The right diagnosis is essential in obtaining the right care. This involves a complete physical examination as well as radiological examinations and laboratory tests.
Diagnosing osteoarthritis begins with an in-depth evaluation by your physician, including a history and physical examination. Your physician will assess:
X-rays are very helpful in diagnosing osteoarthritis because the affected joint will have a characteristic appearance, such as:
Hospital for Special Surgery has developed special x-ray views that increase the sensitivity of conventional x-rays, allowing detection of early changes in the joint before they are evident on routine x-rays,
In some cases, specialized diagnostic imaging examinations are also used because they are more sensitive for the detection of early arthritis. These tests include MRI, CT, Ultrasound and Radionuclide Bone Scans.
For more information about medical imaging, please visit the HSS Department of Radiology and Imaging.
Laboratory tests are helpful in the diagnosis of OA because they are usually normal. Routine tests such as complete blood counts, urinalysis, sedimentation rate (ESR), biochemistries, and specialized tests such as rheumatoid factor and antinuclear antibody (ANA) are useful simply to rule out other diseases that cause joint pain.
However, it should be remembered that as we age, a low level positive test for rheumatoid arthritis (rheumatoid factor) or ANA, and elevations of sedimentation rate (ESR) can sometimes develop without the presence ofthe illness. Although these findings can sometimes be confusing to a patient, they need not be. The clinical picture makes the diagnosis; lab tests are used only to confirm the clinical picture. Laboratory tests should never be used alone to diagnose arthritis.
Synovial fluid is the liquid that is normally found within the joints. It helps nourish and lubricate the joints. It is usually present in only very small amounts. However when arthritis is present, it changes in character and amount. Withdrawing the fluid can reduce swelling and pain. It can also help to confirm the diagnosis.
When synovial fluid is removed, it should be sent for culture, well as tested for cell count. In osteoarthritis, the white cell count (“pus cells”) is usually low and the fluid is clear (like water); higher counts should suggest inflammatory arthritis or infection.
The fluid may also be examined for the presence of uric acid crystals (seen in gout) or calcium pyrophosphate crystals (seen in pseudogout or chondrocalcinosis). The measurement of other biological markers is still experimental.
Normal knee cartilage
Knee with osteoarthritis
Color T2 mapping of the kneecap in a patient with normal cartilage and one with osteoarthritis. This HSS research technique is now being used in clinical patients to detect early changes of OA when x-rays are still normal.