Liquid filled orthopedic apparatus
United States Patent 3922801

An apparatus and method of making it is provided whereby a liquid-filled shoe insole is produced. The insole comprises discreet internal liquid-filled ampules which are strategically placed between upper and lower laminae and sealed in place to provide separate support for various parts of the foot.

Application Number:
Publication Date:
Filing Date:
Primary Class:
International Classes:
A43B13/20; (IPC1-7): A43B13/40
Field of Search:
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US Patent References:
3724106INSOLE STRUCTURE1973-04-03Magidson
2641066Metatarsal length compensating device1953-06-09Filardo
2477588Hydraulic insole1949-08-02Dumm

Primary Examiner:
Guest, Alfred R.
I claim

1. An apparatus for treating foot defects and for promoting foot comfort which comprises:

2. The apparatus of claim 1 in which the liquid is mineral oil.

3. The apparatus of claim 1 in which (a) 2 ampules are provided for the toes, (b) 3 ampules are provided for the metatarsal, (c) 2 ampules are provided for the arch, and (d) 2 ampules are provided for the heel.

4. The apparatus of claim 3 in which one of the ampules provided for the heel is substantially toroidal in shape, the other being substantially cylindrical and positioned centrally inside said toroidal ampule.

5. The apparatus of claim 1 in which one ampule is provided for the heel, said ampule being substantially toroidal in shape.

6. The apparatus of claim 1 in which two ampules are provided for the metatarsal.

7. The apparatus in claim 1 in which the liquid is water.

Orthopedic researchers have over the years developed numerous ways to modify shoes for both remedial and preventative reasons. Arch supports, for example, have long been known to enhance the support a shoe affords persons with weak arches. Pads can be placed in shoes to enhance the comfort of a wearer who suffers pain at the metatarsal. Wedges can be placed in the inside or outside edges of soles or heels to afford a variety of canting to counter many abnormalities of the foot such as "toeing in" or "toeing out", and the like.

Also widely employed are various types of shoe insoles which can be purchased separately from the shoes and installed by the wearer. Generally, such insoles are of two types, those sold by retail merchants and those purchased in accordance with medical prescription. The former usually consist of no more than a soft foam synthetic or rubber and are employed to soften or cushion the feel of the shoe. Although these have enjoyed a reasonable amount of success in the marketplace, the purchaser soon learns of serious disadvantages inherent in such devices. Soon after he begins to wear them he finds that, for reasons including heat, perspiration and wear fatigue, the foam material in the insole compresses and loses its cushioning ability, thereby becoming useless. In addition, these devices have a tendency to absorb moisture without dissipating it. The cellular nature of the foam contains this moisture. Thus precluding rapid drying during periods of non-use. Consequently, the wearer often finds himself wearing damp shoes, a situation which enhances the probability of such disadvantages as odiferousness and a fungus infection closely akin to ringworn known as "athlete's foot."

Prescription insoles, on the other hand, are expensive and rarely confortable, being generally constructed on a rigid backing, usually leather-covered metal. Because they lack an inherent flexibility, the wearer experiences chafing and pressure, especially in the areas of the heel, arch and metatarsal.

Many attempts have been made to avoid these prior art limitations, including the use of liquid fillers, but all have been plagued by one or more undesirable flaws. Indicative of such attempts are U.S. Pat. Nos. 532,429; 1,069,001; 1,193,608; 1,148,376; 1,517,171; 2,546,296; and 2,549,343. These patents teach the use of interconnected fluid compartments filled with air or liquids, foam soles and insoles, honeycomb sole structures, and air-filled outer soles. However, none of these references suggest either the unique structure and method of making the present invention nor the unexpectedly superior results which have been achieved by the present invention.

Despite these and other numerous attempts at enhancing orthopedic therapy and comfort, there has yet to be devised a method of satisfactorily combining all of the desirable features into a single durable insole. To solve this problem, a comprehensive research and development program was engaged in to devise such an insole, taking into consideration the specific sources of discomfort which are common to most sufferers of foot maladies. In the course of this work, the present invention was discovered.

