Although there is no clear-cut set of criteria or tests for psoriatic arthritis, several distinct types have been described. The characteristic symptoms of all types of psoriatic arthritis are red hot, swollen, and tender joints. In contrast to the more common “wear and ear” of osteoarthritis, which is worse at the end of the day or after heavy use, stiffness and pain in psoriatic arthritis tend to be worse in the morning and usually last longer than 45 minutes.
Five types of psoriatic arthritis have been described; they are sometimes referred to as the Moll criteria.
1. Distal arthritis involves the small joints of the hands and feet, especially the fingers and toes.
2. Oligoarthritis is arthritis in which four or fewer joints are affected (oligo- means “few”).
3. Polyarthritis is arthritis in which more than five joints are involved (poly- means “many”). This variant may appear very similar to rheumatoid arthritis.
4. Arthritis mutilans is a very destructive form of arthritis that may cause permanent changes in the shape of joints.
5. Spondylarthropathy is inflammation of the spine and hip joints.
Some people experience more than one of these types, but they all typically respond to the same treatment approaches. Early identification and appropriate treatment can help prevent worsening and possible permanent joint damage.