This invention relates generally to footwear representing an improvement on the design described in my U.S. Pat. No. 4,272,899 which is hereby incorporated by reference.
The footwear of the present invention comprises a sole of composite construction, that is, the sole is formed of a first material positioned for attenuating the impact forces applied to the foot and other skeletal structures during standing, walking and running, and a second harder material for firmly supporting the foot.
When walking and running, the lateral (outside) portion of the heel is generally the first part of the foot to strike the ground, with the foot then pivoting on the heel to bring the lateral part of the forefoot into contact with the ground. At this point, the foot is supinated (inclined upwardly from the lateral to the medial side of the foot), but rapidly pronates to a neutral position in which the bottom of the heel and the metatarsal heads of the forefoot are in contact with the ground, and in which the central vertical plane of the heel is ideally generally perpendicular to the ground. During this sequence of movements, various muscles and tendons contract to stabilize the foot in preparation for movement from the neutral position back to a supinated position prior to the propulsive phase of the gait cycle. (The propulsive phase is sometimes referred to as toe-off or push-off.) The arch (i.e., the bone structural alignment) of the foot should be firmly supported when the foot is in the neutral position in order to prevent the ligaments, muscles and tendons from becoming over stressed. During toe-off, it is preferable that the second and third metatarsals be firmly supported, and that the first metatarsal head plantarflex (move downward) relative the second and third metatarsal heads. The toes also should be firmly supported during push-off so that they remain straight and thus stronger due to the pillar effect of the phalanges.
In view of the foregoing, it will be observed that certain parts of the foot are subjected to higher stress during standing, running and walking, and that other parts of the foot require different degrees of support for maximum biomechanical efficiency. Moreover, high impact forces to the foot are transferred to other skeletal structures such as the shins and knees. The present invention takes these considerations into account and provides the appropriate amount of shock attenuation and support to different regions of the foot, thus protecting those parts of the foot which are subjected to high impact forces, and allowing other parts of the foot to function in a way which provides maximum efficiency to prepare the body for stresses placed on it.
Further, the stiffness of the sole, and of the outsole in particular, tends to inhibit flexure of the foot in the area of the metatarsal phalangeal joints. These joints are located between the proximal phalanges (i.e., the rear toe bones) and the metatarsals (i.e., the bones overlying the forward portion of the arch). The stiffness of the sole inhibits dorsiflexion during which the phalanges flex upward relative to the metatarsals. Because the aforementioned stiffness inhibits flexure, the footwear may be uncomfortable, especially during break-in. There is a need, therefore, for footwear which is more flexible, particularly in an area generally corresponding to the metatarsal phalangeal joints of the foot.
Among the several objects of this invention may be noted the provision of footwear which is tailored to the biomechanical operation of a wearer's foot; the provision of optimizing footwear to one or more of the various needs of a particular wearer and/or task by providing an appropriate amount of support and cushioning applied to regions of the particular wearer's foot; the provision of such footwear which is more comfortable and which reduces the risk of overstress and injury to the foot; the provision of such footwear which readily accommodates the natural flexure of the foot for ease of movement; and the provision of the present invention which may be incorporated in the soles of footwear such as shoes, boots and sandals, or in insoles for placement inside shoes and the like.
In general, footwear of the present invention comprises a sole. The sole has a heel section for supporting a heel of the foot. The heel section has medial and lateral regions. At least a portion of the lateral region has a first compressive resilience for attenuating the shock of impact to the wearer during running and walking. Further, the sole has an arch section forward of the heel section for supporting an arch of the foot. The arch section also has medial and lateral regions. At least a portion of the lateral region of the arch section has the first compressive resilience, and at least a portion of the medial region of the arch section has a second compressive resilience harder than the first compressive resilience for providing firm support for the foot during running and walking. In addition, the sole has a forefoot section forward of the arch section for supporting a ball of the foot including first, second, third, fourth and fifth metatarsal heads and associated metatarsal necks, proximal phalanges and metatarsal phalangeal joints. The forefoot section has a first region for supporting the first, second, third, fourth and fifth metatarsal heads, associated phalanges and metatarsal phalangeal joints, and the metatarsal neck associated with the fifth metatarsal head and a second region for supporting at least one of the metatarsal necks associated with the second and third metatarsal heads. The first region of the forefoot section has the first compressive resilience and the second region of the forefoot section has the second compressive resilience.