Briefly stated, this discovery comprises encasing a liquid medium in a soft, flexible material such that the liquid is encased in strategically located, mutually exclusive, discrete compartments or ampules. These ampules are contained between flexible laminae to provide a shoe insole shaped to substantially conform to the inside bottom of a shoe. More specifically the invention comprises a flexible upper lamina and a flexible lower lamina which are joined at their periphery to form a flexible shoe insole. Inside or between the laminae are flexible, liquid-filled ampules which are fixed in position to support various parts of the foot. At least one separate ampule is provided to support each of (a) the toes, (b) the metatarsal, (c) the arch, and (d) the heel.

Specific embodiments of this invention are shown in the Figures. FIG. 1 is provided to show an insole of the present invention containing 11 ampules in a preferred spatial arrangement to provide maximum support for the toes, metatarsal, arch and heel. FIG. 2 depicts the separate ampules utilized in a preferred embodiment and their individual shapes. FIG. 3 illustrates the formation of the bottom lamina during manufacture of the insole. FIGS. 4a and 4b are cross-sectional views of the heel portion of FIG. 1 along the line 4--4. FIG. 5 shows a die or template which can be used in making the ampules and lower lamina.

FIG. 1 shows a preferred embodiment in which ampules 1 and 2 are provided to cushion the toes, ampules 3, 4, and 5 are provided for metatarsal support, ampules 6 and 7 render arch support and ampules 8 and 9 cushion and support the heel. In another preferred embodiment, ampules 17 and 18 are provided to further support the arch and outside edge of the foot.

The construction of the insole is illustrated by FIG. 4a and 4b which are cross-sectional views of the heel section along lines 4--4 of FIG. 1. Upper lamina 10 is joined and sealed to lower lamina 11 at points 12, 13, and 14. Point 12 is the junction between the outer edges or periphery of the laminae whereas junctions at points 13 and 14 serve to permanently place and seal the heel ampules 8 and 9. Hence, ampule 8 is substantially toroidal in shape, whereas 9 is substantially cylindrical. Of course, ampule 9 may take on equivalent shapes such as ovoid. Alternatively, ampule 9 may be omitted as shown in FIG. 4b. In this embodiment, toroidal ampule 8 is sealed between junctures of the upper and lower laminae 12 and 15, the latter seal defining a circular area central to the toroidal ampule 8.

All of the ampules are substantially filled with liquid 16 illustrated in FIGS. 4a and 4b. The liquid filler may be selected from numerous media including water; alcohols such as ethanol, isopropanol, n-hexanol, cyclohexanol, trichloroethanol, lauryl alcohol, n-octanol, and n-decanol; esters such as ethyl acetate, isopropyl formate, methyl and ethyl propionate, and isopropyl acetate; halogenated compounds such as dichloroethylene, chloroform, and carbon tetrachloride; and oils such as mineral oil and silicon oil. It will be appreciated by a skilled artisan that the choice of liquid filler is dictated by the specific parameters of intended use and materials of construction. Hence, depending on the hydrodynamics desired for a particular use, a liquid of relatively low viscosity may be chosen. Alternatively, it may be desirable to use a liquid of relatively high viscosity such as a mineral oil or a higher alcohol or ester. Of course, any liquid mixture may be employed which satisfies the requirements of viscosity and compatibility with materials of construction. For example, if the insole is constructed of polyvinyl chloride (PVC), one would not employ as a filler a liquid which is a solvent for PVC or which would leach out the plasticizer in the PVC. Although the range of usable liquids is practically limitless, it is preferred to use water or mineral oil because of (a) their low cost and (b) their harmless nature with respect to human skin should the construction material fail and the liquid contact the wearer's foot.

Equally broad is the selection of material from which the laminae and ampules are constructed. This material should be soft and pliant. It should be strong enough to withstand constant flexing under the weight of the wearer. Illustrative of these are rubber, foamed rubber, ABS copolymers, polyethylene, foamed polyethylene, polyvinyl choride and its copolymers, polyurethane, foamed polyurethane, polyisobutylene, and polyisoprene. Also of use are various resin mixtures and copolymers which fall within the framework of softness, strength and compatibility with the filler liquid. In addition, the construction material must lend itself to sealability so that permanent seals between laminae can be achieved.

