Patent Application
20060086004
1. Field of the Invention
This invention relates to a custom molded foot support and footbed assembly for use in footwear. In addition, this invention relates to a method for forming a custom fitted foot support.
2. Description of Related Art
Podiatric orthosis, also a type of shoe insoles, are frequently used to a support a person's foot and to aid or correct the accommodative function of the foot when walking. Shoe insoles are often made from a material formed from a resilient semi-rigid sheet of thermoplastic material.
Orthotics serve to properly adjust the orientation of a person's foot during gait, thereby controlling the motion of the foot in view of mitigating the effects of persons having anomalies in a foot. A patent that describes such a podiatric orthosis is U.S. Pat. No. 6,173,511 to Perrault, which describes an insole formed to conformingly fit against the plantar portion of a foot extending from the anterior metatarsal region to the heel portion. The orthosis is positioned inside a shoe against the plantar portion of the foot with the intermediate portion engaging the foot arch. The heel portion of the orthosis has inner and outer rearward extending residually deformable arms defining a rearward-opened notch therebetween. The front portion of the orthosis has concavities which prevent foot plantar lesions while promoting stabilization and positional self adjustment of the orthosis inside the footwear. An advantage of this orthosis is that the cup-like heel seat partly surrounding the heel serves to concurrently support the foot while allowing positional self-adjustment of the orthosis inside the footwear.
Another example of a shoe insole, that extends to the ball of the foot is shown in U.S. Pat. No. 6,282,816 to Rosendahl and describes a stiff outer plastic shell molded to a dual foam inner layer of rubber-like material and a fabric upper layer engages the underside of the entire foot. A fabric top layer is provided that is cut to the size of the footwear. Under the fabric layer is a composite foam rubber layer that has a main part of soft rubber and an arch part of dense/foam rubber. The composite layer is a polymer-type material such as ethyl vinyl acetate. These two layers are molded into one piece that makes up a foam sub-layer. A rigid plastic outer shell made of nylon or the like is injection molded and extends to the ball of the foot.
A multi-layered insole that underlays the entire foot is shown in U.S. Pat. No. 5,718,064 to Pyle. The insole has a flexible PVC outer member containing on its upper surface a polyurethane insert for shock absorption that increases cushioning. The insole may also have on the upper surface of the outer member a contoured footbed formed of ethylene vinyl acetate.
In U.S. Pat. No. 6,025,414 to Rich there is disclosed an insert for use in an athletic shoe made from a novel heat moldable polymeric composition. The inserts can be placed at the tongue of the shoe, at the heel and/or upon all or some of the length of the insole. The moldable compositions include a combination of a blend of a thermoplastic polymer such as polycaprolactone, a resiliency component such as styrene-butadiene copolymer or styrene-isoprene copolymer, and a softening agent, such as mineral oils.
U.S. Pat. No. 6,110,134 to Clark, Jr., et al. describes gel padded thermoplastic splints. In particular, the synthetic splint materials have a layer of gel-like viscoelastic padding. Preferably, materials for the splint base include those synthetic casting materials providing lightweight cast of low temperature thermoplastic material, i.e., materials that soften under relatively low heat, say, below 200° F., and are capable of being molded with hand pressure and subsequently harden to retain the molded shape on a cooling without undergoing chemical change. Some of the low temperature materials include such things as poly(ethylene adipate), trans polyisoprene and polycaprolactone. The padding material is bonded to the splinting material. The padding materials found to be particularly effective include a viscoelastic having a gel-like property such as polyurethane, a polyvinyl chloride or a silicone material.
There are two classes of custom orthotics available: those that used a cast of foot (in an unloaded position) as an intermediate step and those that are accommodative and mold to the foot in a loaded state. A problem associated with most shoe insoles is that they are not custom fitted to the wearer's foot. The subject invention overcomes this problem by providing a custom molded shoe insole and a method for making same that is molded directly to the foot and thus addresses any abnormality of the foot, heel, arch or toes.
It has been found that a foot support manufactured as part of a footwear or inserted into the footwear conforming to at least a portion of a user's foot may be custom molded from thermoplastic materials. The custom foot support is molded from a piece of thermoplastic material that may cover the entire bottom of the foot or any portion the foot such as the heel, arch or toe or combinations thereof. Preferably the foot support extends from the heel to just short of the ball of the foot, including the metatarsal arch and is molded to conform to the plantar portion of the user's foot and inserted on top of the existing shoe insole or in some cases replace the existing insole. After custom molding, the foot support defines a monolithic resilient supportive member having inner and outer lateral sides, a front portion, a rear portion and an arch portion. The inner side of the support member has a generally convex shape and provides and corrects the accommodative function of the foot when walking. The outer side of the supportive member has a generally concave shape for occupying less volume inside the footwear; thus enhancing comfort of the person using the foot support.
