Method & system for designing an orthosis or patient-matched medical device

Abstract

A method for designing an orthosis. The method includes generating a three-dimensional (3D) representation of an orthosis for a body part from body part data, wherein the 3D representation includes programmable mechanical properties at one or more points on the orthosis. The method also includes determining metamaterial parameters for the 3D representation of the orthosis based on the programmable mechanical properties, and generating instructions configured to control a printing device for printing the orthosis according to the 3D representation and the metamaterial parameters.

Description

[0001] Method & System For Designing An Orthosis or Patient-Matched Medical Device

[0002] TECHNICAL FIELD

[0003] [1] The present invention relates to methods and systems for designing a custom orthosis, including patient-matched, adaptable medical devices and custom-made medical devices, incorporating a functionally graded metamaterial

[0004] BACKGROUND

[0005] [2] Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

[0006] [3] Orthoses, generally, are used to treat or alleviate uncomfortable afflictions and pathologies.

[0007] [4] Medical devices such as foot orthoses are widely used to alleviate foot and leg pathologies, such as diabetes-related foot ulceration, posterior tibial tendon dysfunction (PTTD), and plantar fasciitis, by redistributing pressure and providing support to targeted areas of the foot. Traditionally, these orthoses can be manufactured using flexible foam materials, such as ethylene-vinyl acetate (EVA) or polyurethane, which may be moulded or machined to fit the individual’s foot shape.

[0008] [5] One of the major limitations of these traditional manufacturing processes is the reliance on labour-intensive methods, such as vacuum forming. This method involves multiple steps, from the preparation of foam materials to the manual layering and shaping processes, which results in high production costs and significant lead times. Furthermore, these processes generate substantial material waste due to trimming and shaping operations, contributing to inefficiency and environmental concerns.

[0009] [6] Other methods, such as computer numerical control (CNC) milling, offer improved automation but require expensive equipment that also generate a large amount of plastic waste.

[0010] [7] Another problem with current foot orthosis technology is the lack of precision in controlling the internal mechanical properties of the orthosis. While traditional methods allow for customization of the external shape of the orthosis to fit the foot, they provide limited capability to vary mechanical properties, such as stiffness, within the structure itself. As a result, the orthoses may not provide optimal pressure offloading or support where it is most needed, particularly in high-stress regions of the foot.

[0011] [8] Attempts to improve the mechanical customization of orthoses have included the use of zonal modifications, where regions of the orthosis are fabricated with varying densities or stiffness levels. However, these zonal approaches introduce abrupt transitions between areas of differing stiffness, which could lead to the formation of stress concentrators. Such discontinuities in the material properties could cause localized pressure spikes, resulting in discomfort or tissue damage, which undermines the therapeutic benefits of the orthosis.

[0012] [9] In addition to the mechanical limitations, current orthosis production methods typically involve expensive, specialized equipment and materials, restricting accessibility for widespread clinical use. This has created a barrier to the adoption of more personalized and cost-effective solutions, particularly in settings where rapid prototyping or point-of-care manufacturing would be beneficial.

[0013]

[0010] Advanced manufacturing such as 3D printing (3DP) is also used in the fabrication of personalised and custom orthoses. This involves using 3D scans of the patient’s foot and computed aided design software to create the instructions for controlling a 3D printer. Several 3D printing technologies are used to fabricate the device such as selective laser sintering, stereolithography, and melt-extrusion techniques. The use of 3D printing allows for more precise control over the mechanical properties than traditional approaches through a combination of materials and control over the shape and structure of the orthosis.

[0014]

[0011] The layer-by-layer approach of 3D printing allows for the fabrication of devices with highly complex internal architectures designed for controllable mechanical load transfer and deformation. These 3DP functional metamaterials enable novel device function with overall performance and customisation potential significantly beyond traditional capabilities.

[0015]

[0012] The ability to design orthoses with precisely controlled internal architectures with predictable mechanical properties, based on precise patient measurements, is one of the outstanding challenges in advanced personalised orthosis function. This requires an understanding of the precise dynamics of complex structure deformations combined with the elastomeric properties of 3DP materials, knowledge of the relevant patient metrics and desired device functions, the ability for predictive computational design, and control over the 3D printer hardware to fabricate the device.

[0016]

[0013] Furthermore, some advanced 3D printing techniques that have been explored for creating customized orthoses are either too costly or too complex to integrate into everyday clinical practice, limiting their practicality for widespread use.

