Abstract:
A metatarsal arch support is described, in which the support has a raised section of such a size and shape as to roughly match and fill the open space that exists between the insole of the shoe and the portion of the foot that spans the second, third, and fourth metatarsals, which normally constitutes an arch when the foot is supporting body weight. Shoes typically exert pressure, causing the metatarsal arch to flatten. Use of the arch support prevents this undesirable effect.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a device, and a method of using such a device, to provide support to the metatarsal arch of a human foot.  
         BACKGROUND OF THE INVENTION  
         [0002]    For the purposes of stabilizing the foot, the metatarsal heads constitute an arceate form referred to as the metatarsal arch. The metatarsal arch is present whenever the foot is supporting body weight, such as during standing, walking or running, because it allows the foot to function maximally as a supporting, stabilizing and balancing appendage. The toes flex as a result of the formation of the metatarsal arch, so that the distal phalanges contact squarely the underlying surface to permit balancing. In addition, the formation of the metatarsal arch permits the lateral edge of the foot&#39;s sole to squarely contact the underlying surface, for the purpose of supporting body weight. Finally, various muscles and tendons characteristically interact to stabilize the foot, support body weight and permit balancing against underlying surfaces.  
           [0003]    The term “toe-off” or “push-off” is used to denote the sequence of progressive movements normally experienced in a walking or running gait in preparation for movement from the neutral position, with a neutral position being defined as the subtalar joint being neither pronated nor supinated, to a propulsive phase of the gait cycle. Shoes may apply pressure to the dorsal (upper) surface of the foot because they are not correctly shaped to match the natural contours of the foot, and so prevent entirely the formation of the metatarsal arch. It is sometimes possible to shape a shoe to match the natural contours of the foot so as to not apply pressure to the foot when standing. However, if the shoe is not loose enough or soft enough to apply no pressure to the foot regardless of what position the foot is in, walking or running results in creasing across the top of the shoe when the foot pushes off, applying pressure to the foot and causing the metatarsal arch to flatten.  
           [0004]    Metatarsal arch supports are intended to counter these interactions by providing a force opposed to flattening of the arch. However, although the idea of a metatarsal arch support is not new, existing designs are problematic because they provide support under areas of the foot designed to flatten out during normal foot movement and/or under areas of the foot not designed for direct weight bearing, or are incorrectly shaped to match the natural contours of the foot. As a result such designs create additional problems while attempting to solve the original one. Thus there continues to be a need for methods and devices to support the metatarsal arch without adventitiously creating other problems.  
         SUMMARY OF THE INVENTION  
         [0005]    In one aspect, the invention is a metatarsal arch support for a foot in a shoe, the shoe comprising an insole, the foot comprising:  
           [0006]    (a) a front part and a plurality of toes, the toes comprising first, second, third, fourth, and fifth proximal phalanges,  
           [0007]    (b) first, second, third, fourth and fifth metatarsals joined to the first, second, third, fourth, and fifth proximal phalanges at first, second, third, fourth, and fifth metatarsal heads, respectively,  
           [0008]    (c) a fleshy pad on a plantar surface of the foot comprising a front boundary underlying the first, second, third, fourth and fifth proximal phalanges and a back boundary underlying the first, second, third, fourth, and fifth metatarsals, comprising a recessed apex approximately between the first and second metatarsal heads,  
           [0009]    (d) a first inflection boundary on the fleshy pad underlying the second, third, and fourth metatarsals,  
           [0010]    (e) a second inflection boundary on the fleshy pad underlying the second, third and fourth proximal phalanges, approximately coinciding with the front border,  
           [0011]    (f) a third inflection boundary on the fleshy pad between the first and second metatarsals, and  
           [0012]    (g) a fourth inflection boundary on the fleshy pad between the fourth and fifth metatarsals,  
           [0013]    the arch support comprising a base and an upper surface contoured to comfortably lie adjacent an area of the fleshy pad bounded by the first, second, third, and fourth inflection boundaries, the upper surface comprising a highest point, the base being at a shoe insole level, wherein the arch support rises from the base to the highest point, wherein the highest point underlies the recessed apex.  
