The deformity herewith described is known as pes cavus or arcuatus, hollow or hollow claw foot. Clinically it is characterized by these cardinal points:
An increase in the height of the longitudinal arch.
A dropping of the anterior arch with plantar flexion of the front of the foot.
A variable amount of dorsal retraction of the toes, the claw foot deformity proper, with hyperextension of the metatarsophalangeal, and flexion of the phalangeal joints.
The retraction of the toes is as inherent a part of the deformity as is the abnormal height of the arch; both features are, in fact, genetically interdependent.
Of the nonparalytic cases, a small number are present at, or develop soon after, birth; but the majority of these cases develop during adolescence, first as talipes arcuatus or hollow foot, and progress under certain conditions, to the claw foot stage. Some of these cases present