There are five subtypes of psoriatic arthritis, affecting different parts of the body. Some people may have one kind of psoriatic arthritis and then develop a different form down the road. “The categories tend to bleed into each other,” says Anca Askanase, MD, a rheumatologist and an associate professor of medicine at the Columbia University Irving Medical Center in New York City. “Ultimately, they’re all about joint pain, stiffness, and loss of function.” Knowing which type of psoriatic arthritis you have can help inform your treatment and perhaps your prognosis. Systemic (whole body) and biologic drug treatments are similar for the different forms, but the approach to psoriatic arthritis flare-ups may vary, Dr. Askanase notes.
1. Asymmetric Psoriatic Arthritis
This is the most common subtype, accounting for roughly half of all cases of psoriatic arthritis, according to the patient advocacy group CreakyJoints. While it can affect any joint, its defining trait is that it doesn’t impact the same joints on both sides of the body. When asymmetric psoriatic arthritis involves the fingers and toes, the swelling and redness can make them look like small sausages, a condition known as dactylitis. Even though fewer joints may be affected, asymmetric psoriatic arthritis can be disabling and difficult to treat, Askanase says. For acute flare-ups, steroid injections, nonsteroidal anti-inflammatory drugs (NSAIDs), and physical therapy can help. RELATED: 11 Easy Hand and Foot Exercises for Psoriatic Arthritis
2. Symmetric Psoriatic Arthritis
Rheumatoid arthritis tends to affect the same general areas on opposite sides of the body, and symmetric psoriatic arthritis can follow a similar pattern, says Kathleen Maksimowicz-Mckinnon, DO, a rheumatologist at Henry Ford Health System in Detroit. But with symmetric psoriatic arthritis, the exact same joints may not be impacted. For instance, while joints in the fingers of the right and left hands may be involved, those closest to the fingertips might be affected on the right hand, while those near the base of the fingers might be affected on the left, or vice versa. Symmetric psoriatic arthritis, which makes up about 33 percent of all psoriatic arthritis cases, can also strike the knees, wrists, and ankles. Besides systemic treatments, Askanase says steroid injections, NSAIDs, and physical therapy can help.
3. Distal Psoriatic Arthritis
This type of psoriatic arthritis is usually relatively mild and not as impairing as other kinds, Askanase says. It affects the “distal” joints, meaning it causes inflammation and stiffness in the small joints that are closest to the nails on fingers and toes. Since these joints are so close to the nails, symptoms can include spotting or pitting in the nails or a lifting of the nail from the nail bed. Joint inflammation is typically associated with nail changes on the same fingers or toes, according to a study published in the Journal of Cutaneous Medicine and Surgery in July–August 2015. Fewer than 20 percent of people with psoriatic arthritis have distal psoriatic arthritis by itself; it frequently occurs alongside other kinds of psoriatic arthritis. NSAIDs and physical therapy can help treat acute flare-ups. RELATED: How Psoriatic Arthritis Can Damage Your Nails — and What to Do About It
4. Spondylitis
Pain, inflammation, and stiffness in the neck, spine, and sacroiliac joints (located between the sacrum — the bone connected to your tailbone — and the pelvis) are the telltale signs of this psoriatic arthritis subtype. “The big concern is this disease can progress relentlessly and lead to severe, incapacitating damage to the spine,” Askanase says, causing significant problems a person’s ability to move and function. “TNF inhibitors [a type of biologic therapy that blocks the protein called tumor necrosis factor alpha, or TNF-alpha] have made a huge difference in our ability to control pain and provide continuous functionality in early stages [of spondylitis],” Askanase notes. RELATED: 9 Myths About Psoriatic Arthritis Treatment, Debunked
5. Psoriatic Arthritis Mutilans
A relatively rare subtype, arthritis mutilans can cause serious damage and deformity to the joints in the hands and feet. It can affect other parts of the body such as the neck and back, too. “It may not be as ‘noisy’ in terms of pain and stiffness, yet the end result is quite extraordinary because of the amount of damage it causes,” Askanase says. The most common problems include bone loss, “telescoping” of the fingers due to bone loss (because the soft tissue of the fingers can’t hold them up), and finger shortening, according to a review in the August 2015 Journal of Rheumatology. Early treatment is important. Disease-modifying antirheumatic drugs (DMARDs) can prevent some permanent damage, while NSAIDs can relieve pain. Additional reporting by Julie Marks.