           [0014]    In another aspect, the invention is a method for supporting a foot in a shoe, the shoe comprising an insole, the foot comprising  
           [0015]    (a) a front part and a plurality of toes, the toes comprising first, second, third, fourth, and fifth proximal phalanges,  
           [0016]    (b) first, second, third, fourth and fifth metatarsals joined to the first, second, third, fourth, and fifth proximal phalanges at first, second, third, fourth, and fifth metatarsal heads, respectively,  
           [0017]    (c) a fleshy pad on a plantar surface of the foot comprising a front boundary underlying the first, second, third, fourth and fifth proximal phalanges and a back boundary underlying the first, second, third, fourth, and fifth metatarsals, comprising a recessed apex approximately between the first and second metatarsal heads,  
           [0018]    (d) a first inflection boundary on the fleshy pad underlying the second, third, and fourth metatarsals,  
           [0019]    (e) a second inflection boundary on the fleshy pad underlying the second, third and fourth proximal phalanges, approximately coinciding with the front border,  
           [0020]    (f) a third inflection boundary on the fleshy pad between the first and second metatarsals, and  
           [0021]    (g) a fourth inflection boundary on the fleshy pad between the fourth and fifth metatarsals,  
           [0022]    the method comprising providing in the shoe a metatarsal arch support for the foot, the arch support comprising a base and an upper surface contoured to comfortably lie adjacent an area of the fleshy pad bounded by the first, second, third, and fourth inflection boundaries, the upper surface comprising a highest point, the base being at a shoe insole level, wherein the arch support rises from the base to the highest point, wherein the highest point underlies the recessed apex.  
           [0023]    In yet another aspect, the invention is a metatarsal arch supporting shoe insole for supporting a foot in a shoe, the foot comprising:  
           [0024]    (a) a front part and a plurality of toes, the toes comprising first, second, third, fourth, and fifth proximal phalanges,  
           [0025]    (b) first, second, third, fourth and fifth metatarsals joined to the first, second, third, fourth, and fifth proximal phalanges at first, second, third, fourth, and fifth metatarsal heads, respectively,  
           [0026]    (c) a fleshy pad on a plantar surface of the foot comprising a front boundary underlying the first, second, third, fourth and fifth proximal phalanges and a back boundary underlying the first, second, third, fourth, and fifth metatarsals, comprising a recessed apex approximately between the first and second metatarsal heads,  
           [0027]    (d) a first inflection boundary on the fleshy pad underlying the second, third, and fourth metatarsals,  
           [0028]    (e) a second inflection boundary on the fleshy pad underlying the second, third and fourth proximal phalanges, approximately coinciding with the front border,  
           [0029]    (f) a third inflection boundary on the fleshy pad between the first and second metatarsals, and  
           [0030]    (g) a fourth inflection boundary on the fleshy pad between the fourth and fifth metatarsals,  
           [0031]    the insole comprising a substantially flat section and a raised section, the raised section comprising a base and an upper surface contoured to comfortably lie adjacent an area of the fleshy pad bounded by the first, second, third, and fourth inflection boundaries, the upper surface comprising a highest point, the base being at a level contiguous with the flat section, wherein the arch support rises from the base to the highest point, wherein the highest point underlies the recessed apex.  
           [0032]    In a further aspect, the invention is a shoe comprising an integral metatarsal arch supporting shoe insole for supporting a foot, the foot comprising:  
           [0033]    (a) a front part and a plurality of toes, the toes comprising first, second, third, fourth, and fifth proximal phalanges,  
           [0034]    (b) first, second, third, fourth and fifth metatarsals joined to the first, second, third, fourth, and fifth proximal phalanges at first, second, third, fourth, and fifth metatarsal heads, respectively,  
           [0035]    (c) a fleshy pad on a plantar surface of the foot comprising a front boundary underlying the first, second, third, fourth and fifth proximal phalanges and a back boundary underlying the first, second, third, fourth, and fifth metatarsals, comprising a recessed apex approximately between the first and second metatarsal heads,  
           [0036]    (d) a first inflection boundary on the fleshy pad underlying the second, third, and fourth metatarsals,  
           [0037]    (e) a second inflection boundary on the fleshy pad underlying the second, third and fourth proximal phalanges, approximately coinciding with the front border,  
           [0038]    (f) a third inflection boundary on the fleshy pad between the first and second metatarsals, and  
           [0039]    (g) a fourth inflection boundary on the fleshy pad between the fourth and fifth metatarsals,  
           [0040]    the insole comprising a substantially flat section and a raised section, the raised section comprising a base and an upper surface contoured to comfortably lie adjacent an area of the fleshy pad bounded by the first, second, third, and fourth inflection boundaries, the upper surface comprising a highest point, the base being at a level contiguous with the flat section, wherein the arch support rises from the base to the highest point, wherein the highest point underlies the recessed apex, wherein the insole is permanently affixed to the shoe.  
           [0041]    It has been found that good metatarsal arch support can be provided by the methods and devices of this invention. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0042]    [0042]FIG. 1 is a schematic illustration of the bones of a human right foot, viewed from the dorsal (top) side, showing the first through fifth proximal phalanges, the first through fifth metatarsal heads, and the first through fifth metatarsals.  
         [0043]    [0043]FIG. 2 shows the plantar (bottom) surface of the front part of a right human foot, showing a fleshy pad comprising a recessed apex, and indicating the locations of four inflection borders.  
         [0044]    [0044]FIG. 3A illustrates an arch support for a right foot, in accordance with the present invention.  
