Sole structure suitable for flatfoot

Abstract

The utility model relates to a sole structure suitable for flatfoot, which comprises a sole main body with a low front end and a high rear end, the outer sole of the sole main body is sequentially divided into a metatarsophalangeal area, a waist area and a heel area from front to back, the inner side part of the metatarsophalangeal area is warped forwards and upwards, and the heel area is warped backwards and upwards; the inner waist part of the waist area is an arc surface, and the triangular pattern position of the inner waist part of the waist area shrinks inwards, so that the ground contact area of the inner side area of the waist is reduced; an elastic piece is arranged in the sole body and extends to the metatarsophalangeal area from the heel area. The utility model provides optimization and improvement aiming at the defects in the walking movement under the existing condition of standing on flat feet instead of changing the posture state of the feet during standing and walking, assists in improving the walking capability, is reasonable in design, and effectively solves the problems that the stability of ankle joints is reduced, the off-ground pedaling and stretching capability is reduced and the walking quality is poor during the walking of the flat feet. And the internal rotation angles and moments of ankle joints and knee joints are increased.

Description

Technical Field

[0001] This utility model relates to a shoe sole structure suitable for flat feet. Background Technology

[0002] Flat feet, also known as flatfoot deformity, is a condition characterized by a low or absent medial longitudinal arch of the foot. Flat feet can be congenital or acquired, and can be flexible or rigid, but anatomically, they are all caused by the talus sliding inward and inward along the calcaneus at the ankle joint. The talus is a tarsal bone that is wider at the front and narrower at the back, located within the ankle joint cavity formed by the ends of the fibula and tibia. The inward and inward sliding of the talus along the calcaneus has the following effects:

[0003] First, the wide part of the anterior end of the talus leaves the joint cavity, resulting in a large gap in the ankle joint cavity and leading to ankle instability.

[0004] Secondly, the talus slides inward and downward along the calcaneus, causing calcaneal eversion, which leads to changes in the lower limb alignment and affects walking ability.

[0005] Third, the talus slides inward and downward along the calcaneus, causing the scaphoid, cuneiform, and metatarsal bones to be compressed forward. At the same time, the calcaneus's eversion affects the position and force line of the flexor digitorum longus and flexor hallucis longus tendons, causing hallux valgus and resulting in a decrease in the force of the push-off force.

[0006] Fourth, the talus slides inward and downward along the calcaneus, causing the arch of the foot to sink or disappear. When walking, the inability to provide support for the arch causes internal rotation of the ankle joint, increasing the pressure on the knee joint and other joints during internal rotation.

[0007] The aforementioned anatomical changes lead to compensatory movements in the lower limbs during flatfoot walking to ensure the completion of normal movements. However, the decrease in ankle joint stability and the ability to push off the ground, as well as the increase in internal rotation force of the ankle and knee joints, always exist, affecting the walking function of flatfoot.

[0008] The following are commonly used techniques to reduce the burden on flat feet:

[0009] One is orthotic insole technology. This mainly includes insoles made of relatively hard materials with a three-dimensional structure similar to the shape of a normal heel and arch, correcting heel pronation and supporting the arch; using removable wedge-shaped pads on the heel and forefoot to improve the distribution of pressure on the sole of the foot; using materials of different hardness in the forefoot and heel to cushion the pressure on the sole of the foot; and using inflatable air bladders to support the arch, etc.

[0010] Second, stability support technology. Rigid supports are built into the sole or insole to limit or reduce heel pronation.

[0011] Third, increase the width of the sole. This increases the contact area with the ground, improving the stability of the shoe;

[0012] Fourthly, techniques such as massage, heating, and heat dissipation are used. These mainly involve using massage, electric heating, and breathable heat dissipation to improve blood circulation in the soles of the feet and the temperature and humidity conditions inside the shoe cavity, thereby alleviating the pain of patients with flat feet.

