The present invention relates to footwear, and more particularly to insoles having features that improve the function of the first metatarsal which leads to an improvement in gait and that results in increased comfort and increased efficiency.

In order to understand the prior art and the present invention, it is necessary to understand the anatomy of the foot and the basics of shoe construction. FIG. 1A is a diagrammatic medial side view of the bones of the human foot 10, and FIG. IB is a top plan view of the bones of the human foot. For purposes of this application, references to heelward or rearward mean in the direction of the rear of the foot or heel 20; references to forward or toeward mean in the direction of the front of the foot 30 where the toes or phalanges 31 are located; references to medial mean the side of the foot where the arch 40 is located; references to lateral mean the outside of the foot; and references to upper or top and lower, bottom or under assume the foot or shoe is oriented in an upright position.

Referring to FIG. 1A, the calcaneus (22) is an irregularly shaped quadrangular bone also called the heel bone or os calcis. The medial side of the calcaneal tuberosity, i.e. the lower part of the posterior surface of the calcaneus is not precisely on the same ground or plane as the lateral tuberosity. This slight difference in calcaneal anatomy leads to potential for instability on level surfaces, such as sidewalks, gym floors, hardwood, etc.

Referring also to FIG. IB, the bones of the foot also include the navicular 41, the three cuneiform 42, the metatarsals 45A-45E and the phalanges, or toes 31A-31E, with the big toe 31A visible in FIG. 1. The metatarsal heads 46A-46F are located at the forward end of the metatarsal shafts 47A-47E. Although it's one of the smaller parts of the body, all told the foot contains 26 bones, 33 joints and more than 100 muscles. Together, a person's two feet contain more than a quarter of all the bones in the human body which interact and undergo significant stresses during standing, walking and running.

Human footwear is designed to protect the human foot. However, as currently designed, human footwear is imperfect in providing proper biomechanical support for the human foot.

Also depicted in FIG. 1A is a partial cross-sectional view of the portions of a conventional shoe 50 that underlie the sole of the foot, the top parts of the shoe being shown in phantom. Shoe 50 has a heel 51 which is attached to the lower surface of sole 52 of shoe 50, with the sole 52 in turn supporting an insole board 53 on which a sock liner 54 is placed. In a conventional shoe, the insole board typically is of relatively rigid construction from the region underlying the wearer's heel to the heads of the metatarsals. Sock liners are commonly very flexible and generally are very thin, typically no more than half a millimeter thick. The sock liner is the surface upon which the sole of the foot normally rests.

In prior U.S. Pat. No. 4,597,195 to Dananberg (the '195 patent), there is described a human shoe sole having an area of relief underlying substantially only the location of the first metatarsal head of the wearer's foot. As described in the '195 patent, providing an area of reduced support substantially only under the head of the first metatarsal encourages eversion and plantar flexion of the first metatarsal head as weight shifts from the heel to the first ray. Thus, normal functioning of the foot for plantar flexion and supination is encouraged with beneficial results for improved walking comfort and enhanced “windlass effect”. Prior PCT application WO 2011/017174 Al describes an improvement in a human shoe sole or insole in which a depression provided underlying the first metatarsal head in which the depression has its lowest point skewed to the medial side of center.

The foregoing discussion of the prior art derives primarily from prior US Patent No. 10,702,008 to Hughes and Dananberg (the ‘008 patent), in which there is described a shoe or insole device for insertion into a shoe having a foot supporting upper surface, wherein the shoe or device has an upward facing shallow channel on the foot supporting upper surface adapted to underlie the first metatarsal shaft and heelward of the first metatarsal head of the wearer. The channel is adapted to specifically extend in a direction from the toe end of the shoe heelward only under the first metatarsal shaft to short of the first metatarsal head of the wearer, and is pitched or rotated 4+1 degrees plantargrade, with a toeward end of the channel lower than the heelward end of the channel. The channel is rolled or sloped in a lateral to medial direction downward 9+2 degrees, in the frontal plane and the channel is yawed or rotated 10+5 degrees clockwise relative to a superior view of the transverse plane, for the left foot shoe, and yawed or rotated 10+5 degrees counterclockwise relative to a superior view of the transverse plane for the right foot shoe. The shoe or insole device is contoured and has a dome or raised area supporting surface having its highest point configured to underlie between the first and second metatarsal shafts rearward of the first and second metatarsal heads of the wearer. Millions of pairs of shoes and insoles including custom orthotics have been manufactured and sold incorporating relief under the first metatarsal head as described above. As will be appreciated, providing relief under the first metatarsal head requires proper placement of the reduced support relief. An earlier study “Anthropometry of the Foot and Lower Leg of US Army Soldiers: Fort Jackson, SC- 1985” by Parham et al., September 1992 reports a ball of foot (BOF) length standard deviation of 0.42 inches in the case of men enrolled in the study, and a BOF length standard deviation of 0.43 inches for women enrolled in the study (see FIG. 4). Also, BOF length of an individual’s left and right feet vary. While custom orthotics can be made to essentially exactly fit individual feet, mass produced shoes and insoles are at best compromise when it comes to locating relief under the first metatarsal head. The problem of properly locating relief under the first metatarsal head is further exacerbated in the case of mass produced one size fits all trim to fit aftermarket insoles.