[0017]

[0014] Given the limitations in existing manufacturing techniques, there remains a need for more efficient, cost-effective, and precise methods for fabricating foot orthoses that can offer improved mechanical customization and reduce the drawbacks associated with current zonal and manual approaches. SUMMARY OF INVENTION

[0018]

[0015] In an aspect, the invention provides a method for designing an orthosis, the method comprising: obtaining or generating a three-dimensional (3D) representation of an orthosis for a body part from body part data, wherein the 3D representation includes programmable mechanical properties at one or more points on the orthosis; determining metamaterial parameters for the 3D representation of the orthosis based on the programmable mechanical properties; and generating instructions configured to control a 3D printing device for printing the orthosis according to the 3D representation and the metamaterial parameters.

[0019]

[0016] Preferably, the orthosis comprises functionally graded metamaterial.

[0020]

[0017] Preferably, the 3D representation of the orthosis includes geometry of the orthosis and / or pressure distribution information associated with the body part. Preferably, the geometry of the orthosis includes surface data. Preferably, the pressure distribution information is obtained or determined from a pressure map.

[0021]

[0018] Preferably, the 3D representation of the orthosis comprises volumetric elements. Preferably, the 3D representation of the orthosis includes programmable mechanical properties for one or more volumetric elements of the orthosis.

[0022]

[0019] Preferably, the 3D representation of the orthosis includes thermal properties or visual properties or thermal and visual properties.

[0023]

[0020] Preferably, the method includes obtaining or generating a geometric representation of the body part, including geometry of the body part. Preferably, the geometric representation of the body part is generated from one or more of the following: (1) one or more images of the body part; and (2) one or more videos of the body part. Preferably, the one or more images may be two-dimensional and / or three- dimensional images. Preferably, the one or more images may be obtained from or generated by a scanner suitable for or configured to scan the body part. Preferably, the method includes the step of obtaining and / or capturing the one or more images.

[0024]

[0021] Preferably, the method includes obtaining or generating pressure distribution information associated with the body part. Preferably, the pressure distribution information is obtained from one or more of the following: (1) one or more images of the body part; (2) one or more videos of the body part; and (3) a pressure distribution measuring system or device.

[0025]

[0022] Preferably, the geometry of the body part includes surface data. The surface data may include surface shape data.

[0026]

[0023] Preferably, the method includes obtaining or generating a geometric representation of an orthosis from the geometric representation of the body part. Preferably, the geometric representation of the orthosis includes geometry of the orthosis.

[0027]

[0024] Preferably, the geometric representation of the orthosis comprises a digital mesh file. The digital mesh file may take the form of a stereolithography file.

[0028]

[0025] Preferably, the 3D representation of the orthosis is generated from the geometric representation of the orthosis.

[0029]

[0026] Preferably, the programmable mechanical properties are determined from an optimisation model or optimisation algorithm, wherein the optimisation model or optimisation algorithm identifies mechanical properties of a metamaterial to achieve a goal related to the body part. Additionally, or alternatively, the programmable mechanical properties are input to the 3D representation through a graphical user interface (GUI).

[0030]

[0027] Preferably, the programmable mechanical properties are determined for one or more volumetric elements of the orthosis. More preferably, the programmable mechanical properties are determined for every volumetric element of the orthosis.

[0031]

[0028] Preferably, determining metamaterial parameters within the 3D representation of the orthosis based on the programmable mechanical properties includes determining metamaterial unit cell parameters. Preferably, determining metamaterial parameters within the 3D representation based on the programmable mechanical properties additional or alternatively includes determining metamaterial unit cell parameters for each volumetric element of the 3D representation.

[0032]

[0029] Preferably, determining metamaterial parameters within the 3D representation based on the programmable mechanical properties further includes generating an updated 3D representation including the metamaterial parameters and programmable mechanical properties.

[0033]

[0030] Preferably, the programmable mechanical properties include one or more of stiffness, density, elasticity, pressure, force or load distribution and flexibility.

[0034]

[0031] Preferably, the metamaterial parameters and / or metamaterial unit cell parameters include one or more of wall thickness, unit cell size, unit cell structure, internal lattice design, colour and thermal properties.

[0035]

[0032] Preferably, the method includes receiving calibrated experimental data providing a unit cell structure related to the programmable mechanical properties of the orthosis, and determining metamaterial parameters within the 3D representation based on the programmable mechanical properties and the calibrated experimental data.

[0033] Preferably, the instructions are generated from the updated 3D representation.

[0036]

[0034] Preferably, an instruction file comprises the instructions. Preferably, the instructions comprise g-code or machine-readable file format.