[0013] However, existing techniques in flat-foot shoes for correcting heel eversion and arch collapse are not advisable because they attempt to alter the foot's already balanced internal structure with external force, which not only fails to address the problem but also causes greater pain for the patient. Current support techniques for preventing excessive eversion, however, do have some effectiveness. Furthermore, while increasing sole width can improve stability upon landing, it also increases the balancing torque on the medial malleolus and the torque of internal pronation upon landing; therefore, simply increasing sole width is not recommended. Utility Model Content

[0014] This invention addresses the problems existing in the prior art by providing a sole structure suitable for flat feet.

[0015] To achieve the above objectives, the technical solution adopted by this utility model is: a shoe sole structure suitable for flat feet, including a shoe sole body with a low front end and a high rear end. The shoe sole body is divided into a metatarsophalangeal region, a midfoot region, and a heel region from front to back. The metatarsophalangeal region curves forward and upward, and the heel region curves backward and upward. The lower part of the midfoot region is an arc surface. An elastic sheet is provided inside the shoe sole body, and the elastic sheet extends from the heel region to the metatarsophalangeal region.

[0016] Furthermore, the metatarsophalangeal region and the lumbar region are separated by the metatarsophalangeal joint axis, and the lumbar region and the heel region are separated by a line segment passing through the heel and perpendicular to the midline of the foot of the sole body.

[0017] Furthermore, the metatarsophalangeal region includes the 1st-2nd metatarsophalangeal region and the 3rd-5th metatarsophalangeal region distributed on the inner and outer sides of the midline of the foot; the lumbar region includes the medial lumbar region and the lateral lumbar region distributed on the inner and outer sides of the midline of the foot; the heel region includes the medial heel region and the lateral heel region distributed on the inner and outer sides of the midline of the foot.

[0018] Furthermore, the outsole of the 1-2 metatarsophalangeal region is a single piece of structure. The metatarsophalangeal region curves upward at 10°-15° along a straight line passing through the intersection of the metatarsophalangeal joint axis and the midline of the foot, perpendicular to the midline of the foot. The rear end of the metatarsophalangeal region and the front end of the waist region are transitioned by an arc. The heel region is a single piece of structure. The heel region curves upward at 20°-25° along a straight line passing through the heel center and perpendicular to the midline of the foot. The front end of the heel region and the rear end of the waist region are transitioned by an arc.

[0019] Furthermore, a V-shaped groove is formed on the axis of the metatarsophalangeal joint, and a V-shaped drainage groove A is formed in the metatarsophalangeal region. The V-shaped drainage groove A extends forward from the intersection of the midline of the foot and the axis of the metatarsophalangeal joint, and its depth gradually decreases forward from the intersection of the midline of the foot and the axis of the metatarsophalangeal joint. A V-shaped drainage groove B is formed on the midline of the foot in the heel region.

[0020] Furthermore, the outer heel area is provided with 1-2 parallel V-shaped drainage grooves C, the V-shaped drainage grooves C forming an angle of 5-10 degrees with the midline of the foot outward; the 1-2 metatarsophalangeal areas are provided with 1-2 parallel V-shaped drainage grooves D, the V-shaped drainage grooves D forming an angle of 20-25 degrees with the midline of the foot inward.

[0021] Furthermore, the edges of the 3-5 metatarsophalangeal region are provided with multiple triangular patterns A, one side of which coincides with the edge of the main body of the sole; the remaining parts of the 3-5 metatarsophalangeal region are provided with square patterns, one diagonal of which is parallel to the midline of the foot; the waist region is provided with multiple triangular patterns B, one side of which is located at the edge of the outer waist region coincides with the edge of the main body of the sole, and the distance between which is located at the edge of the inner waist region and the edge of the main body of the sole is more than 1 cm.

[0022] Furthermore, the elastic sheet includes a sheet-like elastic sheet body located at the heel center. The front part of the elastic sheet body is provided with two elastic strips distributed internally and externally. The elastic strip located on the inner side extends forward from the inner heel area to the first toe of the 1-2 metatarsophalangeal region, and the elastic strip located on the outer side extends forward from the outer heel area to the fifth metatarsophalangeal region of the 3-5 metatarsophalangeal region. A front transverse strip is connected between the front ends of the two elastic strips, and the front transverse strip extends from the fifth metatarsophalangeal region to the first toe.