In another aspect, the invention includes a sole for footwear comprising a heel section, an arch section, and a forefoot section. The sole has a first selected effective compression resistance in at least part of the lateral region of the heel section, at least part of the lateral region of the arch section, and the first region of the forefoot section and a second selected effective compression resistance greater than the first compression resistance in at least part of the medial region of the arch section and the second region of the forefoot section. In addition, the sole includes a zone of weakness extending generally transversely with respect to the sole along a curve extending through locations generally corresponding to the five metatarsal phalangeal joints for providing greater flexibility for easier articulation of the metatarsals relative to the phalanges of the foot.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.
Corresponding parts are designated by corresponding reference characters throughout the several views of the drawings.
Referring to
In accordance with the present invention, the sole 10 is formed so that a resilient material is located in the lateral region of the heel section, the lateral region of the arch section, the first region of the forefoot section and the toe section. A harder material is located in the medial region of the heel section, the medial region of the arch section and the second region of the forefoot section. This configuration is best illustrated in
The two bodies 40, 42 or sections of the sole can be bonded to one another in any suitable fashion, as by heat fusion, adhesive, or by a chemical or curing process. The two bodies can be formed of any suitable sole material, such as polyurethane, TPR, PVC, EVA or other materials well known to those of ordinary skill in the art of footwear. Also, the two bodies 40 and 42 can be made of a single material (e.g., PVC or EVA) having different durometer hardnesses, or of different materials having different durometer hardnesses. In addition, the two bodies may be made of different colored materials to enhance the aesthetic characteristics of the insole and to highlight the use of multiple materials for marketability.
The composite sole described above formed by the two bodies 40, 42 may be used in lieu of a midsole of a conventional shoe, in which case the bodies may be permanently bonded or otherwise integrally attached to a wear resistant outsole 54, or the bodies may be used in lieu of a conventional one-piece cup sole. The thicknesses and contours of bodies 40 and 42 may be individually designed to compensate for the various characteristics of a particular wearer or group of wearers. For example, the upper surfaces of the two bodies 40, 42 may be appropriately contoured for the foot of the person wearing the footwear. Further, the upper surfaces of the bodies 40, 42 may be formed with a U-shaped heel seat 60 (FIGS. 1 and 4), an arch support 62 (
As illustrated in
Thus configured, the sole 10 protects those parts of the foot which are subjected to high impact forces, and supports other parts of the foot to function in a way which provides maximum efficiency and prepares the body for stresses placed on it, thereby reducing the risk of injury. The softer material of the first body 40 compresses relatively easily when loaded. However, the harder material of the second body 42 does not compress easily when loaded. Therefore, the areas of the sole 10 incorporating the softer material of the first body 40 deflect to absorb impact forces, and the areas of the sole incorporating the harder material of the second body 42 resist movement to more firmly support the foot.
