Psoriatic arthritis

Photo of a physiotherapist examining a patient's leg (PantherMedia / photographee.eu)

Psoriatic arthritis is a condition that leads to pain and stiffness in joints. It can be caused by psoriasis, but sometimes occurs in people who don't have any visible psoriasis-related skin changes. Various treatments can relieve the symptoms and prevent damage to the joints.

It is estimated that 20% of people who have psoriasis also develop pain and inflammation in certain joints at some point. The joints start hurting and may feel stiff for a while, particularly in the morning. Movement often makes the stiffness disappear within half an hour. The affected joints may also become swollen, feel warm and sensitive to the touch. If the small joints between the vertebrae (spine bones) are inflamed, it might cause back pain.

Psoriatic arthritis can occur in many joints of the body. It often affects the hands, feet, elbows, knees, neck or vertebrae. More than five joints typically become inflamed, including the joints at the end of the fingers and toes. These joints are especially prone to becoming deformed in severe cases. Tendons and tendon sheaths can also become inflamed.

Most people who have psoriatic arthritis also have nail psoriasis. This can lead to small dents in the nails, which may become thicker, change color or start peeling off too. Nail psoriasis is difficult to treat and sometimes mistaken for a fungal nail infection.

How is psoriatic arthritis diagnosed?

An estimated 10% of all people who have psoriasis don't have any visible skin changes. This can make it difficult to distinguish psoriatic arthritis from other conditions affecting the joints – particularly because there aren't any tests that can determine whether it is definitely psoriatic arthritis. One potential important clue is a family history of psoriasis: If someone has joint pain and psoriasis is known to run in their family, it is more likely that they have psoriatic arthritis.

The following examinations and tests can help to diagnose psoriatic arthritis and distinguish it from other inflammatory conditions of the joints:

  • Physical examination: Certain changes are more typical of psoriatic arthritis. For instance, the inflammation may affect a whole finger (dactylitis) or the tendons and tendon sheaths of the hands or feet, such as the Achilles tendon (enthesitis).
  • Blood tests: 90% of people with psoriatic arthritis don't have any of the antibodies in their blood that are typical of rheumatoid arthritis. So if none of these "rheumatoid factors" are found, it's more likely to be psoriatic arthritis.
  • Measuring uric acid levels: High levels of uric acid in the blood are a sign that the joint problems are being caused by gout rather than psoriatic arthritis.
  • Imaging techniques: X-rays and ultrasound scans can help to find out whether someone has psoriatic arthritis, rheumatoid arthritis or osteoarthritis. The images can also help doctors get an idea of the severity and type of joint damage. But changes in the joints are often not yet clearly visible in the early stages of psoriatic arthritis.

What's the typical course of the disease?

It's hard to accurately predict how psoriatic arthritis will continue to develop. Some people always have the same inflamed joints, whereas others keep getting more over time. The inflamed joints may become damaged and deformed, especially without the right treatment.

There isn't a clear link between visible psoriasis on the skin and psoriasis that affects the joints. Some people have severe psoriasis on their skin but no problems with their joints. Others have psoriatic arthritis but no psoriasis on their skin. Or their joints become inflamed before any noticeable skin changes occur.

What are the treatment options?

The aims of treatment for psoriatic arthritis are to reduce symptoms such as pain and swelling, keep the joints working properly, and prevent long-term damage to the joints. Problems affecting the joints, muscles or tendons can be treated with physiotherapy, occupational therapy and orthopedic products such as insoles.

Treatment with medication plays an important role in psoriatic arthritis. There are two different types of treatment, known as symptomatic treatment and disease-modifying treatment. Medication for symptomatic treatment is used for the reduction of acute pain and inflammation. Disease-modifying drugs treat the underlying cause, inhibiting the inflammatory response in the joints. The aim is to stop, or at least delay, the progress of psoriatic arthritis in order to prevent damage to the joints.

Medications for symptom relief include the following:

  • Painkillers: e.g. diclofenac, ibuprofen and naproxen. These medications are known as non-steroidal anti-inflammatory drugs (NSAIDs). They aim to reduce pain, but can't prevent potential joint damage.
  • Corticosteroid injections or tablets: Corticosteroids can be injected into individual joints in order to relieve acute pain. This option is considered for the treatment of particularly persistent joint inflammations or while waiting for other treatments to start working. Short-term treatment with corticosteroid tablets is sometimes possible too. If they are used, though, only small doses should be taken and only for a limited amount of time. They could have severe side effects otherwise. What's more, stopping treatment with corticosteroid tablets can lead to a psoriasis flare-up.

Disease-modifying drugs are used continuously, regardless of whether you have acute symptoms or not. These drugs are also known as DMARDs ("Disease-modifying anti-rheumatic drugs“). There are two groups of DMARDs:

  • The traditional DMARDs include methotrexate and leflunomide.
  • Biological drugs are medications that are produced using biotechnology. They include the drugs adalimumab, certolizumab pegol, etanercept, infliximab, golimumab, secukinumab and ustekinumab. They are considered as a treatment option if traditional DMARDs aren't effective enough. Biological drugs can also be combined with methotrexate.

Another medication that may be considered is apremilast (Otezla). This medication belongs to a class of drugs known as PDE4 inhibitors. Like biological drugs, it is used if treatment with traditional DMARDs isn't effective enough.

When are the different treatments used?

In mild psoriatic arthritis that only affects the knees, elbows or wrists, treatment with NSAID painkillers is sometimes enough. If this isn't effective enough or if there is reason to believe that the disease will develop into a more serious case, treatment with disease-modifying drugs is recommended. Psoriatic arthritis is more likely to become severe if:

  • five or more joints are affected,
  • x-ray images show that the affected joints are already visibly damaged,
  • the inflammation is quite severe (this is determined based on the level of certain substances in the blood), or
  • tendons and connective tissue are inflamed too, not just joints (for instance, if a whole finger or an Achilles tendon is inflamed).

Some medications help to reduce both the visible skin problems and the inflammation in joints. Examples of such medications include apremilast, methotrexate and biological drugs. Because of this double-action effect, they are often the treatment of choice for psoriatic arthritis.

The treatments used for psoriatic arthritis will ultimately depend on various factors:

  • The severity of the inflammation in the joints and the type of symptoms
  • Whether you only have inflamed joints or the psoriasis affects your skin too
  • Which parts of your body are affected
  • How important the advantages and disadvantages of the treatments are to you.

When considering which treatment strategy to adopt, it can be helpful to seek advice from both a dermatologist (skin specialist) and a rheumatologist. It's a good idea for the doctors to talk to each other and share their ideas.