         [0045]    [0045]FIG. 3B shows the plantar (bottom) surface of a right foot with the arch support in place, showing the base of the support.  
         [0046]    [0046]FIG. 4 is a front view of a right foot showing a metatarsal arch in relation to the arch support, whose highest point is indicated.  
         [0047]    [0047]FIG. 5A is a right side view of a right foot shoe, illustrating one embodiment of the invention.  
         [0048]    [0048]FIG. 5B is a cutaway front view along arrows  5 B- 5 B of the shoe illustrated in FIG. 5A, showing the arch support within the shoe.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]    Metatarsal Arch Support  
         [0050]    The invention will next be described with reference to the Figures in which same numerals are used to identify same elements in all Figures. The Figures are used as illustrations of the invention and are not intended to be limiting, nor are they in scale.  
         [0051]    Referring next to FIG. 1 there is shown in schematic representation a dorsal (top) view of human foot  10 . Briefly such foot comprises first proximal phalange  12 , second proximal phalange  14 , third proximal phalange  16 , fourth proximal phalange  18 , and fifth proximal phalange  20 ; first metatarsal  32 , second metatarsal  34 , third metatarsal  36 , fourth metatarsal  38 , and fifth metatarsal  40 ; where the ends of the metatarsals where they attach to the respective phalanges are referred to as the first metatarsal head  22 , the second metatarsal head  24 , the third metatarsal head  26 , the fourth metatarsal head  28 , and the fifth metatarsal head  30 .  
         [0052]    [0052]FIG. 2 shows a schematic representation of the bottom of the front part of a human right foot, identifying certain parts of the foot that are used for the proper location of the arch support relative to the foot, according to the present invention. A portion of the foot identified as a fleshy pad  11  is shown, extending in the front part partially over the first through fifth proximal phalanges  12 ,  14 ,  16 ,  18 , and  20 , and rearward over a portion of first through fifth metatarsal  32 ,  34 ,  36 ,  38 , and  40 . Fleshy pad  11  comprises a recessed apex  13  located roughly between the first and second metatarsal heads  22  and  24 . A first inflection boundary  42  lies across second, third, and fourth metatarsals  34 ,  36 , and  38  at approximately the point where fleshy pad  11  ends at its rearward edge. By “inflection border” is meant a straight or curved line along the plantar surface of the foot where a crease is formed or a change in direction occurs in the curvature of the surface. A second inflection boundary  44  lies across second, third, and fourth proximal phalanges  14 ,  16 , and  18  at approximately the point where fleshy pad  11  ends at its forward edge. A third inflection boundary  46  lies along and between first and second metatarsals  32  and  34 , beginning approximately at first and second metatarsal heads  22  and  24  and extending part way down the length of  32  and  34 . A fourth inflection boundary  48  lies along and between fourth and fifth metatarsals  38  and  40 , beginning approximately at fourth and fifth metatarsal heads  28  and  30  and extending part way down the length of  38  and  40 .  
         [0053]    [0053]FIG. 3A shows in schematic representation an arch support according to this invention. The support has a generally pyramidal structure with a highest point  60 . The support tapers gradually from the highest point in three directions towards points  54 ,  56 , and  58  on a support base  51  and tapers toward the base sharply in a fourth direction towards point  52  on base  51 . In one embodiment the support taper towards point  52  is substantially vertical.  
         [0054]    [0054]FIG. 3B shows the positioning of the support relative to the foot. The pyramidal design of the support and the location of the support relative to the foot are both significant elements of this invention. As is shown, the highest point  60  (i.e. the apex of the pyramid) is located at approximately the position of recessed apex  13  in fleshy pad  11 . The base  51  extends longitudinally and laterally along the insole under the foot in an area roughly bounded by the first through fourth inflection borders  42 ,  44 ,  46 , and  48 . The result of this positioning is that support is provided under second, third, and fourth metatarsals and proximal phalanges, labeled  34 ,  36 ,  38  and  14 ,  16 ,  18 , respectively. However, contact with the insole of fleshy pad  11  under the first and fifth metatarsals  32  and  40 , the first and fifth metatarsal heads  22  and  30 , and the first and fifth proximal phalanges  12  and  20 , is not impeded.  
         [0055]    [0055]FIG. 4 shows in schematic representation the relative position of the support under a right foot  10  viewed from the front. The support shape generally conforms to the natural curvature of the metatarsal arch  62 , defined by the location of the first through fifth metatarsal heads. Support  50  rises gently from the area near the small toe to a highest point  60  between the first and second metatarsals, and then cuts back sharply to insole level  63 , such that the large toe is not supported.  
