U.S. patent number 3,739,501 [Application Number 05/265,913] was granted by the patent office on 1973-06-19 for footwear article and method for facilitating walking.
Invention is credited to John P. Barrett, Jr..
United States Patent |
3,739,501 |
Barrett, Jr. |
June 19, 1973 |
FOOTWEAR ARTICLE AND METHOD FOR FACILITATING WALKING
Abstract
Rheumatoid arthritic patients and others are enabled to walk by
means of an article of footwear which has an un-bendable platform
provided on its upper surface with padding material and provided on
its lower surface with a tread having heel and sole portions. The
tread surface assumes a stable non-rocking condition when at rest
on a flat ground surface. The heel portion has the entirety of its
ground-contacting surface located forwardly of the anatomical rear
edge of the patient's foot to reduce impact loading of the forefoot
at the foot flat portion of gait; and, the sole portion is inclined
forwardly and upwardly to reduce the shear forces on the patient's
foot during the push-off portion of gait.
Inventors: |
Barrett, Jr.; John P.
(Burlington, MA) |
Family
ID: |
23012393 |
Appl.
No.: |
05/265,913 |
Filed: |
June 23, 1972 |
Current U.S.
Class: |
36/11.5 |
Current CPC
Class: |
A43B
3/128 (20130101) |
Current International
Class: |
A43B
3/12 (20060101); A43b 003/12 () |
Field of
Search: |
;36/2.5R,7.5,7.6,11.5,1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawson; Patrick D.
Claims
I claim:
1. An article of footwear for patients who have functionally
foreshortened feet, comprising,
a ground-contacting base including a tread surface which has a sole
portion and a heel portion which are relatively immovable with
respect to each other, said sole portion being inclined forwardly
upward to reduce the shear forces on a patient's foot during push
off,
said heel portion having its rearwardmost ground-contacting portion
located forwardly of the anatomical rear portion of the patient's
foot to reduce impact loading of the forefoot at the foot flat
portion of gait,
a foot-supporting means above the base for conforming to the shape
of the patient's foot, and,
a forefoot retaining means constructed to allow maximum midtarsal
motion,
heel retaining means for laterally positioning the patient's heel
on the foot-supporting means while permitting at least a one-half
inch displacement of the patient's heel from the foot supporting
means during the push-off portion of the patient's gait.
2. An article of footwear according to claim 1 wherein the heel
retaining means includes a generally horizontal loop for encircling
the patient's foot above the instep and means for connecting said
loop to said base.
3. An article of footwear according to claim 2 wherein the means
for connecting said loop to said base is elastic.
4. An article of footwear according to claim 1 wherein the foot
supporting means is a permanently deformable pad means which
extends laterally beyond a patient's foot to provide a ridge which
surrounds the foot and prevents lateral shifting thereof.
5. An article of footwear according to claim 4 wherein the
deformable pad means is of foam material.
6. An article of footwear according to claim 1 wherein the tread
surface has portions which are longitudinally spaced apart and are
positioned to simultaneously contact a flat ground surface, thereby
assuming a stable non-rocking position when a patient is standing
still.
7. An article of footwear according to claim 1 wherein the forefoot
retaining means includes strap means located to overlie a patient's
foot exclusively rearwardly of the toes to avoid discomfort to the
foot during that portion of the gait when the foot is raised and
the article of footwear is supported by the foot.
8. An article of footwear according to claim 7 wherein the opposite
ends of the strap are spaced transversely from the patient's foot
to avoid lateral constriction of the foot and to maximize the
distribution of pressure on the underside of the foot during the
push-off portion of stance phase of gait.
9. A method of facilitating walking by patients with highly
sensitive or functionally foreshortened feet, said method being
performed by attaching to the foot an article of footwear which has
a substantially unbendable platform provided on its upper surface
with a layer of padding material and provided on its lower surface
with a tread surface which has a sole portion and a heel portion,
said tread surface assuming a stable non-rocking condition when at
rest on a flat ground surface, said sole portion being inclined
forwardly and upwardly to reduce the shear forces on a patient's
foot during the toe-off portion of gait, said heel portion having
the entirety of its ground-contacting surface located forwardly of
the anatomical rear portion of the patient's foot to reduce impact
loading of the forefoot at the foot flat portion of gait.
10. The method of claim 9 wherein the article of footwear is
attached to the forepart of the foot by passing a strap over the
forepart of the foot rearwardly of the toes without laterally
constricting the foot, thereby providing for maximum midtarsal
motion during the toe-off portion of gait.
11. The method of claim 1 wherein the foot is laterally confined by
that portion of the padding material which is uncompressed and lies
laterally of the foot.
12. The method of claim 1 wherein the article of footwear is
attached to the foot by forming a loop around the foot in the
vicinity of the ankle, and resiliently biasing the loop toward the
platform with a force having a magnitude such that the heel will
lift off the upper surface of the platform only during the toe-off
portion of gait.
