Patent Publication Number: US-2012023776-A1

Title: Shoe sole inserts for pressure distribution

Description:
FIELD OF THE INVENTION 
     The present invention is directed to inserts for shoes. More particularly, the invention relates to shoe in-sole inserts that provide for pressure distribution across defined areas of the foot. 
     BACKGROUND 
     Shoe inserts are widely available devices that are useful to increase the comfort of shoes or prolong the useful lifetime of shoes. Inserts can also be specifically designed orthotic devices used to relieve painful conditions, such as corns, calluses, metatarsal conditions, or other painful conditions of the foot. Over-the-counter shoe inserts are relatively inexpensive but can provide limited relief of many conditions. Specially designed orthotics can provide more relief, but are expensive, inconvenient to replace, and are typically relatively non-adjustable. 
     Accordingly, there remains a need in the art for shoe inserts that are relatively inexpensive, widely available, provide relief for a wide range of painful and/or damaging foot conditions, and are easily adjustable to provide therapeutic benefit to a wide range of users with a wide range of conditions affecting the foot. The present invention meets this need. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention are directed to a shoe insert that can provide therapeutic benefit to a user by modulating pressure applied to the foot of a user. The shoe insert of the invention makes use of a combination of removable pressure pads and a pressure moderator to beneficially alter pressure transfer between the sole of a shoe and the foot of a user. 
     In one embodiment, the present invention provides a removable insert for placement in a shoe between the shoe sole and the foot of a user. The insert comprises a formed pressure moderator sheet and a series of discrete pressure pads removably and replaceably attached to the moderator sheet. The moderator sheet is positioned to separate the pressure pads from the foot of the user and is particularly useful to locally distribute the pressure between the foot and the pressure pads across the moderator sheet. 
     In further embodiments, the insert may further comprise a cushioning layer. Such layer may have a variety of sizes covering all or a part of the overall area of the insert. In particular, the cushioning layer may be positioned to separate at least a portion of the moderator sheet from the foot of the user. In specific embodiments, the cushioning layer may be absent in the area of the moderator sheet overlying the discrete pressure pads. The cushioning layer may be formed of a variety of materials, such as polyurethane foam. 
     In certain embodiments, the pressure moderator sheet can be described as comprising a top surface and a bottom surface. Moreover, the moderator sheet may be described as being formed to have surface ridges and indentations defined in each of the top and bottom surfaces. According to one aspect, the indentations at least partially interlineate and surround the ridges. In specific embodiments, the ridges of the top surface may correspond to indentations of the bottom surface, and the indentations of the top surface may correspond to ridges of the bottom surface. The formed ridges and indentations may provide specific functions. For example, the discrete pressure pads can be positioned in one or more of the indentations formed in the bottom surface of the pressure moderator sheet. In other embodiments, the cushioning material may be positioned in the indentations formed in the top surface of the moderator sheet. The pressure pads may have various thicknesses in relation to the moderator sheet. For example, each of the discrete pressure pads may have a thickness substantially equal to a height of the at least one indentation formed in the bottom surface of the moderator sheet. Alternatively, each of the discrete pressure pads may have a thickness different than a height of the at least one indentation formed in the bottom surface of the moderator sheet. In one embodiment, the pressure pads and/or moderator sheet is texturized so as to reduce noise between the insert and the shoe during use. Moreover, a thickness of the pressure moderator sheet may be substantially less than a thickness of each of the pressure pads. 
     The pressure pads can be described in terms of number and positioning of the pads. For example, the shoe insert may comprise a series of discrete pressure pad that are purposefully positioned in relation to one another to provide beneficial properties and allow for customization of the insert through removal of only part of the series of pads to design the desired pressure moderation. In particular, the series of discrete pressure pads may comprise a plurality of pressure pad units, each unit comprising a center pad component and a peripheral pad component at least partially encircling the center pad component. For instance, at least one of the peripheral pads may be rectangular in shape and at least one of the center pads may be oval in shape, or at least one of the peripheral pads and at least one of the center pads may be circular in shape. Moreover, other unit combinations would also be encompassed by the invention. 
     The pressure pads are preferably positioned on the shoe insert to correspond to anatomical portions of the foot where pressure points are likely to occur or where foot diseases or conditions related to pressure may occur. In some embodiments, at least a portion of the discrete pressure pads are positioned in an area of the insert corresponding to the ball of the foot of a user. In other embodiments, at least a portion of the discrete pressure pads can be positioned in an area of the insert corresponding to the heel of the foot of a user. In still other embodiments, at least a portion of the discrete pressure pads may be positioned in an area of the insert corresponding to the big toe of the foot of a user. 