Broadly, the insole is made by first forming liquid-filled ampules of the shape desired for the specific orthopedic functions desired. These ampules are then placed between two outer laminae which are shaped to conform to the insole of a shoe. The laminae are then sealed together to permanently position the ampules.

A particular method for making the invention is described as follows:

A die such as that illustrated in FIG. 5 is fabricated from brass and mounted in an aluminum base 20. The die 21 is shaped in accordance with a particular shoe size which is defined by raised ridge 22 which extends peripherally around the insole outline. Inside the raised periphery portion are other ridges or raised portions such as 23, 24 and 25 which define concave sections which correspond generally to the desired ampule shapes. At the bottom of each concave section, a hole is drilled completely through the die and its base. The purpose of these holes are to enable vacuum forming as will become evident, infra.

To form the ampules, a first lower lamina of flexible material impervious to the liquid to be employed as a filler is placed over the die. A heat source sufficient to soften the material is applied from above while simultaneously, a vacuum is drawn from the bottom of the die. Upon removal of the heat source and cooling, the first lower lamina now conforms to the shape of the die having raised ridges defining first concave sections congruent to those of the die. Such a formed lamina is depicted by FIG. 3.

Next, the concave sections are filled with the liquid to be employed and the first lower lamina, while still in place on the die, is covered by a first upper lamina. The two laminae are then sealed at their periphery and at the raised portions, utilizing any of the numerous known methods such as heat fusion, pressure sealing, cement, high frequency sound waves, etc. One preferred method is by use of a 11/2 kilowatt high frequency generator manufactured by Sealomatic Electronics Corporation of Brooklyn, N.Y. The finished ampules are then removed from the die and are left intact as a unitary structure or separated from each other by seal tearing. Hence, the first laminae may be sealed to facilitate tearing to separate the ampules.

A second lower lamina is then formed in the same way as the first lower lamina. The same or a slightly larger die can be used for this purpose and the finished second lower lamina is shaped to provide raised ridges defining second concave sections which conform substantially identically to the ampules and to the first concave sections. The ampules are then placed on the second lower lamina such that each ampule fits into its respective second concave section. The emplaced ampules are then covered with a second upper lamina which is sealed to the second lower lamina at their periphery and at the raised portions thereby completely enclosing the ampules and permanently positioning them.

The following example is provided to further illustate the present invention.


A sheet of polyvinyl chloride manufactured by Union Carbide Corporation under the trademark "Krene", specification No. KDA-2088, which is pinhole-free and having a thickness of 8-20 mils was laid over a die as described supra and shown in FIG. 5. Heat sufficient to soften the material was applied from above and a partial vacuum was applied to the base of th4 die. After the softened PVC had conformed to the die, the heat source was removed and the shaped PVC was cooled by spraying it with compressed air at ambient temperature. The molded sheet was then flooded with water to fill the concave sections formed in it.

Another sheet of the same material was then placed over the water-filled sheet and die and sealed in a 11/2 kilowatt high frequency generator manufactured by Sealomatic Electronics Corporation. Upon removal from the sealing generator, the sealed ampules produced were separated from each other. The separated ampules conformed in shape substantially to FIG. 2 which depicts the separated ampules.

Next, a sheet of the same PVC material was placed over the same die, and formed by application of heat and vacuum substantially as above. After cooling this formed sheet with compressed air, the separated ampules were each placed in their correspondingly shaped concave sections and covered by another sheet of the same PVC. The ampules were then sealed between the PVC sheets using the above high frequency generator. After sealing, the finished insole was removed from the sealing unit and excess PVC was trimmed from the insole periphery.

Other features and embodiments of the present invention will be apparent in light of the foregoing discussion. The foregoing example is presented as merely illustrative of a preferred embodiment and is in no way meant to limit the invention.