Your feet have 28 bones, 30 joints, and more than 100 tendons, muscles, and ligaments. That gives PsA a whole lot of places to attack. But the disease tends to strike some areas of the foot more than others.
Swollen, painful toes are a telltale sign of PsA -- especially when an entire toe (or finger) swells and looks like a sausage. Doctors call this dactylitis, or sausage digits. Research shows that dactylitis in PsA typically:
- Affects feet more than hands
- Affects toes on both feet
- Happens in less than half of people with the disease
- Tends to happen with more severe PsA
- May be the first and only sign of PsA for months
Don’t assume that your painful and swollen toe is psoriatic arthritis. There could be other causes.
For example, rheumatoid arthritis (RA), an inflammatory form of arthritis similar to PsA, often attacks the small joints in the feet. Gout can cause intense pain and swelling in the big toe. And the most common site of foot osteoarthritis (OA) is the big toe, resulting in pain and stiffness.
Heel and Bottom-of-Foot Pain
Foot problems caused by psoriatic arthritis sure can be tricky to pronounce. Besides dactylitis, there’s also enthesitis. This is inflammation of the entheses, which is where ligaments or tendons attach to bones.
PsA often attacks those connection points in a few areas:
- The bottoms of your feet
- Achilles' tendons (at back of your heel)
The affected tissue can become ropey; the medical term for this is fibrosis. It may also become hard, a process doctors call ossification or calcification.
Metatarsophalangeal Joint Pain
Does your foot ache at the base of your big toe? That’s your metatarsophalangeal (MTP) joint, another part of your foot that PsA often attacks.
There are a few things that increase your risk of MTP joint pain if you have PsA. These include:
- High body mass index
- Partially dislocated joint
- Inflammation of the lining of the joint
- Joint erosion
Other Foot Problems
Here are some other ways PsA can affect your feet.
Distal arthritis. That’s the short name for distal interphalangeal predominant PsA. This type of psoriatic arthritis affects the joints closest to the tips of your fingers and toes.
Arthritis mutilans. Rarely, PsA is so severe that it destroys joints in your fingers and toes. As a result, those fingers and toes become shorter.
Nail problems. Almost all people with PsA have nail symptoms. One common problem is pitting, or tiny indentations in the surface of your nail. Another problem is nail separation, when the nail lifts from the tissue underneath.
Foot swelling. Although dactylitis is a common feature of PsA, swollen feet can be a symptom of PsA before specific joints are affected.
Synovitis. Inflammation of the lining of the joint -- the synovium -- is called synovitis. In PsA, though, synovitis is usually followed by bone destruction, especially in the fingers and toes.
Foot Pain Relief
Depending on where your foot hurts and how severe your disease is, your doctor might suggest these and other approaches for foot pain relief:
- Cold packs to bring down swelling
- Keeping toenails short (to reduce risk of separation from the nailbed)
- Steroid injection beneath the toenail to help control nail changes
- Steroid injection into a joint to quickly reduce inflammation
Some experts say that foot complications in PsA don’t get enough medical attention. Make sure your doctor knows if you develop foot problems, from nail changes to pain when you walk. Getting the right diagnosis and treatment for your feet can improve your quality of life.