Artificial limbs

The angular relation of a Sach foot to a shin may be adjusted during assembly to provide a desired heel height so that one type of Sach foot may be stocked for each shoe size and adapted for different heights of heel. The connecting bolt passes through a rotatable trunnion transverse to the length of the foot and is pivotable between fore and aft limits, and material is removed from the confronting surfaces of the foot and shin during fitting or packing material is inserted between them to effect such angular displacement.

FIELD OF THE INVENTION 
This invention is concerned with artificial legs and particularly with the 
attachment of artificial feet to an artificial leg. 
BACKGROUND OF THE INVENTION 
The solid ankle cushion heel (Sach) foot has, for many years, been well 
known in the art as a simple light weight terminal device, easily fitted 
to the limb and stocked in standard shoe sizes. These feet are attached to 
the limb by a bolt passing through the foot and threaded into a nut in the 
limb or an internally threaded part of the limb. 
The Sach foot plays an important role in limb prescription, particularly 
for below knee amputation. Its main disadvantage is that it comes in 
standard shoe sizes but is not easily adjustable for particular heel 
heights. With the advent of fashion shoes, not only for ladies but for men 
also, in all the shoe sizes, the problem of stocking in terms of heel 
heights for each size would be enormous and economically would limit the 
prescription of the foot. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide means for attaching a foot to a 
limb which allows the ready adaptation of a standard foot, or of the limb 
to which it is attached, to different heel heights. 
From one aspect, the invention provides a foot in which the bolt by which 
it is attached to the limb passes through a trunnion transverse to the 
length of the foot, whereby the angular relation of the foot to a limb may 
be varied at the time of assembly of the foot and limb to vary the height 
of the heel in use while maintaining the axis of the bolt substantially 
parallel to the length of the limb. Such variation of heel height may be 
effected by removing material from the upper surface of the solid ankle 
foot or the lower surface of the limb, which surfaces as taken from stock 
are normally perpendicular to the bolt, or by inserting wedge shaped 
packing between the two surfaces. 
From another aspect the invention provides an artificial leg comprising a 
shin portion, a foot portion having a trunnion mounted transversely 
therein for rotation about an axis transverse to the direction of 
elongation of the foot portion, and a bolt passing through said trunnion 
and engaging a threaded member in said shin portion, whereby during 
assembly the angular relation of the foot and shin portions may be varied 
relative to one another to adapt a standard foot for use with shoes having 
a desired height of heel while the bolt and the shin portion in use are 
vertical. 
The foot is preferably a Sach type foot. The shin portion may be a solid 
wooden or rigid plastic shin with an inserted nut into which the bolt is 
threaded, or may be a M.A.P. (Modular Assembly Prosthesis) limb with a 
Sach foot attachment casting.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1, an artificial limb comprises a Sach foot 1 
connected to a shaped shin 2 by means of a bolt 3. The foot 1 is of a 
standard shape for the shoe size of the intended user and comprises a keel 
4 of hard wood encased except for its top surface 5 in foamed polyurethane 
6. A hole 7 passes through the foot 1 with its axis at right angles to the 
top surface 5 when taken from stock. 
The shaped shin 2 which may also be of standard shape has a hole 9 
extending upwardly at right angles to its undersurface which, when taken 
from stock, is represented in FIG. 1 by the line 10. Hitherto the foot and 
the shin have been assembled by placing the surfaces 5 and 10 together and 
inserting a bolt through the holes 7, 9 and threading it into a nut 11 
mounted in the shin 2. The heel height of a shoe that can be worn by the 
user is thus predetermined since it is necessary for the limb and therefor 
the bolt to be substantially upright when the user is standing. 
In order that, during fitting, the limb may be made to meet the user's 
wishes as to the heel height of the shoes he wears, a rotatable 
cylindrical trunnion 12 is provided in the keel 4 of the foot with its 
axis of rotation perpendicular to the axis of the hole 7 and the bolt 3 
passes through this trunnion. The upper portion of hole 7 has a dimension 
substantially equal to the diameter of bolt 3 in a direction parallel to 
the axis of rotation of trunnion 12 as shown in FIG. 2, but is elongated 
in the fore-and-aft direction as shown in FIG. 1 so that the bolt 3 may 
pivot with the trunnion 12 between limits determined by the edges of the 
hole 7. The head 13 of the bolt 3 is entirely within the trunnion 12 to 
avoid interference with the keel when the bolt pivots. 
With this arrangement, the foot 1 may be angled in relation to the shin 2 
to vary the heel height at the time of assembly of the foot and shin. 
Either the undersurface of the shin or the top surface of the foot may be 
adjusted at the time of assembly to permit this. In FIG. 1, the portion 
indicated by A-X-B has been removed from the lower end of the shin, 
enabling the foot to be angled upwardly and thus provide a lower heel 
height than the standard. It would obviously be equally effective to 
remove the portion A-X-B from the top of the foot. 
If a high heel is desired, the foot is angled downwardly by removing 
material in the opposite sense parallel to the line BY in FIG. 1 and as 
shown at the left of FIG. 3. 
Obviously instead of removing a wedge of material such as A-X-B from 
between the shin and the foot, a wedge of packing could be inserted 
between them with the same effect of altering the angular relationship 
between the shin and the foot. 
FIG. 4 shows a modification in which the foot is attached to a M.A.P. limb. 
The limb is formed with an attachment 14 with a threaded bolt 15 into 
which the bolt 3 is threaded to attach the Sach foot 1. In this case, 
material is removed from the top of the Sach foot, for example as 
indicated by the line D-E, to vary the angular relation of the foot and 
shin as described above. 
It will be seen that the invention enables one size of Sach foot to be 
stocked for each size of shoe and readily adapted during fitting to suit 
the user's requirements as to the heel height of his shoes. 
It will be understood that the invention is not restricted to the details 
of the preferred forms described by way of example which may be modified 
without departure from the scope of the accompanying claims.