[0037]

[0035] Preferably, the instruction file is configured to adjust printing parameters of a printer to provide an orthosis comprising functionally graded metamaterial. The printing parameters of the printer include one or more of: tool path, number of tool paths, extrusion rate, layer height, print speed, temperature control and material flow rate to achieve the programmable mechanical properties across different regions and / or volumetric elements of the orthosis.

[0038]

[0036] Preferably, the instructions, when executed by a printing device for printing the orthosis, control the printing device to print the orthosis according to the 3D representation and the metamaterial parameters.

[0039]

[0037] Preferably, the instructions are optimised for 3D printing. Preferably, generating the instructions includes interpolating between volumetric elements of the orthosis.

[0040]

[0038] Preferably, the orthosis comprises an insole for a foot.

[0041]

[0039] Preferably, the method includes operating the printing device using the instructions to print the orthosis.

[0042]

[0040] In an aspect, the invention provides a system for designing an orthosis, the system comprising: a computer configured to: obtain or generate a three-dimensional (3D) representation of an orthosis for a body part from body part data, wherein the 3D representation includes programmable mechanical properties of the orthosis; determine metamaterial parameters for the 3D representation of the orthosis based on the programmable mechanical properties; and generate instructions configured to control a 3D printing device for printing the orthosis according to the 3D representation and the metamaterial parameters; and a printing device configured to receive the instructions and print the orthosis.

[0043]

[0041] In an aspect, the invention provides an orthosis having programmable mechanical properties across different regions and / or volumetric elements.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045]

[0042] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[0046] Figure 1 is a flowchart illustrating a method for designing an orthosis;

[0047] Figure 2 illustrates a system that implements the method of Figure 1 ;

[0048] Figure 3 illustrates a GUI of a proposed thickness (stiffness) map for an orthosis before smooth stiffness grading;

[0049] Figure 4 illustrates a GUI of a proposed thickness (stiffness) map for an orthosis with smooth stiffness grading;

[0050] Figure 5 illustrates a GUI demonstrating the algorithmic setting of wall thickness

[0051] (stiffness) of an orthosis; Figure 6 illustrates a GUI of an insole (orthosis) metamaterial thickness map following smooth grading; and

[0052] Figure 7 illustrates a print tool path for a foot orthosis.

[0053] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0054]

[0043] Figures 1 and 2 illustrate a system and method for designing an orthosis or patient-matched medical device.

[0055]

[0044] It will be appreciated that any references to obtaining material (such as obtaining data, information or otherwise) should generally be understood to refer to obtention from a secondary system or storage. Rather than obtaining, this could also be provided by the secondary system or storage without being considered to deviate from the description below. Any references to generating material (such as generating data, information or otherwise) should generally be understood to refer to generating material directly using an appropriate system or device (such as a scanner to generate images, for example).

[0056]

[0045] Embodiments of the present invention relate to methods and systems for designing a custom orthosis incorporating a functionally graded metamaterial.

[0057]

[0046] Embodiments of the method enable the creation of highly customized orthoses that provide precise support and pressure redistribution based on the user’s unique anatomical and mechanical needs. The use of functionally graded metamaterials ensures smooth transitions between regions of varying stiffness or flexibility, improving comfort and performance.

[0058]

[0047] The present method and system are directed toward the design and fabrication of a custom orthosis, utilizing advanced techniques such as multiscale surface and volumetric representation to incorporate functionally graded metamaterials. The method ensures that the orthosis is optimized to meet the specific needs of the user by capturing multiple levels of detail across the orthosis, including surface geometry and internal material properties.

[0059]

[0048] The generated orthoses can be printed using fused filament fabrication (or other material extrusion processes) which allows for the production of functionally graded metamaterials.

[0060]

[0049] The process begins with obtaining or generating a 3D representation of the orthosis for a body part 201 at box 125. As shown in Figure 2, these steps can be implemented on a computer 203 that may include a graphical user interface. It will be appreciated that a number of additional steps may be taken prior to and / or in order to obtain or generate the 3D representation of the orthosis. These additional steps will be described below.

[0061]

[0050] This 3D representation of the orthosis 201 is derived from body part data 205, which may include geometric data 207 related to the geometry of the orthosis and may also include pressure distribution information 209 associated with the body part. The geometric data 207 provides a detailed map of the body part's surface (in the form of a geometric representation of the body part, for example), while the pressure distribution information 209 can highlight areas of the body part that experience higher and / or lower levels of pressure during use. More specifically, the geometry of the orthosis may include surface data, such as surface shape data, for example. The geometric data may also incorporate higher-dimensional surface data, including shear forces and vector forces distributed over the surface. For example, this data could be represented using 4D tensors, such as a standard stress tensor, to model the distribution of stress across the orthosis geometry.

