Transient synovitis (irritable hip)
Post-viral self-limiting hip synovitis
Overview
The commonest cause of acute hip pain/limp in young children (3–10y), typically days after a viral URTI. A self-limiting diagnosis of exclusion — the critical task is to exclude SEPTIC ARTHRITIS.
Recognise
- Limp / refusal to weight-bear, hip or knee pain, recent viral illness
- Child is systemically WELL, afebrile or only low-grade
- Reduced hip range of movement but not the rigid, exquisitely painful joint of sepsis
Red flags
- Fever, systemically unwell, unable to weight-bear, raised inflammatory markers → treat as septic arthritis until excluded
Differentials & how to tell them apart
Investigations
Kocher criteria to discriminate from septic arthritis (fever >38.5°C, non-weight-bearing, ESR/CRP raised, WCC raised). USS may show an effusion; aspirate/refer if sepsis suspected.
Management
Rest + analgesia + safety-net; exclude septic arthritis first
- 1If the child is well and Kocher-low-risk: rest, analgesia, safety-net, review in 24–48h.Gate: Fever / unable to weight-bear / raised CRP–WCC (Kocher) → treat as SEPTIC ARTHRITIS: urgent orthopaedics + USS-guided aspiration
- 2Should settle within 1–2 weeks; persistent → re-image (Perthes) or reconsider JIA.
Key points
Transient synovitis is a diagnosis of exclusion — never make it in a febrile, toxic, non-weight-bearing child without excluding septic arthritis.
Monitor & prognosis
Resolution within 1–2 weeks; re-evaluate if persistent.
Excellent; self-limiting.
Source: NICE CKS (acute childhood limp); Kocher criteria