A 12-year-old girl is evaluated for bilateral knock knees. The quadriceps angle is measured as the angle between two lines drawn from the anterior superior iliac spine to the centre of the patella, and from the centre of the patella to the tibial tuberosity. In this extended-knee position, what does an abnormally increased Q-angle indicate?
- A Genu varum with lateral patellar tracking risk
- B Excessive femoral retroversion
- C Genu valgum with predisposition to lateral patellar dislocation ✓
- D Isolated tibial torsion without coronal deformity
Correct answer: C. Genu valgum with predisposition to lateral patellar dislocation
Explanation
The Q-angle normally measures up to about 15 degrees in females and somewhat less in males. A larger value indicates genu valgum, because the line of pull of quadriceps diverges further laterally relative to the patellar tendon axis, pulling the patella laterally and predisposing to recurrent lateral patellar dislocation. Genu varum would reduce rather than increase the angle.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.