Juvenile Arthritis (Juvenile Idiopathic Arthritis)

What juvenile idiopathic arthritis is

JIA is not one disease but a group of conditions that share chronic joint inflammation in children. "Idiopathic" means the cause is unknown. The immune system attacks the synovium, the lining of the joint, which thickens and produces excess fluid, causing swelling, warmth and stiffness. Without treatment, ongoing inflammation can damage cartilage and bone and affect growth.

The older name juvenile rheumatoid arthritis is still used in the US, but JIA has replaced it in most medical settings. See juvenile rheumatoid arthritis.

Symptoms

• joint swelling, often of the knee, ankle, wrist or fingers
• stiffness, worst in the morning or after naps, improving through the day
• limping or walking differently in the morning
• reduced use of a hand or arm, or refusing to walk
• pain, though young children may not say it hurts
• warm joints, usually not red
• fatigue, poor appetite and irritability
• fever and rash in systemic JIA
• eye inflammation (uveitis), often without symptoms

Types of JIA

Eye inflammation (uveitis)

Uveitis affects up to about 1 in 5 children with oligoarticular JIA, and can occur in other types. It often causes no redness or pain, but can lead to cataracts, glaucoma and vision loss if missed. Children with JIA need regular slit-lamp eye exams with an ophthalmologist, as often as every 3 months for the highest-risk children, following American Academy of Pediatrics and ACR guidance. See uveitis.

Causes

The cause is unknown. It likely involves genetic susceptibility, including certain HLA types, combined with environmental triggers such as infections. JIA is not caused by injuries, diet or anything the parents did, and it is not contagious.

Diagnosis

There is no single test. Diagnosis requires:

• arthritis in at least one joint for 6 weeks or more, starting before 16
• exclusion of other causes

A pediatric rheumatologist will examine all joints and may order:

• blood tests: blood count, inflammatory markers (ESR, CRP), ANA, rheumatoid factor, anti-CCP and HLA-B27
• tests to exclude other causes: infection, Lyme disease, reactive arthritis, leukemia, bone tumors and inherited conditions
• joint fluid analysis if infection is possible
• imaging: ultrasound or MRI to detect inflammation, and X-rays for damage

Septic arthritis and leukemia are important not to miss, especially in a child with fever, night pain or abnormal blood counts.

Treatment

The goal is inactive disease, protecting joints, growth and vision while allowing a normal childhood.

Medicines

• NSAIDs (naproxen, ibuprofen) for pain and stiffness
• intra-articular steroid injections for a few swollen joints, often giving months of relief
• methotrexate, the main disease-modifying drug
• biologics: TNF inhibitors (etanercept, adalimumab), abatacept, tocilizumab, and IL-1 inhibitors (anakinra, canakinumab) especially for systemic JIA
• JAK inhibitors such as tofacitinib for some children
• short courses of oral steroids for severe flares or systemic disease, used sparingly because of effects on growth and bones

Therapy and support

• physical therapy to maintain range of motion and strength
• occupational therapy for daily activities, splints and school tools
• regular exercise, which is encouraged
• school accommodations through a 504 plan
• emotional support for the child and family
• vaccinations checked before biologics, avoiding live vaccines while immunosuppressed

Outlook

With early, effective treatment, outcomes are much better than in the past. Many children achieve remission, and some stop medicines. Around half continue to have some active disease into adulthood, particularly those with polyarticular RF-positive JIA. Complications such as joint damage, growth problems and vision loss are now less common with modern care and eye screening.

Frequently asked questions

What are the first signs of juvenile arthritis?

Early signs include a swollen joint, morning stiffness, limping, especially after waking, reduced use of an arm or leg, and fatigue. Some children have fever and rash. Young children often do not complain of pain, so parents may notice behavior changes first.

What is juvenile idiopathic arthritis?

Juvenile idiopathic arthritis (JIA) is the most common type of arthritis in children. It starts before age 16 and lasts at least 6 weeks, with no other cause found. It is an autoimmune condition that inflames the joint lining and sometimes the eyes.

Can children outgrow juvenile arthritis?

Some do. Many children, particularly with oligoarticular JIA, go into remission and may stop treatment. Others continue to have active disease into adulthood. Early treatment improves the chance of long-term remission and reduces joint damage.

Why do children with JIA need eye exams?

JIA can cause uveitis, an inflammation inside the eye that often has no symptoms but can lead to cataracts, glaucoma and vision loss. Regular eye exams with a slit lamp detect it early, allowing treatment before damage occurs.

Is juvenile arthritis the same as adult rheumatoid arthritis?

Not exactly. Only one subtype, RF-positive polyarticular JIA, closely resembles adult rheumatoid arthritis. Other JIA types behave differently, can affect growth, and carry a higher risk of eye inflammation. JIA is treated by pediatric rheumatologists.