Flexible prosthetic foot apparatus

Prosthetic foot apparatus includes a tubular element appropriately bent and flattened to provide desired flexibility. The extent of flexibility, and accordingly the extent of the bending and flattening of the tubular element provides desired stiffness or flexibility according to the desired characteristic, complementary of the user of the apparatus. Different embodiments are shown, including an embodiment which includes a separate foot plate secured to and extending into the foot portion of the tubular element.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to prosthetic appliances and, more particularly, to 
a flexible prosthetic foot. 
2. Description of the Prior Art 
U.S. Pat. No. 4,547,913 (Phillips) relates to a composite prosthetic foot 
and leg which includes three portions, a leg portion, a foot portion, and 
a heel portion. The three portions are joined together rigidly. The three 
elements provide a degree of flexibility in response to ankle movements 
and foot movements, but provide sidewise rigidity. Various embodiments are 
disclosed. 
U.S. Pat. No. 4,822,363 (Phillips) provides a different embodiment by the 
same inventor as the '913 patent, discussed above. The apparatus is made 
of laminated material to provide a prosthetic leg connected to a 
prosthetic foot. The leg portion is curved to define the foot, with a 
separate head portion connected to the foot portion. Various stiffness may 
be provided in the foot portion. Again different embodiments are 
disclosed. 
U.S. Pat. No. 5,062,859 (Naeder) discloses a prosthetic foot which includes 
a resilient foot insert. The foot insert is of a general "Z" 
configuration. Different embodiments are illustrated. 
U.S. Pat. No. 5,156,631 (Merlette) discloses a prosthetic foot and leg in 
which a leg element curves to define a foot element, and a separate 
segment is bonded to the forward extending foot portion extension of the 
leg element. The separate foot portion comprises or defines a sole 
element. 
U.S. Pat. No. 5,258,039 (Goh et al) discloses a prosthetic foot apparatus 
made of resin impregnated woven fabric material. The apparatus is made of 
two segments both of which are curved to define a foot and heel portion 
and which provides the substantial degree of flexibility. Various 
embodiments or configurations are disclosed. 
U.S. Pat. No. 5,376,140 (Ryan) discloses a prosthetic foot apparatus made 
of composite material. The apparatus has a general configuration of a 
natural foot with various elements involved, including a foamed polymer 
body, and cushioning material provides elasticity and flexion. 
U.S. Pat. No. 5,486,209 (Phillips) discloses a prosthetic foot apparatus 
made of laminated materials. The apparatus includes an ankle portion, a 
foot portion, and a heel portion. Various configurations are illustrated. 
U.S. Pat. No. 5,507,838 (Chen) discloses an artificial foot apparatus 
having a foot shaped casing and insert elements into the casing. 
U.S. Pat. No. 5,549,714 (Phillips) discloses another prosthetic foot 
apparatus made of different elements secured together. Various elements 
are interchangeable to match the weight, stride, and activity schedule of 
the user of the apparatus. 
U.S. Pat. No. 5,593,456 (Merlette) discloses another prosthetic leg and 
foot apparatus made of a single monolithic elongated composite member. The 
member includes a semi-flexible shank portion, an ankle portion, a 
fore-foot portion, and a toe portion. The apparatus is designed primarily 
for athletic type use. 
U.S. Pat. No. 5,593,457 (Phillips) discloses apparatus similar to that 
disclosed in the above referred '290 patent. Both the '290 patent and the 
'457 patent are continuations of the same parent application. 
SUMMARY OF THE INVENTION 
The invention claims and described herein comprises a prosthetic foot made 
of a single tubular element which is flattened or configured to provide 
the degree of flexibility for the element. A second embodiment includes a 
flat plate appropriately secured to and extending inside of a foot portion 
of the tubular element. 
