What is Juvenile Spondyloarthritis?
Spondyloarthritis (SpA) is a type of arthritis that involves joints along the spine. It also includes joints along the hips, shoulders, knees and ankles.
When there is arthritis in a joint, it can be warm and swollen. There may be joint stiffness, pain or tenderness to touch. These problems happen because of inflammation in the joint. When the arthritis is in a large joint, such as the hip or along the spine, the swelling can be hard to see or is not able to be seen at all on physical exam. This means imaging such as an ultrasound, CT scan or MRI is needed to look at the joint. In SpA, inflammation can happen where tendons attach our muscles to bones. It can also happen where ligaments attach to bones. These areas are called entheses. Inflammation of an enthesis can cause pain, tenderness and swelling.
SpA can happen in children and adults. There are many forms of SpA, including ankylosing spondylitis (AS). To have AS there must be proof that the spine is involved on the imaging study. When this happens in children it is called juvenile ankylosing spondylitis (JAS).
A more common type of SpA in children is called enthesitis-related arthritis (ERA). Read about juvenile idiopathic arthritis (JIA).
SpA often happens in people who are 20 to 30 years old. In children, the average age of diagnosis is 10 to 13 years of age, and it tends to affect males more than females. The number of people with SpA is not known. It happens in about 5 to 9 out of 1,000 people. Since about half of these people have AS, there are close to 500,000 cases in the U.S. alone.
What Causes SpA?
SpA affects people all around the world. The cause is not known. But we do know genetics plays a role. Specifically, being HLA-B27 positive leads to increased risk. Studies have shown that 60-90% of patients with arthritis that affect the spine will be positive for this gene.
What are the Symptoms of SpA?
SpA is a clinical finding/type of arthritis, which is often investigated if a child has one of these listed conditions. People who have SpA, do not definitely have or will have one of these conditions, but it needs to be evaluated.
The conditions that fall under the SpA grouping include:
- Juvenile Idiopathic Arthritis - Enthesitis-related arthritis (ERA) subtype
- Juvenile ankylosing spondylitis (JAS)
- Reactive arthritis
- Arthritis associated with inflammatory bowel disease (IBD) and psoriasis (see Features of Spondyloarthritis below)
Each will be looked at on its own, as they differ in important ways.
Juvenile Idiopathic Arthritis (JIA) - Enthesitis-Related Arthritis subtype (ERA)
ERA can present with arthritis in joints such as knees, ankles and hips. Arthritis in the upper extremities is less common but can involve wrists and shoulders. It is common to have pain and tenderness where tendons or ligaments attach to bones. Common sites for inflammation are:
- The heel
- Top and bottom of the kneecap (patella)
- Ball of the foot
- Bottom of the foot at the heel
- Mid-foot zone
Patients with ERA may have inflammation in other parts of their body. Eye inflammation (called anterior uveitis) occurs in about half of patients. Uveitis in ERA usually affects one eye, and the eye will be painful and red.
Juvenile Ankylosing Spondylitis (JAS)
In JAS, arthritis is in the lower back, the spinal joints, or the sacroiliac joints (sacroiliitis). Children who have arthritis mainly in the spine and sacroiliac joint tend to be older boys (over 11 years old) and HLA-B27 positive.
In children with ERA, spine or sacroiliac joint involvement is not common early in the diagnosis. Arthritis in the spine or sacroiliac joint can develop 5-10 years after the ERA diagnosis. In studies looking at children who developed JAS, the arthritis looked like ERA with lower extremity involvement and pain. They had tenderness where tendons or ligaments attach to bones. Additional studies say up to 40% of children with ERA will go on to develop symptoms of JAS. Different factors play a role in the development of JAS and we are not able to predict who with ERA will get JAS.
Reactive Arthritis (ReA)
Reactive arthritis (ReA) often occurs two to four weeks after an infection. The infection happens in some other part of the body, like the gastrointestinal (GI) tract, urinary tract or the genitals. GI infections most often involve diarrhea, belly pain and cramping. They are caused by bacteria like salmonella. Infection in the urinary tract or genitals may not have a specific symptom (mostly in females). The inflamed joints do not have these bacteria in them, but they are the site where many inflammatory cells collect and cause symptoms for unknown reasons. ReA is more common in people with the genetic marker HLA-B27. In most children with ReA, the arthritis is short-lived and all symptoms eventually go away. Some children may have more chronic symptoms. Some patients may develop complete JAS over several years.
