In the frontal plane, the hip ground reaction force is described as which location?

In the frontal plane, the hip ground reaction force is described as which location?

• A. Medial
• B. Lateral
• C. Anterior
• D. Posterior

Answer: (A)

The key idea is how the ground reaction force aligns with the hip joint in the frontal plane and the torque that alignment creates. If the line of action of the hip ground reaction force passes medial to the hip joint center, the resulting moment tends to pull the thigh toward the midline, producing an adduction moment. That’s why it’s described as medial. Lateral would imply the opposite (an abduction tendency). Anterior or posterior describes directions in the sagittal plane, not the frontal plane, so they don’t describe this frontal-plane alignment.

The key idea is how the ground reaction force aligns with the hip joint in the frontal plane and the torque that alignment creates. If the line of action of the hip ground reaction force passes medial to the hip joint center, the resulting moment tends to pull the thigh toward the midline, producing an adduction moment. That’s why it’s described as medial. Lateral would imply the opposite (an abduction tendency). Anterior or posterior describes directions in the sagittal plane, not the frontal plane, so they don’t describe this frontal-plane alignment.