The limb must not be very tightly braced into the shoe, slight tension, if continuous, suffices to overcome the resistance; and in children if the straps are drawn tight the skin almost invariably inflames, and even sloughs where it is compressed. Before the instrument is applied, the limb should be bandaged with a soft cotton, or Domett’s flannel roller. The foot is first fixed to the sole or shoe, and then the leg to the rod. Traction is increased gradually with frequent small alterations, as the foot yields to the tension and regains its natural position. The accompanying figure (No. 69) represents an instrument made by Mr. Heather Bigg. It shows the shoe restoring a much elevated heel to its proper position after division of the tendo achillis.
There are three common varieties of talipes—equinus, or horse-heel, where the heel is drawn up and the toes only touch the ground; varus, club-foot proper, where the foot is twisted inwards; and valgus, splay-foot, in which the foot is drawn outwards. Equinus is often associated with varus, and sometimes also with valgus, and consequently for such cases the instrument must provide the mechanism proper to each direction of displacement.
In Equinus the heel is raised by the extreme extension of the ankle, and the sole of the foot is shortened by the metatarsus being drawn backwards. In this kind of deformity the shoe must have a joint to bring the astragalus forwards on the tibia, and the sole of the shoe must be well padded beneath the scaphoid and metatarsal bones, that, as the foot is released from its position of extreme extension at the ankle-joint, the anterior parts of the foot may be thrust upwards into their proper relation to the astragalus and os calcis.
Fig. 69—Shoe for reducing talipes equinus.
In Varus, or rather Equino-varus, for varus without elevation of the heel is rare, the displacement is compound, the ankle is extended, the heel raised, the scaphoid and metatarsus are drawn inwards and downwards, so that the scaphoid lies immediately beneath, sometimes even in contact with the internal malleolus. The astragalus and cuboid are drawn forwards so as to lie in front of their natural position against the tibia and os calcis. To bring down the heel the upright stem passes outside the limb, the toe of the shoe can be raised by a circular joint on the stem opposite the malleolus, which by its revolution raises the toes and depresses the heel. A second joint working outwards and upwards elevates the outer border of the foot, and restores the scaphoid to the front of the head of the astragalus. Lastly, the metatarsus is drawn outwards by a horizontal spring toe-bar along the outer border of the foot, to which the toes are fastened.
In Valgus, the plantar arch is flattened or even rendered convex downwards by the sinking of the scaphoid, and in extreme cases, by rotation outwards and upwards of the tarsus. The shoe here has the vertical rod inside the limb, and if necessary, an axis for rotation below the inner malleolus, and an elastic arched pad under the scaphoid to lift it into its natural position.
Casting in Plaster of Paris.—It is often convenient, when ordering an apparatus for deformity, to send the instrument-maker a cast of the deformed part. This is readily made in the following way:—
Apparatus.—1. Two packets of freshly burned plaster of Paris.
2. Some pasteboard, an old bandbox, or several newspapers.