Legg-Calvé-Perthes Disease

LCPD: Basics & Epidemiology - Kid's Hip Crisis

• Idiopathic avascular necrosis (AVN) of capital femoral epiphysis in children; causes ischemia, collapse, remodeling.
• Peak age: 4-8 years (commonest 5-7 yrs).
• Sex: Boys > Girls (4-5:1).
• Laterality: Unilateral in 80-90%; bilateral (10-20%) usually asynchronous.
• Incidence: ~0.2-19.1 per 100,000 children under 15.
• Risk factors: Delayed bone age, low socioeconomic status, family history (uncommon), secondhand smoke exposure.

⭐ Though often unilateral, if LCPD affects both hips, the onset is typically asynchronous_

LCPD: Etiopathogenesis - Bone Blood Blockade

• Core: Idiopathic Avascular Necrosis (AVN) of capital femoral epiphysis.
• Mechanism: Interrupted blood supply to femoral head.
  • Key vessel: Lateral epiphyseal artery.
  • Peak age: 4-8 years (boys > girls ~5:1).
• Risk Factors (multifactorial):
  • Microtrauma, coagulopathy, secondhand smoke, delayed bone age, family Hx.

⭐ Occlusion of the lateral epiphyseal artery, the child's main femoral head supply, is critical.

LCPD: Clinical Features & Diagnosis - Limp Alert & X-ray Eyes

• Clinical Presentation:

  • Insidious onset: Often painless or mild hip/groin/knee pain; intermittent limp.
  • Limp worsens with activity, relieved by rest.
  • Age: Typically 4-8 years (Boys > Girls, ratio approx. 4:1).
  • Examination findings:
    • Limited internal rotation and abduction of the hip.
    • Trendelenburg gait may be present.
    • Thigh and gluteal muscle atrophy.

• Diagnostic Workup:

  • X-rays (AP and Frog-leg lateral views are crucial):
    • Early: May be normal, or show widened medial joint space (Waldenström sign), smaller ossific nucleus of femoral epiphysis.
    • Later: Crescent sign (subchondral fracture - pathognomonic for AVN), fragmentation, flattening, and sclerosis of the femoral head.
    • Waldenström Classification (radiographic stages): Initial → Fragmentation → Re-ossification → Healed/Remodeling.
  • MRI: More sensitive in early stages; detects avascular necrosis (AVN) before X-ray changes, shows extent of involvement.
  • Bone Scan (Technetium-99m): Shows decreased uptake ("cold spot") in the affected femoral head during avascular phase.

⭐ The "crescent sign" on X-ray, a subchondral radiolucent line, is a key early radiographic indicator of femoral head ischemia and impending collapse in LCPD.

LCPD: Classification, Prognosis & Management - Grade, Guess & Guide

• Classification (Prognostic):

  • Herring (Lateral Pillar): Most used.
    • A: >75% pillar height (Good).
    • B: 50-75% (Guarded).
    • C: <50% (Poor).
  • Catterall (Femoral head involvement): I-IV.
  • Stulberg (Late outcome): I-V (sphericity).

• Prognosis Factors:

  • Age: <6 yrs (better) vs >8 yrs (worse).
  • Lateral pillar height (Herring).
  • "Head-at-risk" signs (e.g., Gage sign, lateral subluxation).
  • Range of motion (persistent stiffness = poor).

• Management Goals: Maintain motion, spherical head, prevent OA.

  • Conservative (Younger, Herring A/B): Observation, NSAIDs, physio, activity mod. Containment (brace/cast) if needed.
  • Surgical (Older >8yrs, Herring C, failed cons.): Femoral osteotomy (varus), Pelvic osteotomy (Salter).
  • 📌 C.A.N.E.: Conservative/Containment, Age, NSAIDs/Physio, Eventual Surgery.

⭐ The Herring classification (lateral pillar assessment) is the most reliable prognostic indicator in LCPD.

High-Yield Points - ⚡ Biggest Takeaways

• Idiopathic avascular necrosis of the femoral head in children.
• Typically affects boys aged 4-8 years; often unilateral.
• Presents with painless limp or insidious hip/knee pain.
• Key radiographic stages: Waldenström's (initial, fragmentation, re-ossification, healed).
• Prognostic classifications: Catterall (femoral head involvement), Herring (lateral pillar height).
• Treatment goal: hip containment (bracing/surgery) to prevent femoral head deformity.
• Older age at onset (>6 years) and extensive head involvement signify poorer prognosis.