CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to the Singapore application no. 10202251586 Y filed November 2, 2022, the contents of which are hereby incorporated by reference in their entirety for all purposes.

TECHNICAL FIELD

[0002] This application relates to a footwear and, more particularly, to a device to be worn at the foot for early intervention of knee osteoarthritis.

BACKGROUND

[0003] Knee osteoarthritis (osteoarthritis of the knee) is one of the common types of osteoarthritis. There are currently two main ways to treat knee osteoarthritis, namely, surgery and medication. Surgical treatment include knee joint replacement, arthroscopy to encourage cartilage growth, and osteotomy to cut the bones around the joint, etc. The alternative is medication, e.g., by injecting steroids or hyaluronic acid derivatives into or around the knee joint, which can help to reduce the pain for several months.

SUMMARY

[0004] A footwear for early knee osteoarthritis intervention for a user, including an upper, and a sole. The sole is formed by a plurality of structures. The plurality of structures are at least partially spaced apart. The plurality of structures have a varied configuration across regions of the sole to provide the regions with respective stiffnesses that vary among the regions. The regions are three-dimensional. The regions include a target region that is characterized by a stiffness that is lower than any of the respective stiffnesses of any other of the regions. The target region is shaped and positioned across the sole to coincide with the barefoot centre of pressure (COP) line of the user. The barefoot COP line may be defined based on data of the user walking barefooted and/or data of a group of healthy individuals with no known symptoms or risk factors of knee osteoarthritis. The user has a COP line measurable with respect to the user in movement and a barefoot COP line measurable with respect to the user in barefoot walking movement. The sole has an outer face and an inner face. The sole is coupled with the upper to enable the inner face and the upper to cooperatively receive a foot of the user.

[0005] The varied configuration of the plurality of structures provides a plurality of stiffness gradients in various orientations across the sole, each of the plurality of stiffness gradients biasing a dynamic shifting of the COP line towards the barefoot COP line.

[0006] The plurality of stiffness gradients are configured in decreasing stiffnesses towards the target region along a plurality of stiffness gradients in various orientations.

[0007] The plurality of structures allow free flexing of the foot in movement, in which the regions provide force absorption and regional support to the foot.

[0008] Each of the regions is characterized by a regional stiffness, in which the target region forms a contiguous region characterized by a regional stiffness that is lower than the regional stiffness of any other of the regions.

[0009] The plurality of structures may include a plurality of nub structures, in which adjacent ones of the plurality of nub structures are spaced apart to define a network of gaps.

[0010] The sole may include a base layer with the plurality of structures protruding from the base layer, in which a sole thickness of the sole is formed by a thickness of the base layer and a length of one of the plurality of structures.

[0011] Within any one of the plurality of the regions, the plurality of structures may be similarly configured for the length of the plurality of structures. [0012] Each of the regions may be formed of an elastic foam and/or additively formed metamaterial structure. At least two adjacent ones of the regions may be formed as detachable pieces of the elastic foam and/or additively formed metamaterial structures of different stiffnesses. At least two adjacent ones of the regions are formed with complementary shapes.

[0013] At least two adjacent ones of the regions comprise differently configured structures, in which the at least two adjacent ones of the regions are characterized by different stiffnesses. The at least two adjacent ones of the regions may include different densities of the structures. The at least two adjacent ones of the regions may include differently shaped ones of the structures. The at least two adjacent ones of the regions may include differently sized ones of the structures. The at least two adjacent ones of the regions may include the structures formed of different material stiffnesses.

[0014] Each of the plurality of regions may include a network of a primary material defining compressible structures and/or cavities distributed therein, in which the respective stiffness of each of the plurality of regions is dependent on a density of distribution of the compressible structures and/or cavities.

[0015] The sole may include a base layer defining the inner face of the sole, with the plurality of structures within any one of the regions being similarly configured throughout a sole thickness of the sole.

[0016] The sole may include a base layer, in which each of the plurality of regions is characterized by a flexural stiffness that is dependent on a thickness gradient of the base layer to which the structures are coupled.

[0017] The sole may include an insole and an outsole, the insole providing the inner face and the outsole providing the outer face, in which the plurality of structures are disposed in the outsole. [0018] The footwear further comprising a midsole, the midsole being disposed between the insole and the outsole. The midsole and the outsole may be formed of differently configured ones of the structures and/or cavities. The midsole and the outsole may be formed of similarly configured ones of the structures and/or cavities.

[0019] The midsole and the outsole may be additively formed as an integral component. Alternatively, the sole may include one or more jointed flex features, in which the sole comprises at least two segments coupled by a joint. The joint may have more than one degree- of-freedom.

[0020] The sole may be configured based on a method including: determining a location of a center of pressure line of the user relative to the sole, the center of pressure line being based on any one or both of (i) data of barefoot walking of the user and (ii) on data of a group of healthy persons; defining the target region such that the center of pressure line corresponds to a centerline of the target region target; and configuring a stiffness of the target region and respective stiffnesses of others of the regions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various embodiments of the present disclosure are described below with reference to the following drawings:

[0022] FIG. 1A and FIG. IB are schematic drawings of a sole of a footwear according to various embodiments of the present disclosure;

[0023] FIG. 2A is a top view of the sole showing a distribution of cavities open to an inner face of the sole;

[0024] FIG. 2B is a side view of the sole of FIG. 2A;

[0025] FIG. 2C is a bottom cross-sectional view of the sole of FIG. 2A;

[0026] FIG. 2D is a magnified view of a part of FIG. 2C; [0027] FIG. 3A is an exploded bottom perspective view of a schematic drawing of a sole according to some embodiments of the present disclosure;

[0028] FIG. 3B is a top perspective view of the sole of FIG. 3 A;

[0029] FIG. 4A is a cross-sectional side view of the sole of one embodiment of the present disclosure;