     The beneficial pressure modulation abilities of the inventive shoe insert can particularly be related to the pressure moderator sheet and the properties thereof that allow for distribution of pressure between the foot and an underlying pressure inducer, such as a pressure pad. In specific embodiments, the pressure moderator sheet can comprise a thermoplastic polyurethane sheet, which can have a thickness of less than about 3 mm. Preferably, the pressure moderator sheet is a continuous sheet of thermoplastic polyurethane. The pressure pads may likewise comprise a polyurethane material. 
     The shoe insert can be easily customized by a user through removal of specific pressure pads to adjust the degree of pressure applied to specific portions of the foot and to adjust the softness of the insert in specified areas. The ease of use and customization of the shore insert can be particularly related to the ability to remove and replace the individual pressure pads. Moreover, in specific embodiments, the pressure pads can be directly attached to the pressure moderator sheet without the use of a separate adhesive material. For example, the pressure pads can be attached to the pressure moderator sheet via surface interactions (e.g., surface tension) between the pressure pads and the pressure moderator sheet. The pressure pads may particularly be in the form of gel pods (e.g., a urethane gel at least partially coated with a thin film, such as a thermoplastic polyurethane film). 
     In one embodiment, the invention provides a removable shoe insert comprising: a continuous sheet of thermoplastic polyurethane having a top surface and a bottom surface and being formed to have surface ridges and indentations; a layer of cushioning material integrally adhered to and positioned in the indentations of the top surface of the thermoplastic polyurethane sheet; and a series of discrete pressure pads removably and replaceably attached to and positioned in at least a portion of the indentations in the bottom surface of the thermoplastic polyurethane sheet. 
     According to another aspect, a removable insert for placement in a shoe between the shoe sole and the foot of a user is provided. The shoe insert includes a pressure moderator sheet and a plurality of discrete pressure pads removably and replaceably attached to the pressure moderator sheet via surface interactions therebetween. The pressure moderator sheet is positioned to separate the pressure pads from the foot of the user such that pressure between the foot and the pressure pads are locally distributed across the moderator sheet. 
     According to another embodiment, a method of forming a removable insert for placement in a shoe between the shoe sole and the foot of a user is provided. The method includes providing a pressure moderator sheet and attaching a series of discrete pressure pads to the pressure moderator sheet, the pressure pads being removably and replaceably attached to the pressure moderator sheet. The pressure moderator sheet is positioned to separate the pressure pads from the foot of the user such that pressure between the foot and the pressure pads are locally distributed across the moderator sheet. 
     Aspects of the method include forming the pressure moderator sheet, which may include forming surface ridges and indentations in the pressure moderator sheet. The attaching step may include positioning the discrete pressure pads in at least one indentation formed in the moderator sheet. In addition, the method may further include attaching a cushioning material to at least a portion of the pressure moderator sheet to separate at least a portion of the moderator sheet from the foot of the user. The pressure pads may be directly attached to the pressure moderator sheet via surface interactions (e.g., surface tension) between the pressure pads and the pressure moderator sheet. Thus, in one embodiment, the pressure pads may be directly attached to the pressure moderator sheet without the use of a separate adhesive material. The method may further include detecting high pressure areas on the sole of a foot, such as using iStep® technology, wherein the attaching step includes adding or removing the pressure pads from the pressure moderator sheet based on the detected high pressure areas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to assist the understanding of embodiments of the invention, reference will now be made to the appended drawings, which are not necessarily drawn to scale. The drawings are exemplary only, and should not be construed as limiting the invention in any way. 
         FIG. 1  is a bottom view of a shoe insert according to one embodiment of the invention. 
         FIG. 2  is a bottom view of a shoe insert according to another embodiment of the invention. 
         FIG. 2   b  is a cross-section of the shoe insert of  FIG. 2  along the line A-A. 
         FIG. 3  is a top view of a shoe insert according to the embodiment shown in  FIG. 2 . 
         FIG. 4  is a top view of the shoe insert according to another embodiment of the invention. 
         FIG. 4   b  is a cross-section of the shoe insert of  FIG. 4  along the line B-B. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention now will be described more fully hereinafter through reference to various embodiments. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Indeed, the invention 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. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. 
     Embodiments of the present invention provide shoe inserts having a variety of useful properties. The inventive shoe inserts provide increased comfort generally but can also provide particular therapeutic benefits to specific areas of the foot. This may be accomplished through the specific combination of multiple shoe insert components that function together to modulate localized areas of foot pressure. Moreover, this combination of components can provide a shoe insert that is easily customizable by the user to fit not only the specific needs of multiple individual users but also the changing needs of each user. 
     Accordingly, in one aspect, the present invention is directed to a removable insert that can particularly be designed for placement in a shoe between the shoe sole and the foot of a user. The inventive insert can thus be used in addition to an existing shoe insole or even in addition to another shoe insert. In some embodiments, though, the shoe insert of the present invention can be used to replace an existing shoe insole or an existing shoe insert. In specific embodiments, the shoe insert of the invention may work particularly well when it is the only insert present to modulate pressure between the foot of the user and the permanent shoe sole (e.g., the midsole or a non-removable insole). 