13. The method of claim 12 wherein the article of footwear is
attached to the forepart of the foot by passing a strap over the
forepart of the foot rearwardly of the toes without laterally
constricting the foot, thereby providing for maximum midtarsal
motion during the toe-off portion of gait.
14. The method of claim 13 wherein the foot is laterally confined
by that portion of the padding material which is uncompressed and
lies laterally of the foot.
Description
This invention is related to the structure and use of an article of
footwear primarily intended for rheumatoid arthritic patients and
others who have extreme difficulty in walking as a result of
deformities or sensitivity which renders the foot incapable of
functioning in a normal manner.
Normal walking involves a gait having two principal phases, a swing
phase when the foot is moving forwardly and is not supported by the
ground surface, and a stance phase during which the foot is
supported by the ground surface. The stance phase may be further
subdivided into the heel strike portion when the heel of the foot
or shoe initially contacts the ground surface, a foot flat portion
during which the weight is shared by the heel and the forefoot and
the push-off or toe-off portion during which the weight and
pressure are borne by the forefoot and the foot pushes rearwardly
to provide the forward thrust of the body. Throughout the stance
phase, the foot is constantly undergoing a change in orientation,
with a general rocking motion producing the transition from the
heel strike portion to the foot flat portion, and then from the
foot flat portion to the push-off portion.
For various reasons, many medical patients are unable to walk in a
normal fashion, due to deformities of the foot, paralysis or
extreme sensitivity of the forces created during a normal gait.
Patients having rheumatoid arthritis, leprosy and severe diabetes
are illustrative. For example, arthritic patients have painful
prominent callosities on the sole of the foot, deformities which
create a functionally short foot and sensitivities which prevent
the normal exertion of pressure by the toes. This requires such
patients to perform the push-off portion of gait with the ball of
the foot. This invention is intended to permit such persons to walk
and/or to reduce the degree of pain required to walk. A number of
features of the present invention contribute to its
performance.
According to one feature of the invention, a rigid and unbendable
platform for the foot is provided on its upper surface with a
padding material which minimizes concentrations of pressure and
deforms under the pressure of the foot to provide a
foot-surrounding ridge to prevent shifting of the foot during
walking.
The invention is also intended to promote proper functioning of the
forefoot mechanics of some patients, by avoiding any lateral
constriction of the midtarsal area and permitting the heel to lift
off the platform padding during the transition form foot flat to
push-off portion of gait. This latter feature permits many patients
to use the proper metatarsal motion since the heel must rise to
cause the heads of the metatarsals to come in proper sequence and
shift the pressure profile from lateral to medial. Means are also
provided for biasing the heel portion of the wearer's foot against
the padding on the platform, which is particularly important with
patients who are unable to exert downward pressure with their toes
to restore the heel into contact with the padding.
Another feature involves a novel combination of known sole and heel
structures. The sole tread surface is inclined forwardly and
upwardly to permit a patient to roll toward the push-off, thereby
reducing the extent of shearing forces between the foot and the
article of footwear. The rearwardmost portion of the heel is
forwardly displaced from its usual position in order to reduce
impact loading of the forefoot during the transition from the heel
strike to the foot flat portion gait.
According to the disclosed embodiment of the invention, the patient
is also permitted to stand still with ease since the tread surface
is constructed to assume a stable non-rocking orientation at the
foot flat portion of gait, unlike some prior devices which have had
arcuate surfaces extending continuously throughout the length of
the heel and sole area.
The preferred embodiment of the invention also minimizes discomfort
on the upper surface of the foot during the swing phase of gait
when the article of footwear is supported by the foot. This
advantage is realized by placing the forefoot-retaining strap
immediately behind the extremely pressure-sensitive points at the
base of the great toe and the base of the fifth toe. This feature
is particularly important in footwear designed for patients whose
feet are extremely sensitive to pain.
For a more complete understanding of the invention, a preferred
embodiment is shown in the accompanying drawings wherein
FIG. 1 is a side elevation thereof, showing the position of a foot
supported on the device;
FIG. 2 is a plan view of the device which also illustrates the
principal areas of pressure of a typical arthritic patient;
and,
FIGS. 3-5 illustrate the device of this invention at the three
principal portions of the stance phase of gait.
Referring to FIG. 1, it will be seen that the foot of a patient is
at the location shown in broken lines at 2 where it rests on a
layer of padding material 4 located on the upper surface of a rigid
platform core 6. The areas of maximum pressure of one arthritic
patient's foot are designated by the broken lines 34. On the
undersurface of the platform core 6 is the bottom of the sandal
which is preferably made of cushion crepe and provides a tread
surface having a sole portion 8 and a heel portion 10. Various
materials may be used in the manufacture of the components of the
device, but it is important that its overall structure be
substantially unbendable.
