The peg—attached above by a stirrup or by a mortise, it does not matter which—ends below in a rectangular tenon which fits into a corresponding excavation in the upper surface of the terminal piece, whether peg or foot (Figs. 38 and 44). A transverse bolt, square in section, with a head at one end and a thread at the other, fixes these two parts together. By taking out this bolt the peg can be replaced by the foot or vice versâ.
If the attachment of the foot is made in the heel, a fixed foot is used (Figs. 43 and 45), but it is easy, by making the attachment higher, to use a foot with movable ankle joint (Fig. 40).
The attachment of the show calf piece around the peg is shown in figures 43 and 45.
Most often the wooden thigh piece is to be preferred; the limb is lighter and may last four or five years instead of about two years.
We may add that leather loses its shape and the bucket becomes enlarged, producing inconveniences already described on [page 18].
But leather—indespensable for certain stumps which cannot stand a wooden bucket—has the advantage that it can be employed as a temporary fitting. During the first weeks, sometimes even for the first months, the shrinking of the stump can be accommodated by lacing up the bucket, and, when shrinkage is complete, the leg part of this first apparatus can be attached to a wooden bucket which the improved condition of the stump now renders possible.
This form is a little more expensive (80 frs.) than "the poor man's leg," but I believe a great deal more comfortable. It may be added, that it is easy when the foot is fitted at the end of the apparatus to render flexion of the knee free and to attain the "American walk," of which we shall speak later. All that is necessary is to attach in front an artificial muscle of indiarubber, reaching from the thigh to the leg and an extending sling like that in the American limbs (see [page 47]).
This appliance which we call the "Fédération Leg," because we designed it at the Fédération des Mutilés, has already been imitated without its origin being acknowledged.
IV. Walking with free flexion of the knee
A. Design.—The oldest type, which will suffice for studying the general conditions of stability, is that of Marks, with a fixed foot shaped out of the same piece of wood as the leg: the ankle joint—several types of which we shall describe later—does not affect the question of stability.