The present invention provides improvements over current footwear products in terms of function, comfort, manufacturing and sizing. In one aspect, the present invention provides significant improvement in terms of biomechanical functioning of footwear products, in particular trim to fit insoles, molded sandals and flip-flops, by providing such footwear products with an upper surface having a raised metatarsal pad having a first region rising at a slope inboard from the medial edge and configured to underlie the first metatarsal head of the wearer, a second region configured to underlie the second to fifth metatarsal shafts of the wearer, and a third region sloping downward towards the lateral edge of the insoles, wherein the first region is configured to evert the first metatarsal of the wearer. The footwear product may be in the form of an insole including in particular a trim to fit insole, or a molded sandal or a flip flop. The first region of the raised metatarsal pad is on the medial side and has a slope of about 5 to 9°, preferably about 6 to 8°, more preferably about 7°. The third region of the raised metatarsal pad is on the lateral side and has a slope of about 4° to 6°, preferably about 4.5° to 5.5°, more preferably about 5°. The top edge of the third region is lower than the top edge of the first region. The second region of the raised metatarsal pad has a toeward surface, a top surface and a heelward surface that smoothly bridge across the first and second regions and blend with the top surface of the flat section of the insole the metatarsal pad is added to. This designs results in increased comfort to the wearer as well as simplified manufacturing and sizing by providing a contoured foot supporting surface across a range of several shoe sizes. The raised material pad having a sloped edge in the medial side allows the first metatarsal join to drop and rotate, i.e., evert, which enhances the flexibility of the joint, while the sloped third region on the lateral side allows the fifth metatarsal to invert. By extending the length of the pad and its sloped edge from about 4 cm, to about 8 cm, the insole or foot supporting surface can be configured to accommodate the likely BOF length for two US shoe sizes to a range of BOF lengths which could effectively function over a range of seven US shoe sizes. Note that a 4 cm long pad would need to be correctly positioned for the appropriate BOF length for the respective shoe size. The 8 cm long pad can provide functional support over seven US Shoe sizes, it’s positioning will govern which seven sizes it covers.

The invention also optionally may include modifying the heel area or heel cup area of the foot supporting surface to reduce the pressure on the plantar fascia of the wearer as it travels from its attachment on the medial calcaneus to the proximate phalanges, as described in our aforesaid US Patent No. 10,702,008, the contents of which are incorporated herein by reference. The heel cup includes a hollowed or depressed heel cup region (1-3 mm deep), adapted to underlie the heel of the wearer. The hollowed or depressed heel cup region is asymmetrical with its lowest region located to the medial side of the heel, and has a forward extension on the heel cup medial side.

The raised metatarsal pad can be formed on the foot supporting surface of an aftermarket trim to fit insole, or formed on the foot supporting surface of a molded sandal or flipflop. A feature and advantage of the present invention is that the raised metatarsal pad accommodates various individual’s metatarsal head BOF lengths over several, e.g., up to seven shoes sizes. Thus, in the case of after-market insoles, which typically are made and sold as trim to fit over several sizes, the number of SKU’s required is reduced. By way of example, with this invention three, four, five, six or seven full US shoe sizes, i.e. US Men’s size 7 to 13, or alternatively, US Women’s size 6 to 12, can be functionally accommodated by a single SKU. That is to say, footwear products incorporating a raised metatarsal pad as described may be formed integrally with the foot bed of a molded sandal or flip flop, or as a trim to fit after-market insole. As used herein, “footwear product” is intended to refer to all such embodiments. Further features and advantages of the present invention can be seen, in detailed description, taken in conjunction with the accompanying drawings, wherein:

FIG. 1A is a diagrammatic cross-sectional view of the bones of a human foot;

FIG. IB is a top plan view of the bones of a human foot;

FIG. 2 is a top plan view of a left foot supporting trim to fit insole for a men's shoe in accordance with one embodiment of the present invention, the right foot supporting insole being a mirror image thereof;

FIG. 3A is a top plan view of a left foot supporting surface of a trim to fit insole in accordance with the present invention, with contour lines take at 0.2 mm superimposed thereon, the right foot supporting surface being a mirror image thereof;

FIG. 3B is a top plan view of a left foot supporting surface of a trim to fit insole in accordance with the present invention, showing Trim Lines for length and width changes over six full US show sizes and “landing zones” for the Ball of Foot over multiple full US shoe sizes, the right foot supporting surface being a mirror image thereof;

FIG. 4 is a reproduction of a summary table from the Parham et al. report mentioned earlier; and

FIGs 5A-11B are graphs and pressure loads, as the case may be, demonstrating improvements in gait and in pressure loadings of individuals achieved by the present invention.

