Synopsis
Differentiate self-limiting transient synovitis from destructive paediatric hip infection without using a prediction score or ultrasound effusion to provide false reassurance.
- Transient synovitis usually affects a well child aged about three to eight after viral illness, with mild restriction and ability to bear some weight.
- Septic arthritis is more likely with fever, toxic appearance, complete non-weight-bearing, severe passive-movement pain and raised CRP, but none is an absolute rule.
- Kocher or Caird criteria support probability and escalation; they must never be used as a discharge rule or substitute for repeated clinical judgement.
Key red flags
Fever, tachycardia, toxic appearance or reduced perfusion with an irritable hip indicates sepsis risk and needs emergency escalation.
Investigation priorities
Estimate inflammatory burden, detect bacteraemia and screen for cytopenia or malignant alternatives.
Find SUFE, Perthes, fracture, destructive bone change and late joint-space abnormality.
Management branches
The child is febrile, unwell, unable to bear weight or has severe passive hip pain or raised inflammation.
- Assess ABCDE and sepsis risk, obtain IV access, blood cultures and urgent paediatric, orthopaedic and microbiology input.
- Keep fasting and non-weight-bearing and obtain radiographs and ultrasound without delaying treatment.
Key medicines
Empirical intravenous flucloxacillin for presumed MSSAFor a child older than one month, a commonly used severe bone-and-joint infection regimen is 50 mg/kg intravenously every six hours, up to 2 g per dose, verified against current BNFC and local microbiology policy.
Ibuprofen for low-risk transient synovitisChoose the current BNFC oral dose band from the child's age and weight, prescribe briefly, and record formulation strength, volume and interval.