Arthritis Associated with Inflammatory Bowel Disease (IBD) or Psoriasis
Arthritis can happen with either type of IBD, Crohn’s disease or ulcerative colitis. The arthritis can involve joints in the arms or legs and/or spinal joints and the sacroiliac (SI). When the spine or SI joints are involved, it is often linked to the HLA-B27 gene. Arthritis is seen in some but not all people who have the skin disease psoriasis.
How is Spondyloarthritis Diagnosed?
There are several signs and symptoms doctors use to diagnose SpA. This may come from a medical history, physical exam findings, and abnormal X-rays or MRIs of the sacroiliac joints (ee Features of Spondyloarthritis below for definitions). Making this diagnosis can be hard. Some findings are not there when the disease starts but show up over time. Other symptoms may never appear. This is very true in children, where lower back pain, sacroiliitis and abnormal X-ray findings are less common in the early stages.
The doctor may do a test for HLA-B27 if they think a patient has SpA. But even though most people with SpA have HLA-B27, many healthy people also have HLA-B27 and never have any joint problems. Other symptoms and signs of the disease must be there for the diagnosis to be made. When used with other information, the HLA-B27 test can be very helpful in spotting JAS.
How is Spondyloarthritis Treated?
Children with ERA or JAS are treated like children with JIA in many ways. Treatment is tailored to how severe their disease is and where it affects their bodies. Doctors most often start the treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) such as Naprosyn or Mobic. Arthritis in the knees, ankles and hips can often be treated with a shot of corticosteroids into the joint space. This helps reduce or eliminate inflammation in the joint.
Both Sulfasalazine and Methotrexate have been helpful for patients with SpA and peripheral arthritis. These are called disease-modifying anti-rheumatic drugs (DMARDs). It is unclear if DMARDs are effective in axial disease (mainly affecting the spine and sacroiliac joints) in ERA or in JAS. Blood tests need to be done on a regular schedule to look for side effects from these treatments.
Medications called biologics have been shown to be very good at reducing inflammation in the joints. These medications (like, TNF inhibitor) have been tested in clinical trials, and they are recommended to treat children with ERA and sacroiliitis if NSAIDs are not improving symptoms.
Another part of treatment is physical therapy and activity to stay flexible and get stronger. Activities like swimming are a good choice, as they do not put weight on joints. Some types of shoe inserts or special shoes can be used to ease pain when there is arthritis in the foot. These can help with swelling under or on the back of the heel. Overall, an active lifestyle will help keep your child functioning at the highest level possible.
Long-Term Outlook
What the future will hold is one of the hardest questions to answer, as each person is different.
Some studies where children with JAS were followed for about 15 years show they may not be able to do as much as others their age. Other studies have shown very good outcomes. These studies have shown that more than 75% of patients were either working or taking classes. Only 10 to 20% were disabled after 20 to 30 years. These reported outcomes are likely changing as treatments continue to get better and many benefits have been seen with biologic medications. The future for children with SpA is very hopeful.
Research Resources
If you want more information about SpA or want to contribute to genetic studies, contact the Spondylitis Association of America (SAA). For information, you can visit the SAA website, email (info@spondylitis.org), call toll-free (United States only) 1-800-777-8189, or call 1-818-981-1616. For research questions, email (info@asresearch.org) or call toll-free (1-888-777-8189).
Features of Juvenile Spondyloarthritis
Inflammatory Spinal Pain
Back pain that happens before age 45, that is slow in onset, and gets better with exercise and worse with rest. This goes along with morning stiffness. It must happen for at least three months.
Synovitis
Swelling of the synovium, or the layer of cells lining the joint space. This leads to symptoms of arthritis. This often involves the lower limbs or shoulders in SpA.
Positive Family History
Parents, sisters and brothers, grandparents, aunts, uncles or cousins with any of these: AS, psoriatic arthritis, acute uveitis, reactive arthritis or inflammatory bowel disease with arthritis.
Psoriasis
Psoriasis is a skin disease that causes a scaly, pink rash in patches on the face or scalp. It can occur in many locations on the body.
Inflammatory Bowel Disease
Crohn's disease or ulcerative colitis diagnosed by a doctor.
Buttock Pain
Past or current pain that rotates between either buttock.
Enthesopathy
Past or current pain, or feeling tender, where the Achilles tendon or plantar fascia insert on bone (back of heel or underneath heel). Enthesis is the broad term for where a tendon or joint capsule inserts on bone. Enthesitis refers to swelling at these sites.
Diarrhea
Sudden start of loose, water-like stool within one month before the start of arthritis.
Sacroiliitis
Inflammation in one or both sacroiliac joints. This inflammation can cause stiffness, pain, tenderness and limitation of motion in this joint. Inflammation can be seen on MRI or CT in early stages and on X-rays at later stages.