[0023] Furthermore, the main body of the sole is inclined with the outer end lower and the inner end higher, and the inclination angle is 3-5 degrees; the main body of the sole includes an outsole and a midsole set on the outsole, the elastic plate is set between the outsole and the midsole, the intersection of the midline of the foot and the axis of the metatarsophalangeal joint of the midsole is the forefoot reference point, the heel center is the heel reference point, the height difference between the two reference points is 7-12mm, and the front part of the midsole gradually thins and stops at the front of the sole.

[0024] Furthermore, the lower part of the waist area is a downwardly convex arc surface, wherein the apex of the arc surface is 2mm higher than the intersection of the heel center, the midline of the foot, and the axis of the metatarsophalangeal joint.

[0025] Compared with the prior art, the present invention has the following effects: The present invention does not focus on changing the posture of the foot when standing and walking, but is based on the existing situation of flat feet and optimizes and improves the problems existing in its walking movement, helps to improve its walking ability, and is reasonably designed to effectively solve the problems of decreased ankle joint stability, decreased ability to push off the ground, and increased internal rotation angle and torque of the ankle and knee joints when walking with flat feet. Attached Figure Description

[0026] Figure 1 This is a top view of an embodiment of the present invention.

[0027] Figure 2 This is a bottom view schematic diagram of an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the main structure of an embodiment of this utility model;

[0029] Figure 4 This is a side view of an embodiment of the present invention.

[0030] In the picture:

[0031] 1-Sole body; 101-Outsole; 102-Midsole; 2-Metatarsophalangeal region; 201-1st-2nd metatarsophalangeal region; 202-3rd-5th metatarsophalangeal region; 3-Waist region; 301-Medial waist region; 302-Lateral waist region; 4-Heel region; 401-Medial heel region; 402-Lateral heel region; 5-Elastic plate; 501-Elastic plate body; 502-Elastic strip; 503-Forefoot strip; 6-Metatarsophalangeal joint axis; 7-Heel center; 8-Foot midline; 9-Perpendicular line of foot midline; 10-V-groove; 11-V-shaped drainage groove A; 12-V-shaped drainage groove B; 13-V-shaped drainage groove C; 14-V-shaped drainage groove D; 15-Triangular pattern A; 16-Square pattern; 17-Triangular pattern B; 18-Triangular pattern C. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] like Figures 1-4 As shown, this utility model discloses a shoe sole structure suitable for flat feet, which solves the problems of decreased ankle joint stability, decreased push-off ability, and increased internal rotation angle and torque of the ankle and knee joints when walking with flat feet. Specifically, it includes a shoe sole body 1 with a low front end and a high rear end. The shoe sole body is divided into a metatarsophalangeal region 2, a midsection region 3, and a heel region 4 from front to back. The metatarsophalangeal region 2 curves forward and upward, and the heel region 4 curves backward and upward. The lower part of the midsection region 3 has an arc surface. An elastic plate 5 is provided inside the shoe sole body 1. The elastic plate 5 extends from the heel region 4 to the metatarsophalangeal region 2 to play a role in stability and elasticity.

[0035] In this embodiment, the metatarsophalangeal region 2 and the lumbar region 3 are separated by the metatarsophalangeal joint axis 6, and the lumbar region 3 and the heel region 4 are separated by a line segment (i.e., the perpendicular line 9 of the foot midline) passing through the heel center 7 of the sole body 1 and perpendicular to the foot midline 8 of the sole body 1. Further, the metatarsophalangeal region 2 includes the 1-2 metatarsophalangeal region 201 and the 3-5 metatarsophalangeal region 202 distributed on the inner and outer sides of the foot midline 8; the lumbar region 3 includes the inner lumbar region 301 and the outer lumbar region 302 distributed on the inner and outer sides of the foot midline 8, and the lumbar region 3 has a downwardly convex arc shape at the outer bottom; the heel region 4 includes the inner heel region 401 and the outer heel region 402 distributed on the inner and outer sides of the foot midline 8. 402 means that the outsole of the main body of the shoe is divided into 6 zones. First, the midline of the foot is used as the axis to divide it into left and right zones. Then, the outsole surface is divided into front, middle and back sections by a line segment passing through the heel center and perpendicular to the midline of the foot, and the metatarsophalangeal joint axis. These 6 zones are named in the following order from back to front and from outside to inside: outer heel zone, inner heel zone, outer waist zone, inner waist zone, 1st-2nd metatarsophalangeal zone and 3rd-5th metatarsophalangeal zone.

