Polyarticular JIA

It is horrifying to learn that children get arthritis.  Polyarticular Juvenile Idiopathic Arthritis (aka polyarthritis) is one form of arthritis that begins in people under 16 years of age.  Poly meaning many indicates that five or more joints are affected.

The joints affected by arthritis due to an overactive immune system are usually synovial joints, which include fingers and thumbs, wrists, elbows, shoulders, hips, knees, ankles, and toes.

A fluid-filled synovial sac encapsulates the area where bones meet.  This fluid lubricates the joint, aiding smooth and easy movement.

In polyarthritis, the synovial membrane thickens and swells, and there is an increase in the amount of synovial fluid.  It hurts.

Symptoms

Painful, swollen joints are a key characteristic of this disease.  The joints might feel warm, and children might try to guard the joints to reduce their pain, leading to a limited range of motion.  Children might feel sick and achy, as if they have the flu, and often experience a loss of appetite.  Fatigue is common.

JIA can cause people to be especially stiff and sore first thing in the morning or after sitting still for a period of time.  This can be puzzling to parents (and doctors) trying to document a child’s symptoms.  Why is the child sometimes okay, and other times barely able to move?  When the child gets up and starts moving around, the excess synovial fluid can be absorbed by the body, which leads to a decrease in swelling and pain.  Additionally, symptoms tend to come and go, further confounding attempts at diagnosis.

Comorbidities

Systemic diseases affect the entire body.  Polyarticular JIA is not limited to joints; it is systemic.  Unfortunately, eyes, ears, heart, lungs, the digestive tract, and other body systems can be affected.  This disease can lead to destruction of cartilage and bone at the joints, as well as deformity and permanent disability.  It is extremely important that polyarthritis be diagnosed early and treated aggressively.

Diagnostic Criteria

The doctor should take a complete medical history to determine not only the fact that joints are painful and swollen, but why they are that way.  JIA is not the only cause of joint pain.

  • under age 16 at onset of symptoms
  • joint pain and swelling for more than six weeks
  • all other causes of arthritis ruled out
  • five or more joints affected

In addition to a complete history and a thorough examination, lab work will need to be done.  The child will need to give a urine specimen and a blood sample.  Tests run might include:

If the disease qualifies as polyarticular JIA, and the RF blood test is positive, then the diagnosis is RF+ polyarthritis.  This disease – less than 5% of all JIA diagnoses - is sometimes considered young-onset rheumatoid arthritis.  It is most likely to be seen in adolescent girls.

If the disease qualifies as polyarticular JIA, and the RF blood test is negative, then the diagnosis is RF- polyarthritis.  About 15-20% of JIA cases are this type.  It is most likely to be diagnosed in females during early childhood and has a good prognosis.

Cause

Like all idiopathic diseases, the cause of polyarthritis is unknown.  This disease is not hereditary, although there can sometimes be a genetic component.  More research is needed in this area.

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

Treatment

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.
    • Non-Steroidal Anti-Inflammatory Drugs such as prescription-strength ibuprofen, meloxicam, or dicofenac can be helpful.  NSAIDs must be taken religiously to be effective, and must be taken with food to protect the stomach.
    • Disease Modifying Anti-Rheumatic Drugs will be prescribed, too.   There are many different DMARDs, and there is no way of knowing which patients will respond best to which medicines.  Sometimes it takes trail-and-error to find the most effective treatment.  If inexpensive DMARDs 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.  Rheumatologists will sometimes suggest that families consult with 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.

Cure

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.

Sources

Arthritis in Children - ACR
Q&A About Juvenile Arthritis - NAIMS
Juvenile Idiopathic Arthritis – OrphaNet
Juvenile Idiopathic Arthritis  - printo.it
Early Identification of Juvenile Idiopathic Arthritis - Musculoskeletal Network
Juvenile Idiopathic Arthritis
JIA for the Primary Care Practitioner

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