         [0056]    The arch support according to this invention has been described as having a generally pyramidal shape and has been illustrated as having three distinct faces and a base. The number of distinct faces is not critical even though the preferred number is three. The base is approximately quadrilateral, with the face and boundary of the support along the inflection boundary  44  typically being curved to imitate the typical curvature of boundary  44 . Boundaries and faces of the support corresponding to boundaries  42 ,  44 , and  48  similarly imitate the typically straight geometry of these boundaries, and so are typically straight. The face of the support along which the fleshy pad rests typically is contoured in a manner complementary to the curvature of the fleshy pad, and the highest point  60  is preferably curved, so that the support will not press uncomfortably against the underside of the foot. As well, since the shapes of individual feet vary considerably, the exact dimensions of the arch support will also vary.  
         [0057]    [0057]FIGS. 5A and 5B show the support according to this invention positioned within a shoe. As shown in FIG. 5A, a shoe  64  having an upper portion  66 , and insole  68 , and an outsole  70  is fitted with a support  50  having a highest point  60 . The support is located in the toe section of the shoe, where it may float free or be attached to insole  68 . FIG. 5B is a cutaway front view of shoe  64 , showing the lateral location of support  50  on insole  68 , and the location of highest point  60 .  
         [0058]    The arch support may be attached to or integral with an insole, or may float free above the insole and be allowed to position itself naturally under the metatarsal arch. If the support is attached to or integral with an insole, the insole may be supplied as an insert for placement in a shoe by the user, or may be an integral part of a shoe as supplied. FIGS. 5A and 5B are views of arch support  50  on an insole  68 , which may be integral with a shoe or supplied as an insert.  
         [0059]    According to this invention, there is provided a foot support for use within a shoe. In use, the support is designed such that when placed in a shoe, it lies on the sole directly under the fleshy pad covering the plantar side of the second, third, and fourth metatarsal heads. When so placed, as a person walks or when using shoes with high heels that force the foot in an inclined position, the support maintains the arch in its natural shape working against the shoe material pressure on the dorsal side of the foot.  
         [0060]    The support is preferably constructed of a resilient material, by which is meant that the material is compressible but will return to its original shape after the compressing force is removed. However, the material must be firm enough that it will not be compressed excessively when weight is applied to the foot. It will be appreciated that a variety of factors such as body weight may affect how resistant to compression the material should be for optimal effect, and therefore a variety of materials can be used as needed to suit the needs of different individuals.  
         [0061]    Useful materials include, inter alia, cross-linked polyethylene, poly(ethylenevinyl acetate), polyvinyl chloride, synthetic and natural latex rubbers, neoprene, acrylonitrile-butadiene-styrene or styrene-butadiene-styrene block copolymers, thermoplastic elastomers, ethylene-propylene rubbers, silicone elastomers, polystyrene, polyurea, or polyurethane. A preferred material is a polyurethane foam comprising the reaction product of a polyol comprising a flexible chain with any of a monomeric isocyanate, a prepolymerized diisocyanate based on 4,4′-diphenylmethane diisocyanate, a prepolymerized diisocyanate based on toluene diisocyanate, or a mixture of any of these. The foregoing are examples of useful materials of construction for the support, but others will be well known to those skilled in the art.  
         [0062]    Such foams can be blown with a chlorofluorocarbon, water, methylene chloride or other gas-producing agents, as well as by mechanically frothing to prepare the shock absorbing resilient layer. Such foams advantageously can be molded into the desired shape or geometry. Non-foam elastomers such as the class of materials known as viscoelastic polymers, or silicone gels, which show high levels of damping when tested by dynamic mechanical analysis performed in the range of −50° C. to 100° C. may also be advantageously employed.  
         [0063]    Alternatively, the support can be a laminate construction, that is, a multilayered composite of any of the above materials. Multilayered composites are made from one or more of the above materials such as a combination of polyethylene vinyl acetate and polyethylene (two layers), a combination of polyurethane and polyvinyl chloride (two layers) or a combination of ethylene propylene rubber, polyurethane foam and ethylene vinyl acetate (3 layers). Preferably, the support is made from a molded urethane material.  
         [0064]    In another embodiment of the invention, for example when the support is to be used in conjunction with wooden clogs, the support may be made of a hard, non-resilient material, including but not limited to wood or a hard polymeric material. When a hard material is used to make the support, special attention may be required regarding the specific contouring and dimensions of the support, to accommodate its lack of resiliency. In particular, the highest point  60  may advantageously be not quite high enough to directly contact the bottom of the foot when no load is on the foot, so that the support does not need to be compressed to accommodate foot movements.  
         [0065]    The invention is especially useful for supporting the metatarsal arch of a human foot in a shoe. It reduces or eliminates compression of the metatarsal arch due to pressure resulting from the flexing and creasing of the top of the shoe, and thereby helps to maintain the stabilizing function of the arch. The support can be employed in either a free-floating manner, or permanently affixed to an insole, which itself may optionally be permanently affixed to a shoe.  
         [0066]    Having described the invention, we now claim the following and their equivalents.