[0036] In this embodiment, the outsole of the 1-2 metatarsophalangeal region 201 is a single piece of structure. The entire metatarsophalangeal region 2 is tilted forward and upward by 10°-15° along a straight line that passes through the intersection of the metatarsophalangeal joint axis 6 and the midline of the foot 8 and is perpendicular to the midline of the foot 8. The rear end of the metatarsophalangeal region 2 and the front end of the waist region 3 are transitioned by a rounded arc.

[0037] In this embodiment, the heel area 4 is a single piece of structure; the heel area 4 is raised 20°-25° backward and upward with a straight line passing through the center of the heel and perpendicular to the midline of the foot as the axis, and the front end of the heel area 4 and the rear end of the waist area 3 are connected by an arc.

[0038] In this embodiment, a flexible V-shaped groove 10 is provided on the metatarsophalangeal joint axis 6. The flexible V-shaped groove 10 overlaps with the metatarsophalangeal joint axis 6 to form a through structure, which helps the metatarsophalangeal joint to bend.

[0039] In this embodiment, a V-shaped drainage groove A11 is provided in the metatarsophalangeal region 2. The V-shaped drainage groove A11 extends forward from the intersection of the midline of the foot 8 and the axis of the metatarsophalangeal joint 6. Its depth gradually decreases forward from the intersection of the midline of the foot 8 and the axis of the metatarsophalangeal joint 6. The function of the V-shaped drainage groove A11 is: firstly, to drain water, and secondly, to improve flexibility and foot feel.

[0040] In this embodiment, the heel area 4 has a V-shaped drainage groove B12 on the midline 8 of the foot. The V-shaped drainage groove B12 overlaps with the midline 8 and extends from the heel to the rear end. Its depth is more than 1mm less than the thickness of the heel outsole to maintain the heel outsole as a single piece. The functions of the V-shaped drainage groove B12 are: firstly, to drain water; and secondly, to mitigate the impact of landing and improve flexibility and foot feel.

[0041] In this embodiment, the outer heel region 402 is provided with 1-2 parallel V-shaped drainage grooves C13, the V-shaped drainage grooves C13 forming an angle of 5-10 degrees with the foot midline 8 facing backward and outward; the 1-2 metatarsophalangeal regions 201 are provided with 1-2 parallel V-shaped drainage grooves D14, the V-shaped drainage grooves D14 forming an angle of 20-25 degrees with the foot midline 8 facing upward and outward.

[0042] In this embodiment, the edges of the 3-5 metatarsophalangeal region 202 are provided with multiple triangular patterns A15, one side of which coincides with the edge of the sole body 1; the remaining parts of the 3-5 metatarsophalangeal region 202 are provided with square patterns 16, one diagonal of which is parallel to the midline 8 of the foot; the waist region 3 is provided with multiple triangular patterns B17, one side of the triangular pattern B17 located at the edge of the outer waist region 301 coincides with the edge of the sole body 1, and the distance between the triangular pattern B located at the edge of the inner waist region 302 and the edge of the sole body is about 1 cm or more. Furthermore, the side lengths of the triangular patterns A, B, C, and square patterns are about 1 cm, the square patterns are spaced more than 1 cm apart, and all are frustum-shaped with a thickness of 3-4 mm. The triangular pattern, with one side coinciding with the outer edge, helps maintain grip at the final moment of takeoff. In the square pattern, one diagonal is parallel to the midline of the foot, and the right angles on both sides form sharp angles, facilitating rotation. A square pattern is used in the metatarsophalangeal region, with the right angles facing outwards, meaning the diagonal is parallel to the midline of the foot, to facilitate rotation and reduce the torque of internal rotation.

