Much like adult ankylosing spondylitis which affects more men, JAS usually affects more boys than girls. It appears before age 18, with the average age of onset is 10 years or older. The disease is more common in Caucasians, affecting approximately one in 100 Caucasian boys.

Symptoms 

The symptoms experienced by children and teens with JAS will vary, but the most common symptoms include: 

Joint stiffness in the morningPain in the knees, heels, and feet that worsens with activityPain in the back and/or buttocks that improves with movementSwelling in the joints of the arms and legsTrouble standing up or bendingExtreme fatigueEye pain and rednessSensitivity to lightAnemiaStooped postureInability to take a deep breath if joints between the ribs and spine are inflamed 

JAS can also be associated with intestinal inflammation problems or inflammatory bowel disease (IBD). IBD is an umbrella term describing conditions that cause inflammation of the digestive tract, including Crohn’s disease and ulcerative colitis. Symptoms suggestive of IBD include abdominal pain, weight loss and appetite loss, blood in the stool, and diarrhea.

Many of the symptoms of JAS may be related to other diseases. Therefore, it is always a good idea to consult your child’s doctor for a correct diagnosis. 

Causes

JAS is one of the most common conditions classified as spondyloarthropathies. Spondyloarthropathies share distinctive features, including:  

inflammation of the spine and sacroiliac (SI) joints family history and genetic disposition (inherited risk) the absence of a rheumatoid factor (RF)

An RF is an antibody found in people with certain rheumatic conditions, including rheumatoid arthritis (RA). 

JAS has multiple risk factors, which are involved in causing the condition. These include: 

Genetics.  Variations in certain genes increase the risk of a young person getting JAS.  Heredity also plays a part as families share many of the same genetic characteristics.  Gender. Boys have a higher risk of developing the condition than girls do. Age.  JAS usually develops in late adolescence and early adulthood although it may develop earlier. HLA-B27.  Genes called HLA antigens play a role in whether a child will get a certain disease.  The HLA antigen associated with JAS is B27.  If a child has the HLA-B27 gene, he or she may have an increased risk for developing JAS.  It is important to note that while many people carry the HLA-B27 gene, it does not mean that they will develop JAS. This means a child can test positive for the gene and still not have JAS. Other genes.  There are other gene variations associated with JAS, but researchers are not clear on how these variations increase the risk for JAS.  Researchers also believe there are additional genes not yet identified that may increase the risk for JAS.

Diagnosis

Diagnosis of JAS begins with a medical history and physical examination. During the physical exam, the doctor will ask the juvenile to bend in different directions to test the spine’s range of motion. The doctor will try to reproduce pain by pressing on specific areas of the pelvis and by asking the client to move the legs.  The doctor will also ask the child to take deep breaths to see if he or she has pain or difficulty expanding the chest.                                                                    

Diagnostic testing can help doctors make a diagnose of JAS and may include:  

Imaging.  X-rays of the pelvis and spine will look for damage in the lower back, hips, and spine.  An MRI (magnetic resonance imaging) of the pelvis allows the doctor to look for ongoing inflammation in the low back, hips, and spine.  Ultrasounds can look at inflammation in joints and tendons of the low back and spine. Bloodwork.  There aren’t any specific blood tests that confirm a specific diagnosis of JAS.  However, certain blood tests can check for markers of inflammation.  

Additionally, blood can be checked for the HLA-B27 gene. Bloodwork tends to focus on eliminating the possibility of other conditions that could be causing symptoms. 

However, the diagnosis of JAS in a child can be difficult to make. 

Treatment 

Treatment goals in JAS include reducing pain and stiffness and to prevent deformities and disability.  Further, treatment is aimed at keeping a child as active as possible. JAS treatment is dependent on the symptoms, age, and general health of the child. It is treated similarly to adult AS and may include: 

nonsteroidal anti-inflammatory drugs (NSAIDs) for reducing inflammation and pain corticosteroids for short-term use to reduce inflammation disease-modifying antirheumatic medicines (DMARDs), such as methotrexate, to slow down inflammatory processes biologic medications, including etanercept, to slow down inflammation exercise and physical therapy to strengthen abdominal and back muscles surgery as a last resort if there is severe pain and joint damage

Potential Complications 

Untreated or undertreated JAS may cause complications including: 

Joint damageFusion of the bones in the spine and chestAbnormal curvature of the spineTrouble breathing because of spine and chest inflammationBreaks in the bones of the spineHeart, lung, and/or kidney problems 

Early diagnosis and treatment are key to preventing complications. 

A Word From Verywell 

Juvenile ankylosing spondylitis is a progressive disease with no cure. Steps can be taken to manage the disease and limit its progression. It can be difficult to determine the long-term outcome, especially early on. The disease can last for months or years and go into periods of remission (periods where the disease is inactive). It can also continue into adulthood. 

The outlook for most children and teens can still be positive with the right treatment approaches. Moreover, most can go on to live full lives with a low risk for complications. Children with JAS should be routinely monitored by a pediatric rheumatologist at least three to four times a year.