Note: Descriptions are shown in the official language in which they were submitted.
rne present invention pertains to a podiatric insole and more
particularly to a liquid-filled insole utilized as a cushion to be posi- ;
tioned in contact with the bottom of a user's foot.
The desirability of providing a cushioning surface for the bottom
of the foot has long been recognized. Several prior art patents exist
relating to cushioning materials and insole structures. For example,
United States Letters Patent No. 2,477,588 (Dumm~ issued August 2, 1949
describes a hydraulic insole formed by opposing sheets of flexible material
and incorporating non-communicating oompart~ents therein. Hk~lever, the
oompartments provided by Dumm do not correspond to t.~e major pressure
points of the user's foot and, except for the area ~eneath the toes, are
formesd by essentially longitudinally extending walls. Further, only a
specific comp ætment is provided with a liouid, and the viscosity of the
liquid is that of hom~genized honey. While the Dumm patent represents an
advance over the then-existing prior art, the problem still exists of the
acoommodation of the differing requirements of the different portions of
the user's foot.
Another example of the prior art is United States Letters Patent
1S'
Nb. 3,765,422 issued October 16, 1973 to 5mith. 5mith
suggests the provision of a transverse ~all, in a fluid cushion padiatric
insole, positioned along the forward edges of the netatarsal pressure
points of the foot; thu~s, the positioning of the wall represents a recog- -
nition of the requirement for limiting fluid flow in the æ ea of the
; metatarsus. However, Smith does not solve the problem of the differing
cushioning requirements of the various other portions of the foot.
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Body weight is transmitted through the seven tarsal and five
metatarsal bones to the weight-bearing surfaces of the foot. The ~7eight
is received by the talus positioned on the lower end of the tibia and the
lines of force created by the weight extend dowr~7ard and backward to the r
os calcis, or heel, and also extend downward and forward to the forefoot.
The ~^7eight is generally distributed through the longitudinal and transverse
arches predominantly to three weight-bearing areas. These areas include
the tuberosity of the os calcis, the head of the first metatarsal and the
outer border of the foot. The phalanges do not carry a significant portion
; 10 of the total ~eight but do provide pressure points under non-static condi-
tions such as waLking or running.
It was previously believed that the overall slope of the foot was
basically determined by the muscles and ligaments maintaining the bones in
proper relationship with respect to one another; however, more recent
studies have indicated that the shape of the foot is primarily deternined
by the interfitting of the respective bones and that the muscles and liga-
ments are called upon to retain the shape only during periods of high r
stress when the foot is subjected to forces in excess of the static weight
of the individual. That is, those forces enoountered during the initial
movement of the foot when the individual steps for~7ard or when the indi- --
vidual is running. Without regard to the nature of the shape of the foot,
or the manner in which the shape is maintained, it has now been found that
foot oomfo~t can be enhanced by providing four separate cushioning areas to
contact, respectively, the phalanges, the metatarasal pressure points, the
arch and the tuberosity of the os calcis. The cushioning
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in each o~ the~e ~eRs is i~pQ~tant for ~a~nt~ning overall comfort
and preventing stress concent~ation that could produce damage to the
foot.
It is therefore an object of one aspect of the
present invention to provide a podiatric insole having four distinct
cushioning areas, each for cushioning a separate portion of the bottom
of a user's foot.
It is an ob;ect of another aspect of the present
invention to provide a podiatric insole utilizing a liquid such as
water enclosed within3four separate compartments for contacting four
separate areas of the bottom of a user's foot.
; It is an object of still another aspect of the
present invention to provide a podiatric insole incorporating a pair
of flexible layers bonded along specific lines to form a compartmentalized
structure, each compartment of which is non-communicating with the
others and which contain a liquid, the volume of liquid per unit area
of each compartment being determined by the requirements of that
compartment.
