What is the definition or description of: fallen arches?

Fallen Arch: A fallen arch is commonly known as a flatfoot. The foot loses the arch on the inner side of foot. This is also known as pes planus and there can be either a flexible version and a rigid version. A flexible version is flat only when weight is applied on the foot; a rigid version is flat when the foot is off and when the foot is on the ground with pressure.

An arch: That has fallen is usually referring to a flatfoot.

Foot pronation: When people have 'fallen arches' it usually implies that the sub talar joint of the foot (the joint below the ankle) is actually pronating, or rolling in, more than it should, ideally. This may or may not lead to symptoms of pain in the ankle, heel, arch or the forefoot. If it is causing pain in any of these areas, then it should be evaluated by a podiatric physician.