As used herein the term “sole”, “insole” are used interchangeably. Moreover, a “sole” or “insole” may be an element built into or forming an integral element of a molded footwear product such as a sandal or flip flop, or as removable insole, including trim to fit after-market insole devices spanning several shoe sizes, which may be inserted into a footwear product post-manufacture.

Referring to FIGs. 2 and 3, there is illustrated a trim to fit insole 100 having a metatarsal pad on the foot supporting surface 104 of the insole 100. Metatarsal pad 102 is formed inboard from the medial edge 106 of the insole 100 and has a first sloped region 108, configured to underlie the first metatarsal head of the wearer, a second top surface region 110 configured to underlie the second to fourth metatarsal shafts of the wearer, and a third region 112 configured to underlie the fifth metatarsal head of the wearer sloping downward towards the lateral edge of the insole 100. The first sloped region 108 is configured to evert the first metatarsal of the wearer. The footwear product may be in the form of an insole including in particular a trim to fit insole, or a molded sandal or a flip flop. The raised metatarsal pad first region 108 has a slope of about 5 to 9° on the medial side, preferably about 6 to 8°, more preferably about 7°. The third region 112 of the raised metatarsal pad has a slope of about 4° to 6° on its lateral side, preferably about 4.5° to 5.5°, more preferably about 5° and is configured to invert the fifth metatarsal of the wearer. The top edge of the lateral slope of surface 112 is lower than the top edge of the medial slope of surface 108. The second region 110 of the raised metatarsal pad has toeward and heelward surfaces that smoothly bridge from surface 112 to 108 and to the top surface 104 of the flat section of the insole the metatarsal pad is added to. The top surface of the metatarsal pad 110 smoothly bridges across all of the sloped surfaces of the raised metastarsal pad. The construction of raised metatarsal pad 100 results in increased comfort to the wearer as well as simplified manufacturing and sizing by providing a contoured foot supporting surface across a range of several shoe sizes. The raised material pad 100 having a sloped edge region 108 in the medial side allows the first metatarsal joint to drop and rotate, i.e., evert, which enhances the flexibility of the joint. By extending the length of the pad and its sloped edge from about 4 cm, to about 8 cm, the insole or foot supporting surface can be configured to accommodate a single BOF length or a range of BOF lengths which could effectively function over a range of seven US shoe sizes. Note that a 4 cm long pad would need to be correctly positioned for the appropriate BOF length for the respective shoe size. The 8 cm long pad can provide functional support over seven US Shoe sizes, it’s positioning will govern which seven sizes it covers.

Referring in particular to FIG. 3B, being a trim to fit insole, the insole 100 may include shoe size length trim lines 120 thru 124 and width trim lines 126 thru 129. Also, to facilitate better understanding of the versatility of our invention, FIG. 3B also shows, superimposed over the foot supporting surface, areas marked 130, 132, 134 where a typical wearer’s first metatarsal head may fall, depending on the individual’s BOF length, and shoe size.

The trim to fit insole also optionally may include a heel cup 135 shown in FIG 3 in the form of lop-sided generally round shaped depression 136, with its lowest region 137 preferably located slightly to the medial side of the heel. Heel cup 135 is generally round in plan, and includes a forward depressed extension region 138 on its medial side, which serves to reduce pressure on the plantar fascia of the wearer's foot, as it travels from its attachment on the medial calcaneus to the proximal phalanges. Heel cup 135 typically is 1-4 mm deep at its lowest point, preferably 2-3.5 mm deep, more preferably 2.5-3 mm deep. The region immediately forward heel cup 135 is raised relative to depression 136. Preferably the region 137 of heel cup 135 is elongated and rotated 3+2 degrees clockwise on the left shoe or insole, and 3+2 degrees counterclockwise on the right shoe or insole.

FIGs. 5A-9B are graphs and pressure loads demonstrating improvements in gait and in pressure loadings of a first individual wearing shoes with conventional insoles, and trim to fit insoles made in accordance with the present invention.

As can be seen:

• Graph shapes show marked improvement with versus without the trim to fit insole of the present invention.

• Pressure loads under the great toe show marked reduction with the trim to fit insole of the present invention.

• Heel contact duration shortens with the trim to fit insole of the present invention.

• There is greater overall symmetry with the trim to fit insole of the present invention. FIGs. 10A-11B are graphs and pressure loads of a second individual demonstrating improvements in gait and pressure loadings of a second individual wearing shoes with conventional insoles and trim to fit insoles in accordance with the present invention.

As can be seen, the greatest change was in the pressure sub great toe. The trim to fit insole of the present invention showed marked reduction in great toe pressure changes, consistent with releasing great toe joint effect.

Various changes may be made in the above invention without departing from the spirit and scope thereof.