Definition
Joint effusion / pain / swelling in two or more joints
- > 6 weeks
- patient > 16 years
Variations
- number of joints affected: oligoarticular (<5) v polyarticular (5 or more)
- rheumatoid factor positive or negative
- systematic symptoms (rash / fever / lympadenopathy / organomegaly)
Epidemiology
1:10,000
Familial clusters
HLA-gene associations
The International League of Associations for Rheumatology (ILAR) classification
7 subtypes with different clinical, treatment and prognosis implications
Oligoarticular
- < 4 joints at onset
- usually large joints like the knee
- up to 50% of all cases
- present age 2 - 4
- more common females
- best prognosis
- risk LLD and uveitis
RF negative polyarticular
- 5 or more joints at onset
- negative RF and CCP antibodies
- affects small and large joints / symmetrical
- up to 30% of cases
RF positive polyarticular
- 5 or more joints at onset
- positive RF and CCP antibodies
- affects small and large joints / symmetrical
- <10% of cases
- aggressive and erosive disease
Systematic onset JIA
- > 1 joint + 2 weeks fever / rash / lymphadenopathy / organomegaly
- up to 20% of cases
- growth failure / osteoporosis
+ juvenile psoriatic arthritis / Enthesitis-related arthritis / Undifferentiated arthritis
Differential diagnosis
SLE
Vasculitis
Lyme disease
Septic arthritis / osteomyelitis
Acute rheumatic fever
Investigations
ESR / CRP
RF antibodies
CCP antibodies
ANA
Clinical issues
Anterior uveitis and blindness
- up to 20%
- more common ANA +
- can be asymptomatic
- regular opthamology review
Joint pain and articular cartilage destruction
Growth failure - systemic inflammation
Leg length discrepancy - oligo-articular affects knees
Prognosis
Up to 50% of patients have persistent symptoms
- polyarticular
- RF positive
- systemic disease
Nonoperative management
Medications
NSAIDs
Intra-articular cortisone
DMARDS
Methotrexate (antimetabolite) - first line treatment
Leflunomide (antimetabolite) - second line treatment
Sulphasalazine - second line treatment
Biological DMARDS
TNF-α inhibitors
IL-1 inhibitors
IL-6 inhibitors
Other IL inhibitors - 17 / 12 / 23
CTLA-4 analogues
Systemic steroids
Occasionally used with profound, refractory systemic disease
Operative management
Synovectomy
Indication
Salvage
Failure of medication / injections
- synovectomy associated with improved function and decreased pain
- recurrence up to 15%
- better results with pauci-articular verus polyarticular
Knee
Dell'Era et al J Pediatr Orthop B 2008
- 31 knee arthroscopic synovectomy in JIA
- recurrence oligoarthritis 67%
- recurrence polyarthritis 95%
- recurrence psoriatic arthritis 100%
Hip
- 67 open hip synovectomy in JIA
- 85% very good improvement