[0043] In this embodiment, the elastic sheet 5 is a plastic elastic sheet, which includes a sheet-like elastic sheet body 501 located at the heel center. The front of the elastic sheet body 501 has two inner and outer elastic strips 502. The inner elastic strip 502 extends forward from the inner heel region 401 to the first toe of the 1-2 metatarsophalangeal region 201, and the outer elastic strip 502 extends forward from the outer heel region 402 to the fifth metatarsophalangeal region 202. A front transverse strip 503 connects the front ends of the two elastic strips 502, extending from the fifth metatarsophalangeal region to the first toe. Furthermore, the elastic sheet is approximately 3 mm thick, and the width of the three sides outside the heel (two elastic strips + front transverse strip) is approximately 8 mm. The functions of installing elastic plates are: first, to support the arch of the foot, which is especially important when there is no pattern support in the inner waist of the outsole; second, to provide stability and prevent excessive twisting of the shoe waist; third, to assist the first and second toes in pushing off with elasticity; and fourth, to limit excessive twisting of the toe and prevent bunions.

[0044] In this embodiment, the main body 1 of the sole includes an outsole 101 and a midsole 102 disposed on the outsole 101. An elastic sheet 5 is disposed between the outsole 101 and the midsole 102. The intersection of the midline of the foot and the axis of the metatarsophalangeal joint of the midsole 102 is the forefoot reference point, and the heel center is the heel reference point. The height difference between the two reference points is 7-12mm. The front part of the midsole gradually thins and stops at the front of the sole.

[0045] In this embodiment, the waist area 3 is a downward-convex arc surface at the outsole 101, with the apex of the arc surface 2mm higher than the intersection of the heel center, the midline of the foot, and the metatarsophalangeal joint axis (including the outsole pattern). Multiple triangular patterns are arranged within the waist area, with the triangular patterns on the inner side of the waist area overlapping the edge of the main sole body by approximately 1cm or more. This design reduces the contact area of ​​the outsole with the ground in the inner waist area and facilitates smooth forward rolling after heel strike. One of the biggest challenges of flat feet is the difficulty in rotation upon landing; a large outsole contact area significantly increases the difficulty of rotation. Reducing the outsole contact area in this area weakens arch support, a problem that will be addressed by adding an elastic plate.

[0046] In this embodiment, viewed from the rear end to the front, the main body of the sole is inclined with the outer end lower and the inner end higher, and the inclination angle is 3-5 degrees.

[0047] In this embodiment, the hardness of each area of ​​the midsole is 50-60 degrees overall.

[0048] In this embodiment, the sole is optimized in the following five aspects to further address the problems of decreased ankle joint stability, decreased ground extension ability, and increased internal rotation angle and torque of the ankle and knee joints when walking with flat feet. Specifically:

[0049] First, based on the three-dimensional angle and force direction of the ankle joint when walking with flat feet, the heel upturn angle and drainage groove angle of the sole are designed to increase the contact area and anti-slip force when landing, shorten the stabilization time when landing, and improve stability.

[0050] Secondly, based on the three-dimensional angle and force direction of the ankle joint when walking with flat feet, the structure of the first toe position of the sole and the angle of the drainage groove are designed to increase the contact area and grip when taking off, and improve the push-off ability.

[0051] Third, the triangular pattern on the inner side of the sole is significantly reduced to decrease the contact area with the ground, improving shoe flexibility and reducing pronation upon landing. To compensate for the reduced support of the arch due to the reduced inner side, the following fourth point is used to enhance and supplement the design.

[0052] Fourth, an elastic plate is installed on the midsole to provide stability and rebound:

[0053] Fifth, a square pattern is used in the metatarsophalangeal region, with the right angles of the pattern facing outwards, that is, the diagonal is parallel to the midline of the foot, to facilitate rotation and reduce the torque of internal rotation.

