Final answer:
A knee brace with a medial metal insert is best at preventing the force of Valgus. Valgus force is a lateral force that pushes the knee joint towards the midline of the body. The medial metal insert in the knee brace helps to resist this force and prevent the knee from collapsing inward.
Step-by-step explanation:
A knee brace with a medial metal insert is specifically designed to prevent valgus force. A valgus force is a pressure applied to the knee that pushes it laterally, away from the body's midline, which can be detrimental to the knee's structure. The medial metal insert in the brace reinforces the inner part of the knee, resisting this lateral pressure and offering protection against potential damage caused by valgus forces.