Patent Publication Number: US-5893221-A

Title: Footwear having a protuberance

Description:
TECHNICAL FIELD 
     The present invention relates generally to footwear and more particularly to achieving better support for the foot of the wearer of the footwear. 
     BACKGROUND OF THE INVENTION 
     Footwear in general has an upper and a bottom, the bottom herein will be referred to as the sole and may be a one piece unitary sole with a tread and a foot support region above the tread or may be made of multiple pieces such as an out sole, a midsole, and a sock liner. In general, these footwear all will have an inwardly curved mid region on the medial side of the footwear. The mid region generally runs from a toe box (which houses the toes and ball of the foot) rearwardly to the forward end of a heel cup. Also, the footwear generally will have a longitudinal medial arch support running between the heel cup and the toe box to support the longitudinal medial arch of the foot of the wearer. Various techniques have been employed to improve the support of the longitudinal medial arch support, the toe box and the heel cup to give the wearer of the footwear more stability and to reduce strain on the various joints and tissues of the foot. 
     SUMMARY OF THE INVENTION 
     Applicants have made observations of Pygmy feet and have observed that their medial arches were more prominent allowing for more stability and that the Pygmies&#39; metatarsals (the long bones of the foot) were fanned out, allowing for more stability. With these observations the applicants then constructed a unique bottom for footwear that allowed for more splaying of the metatarsals and provided more support at the longitudinal medial arch by adding a protuberance that extended medially from the inwardly curved mid region of the bottom within the area of the longitudinal medial arch support of the footwear forming a medial (towards the opposite foot) extension of the longitudinal medial arch support to provide midfoot support by reducing excessive plantar and medial displacement of the talus (pronation) during midstance of gait and limiting sub-talar eversion and provides midtarsal joint stability during propulsion, and supporting the medial longitudinal arch reducing strain on the plantar fascia. While these advantages have been achieved, the footwear also simply provides more comfortable wear and improved support for the foot. 
     It is an object of this invention to provide footwear having a protuberance that provides better support for the foot of the wearer of the footwear. 
     It is another object of this invention to provide a footwear having a protuberance which provides midfoot support by preventing excessive plantar and medial displacement of the talus (pronation) during midstance of gait, limits sub-talar eversion and provides midtarsal joint stability during propulsion, and supports the medial longitudinal arch reducing strain on the plantar fascia. The present invention in one embodiment includes a footwear having a bottom and an upper, the bottom having an inwardly curved mid region on the medial side of the foot curved in from an imaginary line running from the widest transverse section of the toe box of the footwear to the widest transverse section of the heel of the footwear, and a unique protuberance extending out and medially from the curved mid region starting at the bottom of the sole at its widest transverse width and rising upwardly to its narrowest transverse width. In preferred forms, the protuberance is convex in top plan view and convex in transverse section through the footwear. Also in the preferred embodiment, the top of the protuberance terminates approximately at the top of the longitudinal medial arch support in the footwear. The protuberance extends in a medial direction (toward the opposite foot) from the longitudinal medial arch support in the curved mid region beyond the imaginary line drawn from the widest section of the toe box of the footwear to the widest section of the heel of the footwear so that it extends out considerably from the inside edge of the curved mid region. 
     The shape of the protuberance in transverse section is preferably convex starting at its widest at the bottom of the outer surface of the sole and narrowing as it rises to its upper end. However, other shapes, such as an angle, providing similar function are also considered within the scope of the invention. 
     Similarly, the preferred shape of the protuberance in top plan view is convex starting from a narrow forward end with a widest section at its midlength and then narrowing again at its rearward end. However, again, other geometric shapes, such as an angle, that provide similar function are also considered within the scope of the invention. In the preferred embodiment the vertical center line along the midlength of the protuberance is slightly rearward of the center line of the longitudinal medial arch of the foot. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric of the footwear employing the inventive features. 
     FIG. 2 is a side elevation looking in at the medial side of the footwear. 
     FIG. 3 is a bottom plan view of the footwear. 
     FIG. 4 is a top plan view. 
     FIG. 5 is a section taken along the section line 5--5 of FIG. 4. 