[0054] This invention is designed based on the biomechanical data of the foot during normal walking, collected and analyzed, and its biomechanical characteristics. The collected biomechanical data includes the three-dimensional angles and torques of the hip, knee, ankle, and metatarsophalangeal joints during the complete support phase of a gait cycle, as well as the three-dimensional force distribution on the sole. The sole design includes the outsole profile, the overall heel-to-toe height difference, the three-dimensional angles of key components, the angles of key patterns, the elastic plate for stability and rebound, and the forefoot flexion groove, etc. Its advantages are:

[0055] 1. Design of the heel area of ​​the sole. Testing and analysis show that when the foot strikes the ground, the ankle dorsiflexes at 25 degrees, meaning the midline of the foot forms a 25-degree angle with the ground, the foot abducts approximately 10 degrees, and the sole forms a 22-degree angle with the ground. There is essentially no inward or outward pronation. The combined force of ground grip is at a 15-20 degree angle to the direction of forward movement. The aforementioned heel angle and V-shaped groove design allow the entire heel area to contact the ground more quickly upon landing, increasing the contact area and providing greater grip, thus enhancing stability upon landing.

[0056] 2. Design of the 1st-2nd toe area. Measurements and analysis show that the foot abducts approximately 10 degrees upon landing, and the resultant force of the push-off is directed 10-15 degrees backward and outward. Therefore, the direction of the V-shaped drainage groove D is 20-25 degrees outward and upward with the midline of the foot. Simultaneously, flat feet exhibit a large forward lean angle and a large dorsiflexion angle during push-off, requiring a significant upward tilt angle in the forefoot. Therefore, an upward tilt angle of 10-15 degrees is selected for the toe area above the metatarsophalangeal joint axis. This design provides a larger grip area and grip force for push-off, enhancing push-off ability.

[0057] 3. Reduce the outsole area of ​​the inner waist. When the foot strikes the ground, the main pressure-bearing parts are the outer heel, outer waist, fifth metatarsophalangeal joint, first and second metatarsophalangeal joints, and the first toe. The inner waist bears less force. Reducing the contact area of ​​this part of the outsole can improve the flexibility of the shoe and make it easier to rotate when wearing it.

[0058] 4. Outsole pattern design. Triangular and square patterns are simple and provide good grip. In the triangle pattern, one side aligns with the outer edge to maintain grip at the final moment of takeoff; in the square pattern, one diagonal is parallel to the center line of the foot, and the right angles on both sides form sharp corners, facilitating rotation.

[0059] 5. Design of the elastic plate. Testing and analysis revealed that flat feet exhibit insufficient push-off force during foot extension, and the metatarsophalangeal joint torque is greater than in normal feet. The functions of installing the elastic plate are: firstly, to support the arch of the foot, which is especially important after the inward compression of the outsole; secondly, to provide stability and prevent excessive torsion of the shoe's midsection; thirdly, to assist the push-off ability of the first and second toes with elasticity; and fourthly, to limit excessive toe twisting and prevent hallux valgus.

[0060] 6. The design features a large V-shaped drainage groove. A V-shaped groove is created along the midline of the heel area, serving two purposes: drainage and impact mitigation. Compared to a flat surface without grooves, this design avoids a stiff feel and improves flexibility and foot feel. A V-shaped groove, gradually decreasing in depth, is created starting from the intersection of the midline and the metatarsophalangeal joint axis. This serves two purposes: drainage and improving flexibility and foot feel. A V-shaped groove along the metatarsophalangeal joint axis also aids in the flexion of the metatarsophalangeal joint area.

[0061] If this utility model discloses or relates to mutually fixedly connected parts or structural components, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured using a casting process) (except where it is obviously impossible to use an integral forming process).

[0062] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in this utility model above include states or shapes that are similar to, close to, or approximate with them.

[0063] Any component provided by this utility model can be assembled from multiple individual components, or it can be a single component manufactured by a one-piece molding process.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.

Claims

1. A sole structure suitable for flat feet, characterized in that: The shoe includes a sole body that is low at the front and high at the back. The sole body is divided into a metatarsophalangeal region, a midsection region, and a heel region from front to back. The metatarsophalangeal region curves forward and upward, and the heel region curves backward and upward. The lower part of the midsection region is an arc surface. An elastic plate is provided inside the sole body, and the elastic plate extends from the heel region to the metatarsophalangeal region.

2. The sole structure suitable for flat feet according to claim 1, characterized in that: The metatarsophalangeal region and the lumbar region are separated by the metatarsophalangeal joint axis, and the lumbar region and the heel region are separated by a line segment passing through the heel and perpendicular to the midline of the foot of the sole body.