     In certain embodiments, an insert according to the invention may comprise one or more pressure pads. As used herein, the term “pressure pad” is intended to mean a thin piece of cushioning material that is sufficiently soft (i.e., has a sufficient degree of recoverable compression) to provide a cushioning effect to a localized area of the foot and that has sufficient bulk such that the absence of the pad in a localized area of the foot would be readily sensed. These characteristics may be achieved through a specific combination of materials and dimensions. For example, a material that is very soft and is easily compressed may need to be thicker than a material that is less soft and is not as easily compressed. 
     Any material providing the above characteristics, particularly recoverable compression, could be used as a pressure pad according to the present invention. For example, a pressure pad could comprise gels, foams, honeycombed materials, batting, or the like. Gels may be particularly useful according to the invention in light of their favorable pressure distribution properties. 
     Gels, such as polyurethane gels, are particularly useful as pressure pads according to one embodiment of the invention due in part to the balanced pressure distribution provided by the gel. Specifically, gels tend to exhibit tri-dimensional deformation properties such that the gel reacts to the applied pressure by deforming along three axes: the X and Y axes in the plane of the gel surface, as well as the Z axis that lies perpendicular to the plane of the gel surface. This leads to an even distribution of the exerted pressure, which lessens the pressure felt by the user at the pressure points. 
     In particular embodiments, it may be useful for the pressure pads to comprise a thermoset or thermoplastic urethane, silicone, or other polymer gel. 
     In some embodiments, the pressure pads that form part of the inventive shoe insert may comprise a combination of materials. For example, the pressure pads may comprise a first material that is at least partially covered or enclosed by a second material. In other embodiments, the pressure pads may comprise multiple layers. Preferably, at least part of the pressure pad comprises a gel material. In a specific embodiment, a pressure pad according to the invention may comprise a gel material and a covering material that completely surrounds and encloses the gel material. In some embodiments, the covering material can be a thermoplastic polyurethane (TPU) material. For example, the pressure pads may be gel pods that comprise a urethane gel coated with a thin film, such as a TPU film, silicone film, or other thermoplastic film. According to one embodiment, the gel material could be partially surrounded by a covering material such that different portions of the pressure pads interact differently with the moderator sheet. For example, only the surface(s) of the pressure pads not contacting the moderator sheet may be covered (e.g., a TPU covered surface not contacting the moderator sheet) such that the raw gel material of the pad contacts the moderator sheet. In this instance, the covered portions of the pressure pads will resist adhering to other surrounding materials due to surface interactions therebetween such as by minimizing surface tension or friction. 
     The thickness of the pressure pads used in the inventive shoe inserts can vary and may particularly be a thickness that is substantially equivalent to the overall thickness of the shoe insert. In specific embodiments, the pressure pads can have a thickness of up to about 10 mm, up to about 8 mm, up to about 6 mm, up to about 5 mm, or up to about 4 mm. In other embodiments, the pressure pads can have a thickness of about 1 mm to about 10 mm, about 1 mm to about 8 mm, about 1 mm to about 6 mm, about 1 mm to about 5 mm, about 2 mm to about 5 mm, or about 2 mm to about 4 mm. 
     A shoe insert according to one embodiment of the invention can comprise a plurality of pressure pads. The plurality of pads can comprise two, three, four, five, six, seven, eight, nine, ten, thirteen, fourteen, fifteen, sixteen, or even more pads. In specific embodiments, it can be particularly useful for a shoe insert according to the invention to comprise a series of pressure pads. As used herein, the term “series” indicates a plurality of pads that are provided on the insert in a defined number, alignment relative to each other, shape, alignment relative to an anatomical portion of the foot, or dimension. In some embodiments, a series of pressure pads may be defined by two or more of these factors in combination. 
     The gel pads being in a series can mean the pads are aligned relative to each other such that two or more pads are in a specific spatial arrangement. For example, a first pad and a second pad may be aligned relative to one another such that the first pad is encircled by the second pad. Of course, further embodiments are also encompassed by the invention, i.e., a third pad encircling the second pad, etc. 
     In light of the above, it is clear that the pressure pads used can take on a variety of shapes, such as square, oval, circle, rectangle, oblong, or the like. Moreover, two or more pads may be shaped specifically to enable the pads to be positioned in a defined spatial arrangement. For example, a pad could be rectangular around the perimeter thereof but could have a cut-out portion (e.g., an oval-shaped cut-out). A second pad could be shaped and sized to nest within the cut-out portion of the first pad. Of course, the cut-out portion and the second pad nested within the cut-out portion could be any shape or size. Likewise, the first pad could be formed such that the perimeter thereof is in a shape other than a rectangle. The shape of the pad may particularly relate to the two-dimensional shape thereof (i.e., length and width). In specific embodiments the third pad dimension (thickness or height) can be understood to be the thickness as described herein with the pad having a relatively flattened shape (i.e., having a relatively uniform thickness). In other embodiments, the pads may be formed to have a thickness that varies across the length or width of the pad (e.g., a dome-shaped or cone-shaped pad). 
