Pes Cavus is a foot shape where your arches are quite high. It tends to be associated with having some claw or hammer toes as well. Pes Cavus is less common than having flat feet. Because high arched feet have less contact with the ground, it means that more impact from walking is being taken through the heel and forefoot. The Pes Cavus foot is referred to as a supinated foot as opposed to a pronated foot. Pronation is the part of the gait cycle where your foot moves from heel strike to the big toe making contact with the ground. This rolling type motion on the inner side of the foot which is referred to as pronation, absorbs some of the impact of walking. It can be compared to absorbing force from a fall by rolling on the ground rather than just hitting the ground. Because the pes cavus foor does not pronate as well it absorbs less of the impact of walking and therefore predisposes to knee, ankle and hip injuries. The pes cavus foot is also less flexible than the neutral foot which is another reason why it can lead to injuries. These injuries can also include ankle sprains.
Since the pronated foot is the most common foot type most trainers are designed for the pronated foot shape. It is possible to get orthotics for pes cavus feet but I think that my recent orthotics actually made me sprain my ankle because the supportive arch that was built into the orthotic made my foot tilt over into more supinated position and made me more likely to have an eversion ankle sprain.