Among the objects of the present invention are the following: 
To provide new and useful prosthetic foot apparatus; 
To provide new and useful prosthetic foot apparatus including a tubular 
element; 
To provide new and useful prosthetic foot apparatus made of a tubular 
element and appropriately flattened or configured to provide a desired 
degree of flexibility; 
To provide new and useful prosthetic foot apparatus including a flat plate 
secured to a tubular element; and 
To provide new and useful prosthetic foot apparatus having a flat plate 
element secured to and extending into the interior of a foot portion of a 
tubular element.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a side view of flexible prosthetic foot apparatus 10 of the 
present invention. FIG. 2 is a front view of the foot apparatus 10 of FIG. 
1. FIG. 3 is a top view of the flexible foot apparatus 10 of FIGS. 1 and 
2. For the following discussion, reference will be made to FIGS. 1, 2, and 
3. 
The flexible foot apparatus 10 comprises a tubular element 12 in which 
there is a bore 14. The foot apparatus 10 may be divided into three 
portions, an upper, straight portion 16, a curved, ankle portion 18, and a 
tapering lower portion 20. The lower portion tapers to a toe end 22 in 
which the tube 18 is substantially flat. The flattening of the tube 12 in 
the lower foot portion 20 results in an outward tapering of the lower foot 
portion 20, outwardly from the curved portion 18 to the end 22. This is 
best shown in FIG. 3. 
In the side view of FIG. 1, the gradual tapering of the tube 12 from the 
upper straight or full diameter portion 16, through the curved portion 18, 
onto the foot portion 20, and terminating in the toe end 22 is shown. The 
degree or extent of flexing varies according to the degree or extent of 
the flattening of the tube. In the embodiment of FIGS. 1-3, there will be 
some flexing in the curved portion 18, as an ankle flexing, but even more 
in the foot portion 20 and in the toe area 22. 
FIG. 4 is a side view, partially broken away, of an alternate embodiment 30 
of the apparatus 10 in FIGS. 1, 2, and 3. FIG. 5 is a view in partial 
section of the apparatus 30 taken generally along line 5--5 of FIG. 4. 
FIG. 6 is a view in partial section taken generally along line 6--6 of 
FIG. 4, while FIG. 7 is a view in partial section taken generally along 
line 7--7 of FIG. 4, and FIG. 8 is a view in partial section taken 
generally along line 8--8 of FIG. 4. For the following discussion, 
reference will be made to FIGS. 4, 5, 6, 7, and 8. 
The flexible foot apparatus 30 is made of a tube 32 which has an interior 
bore 34. The flexible foot apparatus 30 includes a relatively straight 
upper portion 36, which corresponds to the upper portion 16 of the 
apparatus 10. The tubular member 32 includes a bore 34. The tubular member 
32 is generally circular, and accordingly the bore 34 is generally 
circular. 
Downwardly from the upper, straight portion 36 is a partially flattened or 
necked down curved portion 40. The portion 40 corresponds to an ankle 
portion of a natural leg in that there is flexing to a degree permitted in 
the area 40 by the flattening or necking down of the tube 32. The general 
flattening of the tube 32 in the area 40 is illustrated in detail in FIG. 
6. 
Downwardly from the neck down or flattened portion 40 is another circular 
or full cross-sectional area 46. In the area 46, the tubular member 30 is 
at a full diameter cross-sectional configuration, as illustrated in FIG. 
7. 
From the lower circular portion 46, the tubular member 32 tapers to an 
outer end 52. The tapering portion 50 is similar to the tapering front 
foot portion 20 of the apparatus 10. The tapering is accomplished by a 
gradual flattening of the tube 32 until the tubular member 32 is flattened 
to terminate at the end 52. The end 52, in an end view, is substantial the 
same as that illustrated in FIG. 2 for the end 22 of the tubular member 
12. 
In dash/dot line in FIG. 4, the flexing of the "ankle" portion 40 is 
illustrated. The dash/dot arrow adjacent to the tip 52 illustrates the 
relative movement of the foot tapering portion 50 relative to the upper 
straight portion 36. Again, the flexing is permitted or allowed by the 
necking down, or semi flattening of the tube 32 in the area 40, as 
illustrated in FIG. 6. 
