Abnormally High Arches
An overly-high arch ("hollow foot") can also cause problems. Army studies have found that recruits with the highest arches have the most lower-limb injuries and that flat-footed recruits have the least. Contrary to the general impression, the hollow foot is much more common than the flat foot.
Clawfoot, or pes cavus, is a deformity of the foot marked by very high arches and very long toes. Clawfoot is a hereditary condition, but can also occur when muscles in the foot contract or become unbalanced due to nerve or muscle disorders.