In a preferred embodiment, the arch portion of the supportive member is arched for complementary engagement against the foot plantar arch. Moreover, under the resiliency of the supportive member due to the arched shape of arch portion, the latter will have a positive substantially vertical spring-back effect on the foot arch portion during gait, for promoting corrective foot positioning. The front portion is integrally frontwardly extending from the arch portion for complementary engagement near the metatarsal plantar region of the foot. The rear portion has a raised concave periphery formed from the molded material for partial resting abutment of the person's heel onto the sides for engagement around the heel portion of the foot. The cup-like heel seat surrounds the heel to concurrently support the foot which allowing positional self-adjustment of foot support inside the footwear.
In one embodiment, the supportive member is fabricated from an injection molded blank or a sheet of thermoplastic material, that may be formed to shape in a custom application. Preferred materials for the foot support are those low temperature thermoplastic materials providing easily formable shapes that soften at a plastic temperature between 120° F. and 180° F. and are capable of being molded and shaped with hand pressure, and subsequently harden retaining the molded shape on cooling without undergoing chemical changes. A low temperature material, suitable for use as a foot support should soften at sufficiently low temperatures so as to allow for molding directly on the foot without injury due to scalding or burning of the skin. Suitable polymers include poly(ethyleneadipate), poly(epsilon-caprolactone), polyvinyl stearate, cellulose acetate, butrylate and ethyl cellulose poly (propylene oxide) containing co-monomers, trans polyisoprene and cis polyisoprene based thermoplastic materials, and polycaprolactone based materials.
The invention also contemplates a method for custom forming the supportive member. The thermoplastic material is placed in hot water and between 120° F. and 180° F. At this temperature the thermoplastic material becomes very pliable. The softened thermoplastic material is then applied to the bottom of the foot, while the foot is preferably in a non-weight bearing position. When the soft material is applied to the foot it is molded by hand to all the curves and dimensions of the foot from around the heel up to and including the metatarsal arch and toes, if desired. After molding, the shaped foot support is allowed to set. Setting takes place within about 60 seconds. It may take another three to five minutes to fully cure and cool. Once cooled the foot support is placed within the shoe and will support the foot heel pain arch metatarsal arch comfortably. The foot support comes in different sizes, but due to the unique moldability of the thermoplastic material to fit different feet, multiple sizes may not be necessary.
In addition to the use of thermoplastic materials that soften at low temperature, the custom formed foot support of the present invention may be made using chemicals that are reacted at the time of custom molding that will polymerize to the desired shape when molded to the bottom of a foot while the foot is in a non-weight bearing position. Suitable thermoplastic materials include materials for forming polysilicone polymers.
In yet another embodiment of the invention a footbed assembly is formed of a plurality of members including a cushioning top layer overlaying at least a portion of the resilient molded thermoplastic foot support. The footbed assembly may include at least one member made of textile, leather or synthetic material to provide comfort against the skin. In addition, the footbed assembly may include at least one member made of foam to cushion the foot against the rigid supportive member. A suitable cushioning top layer is one that may be readily bonded to the molded thermoplastic foot support after the custom molded foot support formed. Bonding may be accomplished by any of several known suitable systems. The cushioning top layer may be ethyl vinyl acetate (EVA) foam, a Plastizote® material or the like. The cushioning layer extends continuously over the upper surface of the supportive member. The supportive member may also include cut outs and dimples to provide extra shock-absorption and comfort to the user's foot.
It is an object of the present invention is to provide a foot support for engagement inside footwear and for conformingly fitting against a user's foot for compensating podiatric deficiencies.
Another object of the present invention is to provide a footbed assembly having a plurality of layers that provide comfort against the skin and cushion the foot against the rigid supportive member.
Yet another object of the present invention is to provide footwear having the supportive member of the present invention.
Still another object of the present invention is to provide a method for forming a molded foot support that is conformingly fitting against a user's foot made from a low temperature softening thermoplastic material.
The foregoing and other objects, advantages and features of the invention, and manners in which the same are accomplished, will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings which illustrate preferred and exemplary embodiments wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
There is shown in
The arch portion 26 of supportive member 20 is arched for complementary engagement against the foot plantar arch as shown in
The front portion 24 is integrally frontwardly extending from the arch portion 26 for complementary engagement near the metatarsal plantar region of the foot. In a preferred embodiment, the front portion 24 has a sinuous front edge 29 comprising a series of or recesses 30, 30a, and 30b, to form a number of frontwardly facing arcuate concavities. Front edge 29 is generally frontwardly convex so as to conform to the forefoot configuration. The upper surface of supportive member 20 may also have dimples thereon to provide extra shock-absorption and comfort to the user's foot.
The rear portion 25 has a raised concave periphery 28 formed from the molded material for partial resting abutment of the person's heel onto the sides for engagement around the heel portion of the foot. The cup-like heel seat surrounds the heel to concurrently support the foot which allowing positional self-adjustment of supportive member 20 inside the footwear.