As each step is taken, some sections of the foot require more cushioning and others require firmer support. The lateral portion of the heel is generally the first part of the foot to strike the ground. The softer body 40 in the lateral region 22 of the heel section 12 of the sole 10 cushions the initial impact. After the initial impact, the foot pivots downward on the heel, and the lateral portions of the arch and forefoot impact the ground. The softer material in the lateral region 26 of the arch section 14 and in the first region 28 of the forefoot section 16 absorbs the shock of this secondary impact. After the secondary impact, the foot pronates to a neutral position wherein the bottom of the heel and the metatarsal heads M1-M5 of the forefoot contact the ground, and the central vertical plane of the heel is generally perpendicular to the ground. The harder body 42 in the medial region 24 of the arch section 14 firmly supports the osseous alignment of the foot when in the neutral position thereby relieving stress in the ligaments, muscles and tendons which maintain the foot in this position. During toe-off, the harder material of the forefoot section 16 supports the second and third metatarsal necks N2, N3, but the softer material used in the first region 28 of the forefoot section permits the first metatarsal neck N1 and head M1 to plantarflex relative to the second and third metatarsal heads M2, M3. This motion places the foot in an appropriate biomechanical position during the propulsive phase of the gait cycle. This motion also permits the sesamoid apparatus to function properly during mid-stance and toe-off. The softer material under the metatarsal heads M1-M5 also serves to dissipate weight from the mid-stance through the propulsive phases of the gait cycle.
It will be observed from the foregoing that the material properties of the various sole regions appropriately cushion and support various parts of the user's foot. Moreover, the shapes of the first and second bodies 40, 42 enhance the movement and support of the foot. For instance, the bunion cradle 64 of the preferred embodiment permits the first metatarsal head M1 to plantarflex relative to the second and third metatarsal heads M2, M3 during toe-off. Likewise, the arch support 62 and the heel seat 60 support and cradle the osseous structure of the foot to maintain the appropriate neutral position after pronation and to prevent the ligaments, tendons and muscles of the user's feet and legs from being over stressed.
It will be appreciated that the hardnesses presented above may be altered depending upon the intended use of the sole. For example, adult footwear designed for use in situations where the wearer will frequently be carrying a heavy load (e.g., work boots) may require more support than a child's dress shoe. Likewise, footwear made for running may require firmer support in the heel section to absorb the initial shock of each step than would a hiking boot in which more cushion may be required.
In addition, it will be appreciated that the present invention is not limited necessarily to any particular type of footwear and may be equally desirable for use in removable insoles, as well as for use in the soles of shoes, boots and sandals. (“Footwear” as used herein includes all of these items and any other item having or consisting of a sole.) Further, it should be understood that the locations and shapes of the areas of softer and harder material may be altered without departing from the scope of this invention. Likewise, the unique configuration of softer and harder material may be employed at any vertical level of a sole or insole to provide the desired support without departing from the scope of the invention. For example, if the sole or insole is laminated, one or more of the laminae may be configured to have the softer and harder materials in the appropriate areas described above.
As shown in
Although the shape of the insert 214 and cavity 210 may vary somewhat without departing from the scope of the present invention, preferably the insert and cavity are shaped so parts of the lateral regions of the heel section and the arch section of a foot are supported by the softer insert material to absorb shock and cushion the foot. In the embodiment shown in
Further, as illustrated in
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing from the scope of the invention defined in the following claims.
This is a continuation of application Ser. No. 09/379,764 filed Aug. 24, 1999 now abandoned, which is a continuation-in-part of application Ser. No. 09/092,279 filed Jun. 5, 1998, issued Oct. 12, 1999 as U.S. Pat. No. 5,964,046, which was a continuation of application Ser. No. 08/861,579 filed May 22, 1997, issued Aug. 4, 1998 as U.S. Pat. No. 5,787,610, which was a continuation-in-part of application Ser. No. 08/654,726 filed May 29, 1996, now abandoned, all of which are hereby incorporated by reference.
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Number | Date | Country | |
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20030033733 A1 | Feb 2003 | US |
Number | Date | Country | |
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Parent | 09379764 | Aug 1999 | US |
Child | 09855890 | US | |
Parent | 08861579 | May 1997 | US |
Child | 09092279 | US |
Number | Date | Country | |
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Parent | 09092279 | Jun 1998 | US |
Child | 09379764 | US | |
Parent | 08654726 | May 1996 | US |
Child | 08861579 | US |