Figs. 107 and 108.—If the leg bucket is hollowed out too much at the back, the stump is tilted obliquely forward (Fig. 108), the knee loses contact with the bucket, and the flesh at the back of the thigh is pinched.
To diminish further the tendency of the stump to tilt forward the posterior edge of the bucket is flattened so that the shape of the top of the bucket is triangular with curved sides and angles much rounded (the anterior angle over the tuberosity of the tibia being obtuse). This is the natural shape of a section of the top of the calf. In this way the posterior muscles are flattened and no longer tend to escape from the bucket when the knee is flexed. In figures 110 and 111 are shown two ways in which this flattened posterior margin may be shaped.
Fig. 109.
Figs. 110 to 111.
B. Suspension Apparatus.—The leg is attached (a) by a thigh corset taking its hold on the femoral condyles, and (b) by braces over the shoulders.
(a) The thigh corset is made of leather laced in front. Two lateral steels curving in sharply against the upper part of the condyles (Fig. 112) form the most effective part of the support. At their lower ends they are articulated with two steels passing up from the top of the leg to which they are attached. The joint (Fig. 113) is composed of a nut, A, into which fits a screw. Around the nut is a copper ring made to move with the femoral steel by means of a stop-notch. When the knee flexes and extends the wear comes upon this copper ring. The steels remain intact. If the joint works loose it is sufficient to renew the ring.
