During midstance, the external knee moment is what?

During midstance, the external knee moment is what?

• A. Flexion
• B. Abduction
• C. Extension
• D. Plantarflexion

Answer: (C)

In midstance, the external knee moment is extension. This is because the ground reaction force acting through the foot sits behind the knee joint center, creating a torque that tends to straighten the knee. The knee is held near full extension during this phase, with muscles such as the quadriceps generating an internal flexion moment to control and balance that external extension tendency. Flexion would occur if the force vector passed in front of the knee, abduction relates to a side-to-side (frontal plane) load rather than the sagittal knee motion, and plantarflexion involves the ankle, not the knee.

In midstance, the external knee moment is extension. This is because the ground reaction force acting through the foot sits behind the knee joint center, creating a torque that tends to straighten the knee. The knee is held near full extension during this phase, with muscles such as the quadriceps generating an internal flexion moment to control and balance that external extension tendency.

Flexion would occur if the force vector passed in front of the knee, abduction relates to a side-to-side (frontal plane) load rather than the sagittal knee motion, and plantarflexion involves the ankle, not the knee.