Pelvic lateral drop occurs when which of the following happens?

Pelvic lateral drop occurs when which of the following happens?

• A. Lumbar spine instability can cause pelvis drop
• B. Stance-side hip abductors fail to stabilize pelvis
• C. Contralateral knee pain causing pelvis drop
• D. Ankle plantarflexor tightness causes pelvis drop

Answer: (B)

Pelvic lateral drop comes from a failure to stabilize the pelvis in the frontal plane during single-leg stance. The hip abductors on the stance leg (gluteus medius and minimus) actively hold the pelvis level as the body weight shifts onto that leg. When these muscles are weak or not functioning, the pelvis cannot stay level and tilts downward toward the opposite side (the swinging leg). This weakness of the stance-side hip abductors is the mechanism behind the pelvic drop pattern, often seen as a Trendelenburg gait. Other factors listed don’t directly cause this lateral pelvic drop. Lumbar instability can affect posture but doesn’t specifically disrupt frontal-plane pelvic stabilization; contralateral knee pain or ankle plantarflexor tightness don't produce the same gaze-stable pelvic level during single-leg stance.

Pelvic lateral drop comes from a failure to stabilize the pelvis in the frontal plane during single-leg stance. The hip abductors on the stance leg (gluteus medius and minimus) actively hold the pelvis level as the body weight shifts onto that leg. When these muscles are weak or not functioning, the pelvis cannot stay level and tilts downward toward the opposite side (the swinging leg). This weakness of the stance-side hip abductors is the mechanism behind the pelvic drop pattern, often seen as a Trendelenburg gait.

Other factors listed don’t directly cause this lateral pelvic drop. Lumbar instability can affect posture but doesn’t specifically disrupt frontal-plane pelvic stabilization; contralateral knee pain or ankle plantarflexor tightness don't produce the same gaze-stable pelvic level during single-leg stance.