3. A sole structure suitable for flat feet according to claim 2, characterized in that: The metatarsophalangeal region includes the 1st-2nd metatarsophalangeal region and the 3rd-5th metatarsophalangeal region distributed on the inner and outer sides of the midline of the foot; the lumbar region includes the medial lumbar region and the lateral lumbar region distributed on the inner and outer sides of the midline of the foot; the heel region includes the medial heel region and the lateral heel region distributed on the inner and outer sides of the midline of the foot.

4. A sole structure suitable for flat feet according to claim 3, characterized in that: The outsole of the 1-2 metatarsophalangeal region is a single piece of structure. The entire metatarsophalangeal region curves upward at 10°-15° along a straight line passing through the intersection of the metatarsophalangeal joint axis and the midline of the foot, perpendicular to the midline of the foot. The rear end of the metatarsophalangeal region and the front end of the lumbar region are transitioned by a rounded arc. The heel region is a single piece of structure. The heel region curves upward at 20°-25° along a straight line passing through the heel and perpendicular to the midline of the foot. The front end of the heel region and the rear end of the lumbar region are transitioned by a rounded arc.

5. A sole structure suitable for flat feet according to claim 2, characterized in that: A V-shaped groove is formed on the axis of the metatarsophalangeal joint, and a V-shaped drainage groove A is formed in the metatarsophalangeal region. The V-shaped drainage groove A extends forward from the intersection of the midline of the foot and the axis of the metatarsophalangeal joint, and its depth gradually decreases forward from the intersection of the midline of the foot and the axis of the metatarsophalangeal joint. A V-shaped drainage groove B is formed on the midline of the foot in the heel region.

6. A sole structure suitable for flat feet according to claim 3, characterized in that: The outer heel area has 1-2 parallel V-shaped drainage grooves C, with the V-shaped drainage grooves C forming an angle of 5-10 degrees with the midline of the foot outwards; the 1-2 metatarsophalangeal areas have 1-2 parallel V-shaped drainage grooves D, with the V-shaped drainage grooves D forming an angle of 20-25 degrees with the midline of the foot inwards.

7. A sole structure suitable for flat feet according to claim 3, characterized in that: Multiple triangular patterns A are distributed along the edge of the 3-5 metatarsophalangeal region, with one side of each triangular pattern A coinciding with the edge of the main body of the sole. The remaining portion of the 3-5 metatarsophalangeal region is decorated with square patterns, with one diagonal of each square pattern parallel to the midline of the foot. Multiple triangular patterns B are provided within the waist region. One side of the triangular pattern B located at the edge of the outer waist region coincides with the edge of the main body of the sole, while the triangular pattern B located at the edge of the inner waist region is more than 1 cm away from the edge of the main body of the sole.

8. A sole structure suitable for flat feet according to claim 3, characterized in that: The elastic sheet includes a sheet-like elastic sheet body located at the heel center. The front part of the elastic sheet body is provided with two elastic strips distributed on the inside and outside. The elastic strip on the inside extends forward from the inner heel area to the first toe of the 1-2 metatarsophalangeal region, and the elastic strip on the outside extends forward from the outer heel area to the fifth metatarsophalangeal region of the 3-5 metatarsophalangeal region. A front transverse strip is connected between the front ends of the two elastic strips, and the front transverse strip extends from the fifth metatarsophalangeal region to the first toe.

9. A sole structure suitable for flat feet according to claim 1, characterized in that: The main body of the sole is inclined with the outer end lower and the inner end higher, and the inclination angle is 3-5 degrees. The main body of the sole includes an outsole and a midsole set on the outsole. The elastic plate is set between the outsole and the midsole. The intersection of the midline of the foot and the axis of the metatarsophalangeal joint of the midsole is the forefoot reference point, and the heel center is the heel reference point. The height difference between the two reference points is 7-12mm. The front part of the midsole gradually thins and stops at the front of the sole.

10. A sole structure suitable for flat feet according to claim 1, characterized in that: The lower part of the waist area is a downwardly convex arc surface, wherein the apex of the arc surface is 2mm higher than the intersection of the heel center, the midline of the foot, and the axis of the metatarsophalangeal joint.

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