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JUVENILE IDIOPATHIC ARTHRITIS (DDX of childhood arthritis (ORTHOPAEDIC (•…
JUVENILE IDIOPATHIC ARTHRITIS
common chronic childhood disorder (UK prevalence 1/1000; incidence: 1/10 000).
It is a diagnosis of exclusion in children <16yrs old with a history of at least 6wks of persistent arthritis.
7 subsets for research purposes.1 These are not diagnostic categories, but are useful clinical groups. As a child’s symptoms evolve with time (e.g. the appearance of a psoriatic rash), they may change subtype.
• Systemic arthritis:
• Oligoarthritis (persistent or extended):
• Polyarthritis (rheumatoid factor +ve):
• Polyarthritis (rheumatoid factor −ve):
• Psoriatic arthritis:
Enthesitis-related arthritis:
• Undifferentiated arthritis:
DDX of childhood arthritis
ORTHOPAEDIC
• hip dysplasia
• infantile coxa vara
• slipped upper femoral epiphysis
• chondromalacia patellae
• Perthes and other osteochondritides
• irritable hip
MALIGNANCY
neuroblastoma
p bone tumours - benign or malignant
metastatic disease
leukaemia
POST INFECTION
post-streptococcal reactive arthritis
rheumatic fever
reactive arthritis
HYPERMOBILITY
marfans, ehlers-danlos
IBD
benign hypermobility - local or generalised
INFECTION
VIRAL - rubella; parvovirus B19; infectious mononucleosis
Lyme, Brucella, TB
BACTERIAL - septic arthritis; osteomyelitis
CONNECTIVE TISSUE DISEASE
juvenile dermatomyositis
systemic sclerosis—limited or progressive
SLE
METABOLIC DISORDERS
gout
mucopolysaccharidoses
HAEMATOLOGICAL
other haemoglobinopathies
haemophilia
SCD
VASCULITIS
polyarteritis/microscopic polyangitis
Kawasaki disease
HSP
Takayasu arteritis
IMMUNODEFICIENCY SYNDROMES
OTHER INFLAMMATORY DISORDERS
chronic recurrent multifocal osteomyelitis
SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis).
sarcoid
IDIOPATHIC PAIN SYNDROMES
• chronic regional pain syndromes;
• fibromyalgia
• ‘non-organic pain’—a cry for help
HX
• Limp, stiffness and loss of function, pain, or malaise.
• Onset usually gradual. Beware of misleading history of trauma as young children frequently fall without significant injury.
• History of non-use, or change in use.
• Child may not complain of pain. Infant may be ‘irritable’.
• Inflammatory symptoms: worse after rest or inactivity.
• Stiffness is rarely volunteered. Parents sometimes describe child as ‘like a little old person in the mornings’. Toddler’s behaviour may be perceived as being difficult and uncooperative (e.g. refusing to move in the morning, then running in the afternoon).
• History of associated rash, fever, weight loss.
• History of sore throat, URTI, antecedent infections, and travel.
• Family history of arthritis, psoriasis, colitis, rheumatic fever, or acute iritis.
EXAMINATION
• Observe the child before they become self-conscious.
• Watch them playing and walking.
• Examine all the joints and spine for swelling, warmth, pain on movement, or limited movement.
• Measure for leg length inequality and pelvic tilt.
• Examine muscle bulk around affected joints.
• Assess general muscle strength.
• Examine the skin, hair and nails for rashes, psoriasis.
• General examination: vital signs, height, weight, and BP.
• Examine mouth and palate for ulcers, dentition; fauces for asymptomatic tonsillitis; heart for murmurs; abdomen for hepatosplenomegaly.
IX
• FBC may show mild anaemia and thrombocytosis.
• Neutrophilia suggests sepsis or systemic JIA.
• Severe anaemia or thrombocytopenia: consider leukaemia.
• ESR/CRP usually normal or mildly elevated. Very high levels suggest infection or malignancy. High ESR plus thrombocytopenia suggests leukaemia.
• Infection screen: throat swab, urinalysis, blood for ASOT, viral serology (CMV, EBV, parvovirus B19, hepatitis) and culture.
• Rheumatoid factor: non-specific test, but significant in polyarthritis (>5 joints). Exclusion criterion for oligoarticular JIA.
• ANA: non-specific (5% children ANA +ve). In oligoarticular JIA limited prognostic determinant for iritis.
• Muscle enzymes (CK, LDH, aldolase) raised in dermatomyositis, but can be normal. Very high LDH suggests malignancy.
• Imaging:.
• radiographs—exclude fracture or tumour; early JIA—soft tissue swelling, and juxta-articular osteopenia; later—joint space narrowing and erosions;
• US—helpful for confirming synovitis and joint effusion;
• MRI—useful for atypical monoarthritis; gadolinium-enhanced MRI is gold standard for diagnosis of synovitis, but does not differentiate from sepsis.
• Synovial fluid aspirate: culture for sepsis. Microscopy rarely helpful.
MANAGEMENT
GENERAL
• Establish diagnosis and counsel child and parents.
• Start treatment as soon as possible.
• Most children will need regular hospital review to look for presence or reappearance of thickened synovium or effusions.
• Exercise: regular, daily aerobic and ‘range of motion’ exercises.
• Psychological support for children and carers: education and support groups (e.g. Arthritis Research Campaign).
• Ask about school performance and support at school.
• Adolescents may need counselling about contraception and alcohol if taking MTX.
• Amyloidosis: rare complication of severe disease.
JOINTS
• Minimize pain and stiffness using
NSAIDs
:
• ibuprofen (30–40mg/kg);
• diclofenac (1.5–2.5mg/kg bd);
• naproxen (5–15mg/kg bd);
• piroxicam (5–20mg daily according to weight).
• Prevent deformity: regular daily exercises; night splints; intra-articular steroid injections (triamcinolone) may settle inflammation for years.
• Control disease activity: MTX oral or SC in resistant cases.
Etanercept
: anti- tumour necrosis factor (TNF) if unresponsive to NSAIDs and SC MTX.
EYE SCREEN FOR UVEITIS
Must have regular screening, initially 3-monthly, by experienced ophthalmologist.
Treat with topical steroids and midriatics.
Course is independent of joint disease severity. Potentially blinding.
GROWTH
Measure growth velocity; nutritional status; muscular atrophy.
DENTITION
Watch for caries