Psoriatic arthritis (PsA) a type of arthritis affecting joints. PsA may also involve enthesitis, a condition that affects ligaments and tendons where they connect to bone.

Psoriatic arthritis (PsA) is a kind of inflammatory arthritis that can affect people with psoriasis. Between 20% to 30% of people with psoriasis also have PsA.

PsA is characterized by joint pain, swelling, and stiffness. Some individuals with PsA also experience something called enthesitis.

Enthesitis happens when the area where ligaments and tendons connect to bone becomes inflamed. Keep reading to learn more about PsA enthesitis, its symptoms, and how it’s diagnosed and treated.

Learn more about psoriatic arthritis.

The entheses are the areas where your ligaments and tendons insert into the bone. They’re very important for joint movement, as they help to distribute mechanical forces as well as provide support.

There are over 100 entheses in your body. When one or more entheses become inflamed, it’s called enthesitis.

Enthesitis is a common feature of both PsA and axial spondyloarthritis. It’s estimated to affect about 35% of — roughly 1 in 3 — people who have PsA.

Because enthesitis is more frequent in PsA compared to most other types of arthritis, it can be a good indicator of PsA. So, if you visit your doctor because of joint symptoms, they may look for signs of enthesitis to help make a diagnosis.

Some research has indicated that people with PsA who have enthesitis experience higher disease activity. Additionally, a 2017 analysis found that the severity of enthesitis was associated with increased joint damage.

Enthesitis due to PsA can also have other effects. For example, a 2020 survey found, compared to people with PsA who didn’t have enthesitis, those with enthesitis reported:

  • higher amounts of pain
  • increased level of disability
  • lower quality of life
  • a negative effect on work

The main symptoms of enthesitis are tenderness, pain, and stiffness. Because the entheses are important for movement, you’ll notice these symptoms more when you’re moving.

Some visible symptoms of enthesitis are redness/discoloration and swelling in the affected area.

Commonly affected areas

Enthesitis typically impacts only one or two areas of the body at the same time. Some of the most commonly affected areas are the:

  • back of the heel (Achilles tendon)
  • bottom of the foot (plantar fascia)
  • elbow (lateral epicondyles)

Inflammation of fingers or toes

Enthesitis can also occur with another common symptom of PsA, dactylitis. This is a painful inflammation of a finger or a toe.

Changes in fingernails and toenails

In people with PsA, enthesitis is also associated with changes in the fingernails, toenails, or both. Nail changes can include:

Bone spurs

Enthesitis can cause long-lasting (chronic) inflammation, which can lead to bone spurs developing in the affected area. These bone spurs appear differently on X-ray than typical bone spurs. They appear fluffy rather than well-formed.

It’s believed that enthesitis happens due to physical stress that’s placed on an area. Over time, damage accumulates at the affected area.

When the immune system senses that an area has become damaged, it releases chemicals called cytokines, which can result in inflammation.

Enthesitis can sometimes occur in healthy individuals due to overuse of a joint, such as tennis elbow or Achilles tendonitis. It typically goes away with rest, icing, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs).

However, in a person with PsA, the immune system doesn’t function properly, leading to increased levels of inflammation. This contributes to persistent or chronic inflammation at the entheses.

Some individuals with PsA may be at a higher risk of enthesitis. For example, a 2017 cohort study found that the following factors boosted enthesitis risk:

There isn’t a specific laboratory test that can be used to diagnose enthesitis. Your doctor will ask about your medical history as well as the type of symptoms you’re experiencing and where they occur.

They’ll also perform a physical examination, during which they’ll do things like:

  • check for redness, discoloration, or swelling around the affected joint
  • apply a small amount of pressure to the affected area to assess tenderness and pain
  • evaluate the affected joint’s range of motion
  • look for other PsA symptoms that often happen with enthesitis, such as dactylitis or nail changes
  • look for bone spurs that appear “fluffy” on X-ray

Imaging tests can also be used to help your doctor look for inflammation around the entheses. Some examples of imaging technologies that may be used are:

There are a few different treatment options for enthesitis due to PsA. Most are the same types of treatments that are used to treat PsA in general.

Medical treatments

High doses of NSAIDs, which may be applied topically, are a potential early treatment for enthesitis. However, not all instances of enthesitis respond to NSAIDs. In this case, treatment with a biologic drug may be necessary.

A type of physical therapy called iontophoresis may be used. This therapy involves applying a topical medication like a steroid or NSAID and using ultrasound to help the medication penetrate.

A biologic is a type of disease-modifying antirheumatic drug (DMARD) that targets specific parts of the inflammatory process. A few examples of biologic drugs that may be used to treat enthesitis are:

Various biosimilar compounds are available for the above “branded” biologic agents. Biosimilars may be prescribed by your doctor or substituted by your pharmacist. Which version used may be based on the formulary an insurer has approved.

If enthesitis is only impacting a single joint, it’s possible that a corticosteroid injection in the affected area may be an option. This can alleviate inflammation and help with healing.

Home remedies

In addition to the treatments above, you can try the following things at home to help with PsA enthesitis:

  • Exercise: Doing gentle stretches or exercises may help to reduce pain and stiffness. Be sure to ask your doctor about appropriate stretches. It’s also possible that they’ll refer you to a physical therapist.
  • Hot and cold: You may find alternating between a warm and cold compress to be helpful. Applying a warm compress to the affected area can reduce stiffness, while using a cold compress can reduce swelling.
  • Orthotics: If enthesitis is impacting your foot, you may want to consider getting shoe inserts to help provide extra support.

Enthesitis is inflammation in the area where ligaments and tendons connect to bone. It’s quite common in individuals with PsA.

The symptoms of enthesitis can include tenderness, pain, and stiffness. You may also notice swelling and redness or other discoloration. Enthesitis also commonly happens with other PsA symptoms like nail changes and dactylitis.

Enthesitis is treated using many of the same treatments as PsA. Since this condition has been associated with higher PsA disease activity and joint damage, be sure to see a doctor for evaluation and treatment if you think you have enthesitis.