     It can be particularly beneficial for the pressure pads to be located in a series such that they are aligned with an anatomical portion of the foot. Multiple portions of the foot may be subject to particularly increased pressure. Likewise, a variety of diseases and conditions may cause certain areas of the foot to be tender or otherwise increasingly susceptible to further injury caused by the normal pressures to which the foot is subjected in walking, running, or other activities. The pressure pads of the inventive shoe insert may be located on the insert to correspond to these defined areas of the foot. Specifically, the pressure pads may be located to substantially align with one or more of the areas of the foot known as the “ball of the foot” or the area of the foot just before the toes that corresponds to the metatarsal heads. The normal shape of the foot and the normal walking and running motions causes this area of the foot to undergo much pressure. Moreover, improperly fitting footwear and footwear with a narrow toe box can inhibit the walking process (i.e., the normal transfer of forces from the heel through the ball and through the toes). Metatarsalgia can particularly be alleviated or avoided by placement of a series of pressure pads so as to substantially align with the ball of the foot. 
     Another high pressure area of the foot is the heel of the foot. Running may particularly impart excessive pressure to the heel. Accordingly, a series of pressure pads may be placed on the inventive shoe insert to substantially align with the bottom of the heel of the foot. Likewise, the big toe may be an anatomical portion of the foot that is subject to excessive pressure. Harmful pressure to the big toe can arise from an improperly fitting shoe, the nature of a person&#39;s gait, or other causes. The big toe is a common location for calluses, corns, and other conditions arising from excessive pressure. Thus, a series of pressure pads may be place on the inventive shoe insert to substantially align with the big toe. 
     The dimensions of the pressure pads may vary depending upon the shape of the pad, the location of the pad relative to other pads, the location of the pad relative to an anatomical part of the foot, and the overall size of the shoe insert. 
     In addition to the pressure pads, a shoe insert according to one embodiment of the invention further comprises a formed pressure moderator sheet. As more fully described herein, the pressure moderator sheet can provide a unique and specialized function not heretofore recognized as useful in the art. In particular, the pressure moderator sheet can be positioned to separate the pressure pads from the foot of the user. Accordingly, the pressure forces between the foot and the pressure pads can be locally distributed across the moderator sheet. 
     The formed pressure moderator sheet can comprise any material useful to provide the functionality of the moderator as described herein. In specific embodiments, the moderator specifically can be a resilient material that deforms locally, such as around the pressure pads or in areas where a pressure pad is originally positioned but has been removed, as described herein. In some embodiments, the pressure moderator sheet can comprise a sheet of thermoplastic polyurethane (TPU). Any thermoplastic that is durable could be used, with transparent materials affording the most graphic design potential. 
     Preferably, the pressure moderator sheet exhibits sufficient stiffness to resist complete deformation or “bottoming out” in areas where a pressure pad is removed. For example, if the pressure pads have an average thickness of 2 mm, a pressure moderator sheet covering the pressure pads would be considered to bottom out upon application of a force in a discrete area where a pressure pad is absent if the pressure moderator sheet deformed downward by at least 2 mm. This resistance to bottoming out can span a distance of up to about 30 mm, the distance being measured as the open space between two adjacent pressure pads. In specific embodiments, the distance can be measured as an open space between two adjacent pressure pads where there are no additional or intervening layers other than the pressure moderator sheet. In other embodiments, the resistance to bottoming out can span a distance of up to about 25 mm, up to about 22 mm, up to about 20 mm, up to about 18 mm, up to about 16 mm, up to about 15 mm, up to about 12 mm, or up to about 10 mm. In still further embodiments, the resistance to bottoming out can span a distance of about 0.5 mm to about 30 mm, about 1 mm to about 25 mm, about 1 mm to about 20 mm, about 1 mm to about 15 mm, or about 1 mm to about 10 mm. 
     In specific embodiments, the pressure moderator can be a continuous sheet. In other words, a single shoe insert according to the invention would comprise a single pressure moderator sheet, according to this embodiment of the invention. In certain embodiments, the single pressure moderator sheet can also span substantially the entire length and width of the shoe insert. In other words, the pressure moderator sheet would form a layer, according to this embodiment, that is present throughout the entire range of possible shoe insole cross-sections. The use of a continuous, single sheet in the pressure moderator sheet can be particularly beneficial to ensure the pressure moderating properties of the layer is not compromised at any discrete points across the pressure moderator sheet. Sheets could be bonded together to act as a continuous sheet or a partial sheet could be used, although such alternatives may result in insertion problems and be more expensive to manufacture. 
