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Diagnosing arthritis poses a significant challenge to any physician because of the sheer number of conditions that can cause joint discomfort and because there are rarely tests available to establish a definitive diagnosis. Consequently, a doctor must rely heavily on your description of symptoms and other relevant information, plus a physical examination. That's why you should prepare for your appointment by making a list of your symptoms and the circumstances under which they occur. Do you notice them during or after a particular activity? Or first thing in the morning?

Primary care doctors can usually determine at the first visit whether the problem is a form of arthritis or some other musculoskeletal problem. But it may take several visits for your physician to make a more specific diagnosis. While this delay can be frustrating for the patient and family, charting the course of your symptoms is often the only way a doctor can accurately diagnose arthritis.

Your medical history

Your symptoms — what they are, when they first began, and how they've changed over time — provide potent clues to whether arthritis is inflammatory or noninflammatory. Your doctor will need to know about the following:

• type of joint symptoms (such as pain or stiffness)
• effect of activity (such as increased pain or relief of stiffness during or after a particular activity)
• general pattern of joint symptoms (started gradually or suddenly, worsened over time or stayed about the same, migrated from one joint to another, or fluctuated in intensity)
• any other symptoms (fever, fatigue, weight loss, skin problems, bowel problems)
• events that occurred near the time the symptoms first appeared (such as viral illness, bacterial infection, injury, vaccination, new medication, or change in activity)
• time of day that joint symptoms are worst (prolonged morning stiffness suggests inflammatory arthritis; night pain is more typical of noninflammatory joint disease)
• presence or absence of joint swelling, redness, or warmth
• previous episodes of similar symptoms
• family history of arthritis or rheumatic disease.

Pain and stiffness

In rheumatic diseases, pain and stiffness go hand in hand. Pain is a subjective experience that's often difficult for people to describe, quantify, or even pinpoint. Chronic arthritis produces aching pain when the affected joints are moved, as opposed to burning or prickling pain unrelated to motion that typifies neurologic disorders. Most people can describe the location of pain in small joints, such as the hands or feet. However, with large joints, the pain is generally more diffuse and may radiate, making it difficult to pinpoint. For example, hip arthritis may cause pain in the groin, thighs, buttocks, or even knees.

People often describe vague muscle aches as stiffness, but rheumatologists use the term more specifically for joint discomfort when a person attempts to move: Stiffness is the tendency of a joint not to move easily and may be prominent even when joint pain is not. The duration of stiffness in the morning or after any period of inactivity can help doctors distinguish osteoarthritis from rheumatoid arthritis and other types of arthritis.

Mild morning stiffness is common in osteoarthritis and resolves after a few minutes of activity. Sometimes people with osteoarthritis notice more stiffness during the day after resting for an hour or so. In rheumatoid arthritis, however, morning stiffness may not begin to improve for an hour or longer. Occasionally, morning stiffness is the first symptom of rheumatoid arthritis.

The nature and duration of your joint symptoms can be helpful. For example, pain and stiffness that develop gradually and intermittently over several months or years suggest osteoarthritis. Rheumatoid arthritis or another inflammatory arthritis may cause pain, stiffness, and fatigue that worsen over several weeks or a few months. In contrast, sudden pain is more likely to be due to an injury or fracture, and pain that intensifies over several hours is typical of bacterial infection or gout.

Physical examination

Because many other disorders can masquerade as arthritis, a complete physical examination is a necessary part of the diagnostic process. During your visit, the doctor watches how you move and looks at joints for abnormalities. The doctor moves your joints through their range of motion to detect any pain, resistance, unusual sounds, or instability. The doctor also gains information from a visual assessment of how you use your joints, and so may ask you to take a few steps, move your hands and arms, and so forth.

Swelling. An inflamed synovial membrane often produces mild joint swelling. People may describe a sensation of tightness or fullness inside the joint, or it may feel tender. Doctors describe the joint as feeling "boggy" or soft to the touch. Marked swelling usually indicates excessive joint fluid, a sign of inflammation or perhaps bleeding into the joint.

Enlargement. Enlargement of a joint is not the same as swelling. Bony enlargement without joint swelling feels hard to the touch and is not usually tender. This finding is typical of osteoarthritis, although it may also occur in people who have no joint pain and as a consequence of other joint disease, such as rheumatoid arthritis.

Limited motion. Doctors assess joint mobility in two ways: active range of motion in which the person voluntarily moves the joints, and passive range of motion in which the examiner moves the person's joints. By comparing active and passive movement, doctors can often determine whether the cause is muscle weakness, bursitis, or tendonitis (in which case the joint has wider range of motion during passive movement), or whether the problem is with the joint itself. Doctors listen and feel for crepitus, a crunching or grating sensation that is sometimes audible and is caused by rough surfaces rubbing together inside the joint.

Spine flexibility. To evaluate spine flexibility, the doctor may ask you to stand and, without moving your pelvis, bend forward as if touching your toes, bend backward, lean from one side to the other, and twist your upper body from side to side.

Diagnostic studies

In most types of arthritis, laboratory tests and x-rays or other imaging techniques may be helpful, but by themselves rarely provide enough information for doctors to establish a specific diagnosis. However, there are exceptions. A bacterial infection of the joint, gout, and pseudogout can be diagnosed by removing and testing a sample of joint fluid (see "Arthrocentesis"). X-rays are occasionally diagnostic as well. For example, x-ray abnormalities in the pelvis and spine may reveal ankylosing spondylitis (see "Diagnosing ankylosing spondylitis").