By one broad aspect of this invention, a podiatric
insole is providing comprising a) first and second substantially flat
,
layers of flexible material each generally conforming to the outline
of the bottom of a user's foot; b) said layers being joined to each
other i) along the edges thereof; ii) along a line forward of the
metatarsal pressure points; iii) along a line substantially transverse
of the user's foot and rearward of the metatarsal pressure points; iv~
along a line substantially transverse of the user~s foot and forward of the
08 calcls area to form a compartmentalized envelope having four separate
non-communicating compartments beneath the phalanges, metatarsal pressure
points, arch, and 08 calcls~ respectively; and c) each of said
- compartments covering a predetermined area between said layers and
each containing a predetermined volume of liquid per unit area.
By one variant, at least two of said compartmeDts
contaln different predetermlned volumes o liquid per unit area.
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16)4~460
By anpther yariant, the compartments each contain
a different predetermined voiume of liquid per unit area.
By yet another variant, the liquld includes water
and wherein a) the compartment beneath the phalanges of the user~s
foot contains from 3 x 10-6 to 8 x 10 6 grams of water per square
centimeter; b) the compartment beneath the metatarsal pressure
points of the user~s foot contains from 12 x 10 6 to 17 x 10 6 grams
of water per square centimeter; c) the compartment beneath the arch
of the user's foot contains from 17 ~ 10 6 to 24 x 10 6 grams of water
per square centimeter; and d) the compartment beneath the 08 calcis,
or heel, of the user's foot contains 7 x 10 6 to 13 x 10 6 grams
` of water per square centimeter. -
. `
By still another variant, the liquid includes
water and wherein a) the compartment beneath the phalanges of the
user's foot contains from 6.2 x 10 6 grams of water per square
centimeter; b) the compartment beneath the metatarsal pressure
points of the user's foot contains from 15.5 x 10 6 grams of water
per square centimetèr; c) the compartment beneath the arch of the
user's foot contains from 21.7 x 10 6 grams of water per square --
centimeter; and d) the compartment beneath the os calcis, or heel,
of the user's oot contains 10.9 x 10 6 grams of water per square
centimeter.
By a still further variant, the liquid includes
water and wherein the ratio of weight of water per-unit area of the
respective compartments are a) the compartment beneath the phalanges -
of the user's foot to the compartment beneath the metatarsal pressure
points equals 0.4; b) the compartment beneath the phalanges of the
user's foot to the compartment beneath the arch equals 0.28; and c)
the compartment beneath the phalanges of the user's foot to the
' 30
compartment beneath the o~ calcis, heel, equals 0.57.
In accordance with the embodiment chosen for
lllustratlon, a pair of flexible sheets having the general outlioe
of a u8er~s foot àre formed into a two-layered compartmentalized
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structure b~ bonding the laye~s along the outside edge thereof and
by bonding the layers along walls extending substantially transversely
of the wearer's foot. The walls are positioned to provide four
separate non-communicating compartments each posi-
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' tioned beneath a portion of the foot and each provided with a different
- cushioning effect by the control of the liquid placed in each ccnpartment.
In the acccmpanying drawings,
Figure 1 is a plan view of a podiatric insole constructed in
accordance with the teachings of an aspect of the present invention.
Figure 2 is a cross-sectional view of Figure 1 taken along line
2-2.
Referring now to the drawings, a first layer 10 of flexible ma-
teriql is cut to the general outline of the bottom of a user's foot. The
10 outline is typical of shoe soles and insoles; a second layer 11, cut to
the same shape, is bonded to the first along the outside edge 13 thereof.
! me flexible m~terial fr~m which layers 10 and 11 are made may be any of ~ ',
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several well known rubber-like or plastic materials readily oommercially
available and which exhibit sufficient strength and toughness to withstand
the pressures and abrasion encountered in use as an insole. The konding
of layers 10 and 11 may be accomplished using well established bonding
techniques which form no part of the present invention and need not be r
discussed.
