paediatric
Blount's Disease (Tibia Vara)
advanced
6 min
28 marks
6 questions
Clinical Scenario
A 3-year-old obese girl is referred for assessment of progressive bowing of both legs. Her parents noticed the bowing when she started walking at 12 months, and it has become worse. She has no pain and walks normally. On examination, she has bilateral varus deformity of the knees. There is no ligamentous laxity. Internal tibial torsion is present. She is above the 95th percentile for weight.
AP standing radiograph of the lower limbs in a 3-year-old child demonstrating bilateral Blount's disease. There is varus angulation of the proximal tibia bilaterally with characteristic medial physeal beaking. The metaphyseal-diaphyseal angle (MDA) is approximately 16 degrees on both sides (>11 degrees is abnormal). Langenskiöld Stage II changes are present with medial tibial metaphyseal beaking and early fragmentation. Internal tibial torsion is noted clinically.
Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License
Questions
Question 1 (4 marks)
Describe the clinical presentation and differentiate from physiologic bowing.
Question 2 (5 marks)
Explain the radiographic evaluation including the Langenskiöld classification.
Question 3 (6 marks)
What is the pathophysiology and natural history?
Question 4 (5 marks)
Describe the treatment algorithm and surgical options.
Question 5 (4 marks)
How does adolescent Blount's differ from infantile?
Question 6 (4 marks)
What are the complications and recurrence risk?
Exam Day Cheat Sheet
Must Mention
- •MDA: <11° physio, >16° Blount's
- •Langenskiöld I-VI staging
- •Hueter-Volkmann law (pressure inhibits growth)
- •Infantile vs Adolescent differences
- •Osteotomy for Stage III+
- •Overcorrection to prevent recurrence
Common Pitfalls
- •Wrong MDA thresholds
- •Missing Langenskiöld
- •Confusing with physiologic
- •No compartment syndrome awareness
- •Missing adolescent features
- •Inadequate correction