[0030] FIG. 4B is a bottom view of the sole of FIG. 4A;

[0031] FIG. 4C is a schematic diagram of the outsole of FIG. 4B showing multiple regions;

[0032] FIG. 5A is a bottom view of an outsole according to another embodiment of the present disclosure;

[0033] FIG. 5B is a schematic diagram of the outsole of FIG. 5A;

[0034] FIG. 6A is a bottom view of a midsole according to some embodiments of the present disclosure;

[0035] FIG. 6B is a schematic diagram of the midsole of FIG. 6A showing multiple regions;

[0036] FIG. 7 is an exploded top perspective view of the sole according to one embodiment;

[0037] FIG. 8 is an exploded top perspective of the sole according to another embodiment;

[0038] FIG. 9 is a cross-sectional view of a sole according to yet another embodiment;

[0039] FIG. 10A is a top perspective view of a sole without cavities opening at the inner face;

[0040] FIG. 10B is a top perspective view of a sole with cavities opening at the inner face;

[0041] FIG. 11 A is a cross-sectional view showing a sole with a base layer;

[0042] FIG. 1 IB is a schematic bottom perspective view of a portion of the sole;

[0043] FIG. 12 is a bottom perspective view of the sole of FIG. 10B with a frontal cut;

[0044] FIG. 13 schematically illustrates a method of determining a barefoot COP line or barefoot COP region;

[0045] FIGS. 14A - 14D are schematic drawings showing a correlation between the ground reaction forces and various embodiments of the midsole and the outsole; [0046] FIG. 15 shows a centre of pressure (COP) line plotted based on experimental results obtained for a prototype of the present footwear, in comparison with a target COP line and a COP line reported for a conventional footwear;

[0047] FIG. 16 shows an example of a footwear incorporating the present footwear;

[0048] FIG. 17 shows an example of a foot brace incorporating the present footwear; and [0049] FIGS.18A to 18C illustrate an example of the sole of the present disclosure having jointed flex features.

DETAILED DESCRIPTION

[0050] The following detailed description is made with reference to the accompanying drawings, showing details and embodiments of the present disclosure for the purposes of illustration. Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments, even if not explicitly described in these other embodiments. Additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0051] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0052] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance as generally understood in the relevant technical field, e.g., within 10% of the specified value.

[0053] As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0054] According to various embodiments of the present disclosure, the proposed footwear is intended to be wearable by the user at the foot to serve as early intervention for knee osteoarthritis (OA). The sole may be used in the early intervention of knee OA, e.g., delaying the onset of knee OA for individuals with or without predisposed conditions. The device may be in the form of footwear, e.g., worn by the user as a pair of shoes or insoles or braces.

[0055] Referring to FIGS. 1 A to 2D, the present disclosure describes various embodiments of a footwear 200 and more particularly, a sole 250, for early knee osteoarthritis intervention for a user. The footwear 200 includes an upper and a sole 250. The sole 250 has an outer face 514 and an inner face 512. The sole 250 may be coupled with the upper to enable the inner face 512 and the upper to cooperatively receive a foot of the user.

[0056] The user has a barefoot centre of pressure (COP) line that can be measured with the user walking barefoot.

[0057] The footwear 200 may be worn by the user in walking on a level ground, with the entirety of the target region being flat or substantially flat to provide an unbroken physical contact between at least a part of the target region and the level ground, e.g., to mimic barefoot walking. The present sole 250 or footwear 200 is configured to mimic barefoot walking with free flexing of the foot or shifts the COP line of the user when the user walks wearing the present footwear.

[0058] As used herein, the term barefoot COP line may be defined for a user, and may be a personal target COP line that is defined based on any one or a combination of (i) data of the same user, and/or (ii) data of a group of healthy persons who are without symptoms or risk factors of knee osteoarthritis. The barefoot COP line can also be understood as the COP of a user (for whom the sole 250 is customised or personalized) if the same user is walking barefooted and assuming the user has reduced or no symptoms (or risk factors) of knee osteoarithritis. For example, the actual COP line of the user may be defined based on measurements of the user alone, a general target COP line may be defined based on data of a group of healthy individuals (the term healthy being understood in relation to knee osteoarthritis), and a barefoot COP line may be defined between the actual COP line of the user and the general target COP line. For example, the user has a COP line measurable with respect to the user in movement and a barefoot COP line measurable with respect to the user in barefoot walking movement.

[0059] With the barefoot COP line defined, the sole 250 is then configured to promote or enable the user to walk with a barefoot COP line, e.g., the sole 250 is configured to shift dynamically the user’s movement or dynamic COP trajectory towards the target region in the footwear, as will be elaborated below.

[0060] The user is assumed to have a habitual walking style. The user may be put through a series of gait assessments, and with the aid of plantar pressure maps, a dynamic trajectory of the COP axis (vertical imaginary line extending through the net force at an instant when at least a part of the foot is in contact with the ground) may be obtained. If the gait assessments are conducted with the user being barefooted, for the sake of brevity, such COP lines are also called barefoot COP lines. When the same tests are conducted for a user wearing a conventional shoe, it is observed that the COP line deviates from the barefoot COP line. Reference is made to a shifting of the COP line or to a dynamic shift of the COP line. The footwear of the present disclosure includes a sole with an in-built bias to change the walking style of the user dynamically, e.g., concurrently with the user in movement, such as the user walking while wearing the footwear. The varied configuration of the plurality of structures provides a plurality of stiffness gradients in various orientations across the sole, each of the plurality of stiffness gradients biasing a dynamic shifting of the COP line towards the barefoot COP line.

