[6] This is an old French method used in Fouilloy's appliance, which has, however, only become generally used in the suspending braces of the American appliance.
When the patient raises the leg from the ground, the weight of the appliance makes it slip down the stump, tension is thus produced upon this strap and as a result the knee is extended. By an adroit movement of the shoulder this extension can be carried out actively.
When the limb rests upon the ground the weight of the body presses the stump down into the bucket, the tension on the strap is released and consequently the knee is free to flex.
On [pages 44 to 48] will be found figures showing the principal points in this extending brace.
The braces, whether they have or have not an extending strap, may be constructed in three ways:
a. To ease the constant pressure exerted on the shoulders by the strap which is stretched by the weight of the artificial limb, the brace may be made of elastic like the ordinary trousers brace. But the limb they carry is heavy, so they rapidly become overstretched and it is difficult to keep them properly adjusted.
b. The stretching is naturally diminished if the upper part of the brace is not elastic but an elastic section is inserted in its lower third, in front and behind.
c. But the patients almost always say that better command of the limb is obtained with inelastic braces. If the strap is wide on the shoulder, the pressure is well borne, and the lower attachment may be made narrower, consisting of a leather thong ([Fig. 64]).
Figs. 60 and 61.