The wearer's heel is retained on the device by means of a loop 12
which has a buckle 14. The loop 12 encircles the foot above the
instep, in the vicinity of the ankle. A strap 16 having an elastic
or gore portion 18 connects the loop 12 with the platform so that
the elastic 18 biases the wearer's heel against the padding
material 4 of the platform. The biasing force is insufficient to
hold the heel in contact with the padding material 4 during the
latter portions of the stance phase of gait. The heel is permitted
to lift off the padding material by at least about one-half inch as
the elastic 18 extends, thereby permitting normal functioning of
the forefoot mechanics in the midtarsal and metatarsal regions. An
optimum distance of lift-off is about three-quarters of an inch.
The amount of force exerted by the elastic may be adjusted to some
degree by changing the size of the loop 12, thereby changing its
elevation and the amount of tension in the elastic 18.
The forefoot is held against the padding 4 of the platform by means
such as the straps 20 and 22 which have buckles 24 and 26. With
some patients who have unusually sensitive feet, it is important
that the straps 20 and 22 be located rearwardly of the extremely
pressure-sensitive portions of the forefoot, specifically the base
of the great toe and the base of the fifth toe. Furthermore, it is
important that the straps 20 and 22 are spaced transversely of the
foot so they do not laterally constrict the foot to interfere with
the normal distribution of weight and pressure in the midtarsal
region.
The particular materials used for making products according to the
invention are not critical. The padding 4 may be conventional foam
rubber, a thermolabile polyethylene foam material used in
orthopedics and sold under the trademark Plastazote or generic
polyethylene foam preferably providing a durometer reading of about
57-61 Shore. This latter material is particularly desirable since,
after a few weeks, it will bottom-out to conform to the foot of the
wearer so that the foot will be surrounded by a ridge of padding
which will prevent shifting of the foot on the upper surface of the
sandal. In this condition, the padding does not act as a resilient
cushion, but serves to avoid pressure concentrations by conforming
to the sole of the foot.
As will be seen in FIG. 1, the heel has a downwardly and forwardly
inclined rear surface 28 which serves, in a previously-known
matter, to locate the entirety of the sandal heel and its
rearwardmost ground-contacting edge 30 of the heel at least
one-eighth to one-quarter inch forward of the anatomical rear edge
32 of the wearer's foot. This serves to shorten the steps of the
patient, locate the impact-receiving point of the heel closer to
the center of the pressure-sustaining area of the wearer's heel and
to shorten the heel lever to reduce the force of impact created
when the sole portion 8 strikes the ground surface at the foot flat
portion of gait. This latter operation may also be achieved by
providing a slight upward and rearward inclination of the tread
surface of the heel portion 10 so that the heel will rock from its
forward edge 32 into the foot flat portion of gait.
The sole portion 8 is inclined upwardly and forwardly, preferably
in an arcuate fashion known in the prior art, so that the
transition from the foot flat to the push-off portion of gait may
occur gradually without the necessity for excessive shearing forces
between the foot and the padding material 4 at the point of
push-off. The sole 8 has its rearward portion located approximately
in the plane of the undersurface of the heel portion 10 so that a
wearer may stand still with the longitudinally spaced points on the
sole and heel simultaneously contacting the ground surface. The
weight is then distributed on the sole and heel portions of the
device. Accordingly, the wearer is not required to balance himself
on an arcuate tread surface which would produce an unstable,
uncomfortable rocking of the sandal and foot.
The normal use of the invention is shown in FIGS. 3, 4 and 5, with
FIG. 3 illustrating the heel strike portion of gait where the
rearwardmost ground-contacting edge 30 of the tread surface strikes
the ground to create upward pressures on the foot in the heel area
surrounded by the broken lines 34 in FIG. 2.
Continuation of the normal gait causes the tread portion to pivot
downwardly on the rear edge 30 until the foot flat portion of gait
is reached as shown in FIG. 4. This is also the position assumed by
the foot and sandal when the patient is standing still. At this
point, the weight is supported by the forefoot and heel.
Next, the foot rocks forwardly on the arcuate undersurface of the
sole portion 8. During this rocking movement, the forefoot
mechanics are at work with the usual midtarsal and metatarsal
movement occurring for many patients. At this point, the lifting of
the wearer's heel extends the elastic 18 so that the foot will lift
off the padding material 4 to permit the proper functioning of the
forefoot mechanics. The ability of the sole portion to rock
forwardly reduces the amount of shearing force required at the
push-off portion of gait and thereby further avoids or minimizes
the amount of discomfiture to which the patient is subjected.
The disclosed sandal has been found to perform a cadence-monitoring
function which reduces the amount of pain experienced by the
patient. The steps are shorter and less frequent, so there is a
reduction in velocity which also minimizes the forces of impact and
shear produced during the stance phase of gait.
Those skilled in the art will realize that a wide variety of
materials may be used in practicing the invention and that it is
desirable to design the sandal or other article of footwear
according to measurements and analysis of the anatomical and
functional characteristics of the individual patient's feet. In
some instances, only selected features described above will be
required for the patient. Therefore, it is emphasized that the
invention is not limited to the sole embodiment disclosed which
incorporates all important features of the invention, but the
invention is to be construed in the light of the claims which
follow.
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