In use, foot support 10 is positioned inside a footwear (not shown) against the plantar portion of the foot with the arch portion 26 conformingly engaging the underface of the foot arch. The rear portion 25 engages the heel of the person's foot. Raised periphery 28 complementarily engages the heel of the foot so as to partly surround the heel so as to form a cup-like seat for the heel and thus assist positioning the foot support in its proper position.
Thus, positional self-adjustment of the foot support is accomplished during gait by the load of the person being applied on his heel and against the raised periphery 28 that is yieldingly resiliently moved apart and pressed against the footwear inner walls to correctly re-position the support in the footwear if accidental temporary displacement of the support occurs. The raised periphery 28, in addition to promoting positional self-adjustment of the supportive member 20 in the footwear, also provides positive foot support to enhance corrective foot positioning in the footwear. The supportive member 20 comes in different sizes, but due to the unique moldability of the thermoplastic material to fit different feet, multiple sizes are not necessary.
The supportive member 20 shown in
It will be understood by those skilled in the art that the foot support 10 may be manufactured as a component of the footwear on the interior thereof and removed from the footwear for custom fitting replaced in the footwear. The foot support is normally used at temperatures between −20° F. and 125° F.
Particular advantage is achieved in the present invention by fabricating the supportive member 20 from an injection molded blank or a sheet material (which has been precut to a preferred configuration), so that the surface may be later shaped to form a custom application. Preferred materials for the foot support are those low temperature thermoplastic materials providing easily formable shapes. Low temperature thermoplastic and thermoset materials are those which soften at a plastic temperature between 120° F. and 180° F. and are capable of being molded and shaped with hand pressure, and subsequently harden retaining the molded shape on cooling without undergoing chemical changes. Many of these materials change color and opacity when heated to their softening point. A low temperature material, suitable for use as a supportive member should soften at sufficiently low temperatures so as to allow for molding directly on the foot without injury due to scalding or burning of the skin. The materials in its softened state should permanently deform under a load of 15 psi. Suitable polymers which melt or soften at temperatures between 120° F. and 180° F. include poly(ethyleneadipate), poly(epsilon-caprolactone), polyvinyl stearate, cellulose acetate, butrylate and ethyl cellulose poly (propylene oxide) containing co-monomers, trans polyisoprene and cis polyisoprene based thermoplastic materials, and polycaprolactone based materials. In a preferred embodiment of the present invention, the thermoplastic material is polycaprolactone. The softening point of polycaprolactone is about 140° F.
The invention also contemplates a method for custom forming the supportive member 20. The thermoplastic material has a softening point and molding temperature sufficiently low that the material may be heated in a conventional manner such as in hot water, in a microwave, or in a conventional oven, or with a heat gun. Microwave ovens are particularly useful for heating and softening the composition for fitting, as is heated water. In practice, the supportive member may be placed in a forming tray that can contain at least 500 ml of hot water and allowed to soften. A conventional oven may also be used. Additionally, wire filaments may be place into the thermoplastic material. When an electric current is applied to the wire filaments the resulting heat will soften the thermoplastic. The thermoplastic material can be refitted and reused by simply reheating. The preferred thermoplastic materials of this invention become pliable like a wet noodle between the temperatures of 120° F. and 180° F. The softened thermoplastic material is then shaped and detailed to the bottom of the user's foot. The supportive member is preferably formed while the user's foot is in a non-weight bearing position but it should be understood that the molding may be accomplished while the user's foot is in a weight bearing position. The soft material is applied to the foot is molded by hand to all the curves and dimensions of the foot from around the heel up to and including the metatarsal arch and toes, if desired. After molding, the material is allowed to set. Setting usually occurs quickly, often within about 60 seconds. It may take another three to five minutes to fully cure and cool. Once cooled, the foot support is ready to use and may be placed within the shoe and will support the foot heel pain arch metatarsal arch comfortably. Skin burns during the molding process are avoided because of the low molding temperature of the thermoplastic. Further, the composition's low molding temperature allows the thermoplastic material to be held against the user's foot. When cooled, the thermoplastic material preferably will not permanently deform under 25 psi and will have a flexural modulus of CAPA 6500 of about 300 to 500 MPa (ASTM D790) at normal use temperatures.
In addition to the use of thermoplastic materials that soften at low temperature, the custom formed supportive member 20 may be made using two chemicals that are reacted at the time of custom molding that will polymerize to the desired shape when molded to the bottom of a foot while the foot is in a non-weight bearing position. Suitable thermoplastic materials include, for example, polysiloxanes. Suitable materials for forming polysilicone polymers are available from Silcones, Inc. and DowCorning.
The present invention also contemplates yet another embodiment. This embodiment, that is shown in
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
