult to bend
  • weak

Osteoarthritis may also cause joints to make a clicking or grinding sound. Like a good detective, a doctor will ask questions too. Are the pain and other symptoms worse in the morning, when you get out of bed? Do any of your joints hurt when you put weight on them, such as your knees?

If your doctor thinks you may have osteoarthritis, he will recommend taking x-rays of the joints that hurt the most. If these images show certain changes, such as a narrowing space between the bones that form a joint, osteoarthritis is usually the culprit and the diagnosis.

Dr. Scott D. Martin, MD
Orthopedic Surgeon

To diagnose osteoarthritis, your doctor will ask you about your symptoms and medical history, and perform a physical exam. Although an x-ray will not show cartilage damage, it may reveal other changes related to osteoarthritis, including decreased joint space, bone spurs and cysts. A blood test for inflammation helps rule out other possible causes of your symptoms.

If your knee is suddenly swollen for no apparent reason, the doctor may remove some of the synovial fluid in the joint to check for signs of infection or arthritis. An excess amount of normal synovial fluid or synovial fluid that is thinner or less elastic than normal may be a sign of osteoarthritis, whereas synovial fluid that is opaque and deep yellow or greenish yellow may indicate inflammation, which is characteristic of rheumatoid arthritis, the destructive joint disease in which the body attacks its own tissues.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.