     FIG. 6 is an exploded view of the sole portion of the footwear. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The footwear is designed for any type of user from small child to adults and for leisure footwear, such as sandals, athletic footwear, hiking boots, to heavy work boots used by adults who carry heavy loads. In general, the advantages of the footwear are best achieved by locating the transverse center plane 37 of the protuberance slightly rearward of the center plane 36 of the longitudinal medial arch of the wearer&#39;s foot and having the protuberance begin forwardly at about midlength of the first metatarsal bone of the foot and terminating rearwardly at about the sub-talar joint of the foot. In this position the protuberance provides midfoot support by preventing excessive plantar and medial displacement of the talus (pronation) during midstance of gate. It limits sub-talar joint eversion and provides midtarsal joint stability during propulsion. The protuberance supports the medial longitudinal arch reducing strain on the plantar fascia and helping the risk of developing plantar fasciitis. The protuberance provides a bio-mechanically stable platform during gait. It provides a broad base of the midsole and out sole that is stabilizing the foot by providing a broader area of support with increased surface area on the bottom of the foot. 
     As best shown in FIG. 1, the footwear includes an upper 10 a bottom 12 having an inwardly curved mid region 14 on the medial side of the footwear. The mid region extends lengthwise approximately the length of the dimension 15 as shown in FIG. 4. The upper can be a set of straps like as in a sandal of could be a fully closed upper as in a shoe or a boot. In the form of the invention illustrated in FIGS. 1, 5, and 6, the bottom 12 comprises an out sole, outer sole, or tread 16, a midsole 18 and a sock liner 20. The footwear also has a generally wide area in the front of the footwear called a toe box (FIG. 4) or toe end 22, which receives the toes and ball of the foot and a somewhat confined circular area at the rear of the footwear called a heel cup or heel end 24. 
     The out sole 16 is of a high density rubber or synthetic material commonly used for an out sole or tread. The midsole 18 is made from an EVA material (ethyl vinyl acetate) which is an ideal shock absorber and very durable. The sock liner consists of a self-molding material (closed cell, cross-linked, polyethylene) which conforms to the shape of the foot while walking and provides a customized foot bed for enhanced support and comfort. The toe box 22 is wider than normal to allow for natural metatarsal splaying spreading and thus reduces irritation around the medial and lateral bony prominences of the foot. The heel cup 24 is deeply recessed to control motion in the rear foot joints (sub-talar and midtarsal joints) and stabilizes the ankle by reducing inversion and eversion of the heel. Generally a shank 30 is between the out sole and the midsole along the center line of the footwear to provide more stiffness against longitudinal flexing. The midsole also has a longitudinal medial arch support 32 having an upper end 34 on the medial side of the foot and a vertical center line 36 as shown in FIGS. 2 and 4. 
     As can be seen in FIG. 4 the foot bones are shown in dot dashed lines and include a first metatarsal 40 having a midlength 41 and a sub-talar joint 42 at the rear of the talus 43. 
     The unique protuberance of this invention is shown by reference numeral 50. As best shown in FIG. 4, the protuberance is outwardly convex in plan view and has a forward end 52 and a rearward end 54. The ends of the protuberance lay within the curve of the inwardly curved mid region 14 and preferably within the curve of the longitudinal medial arch support 32. The protuberance in transverse section is best shown in FIG. 5 and is upwardly convex starting from its widest lower end 56 and its narrowest upper end 58. The upper end 58 terminates approximately in line with the upper end 34 of the medial side of the longitudinal medial arch support 32. The bottom end of the protuberance extends all the way down to the outside surface of the out sole and is a part of the out sole. The protuberance is, in general, an exaggerated medial extension of the longitudinal medial arch support and extends considerably outwardly beyond an imaginary line 60 drawn between the widest part 64 of the toe box 22 and the widest part 66 of the heel cup 24. Thus, the protuberance is unusual in that it extends outwardly in a medial direction such a considerable distance whereas in a normal footwear the medial edge of the curved mid region of the bottom is well inside of the imaginary line between the widest section of the toe box and the widest section of the heel cup. 
     This location of the protuberance, and its width and length provide for the unique support of the foot of the wearer. 
     While the preferred embodiments of the invention have been illustrated and described, it should be understood that variations in the shape of the protuberance and in the composition of the materials of the footwear will be apparent to those skilled in the art. 
     Accordingly, the invention is not to be limited to the specific form of the invention illustrated in the drawings.