By varying the cross section of the tubular member 32 in the "ankle" 
portion 40, the flexing of the apparatus is varied. The greater the extent 
of the flattening or necking down, the greater the degree of flexing, and 
vice versa. Thus, in addition to the flexing of the portion 40, there will 
also be some flexing in the bottom foot portion 50 due to the flattening 
of the tubular member 32. This latter flexing provides a degree of 
springiness to the apparatus 30. 
FIG. 9 comprises a side view in partial section of an alternate embodiment 
70 of the apparatus of the present invention. The apparatus 70 is another 
alternate embodiment of the apparatus 10 of FIGS. 1, 2, and 3. FIG. 10 is 
a bottom view taken generally along ling 10--10 of FIG. 9. For the 
following discussion, reference will be made primarily to FIGS. 9 and 10. 
The flexible prosthetic foot apparatus 70 is again made of a tubular member 
72 which has a bore 74. The apparatus 70 includes an upper portion 76 
which is generally straight, and accordingly the cross-sectional 
configuration of the tubular member 70 will be circular, such as 
illustrated in FIGS. 3, 5, and 7, for the apparatus 10 and 30. The 
straight upper portion 76 then curves to define a portion 76, which may be 
considered as an ankle portion. From the curved portion 76, the tubular 
member 72 is tapered inwardly and flattened and terminates in a front end 
or toe tip 82. The continual tapering of the flattening of the tubular 
member 72 from the upper straight portion 76 to the toe tip 82 may be 
understood from FIG. 9. 
On the bottom of the tubular member 76, at the tapering foot portion 80, 
there is a slot 84. The front end of a plate 90 extends through the slot 
84 and extends to the tip 82 where the plate terminates in an end 92. An 
appropriate fastener 94, such as a rivet, may be used to secure the plate 
90 to the foot portion 80, if desired or if required. However, as shown in 
FIG. 9, and as also may be understood from FIG. 2 and from FIGS. 1 and 4, 
the end or tip 82 of the tubular member 76 is flattened so that the plate 
90 is held relatively securely therein. Thus, at the front end of the foot 
portion 80, the tips 92 of the plate 90 and 82 of the tube 72 are 
flattened adjacent to each other. 
The flattening of the tube 72 in the foot area 80, resulting from the 
inward taper of the tube 72, results in an outward taper of the portion 
80, as best illustrated in FIG. 10. 
FIG. 11 is a fragmentary view in partial section of an alternate embodiment 
of the apparatus 70 from that illustrated in FIG. 9. Instead of having the 
plate 90 extend through the slot 84 and into the interior bore 74 of the 
tubular member 72 at the foot portion 80, the plate 92 is simply 
appropriately secured to the bottom of the foot portion 80 by a pair of 
appropriate fasteners 96, such as nuts and bolts. This eliminates the need 
for the slot 84. 
Three embodiments of a flexible prosthetic foot are illustrated and have 
been discussed. They all share in construction in that a tubular member is 
used to form the vertical portion of the foot and which is appropriately 
connected to a leg member or other prosthesis, not shown, but as is well 
known and understood. The tubular member curves to define an ankle portion 
between the vertical portion and a foot portion. Deformation of the ankle 
portion provides flexibility to create to a degree the desired movement. 
Flexing of the tubular member varies according to the flattening or 
deformation in the cross sectional configuration, as discussed above. The 
greater the extent of flattening of the tubular member, the greater the 
degree or extent of the flexibility. 
While the principles of the invention have been made clear in illustrative 
embodiments, there will be immediately obvious to those skilled in the art 
many modifications of structure, arrangement, proportions, the elements, 
materials, and components used in the practice of the invention, and 
otherwise, which are particularly adapted to specific environments and 
operative requirements without departing from those principles. The 
appended claims are intended to cover and embrace any and all such 
modifications, within the limits only of the true spirit and scope of the 
invention.