[0061] When the same tests are conducted for the user wearing the footwear as proposed herein, the present footwear 200 (e.g., sole 250) will show a COP line that is closer to the barefoot COP line (as compared to the COP line when a conventional shoe is worn). In a sense, the present footwear 200 shifts the COP line to better track or match the barefoot COP line. [0062] As shown in FIG. 1 A and FIG. IB, the sole 250 includes a plurality of structures 540. The plurality of the structures 540 may be variably configured across regions 600 of the sole 250 to provide the regions with respective stiffnesses that vary among the regions. The regions are three-dimensional. The regions 600 include a target region 610 that is characterized by a stiffness that is lower than any of the respective stiffnesses of any other of the regions 630. The target region 610 is shaped and positioned in the sole to coincide with the barefoot COP line. Each of the regions 600 may be characterized by a regional stiffness. The target region 610 may form a contiguous region characterized by a regional stiffness that is lower than the regional stiffness of any other of the regions 630.

[0063] As shown in FIG. 2C, the varied configuration of the plurality of structures provides a plurality of stiffness gradients 560 in various orientations across the sole, with each of the plurality of stiffness gradients biasing a dynamic shifting 564 of the COP line towards the barefoot COP line, e.g., from the other regions 630 towards the target region 610. The plurality of stiffness gradients 560 are configured in decreasing stiffnesses towards the target region 610 along a plurality of stiffness gradients 564 in various orientations. The plurality of structures 540 may be characterized by a gradient 560 of decreasing stiffnesses towards the target region 610. The plurality of structures allow free flexing of the foot in movement, in which the regions provide force absorption and regional support to the foot.

[0064] The term structures is used herein in a generic sense of a piece of material . Some or all of the structures 540 may be in the form of nub structures 543 as shown in FIGS. 2B to 2D. The plurality of structures 540 may be interconnected (e.g., branched or in the form of a network or matrix) and at least partially spaced apart to define an interconnected network of gaps 546 (or valleys) between the nub structures 543. Cavities 530 may be defined in the structures 540, e.g., each nub structure 543 may include a nub cell wall surrounding a cavity 530. Cavities may be opened to the air at the inner face 512 (as shown in FIG. 2A) and/or at the outer face 514. In some embodiments, the structures 540 may be interchangeably referred to as struts and/or elements of a metamaterial. In some other embodiments, each of the plurality of regions may include a network or a body of a primary material defining compressible cavities 530 distributed therein, in which the respective stiffness of each of the plurality of regions 600 is dependent on a density of distribution of the compressible cavities 530. For example, in some other embodiments, the structures 540 refer to the foam material of a foam, with air bubbles distributed in the foam.

[0065] FIG. 2D is a portion of FIG. 2C, enlarged to better show an example of the sole 250 with nub structures 543 solely to aid understanding and for the purpose of illustration. Each nub structure 543 may be a protruding piece of material extending away from a base layer. At least two adjacent ones of the regions 600 may include differently configured ones of the structures 540, gaps 546, and/or the cavities 530, in which the at least two adjacent ones of the regions 600 are characterized by different stiffnesses. At least two adjacent ones of the regions 600 may include different densities of the structures 540, gaps 546, and/or the cavities 530. At least two adjacent ones of the regions 600 may include differently shaped ones of the structures 540, gaps 546, and/or the cavities 530. At least two adjacent ones of the regions 600 may include differently sized ones of the structures 540, gaps 546, and/or the cavities 530. At least two adjacent ones of the regions 600 may include the nub structures 540 formed of different material stiffnesses.

[0066] The sole 250 may include a base layer 520, in which each of the plurality of regions 600 is characterized by a stiffness that is dependent on a thickness gradient of the base layer 520 to which the structures 540 with/without cavities 530 are coupled.

[0067] The sole 250 includes an insole 300 and an outsole 500, the insole 300 providing the inner face 312 and the outsole providing the outer face 514, and in which the plurality of structures 540 are disposed in the outsole. The sole 250 may further include a midsole 400, in which the midsole 400 is disposed between the insole 300 and the outsole 500.

[0068] The midsole 400 and the outsole 500 may be formed of differently configured ones of the structures 540, gaps 546, and/or cavities 530. The midsole 400 and the outsole 500 may be formed of similarly configured ones of the structures 540, gaps 546, and/or cavities 530. The sole may include a base layer defining the inner face of the sole, with a plurality of structures within any one of the regions being similarly configured throughout a sole thickness of the sole. [0069] The midsole 400 and the outsole 500 may be additively formed as an integral component. In other embodiments, the sole may include one or more jointed flex features, in which the sole is formed as separate parts connectable by complementary ones of the jointed flex features.

[0070] The insole 300 may be shaped with raised edges partially along the perimeter of a heel region, and in which the insole 300 is dimensioned according to the foot profile in a nonweight bearing condition.

[0071] The sole may be configured based on a method including: determining a location of a center of pressure line of the user relative to the sole, the center of pressure line being based on any one or both of (i) data of barefoot walking of the user and (ii) on data of a group of healthy persons; defining the target region such that the center of pressure line corresponds to a centerline of the target region target; and configuring a stiffness of the target region and respective stiffnesses of others of the regions.

[0072] Alternatively described, according to some embodiments of the present disclosure, the footwear 200 includes a sole 250 that includes an insole 300, a midsole 400, and an outsole 500. FIG. 3 A illustrates the sole 250 in an exploded bottom perspective view and FIG. 3B illustrates the sole 250 in an exploded top perspective view. [0073] FIG. 4A is a cross-sectional side view along a longitudinally oriented sectional line 100 extending from a toe 251 to a heel 253 of the sole 250, or along a plane 110. The insole 300 may be a relatively thin insole base 310. Optionally, the insole 300 includes a raised side 322 at least partially along a perimeter 320 of the insole base 310. In use, the insole 300 of the present footwear 200 may be in direct contact with the user's foot. In the sole 250, the function of providing arch support is not primarily provided by the insole 300. That is, the insole 300 may be configured independently of the user’s pronation issues (if any). This does not prevent the sole 300 from providing some support at the arch of the foot simply because the insole 300 is shaped to follow the surface contours of the sole of the foot. For example, the insole 300 of the present footwear 200 may have a substantially similar thickness 370 throughout the insole base. For example, relatively soft materials may be selected for the insole 300 of the present footwear. For example, the insole 300 may be shaped and sized to provide a surface 310 on which the user's foot may rest in relative comfort. In some embodiments, the surface 310 of the insole 300 is the same as the inner face of the sole 250. For example, socks may be optional with the insole 300 of the present footwear 200.

