Psoriatic arthritis can develop gradually and in its mildest form may produce minimal discomfort in those affected. In others, psoriatic arthritis may be severe and, if untreated, patients may become disabled with swollen, deformed joints.
Psoriatic arthritis can produce several symptoms:
- swelling and tenderness of joints
- stiffness and decreased ability to move joints fully
- pain and stiffness that is worse in the morning or with rest
- raised, scaly, red skin lesions may occur
- nail changes are very common, particularly if arthritis involves the joints at the ends of the fingers and toes
- redness and tenderness of the eye
Which Joints Can Be Affected?
Psoriatic arthritis can affect one or many joints, and will occur in certain patterns. To determine the pattern or different locations of joints affected, it is important to know:
- How many joints are affected? Is only a single joint affected (monoarthritis)? Are a few joints affected (oligoarthritis)? Or are multiple joints affected (polyarthritis)?
- Are the joints affected symmetrically (similar joints on both sides of the body)? For example, are the small joints of the right and left hands and feet affected? Or are the joints affected in an asymmetrical way (different joints involved on opposite sides of the body)?
- Is the joint involved causing deformity or mutilation?
End Knuckles of the Fingers and Toes (Distal lnterphalangeal Arthritis)
The small joints at the ends of the fingers and toes are called distal interphalangeal joints (DIP). These joints are so named because they are at the ends of the fingers and toes (distal), and are the knuckles between (inter) the small bones of the finger (phalangeal). On the feet, the small joints are called metatarsal phalangeal (MTP).
Nail changes are usually seen when arthritis affects the end knuckles of the fingers and toes. Nail changes can include pitting, lifting, and crumbling of the nail, and changes in color and thickness of the nail plate.
Many Similar Joints on Both Sides of the Body (Symmetrical Polyarthritis)
This pattern of psoriatic arthritis may involve five or more joints (polyarthritis), and similar joints on both sides of the body (symmetric). This form of psoriatic arthritis may resemble a different type of inflammatory arthritis known as rheumatoid arthritis.
One or Only a Few Joints in an Asymmetrical Pattern (Mono or Asymmetrical Oligoarthritis)
Four or fewer joints are affected, usually in an asymmetrical pattern. This is the most common form of psoriatic arthritis and occurs in about 70 percent of all cases. For example, a large joint such as a knee may be involved with one or two small joints of the finger (DIP) or toe (MTP).
Spinal Involvement
This pattern of psoriatic arthritis involves the spine. The low back is most frequently affected.
Arthritis Mutilans
This is a severe form of psoriatic arthritis, which can be extremely disabling. As the name suggests, this form of arthritis can cause destruction and mutilation (mutilans) of the small joints of the fingers and toes. The fingers may appear swollen and sausage-like. Fortunately, this is a rare form occurring in fewer than 1 percent of all psoriatic arthritis cases.
These patterns can help in diagnosing psoriatic arthritis when the arthritis first develops. Over time, an increasing number of joints can become involved, and the pattern of involvement could change. To find out more, you can check out Psoriasis Arthritis Symptoms.