Related Subjects:
|Developmental Dislocation (Dysplasia) of the Hip (DDH)
|Slipped Upper Femoral Epiphysis (SUFE)
|Perthes disease (Osteochondritis of the Hip)
|Avascular Necrosis of Femoral head
Perthes Disease 🦴👦 = idiopathic avascular necrosis (osteonecrosis) of the femoral head epiphysis in children.
It leads to flattening, fragmentation, and eventual remodelling of the femoral head.
Typically affects boys aged 5–7 (range 3–12), 4:1 male predominance, bilateral in ~10%.
📖 About
- Idiopathic avascular necrosis of the proximal femoral epiphysis.
- Vascular supply interruption → bone death → revascularisation cycles.
- Process: necrosis → fragmentation → reossification → remodelling.
⚙️ Aetiology
- Exact cause unknown.
- Proposed mechanism: repeated vascular occlusion of epiphysis with 2–4 week cycles of necrosis/revascularisation.
- 1 in 10,000 prevalence, mostly boys.
🩺 Clinical Features
- Painless limp or hip/knee pain (often referred to knee, misleading ❗).
- ↓ and painful hip abduction & internal rotation (internal rotation affected most).
- No systemic features, knee exam normal.
🔎 Investigations
- Bloods: FBC, ESR, U&E → usually normal (excludes infection/inflammation).
- X-ray:
- Early: effusion, widened medial joint space, small epiphysis.
- Later: sclerosis, collapse, flattening (coxa plana), widened neck (coxa magna).
- Signs: “Sagging rope sign” = thin sclerotic line across femoral neck.
- USS: hip effusion.
- MRI/CT: more sensitive, esp. early disease.
📊 Catterall Classification
- Stage I: small anterior epiphyseal changes, no sclerosis.
- Stage II: bone resorption + sclerosis, partial collapse.
- Stage III: most of femoral head collapsed, “head within head” appearance.
- Stage IV: complete collapse, flat head, sclerosis, metaphyseal changes.
🔎 Differentials
- Transient synovitis
- Septic arthritis (always rule out 🚨)
- Juvenile idiopathic arthritis
- Other osteonecrosis causes: trauma, leukaemia/lymphoma, SLE, haemoglobinopathies, coagulopathies, steroids
💊 Management
- Goals: Contain femoral head in acetabulum → reduce deformity + maintain motion.
- General: activity restriction, analgesia, physiotherapy, range-of-motion exercises.
- Age <6 years: usually conservative, good prognosis 👍.
- Age 6–8: brace (abduction orthosis) ± containment surgery.
- Age >8 years: higher risk of poor outcome → femoral/pelvic osteotomy often needed.
- Prognosis: Outcome depends on % head involvement (>50% involvement = worse outcome). Age >6 years = poorer prognosis.
📌 OSCE / Exam Pearls
- Classic: 6-year-old boy with limp, painful restricted internal rotation, normal bloods.
- Referred knee pain in children with hip pathology is a common trap.
- Best prognosis = <6 years, minimal head involvement.
- Rule out septic arthritis first (well child vs toxic child).
📚 References
- Rockwood & Wilkins’ Fractures in Children, 9th ed.
- Catterall A. The natural history of Perthes’ disease. J Bone Joint Surg Br. 1971.
- NICE CKS: Hip pain in children. 2022.