[0074] The outsole 500 may include a three-dimensional (3D) component, e.g., including a base layer 520 connecting a plurality of structures 540 with or without variable compressive stiffness, creating an outer surface 514 and an outsole thickness 570. The external outsole surface 514 is intended for direct contact with the external environment, for example, the ground. To aid understanding and for the sake of brevity, the term "outsole thickness" 570 will be used herein to refer to the thickness of the outsole 500. The outsole thickness 570 may be substantially similar throughout the whole outsole 500 of one footwear 200. Different embodiments of the footwear 200, or the sole 250, may have outsole thicknesses 570 that vary from embodiment to embodiment, or an outsole thickness 570 that vary in one footwear. [0075] FIG. 4B and FIG. 5A are cross-section views of different exemplary embodiments of the sole 250 showing that the outsole 500 includes a plurality of regions 600 of different physical properties, including flexural stiffness and structures 540 with or without variable compressive stiffness. For greater clarity, the plurality of regions in the outsoles 500 of FIG. 4B and FIG. 5A are outlined in dashed lines in FIG. 4C and FIG. 5B, respectively. Each region 600 extends generally or substantially longitudinally along a length 501 of the outsole (the length of the outsole may be taken as the longest length along a longitudinal axis running from a toe 251 to a heel 253 of the sole 250). In the examples illustrated, the outsole 500 includes three regions 600. The outsole 500 includes, for example, a target region 610 with a first region 631 and a second region 632 disposed on either lateral side of the target region 610. The first region 631 adjoins the target region 610 along the length 501 of the outsole 500. The second region 632 adjoins the target region 610 along the length 501 of the outsole 500. Each of these regions 600 may be substantially homogeneous throughout a thickness 570 of the outsole 500. [0076] In some embodiments, the flex feature 660 is integrated in the metamaterial structure of the outsole 500, such that the flex features 660 are more subtle or less obviously visible. In various embodiments, the flex line of feature 600 is a combined string of gaps or valleys of voids 546 formed between structures 540 of the outsole 500.

[0077] In various embodiments, the outsole 500 includes one or more flex features 660. For greater clarity, the flex features 660 of the outsole 500 in FIG. 5A are shown in solid lines in FIG. 5B. The flex feature 660 may define a curvilinear groove or slot, for example, a cut in the external surface 514 of the outsole 500. The flex feature 660 may be straight, curved, or curvilinear groove defining a smaller outsole thickness relative to the rest of the outsole 500. Each of the one or more flex features 660 extends transversely, or in one or more orientations non-parallel to the longitudinal direction or the longitudinal axis 100. A flex feature 660 may extend across an entire width of the outsole 500, or the flex feature 660 may extend partially along the width of the outsole 500. In the example illustrated in FIG. 5A and FIG. 5B, the outsole 500 includes three regions 600 which are divided by two flex features 660. As illustrated, the flex features 660 extend transversely and may be differently oriented relative to one another.

[0078] In various embodiments, the outsole 500 is elastic or compressible in more than one direction. In various embodiments, the outsole 500 is formed with 3D-printed struts or flexconnectors 545. The outsole 500 may be configured with a metamaterial configured to relieve stress concentrations and allow greater cyclic loading. In various embodiments, the outsole 500 is configured with a target region 610 that is characterized by a lower flexure stiffness than the respective flexure stiffnesses of the other non-target regions 630. For example, the target region 610 is configured to be less stiff or more flexible than each of the first region 631 and the second region 632. For example, the outsole 500 is configured such that the elastic modulus of the target region 610 is the lowest of all of the at least three regions 600. In various embodiment, the outsole 500 is configured with a target region 610 that is characterized by a lower flexure stiffness and composed of a plurality of structure 540 of lesser compressive stiffness than the respective flexure and compressive stiffness of the other non-target regions 630.

[0079] The outsole 500 may have an external outsole surface or outer face 514 that defines a mostly flat surface area for contact with the ground. The outer face 514 may be described as being flat or substantially flat in this sense, disregarding irregularities owing to the nature of the metamaterial forming the outsole 500. The outer face 514 is essentially planar or flat so that the foot and leg muscles are in a condition similar to a state of being barefooted. The external outsole surface 514 is sufficiently flat so that when the user is standing still, the foot provides stable support to user. For example, the plurality of regions 600 may collectively co-planarly define the external outsole surface 514. For example, in the example where the outsole 500 includes at least three regions 600 (the target region 610 with a first region 631 and a second region 632), all the regions 600 define respective coplanar portions of the external outsole surface 514.

[0080] The sole 250 may include a midsole 400 disposed between the insole 300 and the outsole 500. In some embodiments, the midsole 400 is configured differently from the outsole 500. FIG. 6A shows a bottom view of the midsole 400 according to some embodiments of the present disclosure, in which the plurality of structures in the midsole 400 are configured differently from the plurality of structures in the outsole 500 (e.g., as shown the outsole 500 of FIG. 4B). The midsole 400 includes an elastic body with a plurality of midsole zones 700 of different mechanical properties. For better clarity, FIG. 6B shows different midsole zones 710,720 outlined in dashed lines.

[0081] For example, the midsole 400 may include a main body 410 characterized by an elasticity and a plurality of zones 700, each characterized by a respective elasticity E ₂ , E ₃ , ... , E _n , etc. The respective elasticity may be varied according to the amount of force absorbency required for the respective zone 700, as will be described further below. The shape and dimensions of each zone 700 may be varied accordingly, as will be described further below.