     According to one embodiment, the moderator sheet may be multiple layers and formed using, for example, a “double shot” molding process. In this regard, a first layer or skin of a moderator sheet (e.g., TPU material) may be placed into a mold and a first shot of polymeric material (e.g., thermoset or thermoplastic polyurethane) may be placed on the skin and the mold closed to cure the first shot and form a first layer of polymeric material on the skin. The mold may then be opened and a second shot of polymeric material (e.g., thermoset or thermoplastic urethane) may be placed on the skin and the first layer of polymeric material. The mold is then closed to cure the second shot and form the second layer of polymeric material. The first and second layers formed on the skin may have different material properties from one another, such as different stiffness and/or elasticity. For example, the first layer formed on the skin may be stiffer than the second layer formed on the skin. 
     In certain embodiments, it can further be useful for the pressure moderator sheet to be formed of a solid material. More specifically, it can be useful to avoid the use of foamed materials. While not wishing to be bound by theory, it is believed that the use of foamed materials reduces the ability of the layer to function as a true pressure moderator. Foamed materials tend to resist full deformation of the layer. When a pressure is applied to the top surface of a foam layer, while there may be deformation to some discrete depth of the foam layer, the bottom surface of the foam layer does not necessarily deform (or at least does not deform in proportion to the deformation at the top of the layer). Thus, a foam layer does not moderate an applied pressure across a void space—rather, the foam itself absorbs the pressure. This does not provide the type of pressure moderation achieved according to the present invention. In addition to moderating pressure, the moderator sheet also acts as a canvas for decoration, which can be done on the inside of the sheet and shown through, so that the graphics potential is increased and more durable. As more fully described below, the use of a relatively thin, solid, continuous, resilient sheet as the pressure moderator sheet provides a beneficial moderation of applied pressure that functions in combination with the pressure pads to provide a unique and useful pressure relief that is both comfortable and therapeutically beneficial. 
     The pressure moderator sheet used in the present invention may be described as being a “formed” sheet. This terminology denotes a specific structure that is not an inherent quality of any known standard method of manufacturing a sheet material. Rather, the pressure moderator sheet is expressly formed to have ridges and valleys or indentations. 
     As more clearly described below in relation to the various drawings, a pressure moderator sheet according to the invention can be characterized as having a top surface and a bottom surface, and the sheet further can be characterized has having surface ridges and indentations. More particularly, the top surface can be defined in terms of specific ridges, and the top surface can thus have indentations, which are the areas between the ridges that are lower than the ridges when viewed in the plane of the pressure moderator sheet. Likewise, the bottom surface can be defined in terms of specific ridges, and the bottom surface can thus have indentations, which are the areas between the ridges that are higher than the ridges when viewed in the plane of the pressure moderator sheet. In specific embodiments, the ridges of the top surface of the pressure moderator sheet substantially correspond to the indentations of the bottom surface of the sheet, and the indentations of the top surface of the pressure moderator likewise correspond to the ridges of the bottom surface of the sheet. 
     The presence of the indentations and ridges in the formed pressure moderator sheet can provide particular benefits to the present invention. For example, in certain embodiments, the indentations of the top surface of the pressure moderator sheet can provide an area for placement of the pressure pads. Moreover, in certain embodiments, the ridges formed in the pressure moderator sheet can have a height (in reference to the bottom of the indentations in the formed pressure moderator sheet) that can be substantially identical to the height (or thickness) of the pressure pads. In other embodiments, however, the height (or thickness) of the pressure pads can be somewhat greater or less than the height of the ridges in the pressure moderator sheet. 
     The formed ridges and indentations can also take specific shapes. A ridge (and thus its corresponding on the reverse side of the pressure moderator sheet) could have a substantial length and/or width. For example, a ridge could have a length and/or width of up to almost the entire width of the shoe insert. In other embodiments, a ridge could have a length and/or width of up to about 50 mm, up to about 45 mm, up to about 40 mm, up to about 30 mm, up to about 25 mm, up to about 20 mm, up to about 15 mm, or up to about 10 mm. Of course, such dimensions could also be related to the shape of the ridge (e.g., a diameter for a circle or oval shape, etc.). Ridges could also have a substantial length while having a very insubstantial width (or vice versa). For example, a ridge could have a width of only about 1 or 2 mm and have a length that is much greater (e.g., 3, 4, 5, 6, 7, 8, 9, 10 mm, or even up to substantially the width of the shoe insert). 
     The term formed can also refer to other characteristics of the shoe insert. For example, the shoe insert can be formed to have the overall shape of a foot or a shoe. Moreover, the shoe insert can be formed to have specific contouring, such as to take on the three-dimensional shape of the bottom of a foot. 
