Enthesitis Related Arthritis is a form of arthritis that begins in people under 16 years of age.  Although it is more commonly diagnosed in boys, girls can also have ERA.  Onset is usually between the ages of 9-12.

ERA is also sometimes simply called enthesitis.  If a child has been diagnosed with enthesitis by a pediatric rheumatologist and requires long-term follow-up, verify with the doctor that the full name of the disease is ERA aka enthesitis-related juvenile idiopathic arthritis.  Not only is enthesitis one of the forms of JIA, but it is also part of a group of diseases called spondyloarthropathies.

This type of arthritis is significantly different from osteoarthritis, which is the type of arthritis typically seen in older people and athletes. In osteoarthritis (OA), the cartilage cushion at the joint between two bones wears away.   Bone-on-bone is extremely painful.  With OA, tylenol can help.  So can surgery to replace grandma’s worn-out joint.  In stark contrast, ERA is an autoimmune disease (from G. autos – self, and L. immunus – from which we get our word “immune”).  In autoimmune diseases, the immune system commits treason and turns on the body’s tissues that it’s supposed to be protecting.  Tylenol does not help.  A full-body attack by the immune system is dramatically different than the wearing away of a single joint.

To understand ERA, a quick anatomy review is helpful:

  • ligaments attach bones to one another
  • tendons attach muscles to bones

The point at which ligaments and tendons attach to the bone is called the enthesis (plural entheses).  In Enthesitis Related Arthritis, the entheses are inflamed.



The pain of enthesitis can be very similar to tendonitis and bursitis.   Such pain without an injury to cause it can be puzzling.  Often, children with ERA complain that their heels hurt.  Or perhaps it’s their feet or knees.  Around the knee, tender spots are at 6:00, 10:00, and 2:00 circling the patella. Other common sites are the Achilles tendon insertion points, and the plantar fascia attachments. This pain can lead to limited range of motion.

In ERA, it’s typically the larger joints of the lower extremities that are painful, so hips are sometimes involved.  Shoulders can also be affected.  Later on, there might be spinal (back and neck) involvement.  Other symptoms of ERA can be weight loss, lack of appetite, abnormally slow growth, and Irritable Bowel Disease.


Enthesitis Related Arthritis is not limited to joints; it is systemic.  That means organ tissues can be affected.  With ERA patients, it is particularly important to watch the eyes for signs of uveitis.  Acute anterior uveitis occurs in 27% of ERA patients.

Another disease linked to ERA is IBD, ie Crohns or ulcerative colitis.  Flares of IBD coincide with flares of ERA.

Dental problems seem to be more common with JIA, perhaps because children are extremely sore and don’t brush as well as they ought.  Attention to good oral hygiene is important.

Diagnostic Criteria

There are two different ways that a child can qualify for an ERA diagnosis.

  • Both arthritis (joint inflammation) and enthesitis (inflammation of a tendon-insertion site),


  • Either arthritis or enthesitis, and at least two of the following
    • inflammation of the sacroiliac joints
    • positive HLA-B27 blood test
    • arthritis in males age 7-16 (some lists say ages >8)
    • a parent, full-sibling, half-sibling, aunt, uncle, niece, nephew, or grandparent diagnosed with a spondyloarthropathy (ie AS, USpA, ERA, or SI-joint inflammation plus IBD)
    • Acute anterior uveitis


Like all idiopathic diseases, the cause of ERA is unknown.  This disease is not hereditary, although there can sometimes be a genetic component.  There is a link to the HLA-B27 gene, however not everyone with the gene develops ERA, and not everyone with ERA has the gene.

ERA, like all forms of JIA, is not contagious.


The goal is to allow kids to live a normal life, so treatment will be multifaceted.

  • A professionally-developed stretching and exercise plan is important for the purpose of relieving pain, protecting joints, improving joint function, strengthening muscles to allow smooth movement of joints, and keeping heart, lungs, and bones strong.  A physical therapist can help design a good exercise routine, and will usually focus on the lower extremities and large joints.  An occupational therapist will contribute to the exercise routine, too, focusing on the upper extremities and small joints/fine-motor skills.
  • Medication will be used to reduce inflammation and pain, and slow progression of the disease.  A good relationship with your pharmacist can be helpful.
    • The first-line treatment of ERA is Non-Steroidal Anti-Inflammatory Drugs such as prescription-strength ibuprofen, meloxicam, or dicofenac.  NSAIDs must be taken religiously to be effective, and must be taken with food to protect the stomach.
    • If NSAIDs do not provide sufficient relief, Disease Modifying Anti-Rheumatic Drugs can be prescribed.   There are many different DMARDs.  If inexpensive DMARDs such as sulfasalazine and methotrexate are not effective enough, another class of DMARDs, called biologics or Biologic Response Modifiers can be prescribed.
    • Steroids such as prednisone can be extremely helpful short-term.  These medications can cause problems such as skin thinning, weight-gain, and moon-face when taken long-term, so doctors will prescribe them cautiously.  Steroids should not be stopped abruptly.  It is extremely important to follow a doctor’s tapering schedule when discontinuing prednisone and other steroid medications.
  • Dietary modification might be needed to include all vitamins and eliminate foods that trigger symptoms.  Anecdotes abound of children whose symptoms improve when they eliminate trigger-foods from their diet.  This is particularly true of people with IBD, but helps others, too.  Common triggers are gluten, dairy products, nightshades, and sugar.  Rheumatologists will sometimes write a referral to a dietician.
  • Counselling, if needed, can help children and families deal with the psychological aspect of living with a chronic disease.
  • Professional eye care will be needed to treat uveitis if it occurs.

Children experiencing a flare-up of symptoms are sometimes soothed by the application of heat to the affected joint.  Heating pads and hot water bottles are quite helpful.


This is a chronic condition, meaning that the goal of treatment is to minimize symptoms and slow possible disease progression.  There is not yet a cure.  Some children diagnosed with ERA will deal with it their entire lives.  Some go into remission.  A better outcome is anticipated when the arthritis is limited to peripheral joints.  When the disease is more aggressive, sacroilliac joints and spine are involved.  Remission rates range between 17% to 37%.


Q&A About Juvenile Arthritis
Juvenile Enthesitis-Related Arthritis
Exercises for Enthesitis and Arthritis
Enthesitis-Related Arthritis: A Guide for Teenagers
Enthesitis Related Arthritis – MedScape
Enthesitis Related Arthritis – OrphaNet
Outcome in patients with enthesitis related arthritis
Classification of juvenile spondyloarthritis: enthesitis-related arthritis and beyond
Juvenile Spondyloarthropathies
Juvenile Idiopathic Arthritis (page 4)
Early Identification of Juvenile Idiopathic Arthritis
Juvenile Idiopathic Arthritis >> Forms
JIA for the Primary Care Practitioner
Arthritis in Children

5 thoughts on “ERA

  1. Thanks for the thorough description! Enthesitis is defininately something I’ve battled including three Achilles/ankle surgeries. Plus, my first symptom was acute anterior uveitis. My rheumy believes that I show signs of both RA and SA…although I’m RF positive and HLA-B27 negative. I hope you’re not writing this because one of your children is experiencing symptoms!

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