[0082] In some embodiments, one or more midsole zones 700 of the midsole 400 may be moulded or additively formed. In some embodiments, the midsole 400 may be an assembly of separately fabricated parts in which any of the parts may be moulded or additively formed. In some embodiments, as illustrated schematically in the exploded view of FIG. 7, the midsole 400 may include a main body 410 with one or more cavities 420 defined therein to receive complementary one or more inserts 430.

[0083] In some embodiments, as illustrated in FIG. 7, the midsole 400 and the outsole 500 are separately fabricated before being assembled. In some embodiments, as illustrated in the exploded view of FIG. 8, at least a part of the midsole 400 (e.g., the main body 410 of the midsole 400) and the outsole 500 are moulded or additively formed in a continuous process as an integral article.

[0084] FIG. 9 is a cross-sectional view of an example of the sole 250 showing structures 540 in the form of struts 545 defining gaps 546 between struts 545 and/or defining cavities 530 within a struct 545. In some examples, as shown in FIG. 10A, the sole 250 may have gaps 546 cutting through the outer face 514 of the sole 250. In some examples, as shown in FIG. 10B, the sole 250 may have cavities 530 opening at the inner face 512 of the sole 250.

[0085] In some embodiments, as illustrated in FIG. 11 A, FIG. 11B, and FIG. 12, the plurality of regions 600 of variously configured compressive structures 540 may be characterized by respective stiffness k ₂ , k ₃ , k _n , etc. The respective stiffness may be varied according to the amount of stiffness required for the respective region 600. The gaps 546 may be contiguous and defined by the nub structures 543. The nub structures 543 and together with the base layer 520 may together form a total thickness 370 of the sole 250 (for the sake of brevity, also referred to as “sole thickness” 370). The sole thickness 370 (e.g., total thickness or the overall thickness of the sole 250) may be varied by incorporating cavities 530 or other additional flex features 660. The gaps 546 may be configured in different orientations and/or depths relative to the nub structures 543. For example, a gap 546 of a depth corresponding to substantially almost the entire sole thickness may be provided for less stiffness. Alternatively, a gap 546 of a shallower depth (d) (compared to the structure length or the length of the nub structure) may be provided. In some embodiments, some or all of the nub structures 543 may have define a cavity 530 or an internal cavity with a depth (c). The depth and size of the cavities 530 may be variably configured to contribute towards the variable stiffness configuration across the sole 250.

[0086] The size, shape, density, pattern of distribution, and/or material composition of the nub structures 543 and/or gaps 546 may be varied from region to region, so as to form a target region with the greatest flexibility or the lowest stiffness. The gaps 546 are defined by the nub structures 543 to define an interconnected paths of bias or a network of decreasing stiffness. The varied configuration of the plurality of structures (in this example, the nub structures 543) provides a plurality of stiffness gradients 560 in various orientations across the sole 250. As the user walks, each of the plurality of stiffness gradients 564 provides a bias that results in a dynamic shifting of the COP line towards the target region 610, i.e., towards the barefoot COP line defined for the user.

[0087] The conventional insole having a lateral wedge tends to shift the user's weight on the foot laterally to the side of the foot. For the user with knee osteoarthritis, such a lateral shift merely shifts the pain from one region of the knee to another region of the knee. Besides, users with early knee osteoarthritis may not benefit with a lateral shift of the centre of pressure. Loading at the knee for such users are different from those with advanced knee osteoarthritis.

[0088] According to some embodiments, the present footwear 200 includes a sole 250 configured to guide the user towards walking with a healthy center of pressure (COP) line 690, in which the healthy or target COP line 690 is based on data of a healthy population and/or based on data from the user. In the present disclosure, healthy participants may refer to subjects with no knee OA symptoms and low risk factors of developing knee OA. The sole 250 of the present footwear 200 is configured such that the relative difference in stiffness in different regions 600 of the sole 250 facilitates the unconscious shifting of weight such that the actual pressure line tends to lie in the target region 610. In various examples, the target region 610 is shaped and dimensioned based on centre of pressure (COP) measurements taken with the user walking barefoot, as schematically illustrated in FIG. 13. To differentiate such COP measurements, the COP data used for the present disclosure may be referred to as barefoot center of pressure (COP) data. For example, the target region 610 may be shaped and dimensioned to correspond to a barefoot COP region, in which the barefoot COP region is defined about a center of pressure line 690 measured for barefoot walking. In some examples, the barefoot COP line 690 may form a centerline of the target region 610.

[0089] Conventional wisdom teaches to make the part of the shoe coincident with the COP line to have the greatest stiffness as the part of the sole coincidental with the COP line would have to bear the weight of the user. The sole as proposed in the present disclosure is therefore counterintuitive as the target region 600/610 is configured to have the lowest stiffness compared to the other regions 610 of the sole 250.

[0090] Reference is now made to FIGS. 14A to 14D to describe exemplary methods of making various embodiments of the present sole 250. FIGS. 14A to 14D are schematic drawings correlating the configuration of the various parts of the sole 250 to a footprint or a foot tracing. [0091] FIG. 14A illustrates an analysis that integrates a foot tracing (such as one illustrated by FIG. 13) and a plantar pressure distribution map (such as one illustrated by FIG. 13). FIG. 14A includes indications of one or more zones 700 associated with high impact 710 and one or more zones associated with low impact 720. The foot arch 730 in this example represents an area where there is low impact in the case of barefooted walking. FIG. 14A also shows a target COP line 690 with respect to the foot tracing.

