Define Transient Synovitis of the Hip. Describe its clinical features, management and diagnosis.

Definition

Transient synovitis (irritable hip) is a common, benign, self-limiting inflammation of the hip synovium in young children, often following a recent viral upper respiratory infection. It is the commonest cause of acute hip pain and limp in children aged 3–8 years. Its importance lies chiefly in distinguishing it from septic arthritis.

Clinical Features

A child with acute limp and hip/thigh/knee pain, mild restriction of movement, but who is systemically well, afebrile (or only mildly febrile) and can usually bear weight — in clear contrast to the toxic, febrile child of septic arthritis. Inflammatory markers are normal or only mildly raised.

Management

Once septic arthritis is excluded, transient synovitis is treated with rest, analgesia/NSAIDs and observation; it settles within 1–2 weeks. Follow-up ensures resolution and that a Perthes disease (which can present similarly) is not evolving.

Diagnosis of Exclusion

Transient synovitis is fundamentally a diagnosis of exclusion: the same presentation — a limping, hip-painful child — can be produced by conditions that are far more serious, above all septic arthritis and osteomyelitis, and also early Perthes disease. Ultrasound typically shows a small effusion; blood tests are reassuringly normal. Because the consequences of missing a septic hip are severe, clinicians keep a low threshold for aspiration and for review if symptoms fail to settle in the expected week or two.

Kocher criteria distinguish it from septic arthritis — the critical decision.

• Benign self-limiting hip synovitis, often post-viral; children 3–8 y; commonest cause of childhood limp.
• Systemically well, afebrile, usually weight-bearing — unlike septic arthritis.
• Exclude septic arthritis (Kocher criteria ± aspiration).
• Rest, NSAIDs, observation; resolves in 1–2 weeks; follow up to exclude Perthes.