Health matters

Psoriatic arthritis a common cause of joint pain

Conway McLean, DPM, Journal columnist

Do you have a painful joint? Join the legions of Americans living with some limb or body part causing them significant discomfort on a regular basis. But is this negative sensation that is pain a necessity, a requirement of life and aging?

The subsequent question should be “why do you have musculoskeletal pain on a regular or recurring basis?” Although few healthcare providers will admit it, too many Americans have recurrent joint pain and never learn why.

The number of candidates for potential causes of recurrent joint pain, one that returns regularly, is extensive and intimidating. The subtle characteristics differentiating one form from another can be nearly impossible to discern, and thus the explanation for our failure to diagnose.

One condition seen frequently in the office of a lower extremity podiatric specialist is that of joint pain of the toes. Too often, symptomatic relief is attempted without seeking an answer to the question of why.

Patients with joint pain are often seen by various healthcare providers on their medical journey. Some of these individuals have a condition called psoriatic arthritis (PsA). In fact, some estimates state two out of every 500 people have psoriatic arthritis. And not all of these individuals will have the skin changes associated with this common dermatologic condition.

The numbers are fuzzy concerning the incidence of psoriatic arthritis, since it may be diagnosed as rheumatoid arthritis, osteoarthritis, or some other autoimmune disease. Or quite commonly, nothing at all is diagnosed and it is simply labeled good, old “arthur-itis,” meaning only that a joint is inflamed. The similarities in clinical presentation of PsA and other diseases affecting our joints and related structures (tendon, ligament, and muscle) can make a differential diagnosis challenging.

There is no lab test able to definitively diagnose PsA. There are some which help to guide these efforts, but these tests are not specific and serve only to point you in a general direction. Certain changes can be visualized on x-rays, but these occur only when the disease has progressed significantly, and they are not reliably seen. Maybe most critical to diagnosing psoriatic arthritis are particular clinical findings, considered necessary to determine the cause.

The development of localized swelling of the toes, referred to as “sausage toes,” is also not characteristic to PsA, but it occurs almost half the time. Again, not enough to make a definitive diagnosis, but taken together, a constellation of facts and findings allow the cause to be determined. Various classification systems are provided to healthcare providers to aid them in making this decision. Regardless, it remains challenging.

Psoriasis is a common condition, and appropriately is associated with the skin changes seen with this primarily dermatologic disease. The skin condition that is psoriasis affects about 2% of the US population, typically appearing between 30 and 50 years of age. Roughly a third (we guess) of those with psoriasis have the “rheumatic” problems, which consist of symptoms of the joints, tendons, ligaments, muscles, etc. PsA can affect any of these structures (rheumatoid arthritis is usually confined to the joint). Like rheumatoid arthritis (RA), it is an auto-immune disorder, meaning the disease develops because the immune system attacks some part of the body.

Both RA and PsA cause joints to become painful, swollen, and warm to the touch. But psoriatic arthritis is somewhat distinctive in its preference for the farthest small joints of the fingers and toes. Other findings associated with PsA include stiffness after rest, lower back pain, nail changes, and fatigue. Muscle pain and weakness are also frequently seen.

The disease can affect any part of the body, including the spine, and can range from mild to severe. Flares of the symptoms can alternate with periods of remission. Foot pain is common since it can cause pain at the points where tendons and ligaments attach to your bones, especially at the back of your heel, leading to Achilles tendinitis. Another frequent site of pain where a ligament attaches to bone is at the bottom of your foot at the heel, resulting in plantar fasciitis. Thus, many podiatrists have the opportunity to see patients so afflicted and make this challenging diagnosis.

There is no cure for psoriatic arthritis, understandable since we don’t know what causes it. Treatment focuses on controlling inflammation, most importantly in the affected joints. These efforts can help to prevent joint pain and disability. But, because of the delay which too often occurs from the onset of symptoms to arriving at the diagnosis, progression of the disease is common. Without intervention, bone changes will occur, which can be seen on radiographs (x-rays), and potentially progressing to a severe, mutilating arthritis, especially if treatment has been less than optimal.

Treatment may include medication to reduce inflammation (e.g. non-steroidal anti-inflammatories like ibuprofen), steroid injections, or joint replacement surgery. One of the most common treatments are prescription medications called disease-modifying antirheumatic drugs. One of the most effective approaches is to avoid triggers, environmental and lifestyle factors that are known to stimulate symptoms of psoriatic arthritis. Some of these recognized triggers include cigarette smoke, skin wounds, stress, cold weather, and excessive alcohol consumption.

The exact prevalence of psoriatic arthritis is unknown, but we are certain it is a common cause of pain. If you have symptoms similar to those described and you have psoriasis, it is fairly likely you have PsA but have not yet been diagnosed. Since it is possible to have the musculoskeletal signs and symptoms of psoriatic arthritis without the skin problems of psoriasis, don’t assume your pain can’t be psoriatic. It may take a visit to a specialist to receive a definitive diagnosis, but a high index of suspicion for PsA goes a long way towards figuring out why your toes or foot hurts much of the time. We recognize it’s a challenge: getting an accurate diagnosis of PsA escapes many Americans. But don’t give up, the truth is out there.

EDITORS NOTE: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.


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