[0092] After determining the target COP line 690 and the plantar pressure distribution, the outsole 500 can be configured based on with correspondingly shaped multiple regions 600 of variable stiffness or variable flexibility and/or one or more flex features 660. For example, as illustrated in FIG. 14B, the shape of the target region 610 may coincide with the target COP line, with non-target regions 630 being spaced apart from the target COP line. The outsole 500 may be configured to allow horizontal flexing and/or diagonal flexing, with at least one flex feature 660 intersecting a high impact region. In the example illustrated, the flex features include a forefoot flex line and a heel flex line. [0093] The midsole 400 can be configured based on the zones of high impact 710 and zones of low impact 720 determined. FIG. 14C illustrates an example of the midsole 400 made of foam with inserts 430 in a main body 410 to provide variable elasticity and variable compressive properties across the area of the midsole 400. In the example illustrated, a main body 410 of the midsole corresponds to the low impact zone 720. A forefoot insert 431 of the midsole is shaped and sized to generally correspond to a high impact zone 710 in the forefoot. A heel insert 432 of the midsole is sized and shaped to generally correspond to a high impact zone 710 in the heel. An arch insert 433 of the midsole is sized and shaped to generally correspond to the arch profile 730 of the foot.

[0094] FIG. 14D illustrates another example of the midsole 400 made by 3D printing to provide functionally graded metamaterial structure of variable stiffness and variable compressive properties (elasticity) across the area of the midsole. The respective densities/ stiffness of the regions 600 may be distributed according to the plantar pressure distribution map. The midsole 400 may be a 3D printed matrix of voxels or cells 440. The midsole 400 may include regions 600 of a plurality of cells and/or zones 700 of varying force absorbency. Cells/voxels within the same zone may be characterized by a common density, material, shape, and/or size, e.g., such that the zone has a similar force ab sorb ency/elasti city. Different zones are characterized by at least one difference in the respective densities, materials, shapes, and/or size of the cells/voxels, such that different zones have different force absorb ency/elasti city. Collectively, the midsole is characterized by a variable stiffness/elasticity across the entire midsole. For example, the midsole may be 3D printed with a first voxel configuration 441 corresponding to zones of high impact 710 and with different voxel configurations 442, 443 corresponding to zones of low impact 720. [0095] The following describes a footwear suitable for use in early knee OA intervention for a specific user, nonetheless, it will be understood that this does not preclude the configuration of the sole 250 so that it is suitable for use by multiple users.

[0096] In some embodiment, the outsole 500 may be configured without regard to address any pronation or supination of the foot. In some embodiments, the midsole 400 is configured to provide greater flexibility and easy flexion of the whole midsole-and-outsole 440, 500 along the target region 610 or along the target center of pressure line. In some embodiment, the outsole 500 is configured to support the required weight of the user while having the attribute to shift the user’ s walking COP line dynamically. The insole 300 is configured based on the foot outline (or perimeter as viewed in a plan view) and dimensions of the user's foot so as to provide an insole 300 that is shaped and sized to receive the foot, e.g., the whole of the foot is on the insole 300 whether the foot is stationary or in motion. The material of the insole 300 is preferably thin and flexible. The material of the insole 300 may be one selected for comfort. Examples include but are not limited to leather, cotton, fleece, piled fabrics, and various natural and/or synthetic materials comfortable against the barefoot.

[0097] The midsole 400 is configured based on the plantar pressure distribution map 820 of the user's foot acquired in the usual manner with the user in movement, e.g., during walking. Based on the plantar pressure distribution map 820, a topology can be outlined for the midsole 400 in terms of bands of pressure values. For example, one or more regions 600 may be defined as high impact zones 710, another one or more regions 600 may be defined as low impact zones 720. The midsole 400 is configured with a greater force absorbency/elasticity in the one or more high impact zones 710. The midsole 400 is configured with a lower force absorbency/elasticity in the one or more low impact zones 720. More than two levels of impact may be defined for a more graded change in force absorbency across the midsole 400. In various embodiment where the midsole 400 is absent, the plurality of compressive structures 540 on the outsole 500 takes on the load-attenuating characteristics of the midsole 400 as described above.

[0098] In some embodiments, different materials may be selected to provide different degrees of stiffness and/or force absorbency in the different regions 600. In one non-limiting example of a midsole 400, the high impact zones 710 are made of soft, elastic rubber and the low impact zones 720 are made of hard rubber. In some embodiments, similar materials of different grades may be selected to provide different degrees of stiffness in the different regions 600. In one non-limiting example, the midsole 400 includes high impact zones 710 made of a more force absorbent ethylene vinyl acetate (EVA) foam than low impact zones 720. In some embodiments, the midsole 400 may be formed using materials of different densities, e.g., high impact zones 710 of a low-density foam and low impact zones 720 of a high-density foam. In some embodiments, the midsole 400 may be a metamaterial 3D printed with a less dense matrix structure in the high impact zones 710 and with a denser matrix structure in the low impact zones 720.

[0099] In some embodiments, the midsole 400 may include a molded midsole body 410 made using a dense material. The midsole body 410 may define one or more cavities 420 corresponding to the regions 600 of different degrees of stiffness (relative to the stiffness of the midsole body). Inserts 430 of different degrees of stiffness may be molded or 3D printed, with complementary shapes and sizes to be fitted into the respective cavities 420.

[00100] In some embodiments, the entire midsole 400 is molded, 3D printed, or made by a combination of moulding and 3D printing, as one article. In some embodiments, the midsole 400 and the outsole 500 are molded, or 3D printed, as one article. In some embodiments, the midsole 400 and the outsole 500 are formed as one article with a raised border 550 to provide a partial casing in which the insole 300 may be received. In some embodiments, the outsole 500 includes a raised border 550 to provide a partial casing in which the midsole 400 may be received.