     In some embodiments, the shoe insert of the invention can include one or more pressure pads removably and replaceably attached to the insert. More specifically, the pressure pads may be removably and replaceably attached to the formed pressure moderator sheet. In particular embodiments, one or more pressure pads may be removably and replaceably attached to the pressure moderator sheet and located in one or more indentations formed in the moderator sheet. The pressure pads are removably and replaceably attached in that the pressure pads are attached to the pressure moderator sheet but are not permanently attached. Rather, the pressure pads may be removed from the pressure moderator sheet by the express action of a user (e.g., purposefully removing one or more of the pads). The pressure pads are replaceably attached in that, after removal, the pads may be re-attached to the pressure moderator sheet. Preferably, the pads may be removed and replaced an unlimited number of times. 
     The means for removably and replaceably attaching the pressure pads to the pressure moderator sheet can be any means recognizable as useful in the art. In some embodiments, it can be useful for the pressure moderator sheet and the pressure pads to be formed of materials whereby the pads are directly attached to the sheet without the use of any separate adhesive material. For example, the pressure moderator sheet and the pads may both comprise a TPU material, and the attachment of the pressure pads to the pressure moderator sheet may be through surface charge interactions that naturally arise between the materials. In particular, the surface tension between the pressure pads and the moderator sheet allows sufficient attachment therebetween. Thus, adhesives or other attachment techniques (e.g., Velcro) are not required in order to secure the pressure pads directly to the moderator sheet. Moreover, one surface of the pressure pads may be formed of a material or covering that attaches to the moderator sheet via surface interactions, while another surface may be formed of a different material or covering that will resist adhering to the moderator sheet or other materials. For instance, the bottom surface of the pressure pads may be uncovered and configured to be positioned in direct contact with the moderator sheet while the surfaces not in contact with the moderator sheet may be covered with a material that does not attach to the moderator sheet or other materials in the shoe (e.g., a gel pod with a TPU film covering). 
     The pressure pads may be applied to the pressure moderator sheet such that the pressure pads are separated from the foot of a user by the pressure moderator sheet. Thus, the pressure pads may be attached to the bottom surface of the pressure moderator sheet. Accordingly, the pressure pads may be attached to the bottom surface of the overall shoe insert. 
     The shoe insert of one embodiment of the invention may comprise one or more additional components. Such additional components may be positioned on either the top surface of the pressure moderator sheet, the bottom surface of the pressure moderator sheet, or both the top and bottom surfaces of the pressure moderator sheet. 
     In some embodiments, the additional component may be positioned on the pressure moderator sheet (and thus the shoe insert) to be present only in discrete areas of the insert. For example, in some embodiments, the additional component may be positioned only in one or more of the indentations formed in the pressure moderator sheet. In particular embodiments, the additional component may be positioned only in indentations formed in the pressure moderator sheet on the side of the pressure moderator sheet opposite the attachment of the pressure pads. 
     The additional component can be used to fill all of the indentations formed on a single side of the pressure moderator sheet. Thus, the additional component may form a substantially continuous layer on a single side of the pressure moderator sheet. The additional component may otherwise form one or more discrete, non-continuous layers on one or both sides of the pressure moderator sheet. 
     The additional component preferably comprises a material providing a favorable degree of cushioning. Any material providing such cushioning may be used, including but not limited to gels, foams, batting, honeycombed materials, and the like. In specific embodiments, the additional component may comprise a polyurethane foam, an ethylene vinyl acetate, a polyethylene, or a blown silicone. In one embodiment, the polyurethane foam is a thermoset material with very low densities typical of footwear products. 
     A shoe insert according to the invention may be more specifically described in relation to the various drawings, wherein specific embodiments are illustrated for the sake of complete description and are not intended to limit the scope of the disclosure. 
     As seen in the bottom view of  FIG. 1 , a shoe insert  10  according to the invention can comprise a pressure moderator sheet  20  having a plurality of pressure pads  30 ,  40 ,  50 ,  60 , and  70  attached thereto, particularly being positioned in relation to the ball of the foot of a user when inserted into a shoe. The shoe insert  10  of the embodiment of  FIG. 1  further includes pressure pads  80  and  90  positioned in relation to the big toe of the foot of a user and pressure pad  100  positioned in relation to the heel of the foot of a user. Of course, in other embodiments, the shoe insert may comprise more or fewer pressure pads, and the pads may be in different positions. In the presently illustrated embodiment, the pressure pads are beneficially located to correspond to areas of the foot that typically undergo the greatest and/or potentially most damaging pressure on the foot. 
     Another embodiment of a shoe insert  10  is illustrated in the bottom view of  FIG. 2 , which illustrates a formed pressure moderator sheet  20 . The moderator sheet  20  is particularly formed to have a plurality of ridges  200  that take on a variety of shapes and sizes. The moderator sheet  20  is further formed to have a plurality of indentations  250  that at least partially interlineate and surround the ridges  200 . The illustrated shoe insert also includes a series of pressure pads. In this embodiment, the pressure pads are shaped to comprise a series of pad units, each unit formed of a perimeter pad ( 30 ,  40 ,  50 ,  60 ,  70 ,  80 ,  90 ,  100 ) surrounding a center pad ( 35 ,  45 ,  55 ,  65 ,  75 ,  85 ,  95 ,  105 ). Of course, the pressure pad units could be formed of other combinations of pad components, the different pad components forming the units varying in number, size, and shape. 
