What is psoriatic arthritis?

Psoriatic arthritis is an inflammatory joint disease associated with psoriasis. Like all arthritis, psoriatic arthritis can cause stiffness, pain and lack of movement in affected areas. It most commonly affects the joints in the hands and feet, but can also cause inflammation, swelling and pain in larger joints, including the knees, elbows, hips and the spine. The inflammation in psoriatic arthritis can also affect the tendons (the fibrous tissue that attaches the muscle to the bone).

What are the symptoms?
Symptoms of psoriatic arthritis range from mild to severe and can wax and wane in a similar way to skin psoriasis. Generally, one or more of the following symptoms appears:
· General tiredness
· Tenderness, pain and swelling over tendons
· Swollen fingers and toes
· Stiffness, pain, throbbing, swelling and tenderness in one or more joints
· A reduced range of movement
· Nail changes

Which joints are involved?
Psoriatic arthritis usually affects the joints that are closest to the nail (distal joints) in both the fingers and the toes. The lower back, wrists, knees and ankles, alongside the neck, shoulders and elbows may also be affected. There are five subgroups of psoriatic arthritis, although there is some overlap between the groups.
Asymmetrical oligoarticular arthritis accounts for approximately 70% of cases, and this pattern tends to be the least severe. The arthritis affects less than five joints, on one side of the body (‘oligo’ means a few). Dactylitis - swelling of an entire finger or toe so it appears “sausage-like” is common. An example may be for one large joint to be affected (such as the knee) plus a few small joints in the fingers or toes.
Symmetrical polyarthritis makes up about 15% of cases of psoriatic arthritis and resembles rheumatoid arthritis – although it is generally milder with less deformity. It usually affects several joints (poly) and occurs in the same joints on both sides of the body (symmetrical) – the joints can be large or small.
Distal interphalangeal joint predomination (DIP) occurs in approximately 5% of people with psoriatic arthritis. This type picks out the small joints in the fingers and toes and usually involves changes in the appearance of the nails.
Spondylitis is inflammation of the joints and discs in the spinal column. Symptoms can include stiffness and pain in lower back and neck. Other joints, such as the hips, hands and feet can also be affected. This type of psoriatic arthritis occurs in about 5% of people with the condition.
Arthritis mutilans makes up about 5% of cases of psoriatic arthritis. This form of arthritis principally affects the small joints of the hands and feet but can also affect the spine. It is a severe form of psoriatic arthritis, and can be very destructive causing marked deformity of the joints.

Who gets psoriatic arthritis?
Psoriasis is a common skin condition affecting 2-3% of the population of the UK and Ireland. An estimated 5-7% of people with psoriasis have psoriatic arthritis. This figure can increase to approximately 40% in people who have severe psoriasis. Men and women are equally likely to develop psoriatic arthritis with the peak onset being between the ages of 30 and 50 years (however psoriatic arthritis can occur at any age).
In most cases (70%) psoriasis precedes psoriatic arthritis, in 15% of cases the skin and joint conditions occur at the same time and in the remaining 15% psoriatic arthritis is present before the skin condition psoriasis appears.
It is worth noting that people with psoriasis can also develop other forms of arthritis such as rheumatoid arthritis and osteoarthritis.

How does psoriatic arthritis get diagnosed?
There is no specific test for psoriatic arthritis. Diagnosis is made by looking for a history of psoriasis in you or your family, together with arthritis and inflammation in at least one joint. The pattern of the disease is also assessed to see if your symptoms fall into one of the subsets of psoriatic arthritis. Fingernails and toenails are commonly affected in people with psoriatic arthritis – the nail may show signs of pitting and/or becomes separated from the nail bed, and so the doctor may check for changes in the appearance. Some tests (such as blood tests and x-rays) can be done in order to rule out other forms of arthritis. Unlike rheumatoid arthritis, there is not a blood test available to specifically diagnose psoriatic arthritis – the blood test for rheumatoid arthritis appears negative in psoriatic arthritis patients. An x-ray of the joints involved can help to diagnose psoriatic arthritis, as the appearance tends to be different from other forms of arthritis.

What treatments are available?
There are many different treatments available for psoriatic arthritis depending on the type and severity. You may see different health professionals at various stages of your treatment; these may include your GP, Rheumatologist, Nurse, Physiotherapist, Occupational Therapist and Podiatrist. The various health professionals can offer you treatments ranging from exercises to splints in order to support inflamed joints, through to tablets and injections to reduce the pain and inflammation, and slow down the progression of the arthritis.