etal foot is
very easily moulded into abnormal attitudes by external pressure such
as might be exercised by the wall of the uterus when the liquor amnii
is deficient. In a number of cases there are indications of such
pressure over the bony prominences of the foot, in the shape of
circumscribed scar-like areas in which the skin is atrophied; and in
the infant, the intra-uterine position can be reproduced, thus
demonstrating its method of origin. The occurrence of club-foot in
several generations is alleged to support the Mendelian law.

[Illustration: FIG. 142.--Bilateral Congenital Club-foot in an
infant.]

_Pathological Anatomy._--In well-marked cases the foot presents a
concavity towards the medial side, the maximum point of the curve
being opposite the mid-tarsal joint. When the patient attempts to
stand, only the lateral border of the foot touches the ground, and the
weight is borne on the fifth metatarsal, the cuboid, and the greater
process of the calcaneus.

[Illustration: FIG. 143.--Radiogram of Bilateral Congenital Club-foot
in an infant.]

The individual tarsal bones, especially the talus and calcaneus, are
altered in shape as well as in their relations to one another and to
the tibio-fibular socket. The navicular and cuboid are rotated
medially around the anterior ends of the talus and calcaneus
respectively, and the tubercle of the navicular comes to lie close to
the medial malleolus. The lower third of the tibia is twisted medially
on its vertical axis.

The changes in the soft parts follow the general law that tissues
which are relaxed become shortened, while those that are put on the
stretch are lengthened. All the tissues on the medial, concave side of
the foot are shortened, the structures most affected being the medial
and the posterior ligaments of the ankle, and the inferior
calcaneo-navicular ligament. There is also shortening of the muscles
inserted into the tendo Achillis, and to a less extent of the tibiales
anterior and posterior. The extensor tendons on the dorsum are
displaced medially.

_Clinical Features._--_In children who have not walked_, the degree of
deformity varies, sometimes being very slight; in pronounced cases,
the foot is turned medially, and in that position forms a right angle
with the leg; the sole looks backwards and the medial border upwards.
The foot appears shortened because it is curved on itself, the heel is
narrower and more vertical than normal, the medial ma