Which of the following is a common contributing factor to dynamic knee valgus?

• A. Weak knee flexors
• B. Excessive tibial external rotation
• C. Strong plantarflexors
• D. Weak hip abductors and external rotators

Answer: (D)

Dynamic knee valgus happens when there isn’t enough control at the hip during weight-bearing moves. If the hip abductors (gluteus medius/minimus) and external rotators are weak, the pelvis drops and the femur tends to adduct and rotate internally. That upstream movement pulls the knee inward, creating valgus alignment and loading the medial knee structures more than normal. Strengthening these hip muscles improves control of the leg’s movement at the hip, which reduces the tendency for the knee to collapse inward.

Other factors may influence knee alignment, but they don’t address this proximal control as effectively. Weak knee flexors aren’t the primary stabilizers for frontal-plane knee control, and while tibial rotation can affect knee position, the most consistent and trainable contributor to dynamic knee valgus is the strength of the hip abductors and external rotators.