What Is Enthesitis-Related Juvenile Idiopathic Arthritis?

Enthesitis-related juvenile idiopathic arthritis is a type of juvenile idiopathic arthritis (JIA). JIA is a group of disorders that causes arthritis (stiff, swollen, painful joints) in children.

Children with this type of JIA have enthesitis (en-thi-SYE-tis), which is inflammation where tendons and ligaments connect to bones.

Treatments can help with symptoms, so children can live a full and active life. The symptoms can go away for a time (called remission). In some kids, the condition goes away permanently.

What Are the Signs & Symptoms of Enthesitis-Related Juvenile Idiopathic Arthritis?

Enthesitis-related JIA usually causes symptoms in the low back, knees, ankles, and hips. Symptoms can start when a child is as young as 1 year old.

When the arthritis and enthesitis affect the joints of the low back, it is called juvenile ankylosing spondylitis (an-kih-LOE-sing spon-dih-LYE-tis).

Other problems can include:

• joint damage
• uveitis (inflammation inside the eye)
• inflammatory bowel disease (IBD)

What Causes Enthesitis-Related Juvenile Idiopathic Arthritis?

Enthesitis-related JIA happens when the immune system, which normally attacks germs, mistakenly attacks the joints. This causes inflammation (swelling and irritation) in the joints and other problems in the body.

Doctors don’t know exactly why kids and teens get JIA. “Idiopathic” means “from an unknown cause.” It can run in families but often does not. It’s likely due to a combination of:

• genetic (inherited) causes
• the way the immune system responds to infection and illness
• a trigger, such as an infection

How Is Enthesitis-Related Juvenile Idiopathic Arthritis Diagnosed?

To diagnose enthesitis-related JIA, doctors:

• ask about symptoms
• do an exam
• ask whether other family members have had similar problems
• do X-rays or other imaging studies to look inside the joints
• order blood tests to check for:
  • anemia or other blood problems
  • inflammation in the body
  • markers for some types of arthritis or autoimmune diseases

Sometimes, an orthopedic surgeon (bone doctor) takes samples of joint fluid or synovium (the lining of the joints). The sample is sent to a lab for testing.

How Is Enthesitis-Related Juvenile Idiopathic Arthritis Treated?

Enthesitis-related JIA is treated by a care team that includes:

• a rheumatologist (for problems with joints and connective tissue)
• a primary care doctor (such as a pediatrician or family medicine doctor)
• a physical therapist

Treatment goals are to ease pain and inflammation, improve strength and flexibility, and prevent joint damage. Treatment usually includes medicines to ease inflammation and physical therapy.

Sometimes surgery is needed for damaged joints.

How Can Parents Help?

Enthesitis-related JIA usually is a lifelong disease, but treatments can help ease pain, keep kids active, and prevent long-term joint damage. To help your child:

• Be sure your child takes all medicines exactly as directed.
• Work with the physical therapist to develop a regular exercise program. This will help keep your child’s muscles strong and flexible. 
• Learn all you can about enthesitis-related JIA with your child. Your care team is a great resource. You also can find information and support online at:
  • The Arthritis Foundation