Deformities of the Knee
Alignment deformities of the knee are common in childhood (often physiological) but can be pathological in adults due to arthritis or trauma.
1. Genu Valgum (Knock Knees)
- Deformity: Knees touch, ankles are apart.
- Measurement: Intermalleolar Distance (Distance between medial malleoli when knees touch). > 8-10 cm is pathological.
- Causes: Physiological (Age 3-5), Rickets, Renal Osteodystrophy, Cozen's Fracture (Proximal Tibia).
- Gait: Circumduction gait (to clear the knees).
2. Genu Varum (Bow Legs)
- Deformity: Ankles touch, knees are apart.
- Measurement: Intercondylar Distance (Distance between femoral condyles when ankles touch).
- Causes: Physiological (Age 0-2), Rickets, Blount's Disease (Tibia Vara), Osteoarthritis.
3. Genu Recurvatum (Hyperextension)
- Definition: Hyperextension > 10 degrees.
- Causes: Ligament laxity (Ehlers-Danlos), Polio (Quadriceps weakness), CVA.
25 Practice MCQs
Q1. Genu Valgum is also known as:
Answer: A). The knees "knock" together.
Q2. Physiological Genu Varum (Bow legs) is normal up to age:
Answer: A). Infants are born varus, straighten by 2, become valgus by 3-4.
Q3. Intermalleolar distance is used to measure:
Answer: A). Distance between ankles when knees touch.
Q4. Blount's Disease involves:
Answer: A). Pathological Genu Varum.
Q5. Which fracture typically leads to Valgus deformity (Cozen's phenomenon)?
Answer: A). Due to overgrowth of the medial side during healing.
Q6. Rickets typically causes:
Answer: A). Soft bones bend under weight. "Windswept deformity" involves one varus, one valgus.
Q7. Genu Recurvatum is:
Answer: A). Often due to polio or laxity.
Q8. Osteotomy for Genu Varum is usually:
Answer: A). Shifts weight line to lateral compartment.
Q9. Epiphysiodesis (Guided Growth) uses:
Answer: A). "8-Plate" technique. Corrects deformity as child grows.
Q10. Which compartment of the knee is overloaded in Genu Varum?
Answer: A). Predisposes to medial OA.
Q11. Intercondylar distance of > 10 cm indicates:
Answer: A). Distance between knees when ankles touch.
Q12. Genu Valgum predisposes to:
Answer: A). Increases the Q-angle.
Q13. Circumduction gait is associated with:
Answer: A). To avoid hitting the knees.
Q14. Physiological Valgus peaks at age:
Answer: A). Then corrects to adult alignment (5-7 deg valgus) by age 7.
Q15. Mermaid Splint is used for:
Answer: A). Keeps legs together straight.
Q16. Drennan's Angle (Metaphyseal-Diaphyseal Angle) > 16 deg indicates:
Answer: A). Radiographic sign for Tibia Vara.
Q17. Q-Angle is increased in:
Answer: A). Lateral pull on patella increases.
Q18. Quadriceps weakness following polio often leads to:
Answer: A). "Hand-to-knee" gait.
Q19. Normal tibiofemoral angle in adults is:
Answer: A). Slight valgus is physiological.
Q20. Unilateral Genu Valgum suggests:
Answer: A). Bilateral is usually metabolic/physiological.
Q21. Management of physiological Genu Varum in a 1-year-old:
Answer: A). It will correct itself.
Q22. Medial compartment OA is treated with which osteotomy?
Answer: A). Offloads the medial side.
Q23. Anterior knee pain is common in:
Answer: A). Maltracking issues.
Q24. Epiphyseal stapling acts by:
Answer: A). Compression retards growth.
Q25. Beaking of the medial tibial metaphysis is seen in:
Answer: A). Classic radiographic sign.
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