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Psoriatic arthritis (PsA) is a type of inflammatory arthritis that affects up to one-third of people with psoriasis, causing joint pain, stiffness, and swelling.
Although it shares symptoms with osteoarthritis, rheumatoid arthritis, and other related conditions, PsA is a distinct type of inflammatory arthritis with its own diagnostic criteria. X-rays are a type of imaging test commonly used to both diagnose and monitor people with PsA.
X-rays produce images called radiographs. This is done using a technique known as radiography.
These images can help your doctor identify changes in the joints that occur as a result of PsA. Because PsA is a progressive condition, X-ray images are also helpful for assessing disease progression and how it has affected your joints.
It’s important to note that some of the characteristics of PsA do not show up on X-rays until the condition has considerably advanced. For this reason, doctors will not rely on X-rays alone to diagnose psoriatic arthritis, especially if your PsA is still in the early stages. Instead, they will use them alongside other diagnostic criteria to determine whether your diagnosis is PsA or another type of arthritis.
Along with X-rays, the diagnostic process for PsA usually includes a medical evaluation, as well as other imaging tests.
Your doctor or rheumatologist will assess your health history and discuss the specific symptoms potentially related to PsA. They will also conduct a thorough medical evaluation to look for other signs of PsA. This assessment will likely include an examination of your fingernails to see if they are flaking or have other abnormalities, such as pitting or ridging, both of which are symptoms of PsA.
Your health care provider will use X-rays to identify any changes in your joints that indicate PsA. Your doctor may also use other imaging tests, including magnetic resonance imaging (MRI), to assess PsA-related changes in the body.
X-rays and MRI allow doctors to identify changes in your joints that are specific to psoriatic arthritis, making it easier for them to diagnose you with that condition. Your doctor or rheumatologist can also use imaging tests to see if your treatments are working or to monitor the progression of your PsA by noting changes in your joints or the surrounding tissues.
Your doctor will look for indications of joint damage caused by psoriatic arthritis, especially those that are specific to PsA and not other types of arthritis. They can tell you exactly which of the features of PsA show up on your X-rays. If none of them do, it does not necessarily mean that you should not be diagnosed with PsA. Instead, it may mean your condition has not yet progressed that far at this point, and you are still in the early stages.
Physical changes caused by PsA may show up in X-rays of your affected joints.
Enthesitis refers to inflammation in the enthesis — one of the more than 100 sites in the body where ligaments or tendons insert into the bones. Enthesitis is common among individuals with PsA, affecting up to 1 in 3 people with the condition.
Because of its prevalence in PsA, rheumatologists often use the presence of enthesitis to confirm a diagnosis of psoriatic arthritis. Imaging tests like X-rays can reveal physical changes, such as bone spurs (abnormal growths that develop on the edge of a bone), which can occur as a result of enthesitis.
Pencil-in-cup deformities cause the connections between finger joints to look like a pencil in a cup rather than like flat bones held together by connective tissue. These deformities, which are visible in plain X-ray images, are classically associated with PsA. However, because they are sometimes seen in several other conditions that affect the bones and tissues, pencil-in-cup deformities alone may not be enough to indicate that you have PsA.
Bone proliferation, which leads to soft tissue swelling and bone erosion, is commonly found in people with rheumatoid disorders like PsA. This condition causes the joints to look fuzzy or blurry, rather than clearly defined, in X-ray images.
Dactylitis, also referred to as a “sausage digit,” occurs when a finger or toe swells significantly without a specific injury or known cause and without related swelling around it. The inflammation is usually severe. X-ray images can reveal swelling in the soft tissues related to dactylitis.
Periostitis, which often results from bone proliferation, occurs when the membrane surrounding your bones becomes inflamed or irritated. Periostitis causes this membrane to appear thicker or denser than usual in imaging tests, including X-rays.
Your interphalangeal joints (the joints between your fingers) may actually be partially or completely dislocated because of swelling or changes to the bone. Although you may not feel this or feel any changes in your joints, this swelling or structural abnormality is visible on X-rays.
Arthritis mutilans is the most severe form of psoriatic arthritis, affecting less than 5 percent of people with PsA. It causes deformities and dysfunction primarily in the small joints of the fingers and toes. If enough joint damage occurs, the bones begin to dissolve and the soft tissues cannot support them. This condition can cause your bones to pull apart like a telescope, which can be seen in X-rays.
Sacroiliitis refers to inflammation and degeneration of the sacroiliac joint in the pelvis, which is visible on X-ray images. This condition is often asymmetrical in people with PsA, meaning it only affects one side of the body.
Ivory phalanx occurs when an entire piece of your bone becomes denser than usual, causing it to show up as ivory or white in X-ray images.
Roughly 20 percent of people with PsA develop psoriatic spondylitis, which causes inflammation of the spine. This inflammation often appears asymmetrically in people diagnosed with PsA. X-ray images can reveal spondylitis-related changes in the joints and bones, although the signs of spondylitis may not be visible early on in the disease course.
Your primary care physician or rheumatologist may order X-rays if they believe you have psoriatic arthritis. Getting an X-ray for PsA is like an X-ray for any other condition.
Most X-rays don’t require special preparation. Before your X-rays, you will be asked to remove any metal items, as these could interfere with the X-ray machine. It’s a good idea to leave items like jewelry or watches at home.
Once it’s time for your X-ray, you’ll meet the technician who will perform the procedure. You will put on protective gear so that other parts of your body are not exposed to the X-rays. Then, your technician will position your body in such a way that they can get the images your doctor or rheumatologist ordered. If you are in pain at any point, let them know, and they will do everything they can to make you as comfortable as possible.
When your body is in the correct position, your technician will leave the room so that they are not exposed to the X-rays. They will push a button to take the X-ray and return to reposition your body for another image, if needed. If not, they will remove your protective gear so you can leave.
The technician may be able to check the images to make sure they’re clear before you leave, so you don’t have to come back because something was blurry. Your images will then be sent to a radiologist for evaluation. The radiologist will notify your doctor of the results, and your doctor will contact you to discuss the results and next steps.
MyPsoriasisTeam is the social network for individuals diagnosed with PsA and psoriasis and their loved ones. On MyPsoriasisTeam, you gain a community of more than 87,000 people who understand life with psoriatic disease.
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Ariel D. Teitel, M.D., M.B.A.
is the clinical associate professor of medicine at the NYU Langone Medical Center in New York. Review provided by VeriMed Healthcare Network.
Learn more about him here.
Sarah Winfrey
is a writer at MyHealthTeam.
Learn more about her here.
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