Coxa Vara
Coxa Vara is a deformity of the hip where the angle between the neck and shaft of the femur is decreased (less than 120 degrees). This alters the biomechanics of the hip abductors, leading to a limp.
1. The Neck-Shaft Angle
- Normal: 120° - 135°.
- Coxa Vara: < 120° (Decreased).
- Coxa Valga: > 135° (Increased).
2. Etiology
- Congenital: Developmental Defect (Fairbank's triangle).
- Acquired: Rickets (Soft bone bends), Slipped Capital Femoral Epiphysis (SCFE), Perthes Disease, Malunion of fracture.
3. Clinical Features
- Limp: Painless Trendelenburg lurch (abductor weakness).
- Shortening: True shortening of the limb (trochanter moves up).
- ROM: Abduction and Internal Rotation are limited.
4. Management
- Observation: If angle > 110° and asymptomatic.
- Surgery: Valgus Osteotomy (Pauwels or Y-osteotomy) to restore the angle and mechanics.
25 Practice MCQs
Q1. Coxa Vara is defined as a neck-shaft angle:
Answer: A). Normal is 120-135.
Q2. The primary biomechanical effect of Coxa Vara is:
Answer: A). Greater Trochanter moves up, slackening the abductors -> Trendelenburg gait.
Q3. A positive Trendelenburg test indicates:
Answer: A). Weak abductors on the stance side cannot hold the pelvis level.
Q4. Developmental Coxa Vara typically presents:
Answer: A). Weight bearing reveals the defect.
Q5. The "Fairbank's Triangle" is seen in:
Answer: A). Inverted Y ossification defect.
Q6. Hilgenreiner's Epiphyseal Angle (HEA) > 60 degrees suggests:
Answer: A). Vertical physis experiences shear stress.
Q7. Which range of motion is characteristically limited?
Answer: A). The greater trochanter impinges on the ilium.
Q8. Surgical treatment involves:
Answer: A). Increases the angle to restore mechanics.
Q9. Bilateral Coxa Vara causes:
Answer: A). Duck-like waddle.
Q10. Limb shortening in Coxa Vara is:
Answer: A). The neck becomes horizontal, lowering the head relative to the trochanter.
Q11. Rickets causes Coxa Vara because:
Answer: A). Weight bearing bends the femoral neck.
Q12. Shepherd's Crook Deformity (severe varus) is typical of:
Answer: A). Characteristic shape.
Q13. Acquired Coxa Vara can result from Malunion of:
Answer: A). Collapses into varus if medial support is lost.
Q14. Cleidocranial Dysostosis is associated with:
Answer: A). Congenital syndrome association.
Q15. Pauwels' Y-shaped osteotomy is designed to:
Answer: A). Promotes ossification and stability.
Q16. Does Coxa Vara cause pain?
Answer: A). Mechanical disadvantage tires the muscles.
Q17. Retroversion of the femoral neck is often:
Answer: A). Further limiting internal rotation.
Q18. If HEA angle is < 45 degrees, treatment is:
Answer: A). Benign course.
Q19. Greater Trochanteric Overgrowth occurs because:
Answer: A). Contributes to impingement and weak abduction.
Q20. What happens to the Acetabulum in long-standing Coxa Vara?
Answer: A). Secondary dysplasia.
Q21. Perthes Disease heals with Coxa Vara/Magna because:
Answer: A). Sequelae of avascular necrosis.
Q22. Shoe lift is used for:
Answer: A). For mild cases or if surgery is contraindicated.
Q23. Premature closure of the capital femoral physis causes:
Answer: A). Asymmetric growth arrest (e.g., post-infection).
Q24. Valgus osteotomy aims to achieve a neck-shaft angle of:
Answer: A). To compensate for recurrence and maximize mechanics.
Q25. Unilateral Coxa Vara results in:
Answer: A). Unlike bilateral which waddles.
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