Continuing Medical Education: Spondyloarthropathies.

Edited By: Gregory C. Gardner, M.D.
Last updated Friday, January 07, 2005

Psoriatic arthritis

What is psoriatic arthritis?

What are the clinical subgroups of psoriatic arthritis?

There are five patterns of joint disease in psoriatic arthritis and are listed below. One pattern can evolve into another.

1. Asymmetric oligoarthritis

   This is the most common type and occurs in over one half of the patients with psoriatic arthritis. The DIPs PIPs of the hands and feet as well as the MTPs are frequently involved. In addition, the knees, hips, ankles, and wrists are commonly affected. A common finding is the whole digit to be swollen when the tendon sheath is involved and this gives the digit a sausage appearance.

2. DIP Arthritis

   This is a less common form and makes up five to ten percent of patients with psoriatic arthritis. The DIP joints are affected in a oligoarticular pattern in association with classic nail changes of psoriasis (pitting, hyperkeratosis, separation of the subungual bed).

3. Arthritis Mutilans

   This typically occurs in patients with wide spread severe psoriasis and there is often a spondylitis present. The affected digitis undergo significant osteolysis leading to so called "opera glass deformities."

4. Symmetric Polyarthritis

   This form has a pattern similar to rheumatoid arthritis but usually with less deforming disease. One characteristic is fusion of the wrist which does not typically occur in rheumatoid arthritis.

5. Psoriatic Spondylitis

   Twenty to 40 percent of patients with psoriatic arthritis may have some degree of sacroilitis often asymptomatic. The spondylitis is typically more asymmetric than with AS with paravertebral ossification between the vertebrae rather than syndesmophytes.

What are the radiographic features of psoriatic arthritis?

1. Reactive Periostitis

   This "fluffy" appearing bony change at the enthesis is a hallmark for all of the spondyloarthropathies. Enthesitis occurs in psoriatic arthritis just as in AS with similar locations. In addition, reactive bony changes occur in the peripheral joints in association with erosions.

2. Marginal Erosions

   These occur in similar fashion to rheumatoid arthritis but the distribution of the involved joints along with the reactive bone changes help to distinguish it form rheumatoid arthritis. A characteristic lesion is the "pencil in a cup" deformity at the interphalangeal joints of the digits.

3. Sacroilitis

   As discussed above, it may be less symmetric in nature than AS.

4. Paravertebral Ossification

   Also called non-marginal syndesmophytes. These can be seen in the absence of sacroilitis and may be more asymmetric and sporadic than the syndesmophytes of AS.

How is psoriatic arthritis treated?

1. NSAIDs

   These are the mainstay of treatment but be aware that shunting of arachidonic acid to the lipoxygenase pathway may lead to a flare of the skin disease.

2. Corticosteroids

   Very useful for the peripheral joint disease. Both low dose orally or intra-articular corticosteroids in a fashion similar to rheumatoid arthritis can be used. The skin may also be benefited from oral corticosteroids.

3. Antimalarials (hydroxychloroquine, chloroquine)

   These agents have been used successfully for treatment of the peripheral joint disease but also may flare the skin especially chloroquine.

4. Gold Compounds

   Both oral and IM gold are effective in treating the peripheral joint disease. Given in a similar fashion to rheumatoid arthritis.

5. Sulfasalazine

   This agent has been shown to be effective in a variety of inflammatory forms of arthritis. Beneficial for both the peripheral and axial involvement.

6. Methotrexate

   Methotrexate has been in use for psoriasis for many years and is one agent that can treat skin, peripheral joint, and axial skeletal involvement. Dosed as per rheumatoid arthritis one time per week.

7. Miscellaneous

   Cyclosporin, PUVA, etretinate, azathioprine, have all been reported useful in small groups of patients.

Surgery for arthritis at the University of Washington

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