The layers 10 and 11 are also konded together to form ~7alls 15,
16 and 17. The wall 15 is positioned for~7àrd 'of the heads of the
metat æ sus and is generally transverse of the user's foot. The wall 15 is i'
curved as shLw,n to generally follow the
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contour, as viewed from above, of the metatarsal pressure points of the user.
m e wall 15 forms a ccmpartment 19 which is forward of the metatarsus and
generally provides cushioning for the phalanges.
me wall 16 is generally transverse of the user's foot but is
somewhat angled and defines a ocmpartment 21 that is generally positioned
beneath the metatarsal pressure points. The wall 17 is transverse to the
wearer's foot and separates ccnpartment 22 fram compartnent 24. The conr
parbment 22 is positioned beneath the arch of the foot; however, the ccmr
partment does not extend upward to contact and support the arch as suggested
10 in the prior art; instead, the insole of the present invention relies on the
arch of a shoe to provide ~ajor supp~rt to the arch of the foot. The com-
partment 22 only provides the proper cushioning. This cushioning is extremE-
ly important since the outer border of the foot along the border designated
at 25 assists in the support of the weight of the user.
The come~rtment 24 is positioned beneath the os calcis, or hee~,
and cushions the foot of that area. Each of the ccnFartmcnts 19, 21, 22
and 24 oontains liquid which may be ~ater although other liquids such as,
for example, aloohol may be found suitable. Usually, water is satisfactory
and may contain chemicals such as an algacide. In oolder climates the J
20 presence of an antifreeze in the water is advantageous. The weight or
~Dlume of the water used to fill the compartments has been found to greatly
affect the comfort afforded by the present insole. For example, it was
found that the oomfort of the insole was enhanced when the weight or volume
per unit of the liquid in ccLpartment 22 was essentially twice t'nat in
comparbment 24. This relationship is quite unex-
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1 ¦pected since the weight borne by the os calcis in contact with
2 ¦com~artment ?4 is su~stantially greater than the weight borne by .
3 ¦that portion of the foot in contact with compartment 22. Speci-
4 ¦fically, I have found the following values of liquid weight - ,
5 ¦tusing water as the liquid) per unit area o~ the respective com-
6 ¦partments to be ideal for use by men and women:
71 . .
8¦ For Men .
9 Compartment 19 6.2 x 10-6 grams per square-
. ce~timeter
11 ` Compartment 21 15.5 x 10-6 grams per square
centimeter - -
12 ` Compàrtment 22 21.7 x 10-6 grams per square .
13 centimeter .
14 - Compartment 24 10.9 x 10-6 grams per square
. . centimeter .
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16 For Women . .
7 Compartment 19 4.7 x 10-6 grams per sguare .
18 - . centimeter .
19 Compartment 21 13.9 x 10-6 grams per sguare
centimeter
Compartment 22 18.6 x 10-6 grams per square ~ :~
21 . centim~ter .
22 Compartment 24 9.3 x 10-6 grams per square .
- centimeter ~.
23 . . . -
24 While the above weights per unit area were found to -
25 be substantially ideal, the following ranges will provide satis- :
26 factory cushioning for the various areas of the foot:
27 . . .. ~-.
28 Compartment 19 3 x 10-6 to 8 x 10-6
29 Compartment 21 12 x 10-6 to 17 x 10-6
Compartment 22 17 x 10-6 to 24 x 10-6
32 . Compartment 24 7 x 10 -6 to 13 x 10-6
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1 I The specific values of liquid weight per unit area ~7ill
2 ¦depend to some extent on~he shape and size of the user's foot.
3 ¦For example, I have found that slightly more liquid may be
4 ¦reguired in the compartment under the arch of a woman's foot
5 Irelative to the same compartment under the arch of a man's foot. .,
61 However, the above range of values are appropriate for the entire
71 range of men's and women's foot sizes, assuming, of course,
8 rhat the user's foot is normal.
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