Psoriatic arthritis is a type of inflammatory arthritis that affects around 20% of people suffering from the chronic skin condition Psoriasis. It occurs more commonly in patients with tissue type HLA-B27. Treatment of psoriatic arthritis is similar to that of Rheumatoid arthritis. More than 80% of patients with psoriatic arthritis will have psoriatic nail lesions characterised by pitting of the nails. Psoriatic arthritis is said to be a sero-negative spondyloarthropathy.

Psoriatic arthritis can develop at any age, however on average it tends to appear about 10 years after the first signs of psoriasis. For the majority of people this is between the ages of 30 and 50, but it can also affect children. Men and women are equally affected by this condition. In about one in seven cases the arthritis symptoms may occur before any skin involvement.

As well as causing joint inflammation, psoriatic arthritis can cause Tendonitis and a sausage-like swelling of the digits known as dactilytis.

Types of Psoriatic Arthritis

There are five main types of psoriatic arthritis; these are symmetric, asymmetric, distal interphalangeal predominant (DIP), spondylitis and arthritis mutilans.

Symmetric

This type accounts for around 50% of cases, and affects joints on both sides of the body simultaneously. This type is most similar to Rheumatoid arthritis and is disabling in around 50% of all cases.

Asymmetric

This type affects around 35% of patients and is generally mild. This type does not occur in the same joints on both sides of the body and usually only involves less than 3 joints.

Arthritis Mutilans

Affects less than 5% of patients and is a severe, deforming and destructive arthritis. This condition can progress over months or years causing severe joint damage.

Spondylitis

This type is characterised by stiffness of the spine or neck, but can also affect the hands and feet, in a similar fashion to symmetric arthritis.

Distal Interphalangeal Predominant

This type of psoriatic arthritis is found in about 5% of patients, and is characterised by inflammation and stiffness in the joints nearest to the ends of the fingers and toes. Nail changes are often marked.

Treatments

Treatments for this disease include joint injections.