paediatric
Legg-Calvé-Perthes Disease
advanced
6 min
28 marks
6 questions
Clinical Scenario
A 7-year-old boy presents with a 3-month history of progressive left hip pain and limp. The pain is in the groin and anterior thigh, worse with activity. He has no history of trauma or systemic symptoms. On examination, he has an antalgic gait. Left hip examination reveals limited abduction (30°) and internal rotation (10°). He can straight leg raise without pain.
AP pelvis radiograph demonstrating left hip Legg-Calvé-Perthes disease in the fragmentation stage. There is increased radiodensity, flattening, and fragmentation of the femoral epiphysis. The lateral pillar height is reduced to approximately 40% (Herring Group C). Note the 'head at risk' signs: lateral subluxation with break in Shenton's line and horizontal physis. The contralateral hip is normal for comparison.
Source: Combined Shelf Acetabuloplasty with Femoral Varus Osteotomy in Severe Legg-Calve-Perthes Disease • PMC4667119 • CC-BY
Questions
Question 1 (4 marks)
Describe the clinical presentation and natural history of Perthes disease.
Question 2 (5 marks)
Explain the radiographic staging and classification systems.
Question 3 (6 marks)
What are the prognostic factors and 'head at risk' signs?
Question 4 (5 marks)
Describe the treatment principles and options.
Question 5 (4 marks)
What is the containment principle and surgical techniques?
Question 6 (4 marks)
What are the long-term outcomes?
Exam Day Cheat Sheet
Must Mention
- •Herring lateral pillar: A (100%), B (50-100%), C (<50%)
- •Age <6 = good prognosis, >8 = poor prognosis
- •Waldenström stages (4 stages, 2-4 years total)
- •Head at risk signs (Gage, subluxation, horizontal physis)
- •Containment principle (acetabulum molds head)
- •Stulberg classification for long-term outcome
Common Pitfalls
- •Using Catterall (outdated)
- •Operating on young Herring A
- •Not knowing containment
- •Missing head at risk signs
- •Wrong age prognosis
- •Confusing stages/classifications