     As illustrated in  FIG. 2 , the pressure pads can be positioned in a indentation formed in the bottom surface of the formed pressure moderator sheet. The pressure pad unit formed of peripheral pad  60  and center pad  65  is illustrated in  FIG. 2  with dashed lines to indicate its absence from the figure. It is thus shown that the removal of the pads reveals a corresponding portion of the indentation  250  in which the pads are positioned. 
       FIG. 2   b  provides a cross-section of the shoe insert of  FIG. 2  along line A-A. The cross-section shows the relatively thin profile of the pressure modulator sheet  20  and the construction of the shoe insert arising from the formed nature of the modulator sheet. The pressure modulator sheet  20  is formed to have ridges  200  and indentations  250 . Residing in one indentation is the pressure pad unit for the heel area of the shoe insert, specifically peripheral pressure pad  100  and center pressure pad  105 . The outer edges of the pressure modulator sheet  20  are further formed to have a three dimensional contour. 
       FIG. 3  illustrates a top view of the shoe insert  10  from  FIG. 2 . In this view it is apparent how the ridges on a first side of the pressure moderator sheet  20  correspond to indentations on the opposing side of the pressure moderator sheet and how the indentations on the first side of the pressure moderator sheet correspond to ridges on the opposing side of the pressure moderator sheet. Specifically, ridges  350  on the top surface of the pressure moderator sheet  20  correspond to the indentations  250  from  FIG. 2 , and indentations  300  on the top surface of the pressure moderator sheet  20  correspond to ridges  200  from  FIG. 2 . Ridge  308  is an expanded ridge that corresponds to the indentation in  FIG. 2  where the pressure pads are positioned. Similarly, ridge  310  is an expanded ridge that corresponds to the indentation in  FIG. 2  where the pressure pads are located. 
       FIG. 4  illustrates a top view of a shoe insert  10  according to one embodiment of the present invention. The shoe insert comprises a pressure moderator sheet  20  that is formed to have surface ridges  350  and indentations (not visible in this view). In this embodiment, the pressure moderator sheet  20  is clear, and the pressure pads removable and replaceably attached to the opposing side of the pressure moderator sheet are visible (shown as dashed lines). Particularly illustrated are center pressure pads  35 ,  45 ,  55 ,  65 ,  75 ,  85 ,  95 ,  105  and peripheral pressure pads  30 ,  40 ,  50 ,  60 ,  70 ,  80 ,  90 ,  100 . The shoe insert of this embodiment further comprises an additional component, which is a polyurethane foam material  400 . The foam material  400  is positioned within the indentations formed on the top surface of the shoe insert  10 , thus rendering the indentations not visible in this view. The filling of the indentations is further illustrated in  FIG. 4   b , which shows a cross-section of the insert from  FIG. 4  along line B-B. 
     As seen in  FIG. 4   b , the pressure modulator sheet  20  again has a relatively thin profile. The pressure modulator sheet  20  is formed to have ridges  200  and indentations  250  in the bottom surface thereof. Ridges  350  are also present on the top surface of the shoe insert; however, the indentations of the top surface are filled with the foam material  400 . Residing in one indentation in the bottom surface is the pressure pad unit for the heel area of the shoe insert, specifically peripheral pressure pad  100  and center pressure pad  105 . As seen in this embodiment, the foam material (or other coating material) can be specifically positioned on the shoe insert to separate at least a portion of the pressure moderator sheet from the foot of a user. The foam material can be particularly described as a cushioning layer. Such cushioning layer may cover substantially the entire area of the top surface of the pressure moderator sheet. In other embodiments, the cushioning layer may cover only discrete portions of the top surface of the pressure moderator sheet (e.g., within the indentations  300  on the top surface of the pressure moderator sheet  20 ). 
     The shoe insert of the present invention can be particularly characterized by the utilization of the formed pressure modulator, especially in combination with the series of pressure pads. The use of padding material at pressure points has been tried for relieving inordinate foot pressures. The present invention realizes, however, the ability to evenly distribute pressures on the foot by both applying beneficial pressure and simultaneously modulating that pressure. This provides a unique system for providing foot comfort through the use of a shoe insert. 