Blood tests

Doctors often order a complete blood cell count and blood chemistry tests to look for evidence of systemic diseases, including anemia and infection.

Antibody tests. These tests detect various antibodies whose presence may suggest particular types of arthritis. When rheumatoid arthritis is a possibility, many doctors order a test for rheumatoid factor, an antibody that's present in 70%–80% of people with rheumatoid arthritis. But the test is not definitive, so often a second, newer blood test, the anticitrullinated cyclic protein (anti-CCP) test, will usually be ordered as well (see "Blood tests for rheumatoid arthritis"). Antibody tests also exist for other types of arthritis. When lupus is a consideration, for example, doctors will often order a blood test to detect antinuclear antibodies (ANAs).

Erythrocyte sedimentation rate and blood level of C-reactive protein. These blood tests are general measurements of inflammation of any kind: The higher the result, the more severe the inflammation. Most people with osteoarthritis have normal values, but those who have inflammatory conditions, such as rheumatoid arthritis, usually have elevated levels (see "Blood tests for rheumatoid arthritis").

Serum uric acid test. This test measures the level of uric acid in the blood, which is usually elevated in people with gout (see "Diagnosing gout").

Other blood tests. A person's history may indicate the need to test for Lyme disease or other infections, which can cause reactive arthritis and other types of infectious arthritis.

Imaging tests

Doctors may order one or more imaging tests to better evaluate your joints. The type of test ordered depends on the suspected diagnosis.

X-rays. Most forms of arthritis can cause joint abnormalities that are detectable on x-ray examination (see Figure 4). But in most cases, such changes can't be detected until months after the onset of the disease. Sometimes the changes are reasonably specific and suggest a particular kind of arthritis. In other cases, they are more general. For example, bone damage (called erosion) is often found in rheumatoid arthritis and may occur in gout, but the damage from each cause differs enough in appearance that a radiologist can often tell them apart.

Figure 4: Osteoarthritis of the hip Osteoarthritis of the hip This x-ray, or radiograph, shows osteoarthritic changes of the left hip. The normal "ball-in-socket" shape has noticeably deteriorated.

Often, the changes revealed in x-rays bear little relationship to the actual symptoms, especially in osteoarthritis. An x-ray showing large bone spurs on the finger joints may belong to a woman with occasional mild aching in her hands, while an x-ray revealing much less dramatic abnormalities may be that of a woman who can no longer garden because of hand pain.

In their early stages, osteoarthritis and rheumatoid arthritis may appear quite different on x-ray examination, but later they may look similar. In rheumatoid arthritis, the pannus (inflamed tissue) erodes cartilage, and in many cases, the joint damage eventually leads to secondary osteoarthritis, even after the inflammation subsides.

Magnetic resonance imaging (MRI). In evaluating patients with joint problems, this test is helpful to assess soft tissues, cartilage, tendons, and joint inflammation. It's also quite good for spinal cord and nerve root compression that can be caused by spondylitis or degenerative disk disease. MRI has been used to help diagnose rheumatoid arthritis, although some fear it is being overused in this regard (see "Diagnosing rheumatoid arthritis").

Scintigraphy. Another technique for detecting bone abnormalities is scintigraphy, usually done as a whole-body scan several hours after a special radioisotope (a radioactive dye) is injected into a vein. Scintigraphy does not provide as much specific information as MRI, but it can be useful for detecting bone disease.

Other tests. Researchers are studying the ability of ultrasound to detect erosions in rheumatoid arthritis and other types of arthritis. This type of test uses sound waves to assess fluid in soft tissues and abnormalities in muscles or tendons.

Doctors occasionally order computed tomography (CT) scans to evaluate joints for hidden fractures, torn cartilage, and other structural abnormalities. CT imaging uses a rotating x-ray tube housed in a doughnut-shaped machine to take thin-slice x-rays of your anatomy. A computer then assembles these slices into a three-dimensional picture.

Arthrocentesis

People with sudden or unexplained joint swelling may undergo arthrocentesis, in which a physician removes some of the synovial fluid for examination. Excess synovial fluid may indicate a bacterial infection in the joint, crystal deposits, injury, bleeding into the joint, or synovial inflammation. In cases of relatively mild chronic arthritis, arthrocentesis may help distinguish between osteoarthritis and inflammatory joint disease; this can help to narrow down the diagnostic possibilities and guide treatment.

This procedure can be done in the doctor's office and only takes a few minutes. First the skin over the joint is cleaned and an anesthetic agent (typically given by injection under the skin or as a spray) is used to numb the area. The doctor then inserts a needle through the numbed area into the joint space and withdraws some synovial fluid.

Physicians can often get a good idea of whether the problem is inflammatory by the appearance of the fluid. Normally it's translucent and pale-to-medium yellow. Significant inflammation may produce a deep yellow or greenish-yellow opaque fluid. Cloudy fluid may be a sign of crystals or infection.

Laboratory technicians examine the fluid under a microscope for crystals that indicate gout or similar disorders. Your doctor often requests other laboratory tests on the fluid, such as a white blood cell count; a large number of white blood cells could indicate either infection or severe inflammation. Arthrocentesis itself is often beneficial because removing some of the excess synovial fluid can relieve pain and pressure.

Source: from Harvard Health Publications, Copyright © 2008 Harvard University. All rights reserved. Harvard Medical School does not endorse products.
Used with permission of StayWell.
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