What is Psoriatic Arthritis?
Psoriatic arthritis, a form of rheumatoid arthritis is a chronic inflammatory disease which affects both the joints and connective tissue.
Psoriatic arthritis was first described by French physician Baron Jean Louis Alibert during the early 19th century.
However, it was over 100 years later during the 1950s that psoriatic arthritis was recognized as a form of arthritis in its own right.
There is a link between psoriatic arthritis and psoriasis on the skin. Approximately 10 - 30 % of people with another type of psoriasis go on to develop psoriatic arthritis (source: National Psoriasis Foundation).
Types of psoriatic arthritis
There are 5 types of psoriatic arthritis.
- Asymmetric arthritis
- Arthritis mutilans
- Distal interphalangeal predominant (DIP)
- Symmetric Arthritis
Onset & Development Of Psoriatic Arthritis
The onset of psoriatic arthritis can be slow with mild symptoms or sudden with a more severe outcome. A sudden onset of psoriatic arthritis sometimes occurs after injury to a joint.
Factors affecting Psoriatic Arthritis
Environmental and genetic factors are linked to this disease. Psoriatic arthritis can often run in families.
Symptoms Of Psoriatic Arthritis
- Pain, tenderness and swelling over the tendons
- Inflexibility / reduced range of motion
- Swollen fingers and toes
- Nail psoriasis – symptoms include pitting and the nail separating from the nail bed
- Eye problems including redness and pain. Conjunctivitis is associated with psoriatic arthritis
- General morning stiffness and tiredness
Not all of these symptoms will be experienced by a person with psoriatic arthritis although swelling over the joints is found in most cases.
In fingers and toes, psoriatic arthritis usually affects the distal joints which are the joints closest to the nail.
Areas of the body often affected by psoriatic arthritis include:
- All joints of knuckles, fingers and thumbs
- Base of spine
Psoriatic Arthritis Diagnosis
The joint inflammation symptoms of psoriatic arthritis can be sometimes be mistaken for other conditions including cartilage tear.
A diagnosis of psoriatic arthritis is usually made after recurrent episodes so other arthritic diseases can be ruled out.
Conditions with similar symptoms to psoriatic arthritis
- Gout – pain in the joints, particularly in the big toe can caused by gout.
- Reactive arthritis – this form of arthritis can also affect the eyes but is triggered by infection.
- Rheumatoid arthritis
Testing For Psoriatic Arthritis
There is no single test for psoriatic arthritis.
A diagnosis for psoriatic arthritis is made after eliminating other possible conditions, typically those in the list above.
To help diagnose psoriatic arthritis, one or a combination of the following tests may be used:
Blood tests – in rheumatoid arthritis, an antibody known as the rheumatoid factor is usually found in the blood. A blood test which indicates that no rheumatoid factor is present can help rule out rheumatoid arthritis as the cause of symptoms.
Patients medical history.
Physical examination – bumps found under the skin and symmetrical distribution of symptoms in the joints indicate that the condition is more likely to be rheumatoid arthritis than psoriatic arthritis.
MRI - magnetic resonance imaging used to image internal body structure.
X-rays - x-rays are more effective in showing later stage symptoms of psoriatic arthritis. During the later stages, the 'pencil in the cup' phenomenon can arise in which the bone can get carved down to a fine point. This is easily observed using an x-ray and distinguishes it from other arthritic diseases.
When psoriatic arthritis has been diagnosed, appropriate treatment can be given.