[00101] The outsole 500 is configured based on barefoot COP data obtained from the user or from other representative sets of barefoot COP data. The term "barefoot COP line" 690 as used herein refers to an imaginary line traced relative to a footprint or foot tracing 810 to show the changing center of pressure placed on the particular foot over a course of movement of the subject/user. Various tracings of COP lines may be acquired for the same foot, depending on the conditions under which the COP data are acquired. For the purposes of the present disclosure, the COP data is acquired (e.g., as a part of gait analysis) over a period of time when the subject/user is walking barefooted at a normal pace, and referred to as the barefoot COP to avoid confusion with COP data acquired under different conditions (which may produce a differently shaped COP line). Alternatively, the barefoot COP line for a user may be determined based on COP data acquired from a group of healthy subjects.

[00102] The target region 610 of the outsole 500 is defined based on the barefoot COP line 690. Although, for the sake of brevity, the present disclosure describes the various embodiments by referring to one foot, the barefoot COP line 690 may be determined for each of the two feet of the user to account for asymmetry in gait. The rest of the outsole 500 that is not the target region may be designated as one or more non-target regions 630.

[00103] The outsole 500 is a three-dimensional article with an outsole thickness 570 that is uniform or substantially uniform throughout the plurality of regions 600. The target region 610 may be described as a certain width longitudinally extending from the toe 251 to the heel 253 of the sole 250, the barefoot COP line 690 defining a centerline of the target region 610.

[00104] In some embodiments, the outsole 500 is molded, or 3D printed, such that the target region 610 has a lower target region flexure stiffness and the one or more non-target regions 630 each has a flexure stiffness higher than the flexure stiffness of the target region 610. In some embodiments, the outsole 500 is made of a foam and/or rubber or rubber-like materials. In some embodiments, the outsole 500 is a metamaterial that is 3D printed. In some embodiment, the plurality of compressive structures 540 of thickness 570 of the outsole 500 is moulded or 3D printed with load-attenuating qualities in respective regions 600. As used herein, the term "metamaterial" refers to an interlinked or inter-connected network of physical struts or components that can move relative to one another and thereby endow the bulk material with flexibility and/or elasticity. Various non-limiting examples of metamaterial are described in the foregoing. The target region 610 is connected to at least one non-target region 630, at least at a plurality of gradients 560 or connecting points 640 distributed longitudinally along a perimeter 642 of the target region. The connections or connecting points 640 between the physical structures or materials of the target region 610 and the one or more non-target regions 630 facilitate the transfer of stresses to the less stiff target region. The present sole 250 is configured to inherently shift the pressure towards the target region 610 so that the resultant effect is similar or tends towards walking barefooted or towards a targeted COP based on data of healthy participants.

[00105] FIG. 15 shows experimental results to compare the performance of a prototype of the present sole 250 against that of a conventional shoe. The results show that use of a prototype of the present sole 250 produced a measured COP line 682 that is nearer to the target COP line 681 (barefoot COP line) than the COP line 683 reported for a conventional footwear. [00106] Various embodiments of an upper member 270 may be joined to the sole 250 to cooperatively form a footwear 200 that can receive or is wearable at the foot 150 of the user. The term footwear 280 is used loosely in the present disclosure to refer to anything that may be secured at the foot with the insole 300 sitting under the foot. Examples of footwear 280 include but are not limited to shoes, slippers, boots, etc. The term "footwear" as used herein can also refer to a foot brace 282, for example, an article worn at the foot 150 and configured to brace or support a part of the foot or ankle. Non-limiting examples of the footwear 200 in the form of a shoe and a brace are illustrated in FIG. 16 and FIG. 17, respectively. In some examples, the upper 270 may include one or more fasteners 271, such as but not limited to a Velcro fastener. In some examples, the upper 270 may include a lining 272 therein for a better grip of the upper 270 on the skin of the foot 150. In some examples, the upper 270 may include configurable metamaterial structural units 273 that may be customized to the user’s needs.

[00107] In one aspect, the present disclosure describes various embodiments of a footwear for early knee osteoarthritis intervention for a user. The footwear includes a sole. The sole extends longitudinally along a longitudinal direction from a toe to a heel, along a sole length. The sole length is configured to be at least as long as a foot of the user. The sole includes: an insole; and an outsole. The outsole includes: an inner outsole area; an outer outsole area; and an outsole body defining an outsole thickness between the inner outsole area and the external outsole area. The outsole body includes a plurality of regions that are elastically compressible. The plurality of regions include at least one non-target region and a target region. Each of the at least one non-target region is characterized by a respective regional stiffness in the first direction. The target region adjoins the at least one non-target region. The target region is characterized by a target regional stiffness. The target regional stiffness in the first direction is lower than the respective regional stiffness in the first direction of any of the at least one non- target region. Target region extends longitudinally from the toe to the heel.

[00108] The target region may be defined based on a barefoot center of pressure (COP) line. The COP line may be based on data of barefoot walking of healthy subjects. The COP line may be determined with respect to barefoot walking. The COP line may be based on data of barefoot walking of a particular user. [00109] The external outsole area may include at least one flex feature extending transversely relative to the sole length. The at least one flex feature may be a groove with a groove depth smaller than the outsole thickness.

[00110] The sole may be bendable about a transverse axis defined by one of the at least one flex feature. Each of the plurality of regions may include a network of a primary material defining compressible structures distributed therein. The respective flexure stiffness of each of the plurality of regions may be dependent on a density of distribution of the compressible nub structures. The respective flexure stiffness of each of the plurality of regions may be dependent on a material stiffness of the primary material. The respective flexure stiffness of each of the plurality of regions may be dependent on the thickness gradient of the base layer.

[00111] In some embodiments, the flex feature 660 may include one or more jointed flex features 668, as shown in perspective view in FIG. 18A and FIG. 18B. As described in the foregoing in respect of various embodiments of the present disclosure, the outsole 500 and the midsole 400 may be similarly configured in terms of the structures within the same region or differently configured in terms of the structures within the same region. For the sake of brevity, it would be understood that reference to the outsole 500 in the present disclosure may refer to an outsole that integrates the midsole 400 or to an outsole that is distinguishable from a midsole 400. To avoid obfuscation, the illustration of the sole 250 / outsole 500 has been simplified and not all details of the structures are shown in full in FIGS. 18A to 18C.

