What is the purpose of the Trendelenburg sign test?

• A. To assess gluteus medius function during single limb stance.
• B. To measure hamstring flexibility.
• C. To evaluate knee joint laxity.
• D. To assess ankle dorsiflexion.

Answer: (A)

The Trendelenburg sign tests hip abductor strength, especially the gluteus medius, during single-leg stance. When you stand on one leg, the stance-side hip abductors must contract to keep the pelvis level. If those muscles are weak or the nerve supply is compromised, they can’t hold the pelvis up, so the pelvis drops on the opposite (unsupported) side. That pelvic drop is a positive sign and indicates insufficient hip abductor function to stabilize the pelvis during gait. The other options don’t fit because hamstring flexibility, knee joint laxity, and ankle dorsiflexion involve different joints and functions and are not assessed by this test.