Perthes disease (Legg-Calvé-Perthes disease)
Overview
Perthes disease is avascular necrosis of the femoral head's capital epiphysis in childhood that progresses through ischaemia, collapse/fragmentation and re‑ossification. It commonly presents to the ED as an atraumatic limp or intermittent hip/groin/knee pain in a school‑age child.
ED priorities are to recognise the condition, exclude urgent mimics (septic arthritis, osteomyelitis, SUFE), provide analgesia and safe mobility, obtain appropriate imaging, and arrange timely orthopaedic follow‑up.
Epidemiology and natural history
- Typical age: 3-12 years (median ~6 years).
- Sex: more common in boys (≈5:2).
- Laterality: unilateral most commonly; bilateral in 10-20% (often asynchronous).
- Course: disease evolves over months to years (ischaemia → fragmentation/collapse → revascularisation → remodelling).
- Prognosis by age: younger children have greater remodelling potential; older children (>8-10 years) are at higher risk of residual deformity and early osteoarthritis.
Pathophysiology
Loss of blood supply to the femoral head causes bone necrosis and structural weakness. During revascularisation the epiphysis can collapse and fragment; subsequent remodelling may restore shape but persistent flattening or asphericity leads to joint incongruity and risk of early degenerative change.
Clinical presentation
- Symptoms: insidious limp, activity‑related hip/groin pain or referred knee pain (up to one‑third present with knee pain); intermittent symptoms over weeks.