[00112] As shown in FIG. 18 A, the jointed flex features 668 may be provided in the form of a gap 660 that cuts through all or a substantial part of the sole thickness, with at least one joint 669 coupled the interfaces of the gap 660. As shown in the exploded view of FIG. 18B, the jointed flex feature 668 may include one or more pairs of complementary joint elements (forming one or more joints 669) at the interface of two adjacent segments 502 of the sole 250 / the outsole 500. Various types of joints 669 may be provided. Optionally, the jointed flex feature is configured with more than one degree of freedom or with a greater range of movement in at least one direction. For example, the joint may be a ball and socket joint or linkage. Optionally, the joint elements are shaped to enable the joint elements to be integrally and additively built along with the additive manufacture of the segments. The insole 300 may be provided as an interface between the foot and the rest of the sole which is segmented.

[00113] The bottom view in FIG. 18C of the segmented part of the sole 250 shows that the jointed flex feature 668 may be disposed among the plurality of structures 540, to further promote the dynamic shift of the COP line towards the barefoot COP line 690 or to further allow natural multi-segmental flexing of the foot to mimic barefoot walking. The barefoot COP line 690 is disposed in the target region 610 but the latter is not drawn here to avoid obfuscation. The plurality of structures 540 may include any one or combination of two or more of the following: nub structures, struts, cavities, and gaps, disposed and/or configured to promote the dynamic shift of the COP line towards the barefoot COP line or towards the target region 610. As described in respect of various embodiments above, the nub structures 543 may or may not include cavities 530 defined in each nub structure 543.

[00114] The multiple segments 502 may correspond to various ones of the regions 600. Each segment 502 may form parts of more than one region 600. The multi-segmented sole 250 may be configured such that the barefoot COP line 690 entirely or substantially lie along a jointed flex feature that extends from the toe 251 to the heel 253 of the sole 250. Any of the jointed flex features (also referred to as flexural gaps) 668 may be positioned/oriented in the sole 250 to follow the orientation or movement of one or a combination of several bone joints in the foot. In some examples, the entire outsole 500 is formed by multiple segments 502 interlinked by jointed flex features 668, in which each segment 502 includes a plurality of structures 540 with stiffness gradients 560 that promote dynamic shifts of the COP line towards the barefoot COP line 690, in which the barefoot COP line 690 coincides substantially or entirely with one or more of the jointed flex features 668.

[00115] In another aspect, the sole may be configured based on a method including: (i) determining a location of a center of pressure line of the user relative to the external outsole area, the center of pressure line being based on data of barefoot walking; (ii) defining the target region such that the center of pressure line corresponds to a centerline of the target region target along the longitudinal direction; and (iii) configuring the target region stiffness and the respective region stiffness of the non-target regions. The barefoot walking may be performed by a group of healthy participants or by the user. The user may be a person suffering from early knee OA or at risk of suffering from knee OA.

[00116] The insole thickness may be configured independently of the plantar pressure distribution of the foot. The insole may include a heel cup. The heal cup may be formed by one or more raised edges, in which the one or more raised edges at least partially extend along a perimeter of the insole base at or proximal to the heel region. The heel cup beneficially provides an improved fitting, better stability, and more even plantar pressure distribution.

[00117] In one aspect, the present application discloses various embodiments of a footwear for early knee osteoarthritis intervention for a user, the user having a barefoot centre of pressure (COP) line measurable for the user in barefoot walking, the footwear including: an upper; and a sole. The sole has an outer face and an inner face, the sole being coupled with the upper to enable the inner face and the upper to cooperatively receive a foot of the user. The sole includes a plurality of structures. The plurality of structures is interconnected and partially spaced apart to define a distribution of gaps to allow free flexing of the foot in movement. The plurality of the structures is variably configured across regions of the sole to provide the regions with respective stiffnesses that vary among the regions to provide regional support and absorb force. The regions are three-dimensional. The regions include a target region that is characterized by a stiffness that is lower than any of the respective stiffnesses of any other of the regions. The target region is shaped and positioned in the sole to coincide with the barefoot COP line or the targeted average COP line, based on the average COP line derived from data of a group of healthy participants. At least the outer face of the target region is planar relative to the inner face of the sole.

[00118] The plurality of structures may be characterized by a gradient of decreasing stiffnesses towards the target region. Each of the regions may be characterized by a regional stiffness. The target region may form a contiguous region characterized by a regional stiffness that is lower than the regional stiffness of any other of the regions.

[00119] The footwear according to any described above, in which the sole includes an insole and an outsole, the insole providing the inner face and the outsole providing the outer face, and in which the plurality of structures are disposed in the outsole. The footwear may further include a midsole, in which the midsole is disposed between the insole and the outsole. The midsole and the outsole may be formed of differently configured ones of the structures and/or cavities. The midsole and the outsole may be formed of similarly configured ones of the structures and/or cavities. The midsole and the outsole may be additively formed as an integral component.

[00120] The insole may be shaped with raised edges partially along the perimeter of a heel region, and in which the insole is dimensioned according to the foot profile in a non-weight bearing condition.

[00121] The footwear according to any described above, in which the sole is configured based on a method including: determining a location of a center of pressure line of the user relative to the sole, the targeted center of pressure line being based on data of barefoot walking of the user or on data of a group of healthy persons, without symptoms or risk factors of knee osteoarthritis; defining the target region such that the center of pressure line corresponds to a centerline of the target region target; and configuring a stiffness of the target region and respective stiffnesses of others of the regions so as to allow dynamic shift of the user’s movement COP towards the targeted COP line in the footwear.

[00122] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding, and are not intended to be limiting or exhaustive. Modifications may be made by one of ordinary skill in the art without departing from the scope of the invention as claimed.