     This pressure modulation is particularly seen in reference to the cross-section of  FIG. 4   b . For example, when pressure pads  100  and  105  are present, downward pressure by a foot in that area is distributed across the pressure pads themselves. In other words, there is even pressure distribution across the entire area. In particular individuals, though, there may arise unnatural pressure points, such as from an injury, from a deformation, or from an unnatural gait. The unnatural pressure in the area may be relieved by removal of one or both of pressure pads  100  and  105 . If the foot was directly interacting with the pressure pads, the removal of one or both could cause a very unnatural feeling and a could actually cause increased localized pressure on the foot. The separation of the pressure pads from the foot, however, by the pressure moderator sheet evens the change in pressure distribution across the foot arising from the removal of the pressure pad. For example, if pressure pad  105  was removed and the pressure moderator sheet was not present, the foot would easily recognize a “hole” in the shoe insert, and the uneven pressure in the area could cause injury. The pressure moderator sheet, though, evens out the pressure changes such that the decrease in pressure where the pressure pad is absent is lessened and the increase in pressure where the adjacent pressure pad is still present is also lessened. Thus, instead of having to accommodate sharp pressure changes, the removal of the pressure pad results in a comfortable, reduced pressure zone and not an uncomfortable, zero pressure zone. This unique system for pressure moderation is only achieved by embodiments of the present invention through the combination of the various components as described herein. 
     It should also be noted that, in certain embodiments, a shoe insert according to the invention may be described as comprising two layers, three layers, or even more layers. In preferred embodiments, the shoe insert comprises at least the pressure moderator sheet. In other embodiments, the shoe insert can comprise at least the pressure moderator sheet and one or more pressure pads. Thus, the shoe insert could be described as having two layers: the pressure moderator sheet and the pressure pad(s). In still other embodiments, the shoe insert can comprise the pressure moderator sheet, one or more pressure pads, and an additional component, such as a foam material. Thus, the shoe insert could be described as comprising three layers: the pressure moderator sheet, the pressure pad(s), and the foam material. The cross-section of  FIG. 4   b  illustrates a three-layer embodiment, wherein the foam material  400  is the top layer (or cushioning layer), the pressure moderator sheet  20  is the intermediate layer, and the pressure pads  100 ,  105  form the bottom layer. Of course, it is recognized that each individual layer may comprise multiple components (e.g., multiple pressure pads or multiple, discrete areas of foam). Preferably, the pressure moderator sheet is a single component (i.e., a continuous, solid sheet). Moreover, it is not required that all three layers be present in all areas of the shoe insert. For example, in some embodiments, the cushioning layer can be absent in the area of the pressure moderator sheet overlying the pressure pads. 
     The use of the formed pressure moderator sheet is also beneficial in that it allows for dynamic printing of graphics on the shoe insert. For example, the use of a clear TPU pressure moderator sheet allows for printing on one surface thereof to be visible on the opposing surface. In some embodiments, the pressure moderator sheet is provided with desired graphics through use of water transfer printing techniques. Of course, any printing method could be used for providing graphics on the shoe insert. Moreover, decals and printing may be applied to one or both surfaces of the moderator sheet and printing registration may be employed for decorating both surfaces of the sheet while being able to view both graphics from one vantage point. 
     Furthermore, the pressure pads and moderator sheet may be formed of materials and/or configured to reduce noise during use. In this regard, the pressure pads and/or moderator sheet may be texturized to reduce if not eliminate noises while a user is wearing the insert. For example, the pressure pads and/or moderator sheet may be texturized in specific areas in order to reduce frictional noise or squeaking between the insert and the interior of the shoe. In one embodiment, the moderator sheet is texturized using a micro finish (e.g., ridges and indentations) or mat finish. For instance, portions of the moderator sheet that are expected to interface with the shoe could be texturized, such as the sidewall surfaces of the moderator sheet (i.e., those between the major opposing surfaces of the moderator sheet), which could include those surfaces in the region of the arch, heel cup, and/or other outer edges of the moderator sheet. The moderator sheet could be texturized using other techniques such as by adding an additional layer of fabric or other material or adding a lubricant such as silicone. 
     In another embodiment, the removable insert may be adaptable for use with the iStep® technology (Aetrex Worldwide, Inc). For example, the iStep® technology could be used in order to customize a removable insert by adding or removing particular pressure pads that correspond to pressure points indicated by the iStep® technology. According to one embodiment, such a method for detecting pressure areas and customizing an insert is disclosed in U.S. Pat. No. 7,493,230, which is assigned to the present assignee and incorporated herein by reference. Thus, a pressure plate may be employed that is capable of detecting pressure areas on the sole of a foot, and the insert with removable pressure pads can be modified to account for and ease high pressure areas on the sole of the foot. According to one aspect, the pressure plate includes an array of pressure sensors that detect pressure and collect data related to areas of high relative pressure in order to generate a pressure map of the sole of the foot. Such data may be received from the pressure plate by a computer-based apparatus, and a display may show data associated with regions of high relative pressure which correspond to specific removable pressure pads of the insert. Regions of high relative pressure may be determined by locating regions exceeding a predetermined relative pressure level within the pressure map. 
     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. 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.