Which forces are part of the 3-point pressure system on a UCBL for pes valgus/pronation?

The three-point pressure system is a classic biomechanical concept used in orthotic management to control foot deformities, such as pes valgus or excessive pronation. This system employs three strategically applied forces to achieve balance and correction of the foot's position during stance and ambulation.

In the case of the UCBL (University of California Biomechanics Laboratory) orthosis for managing pes valgus, the structure itself is designed to apply specific forces that counteract the pronation. The correct choice describes a lateral directed force at the arch, a medial directed force at the lateral calcaneus, and a medial directed force at the head of the 5th metatarsal.

The lateral force at the arch helps to stabilize the pronating foot by providing a counteracting force that prevents further inward rolling. The medial directed force at the lateral calcaneus helps to correct the lateral tilt of the heel that is often present in pes valgus, promoting a more neutral foot position. Lastly, applying a medial directed force at the head of the 5th met contributes to a better alignment of the forefoot, resisting adduction and maintaining the correct toe alignment. This combination of forces effectively stabilizes the foot and minimizes the excessive motion associated with