[0051] It will be appreciated that the body part data 205 may be generated or obtained (in boxes 110 and 115) before obtaining or generating the 3D representation of the orthosis to then be provided for generating the 3D representation.

[0062]

[0052] With the above in mind, a number of steps related to obtaining or generating the body part and the 3D representation will be described below.

[0063]

[0053] To create the 3D representation of the orthosis 201 , the method, at box 110, may include obtaining or generating body part data 205. The body part data 205 may include a geometric representation of the body part (geometric data) as seen in box 115. In some embodiments, steps 110 and 115 may be optional. This can be accomplished using one or more images and / or videos of the body part including both 2D and 3D images. The images and / or videos may be obtained from a database or generated directly from scans of the person’s body part.

[0064]

[0054] These images may be obtained from a scanner 211 configured to capture the body part's surface geometry accurately or from a database. In some cases, the scanner 211 may also provide pressure distribution information, which may be useful for customizing the orthosis to the user's specific needs.

[0065]

[0055] In some embodiments, and in particular those embodiments that relate to foot orthoses and insoles, a 3D scan of a shoe and the inner shape of the shoe may be obtained. Data relating to the material properties of the shoe may also be obtained. These scans and data may be used to further inform the characteristics of the orthosis. For example, the stiffness of the insole at the insole / shoe interface could be programmed to differ from that at the insole / foot interface.

[0066]

[0056] In embodiments where the geometric representation of the body part is generated, rather than obtained, a pre-emptive step of generating or obtaining the images and / or videos may be required at box 105.

[0057] Additionally, at box 115, the method may include obtaining or generating pressure distribution information 209 (or dynamic pressure data) from the user using motion scans or time-series pressure data, thereby allowing the resulting orthosis to be designed and configured to adapt to real-time conditions and improve its effectiveness in active use cases. For example, this information can be used to optimize the orthosis for movement, ensuring that it adapts to changes in pressure or stress as the user moves.

[0067]

[0058] At box 120, the method may also include obtaining or generating a geometric representation of an orthosis 213 from the geometric representation of the body part, which may include geometric data relating to the geometry of the orthosis.

[0068]

[0059] The geometric representation of the orthosis comprises a digital mesh file. The digital mesh file may take the form of a stereolithography file.

[0069]

[0060] In some embodiments, the 3D representation of the orthosis 201 , generated at box 125 as set out above, may be generated from the geometric representation of the orthosis 213

[0070]

[0061] This 3D representation of the orthosis 213 also includes programmable mechanical properties, which vary across different regions of the orthosis to provide the appropriate level of support or flexibility.

[0071]

[0062] The 3D representation may take the form of one or more discrete volumetric elements (voxels), continuous functions, and parameters within an artificial neural network.

[0072]

[0063] A discrete voxel representation includes the virtual coordinates of each volumetric element and dimensions. To facilitate calculation of global object parameters, voxels may include information exchange values for each boundary (e.g. cube voxel with a vector on each side to represent communication of forces / temperatures / internal deformations etc with the 6 neighbour voxels). In some implementations, these voxels may be non-rectangular or optimized shapes allowing for irregular or customized voxel geometries to enhance the accuracy and efficiency of simulations.

[0073]

[0064] The 3D representation includes both surface and volumetric elements to provide a holistic and comprehensive representation of the orthosis. The surface data represents the outer geometry of the orthosis, ensuring that it conforms to the contours of the user’s body part. The volumetric elements, such as voxels, for example, provide a detailed internal representation, allowing for the continuous variation of material properties like stiffness or elasticity. The volumetric elements may include additional information exchange values, allowing the 3D model to account for interactions between neighboring elements, such as the transfer of force or heat across boundaries.

[0074] Determining Metamaterial Parameters

[0075]

[0065] The method, at box 130, also includes determining metamaterial parameters based on the programmable mechanical properties required for the orthosis. In particular, the method includes determining metamaterial parameters for the 3D representation of the orthosis 201 based on the programmable mechanical properties. These parameters may include several aspects that directly influence the behaviour of the orthosis. This can be seen in the geometric representation of the orthosis 213 in Figure 2 in the form of different coloured sections indicating thickness across a scale.

[0066] One aspect of the parameters to be considered may be the wall thickness of the material in different regions, which affects the stiffness and flexibility of the orthosis.

[0076]

[0067] Another parameter may be the unit cell size, which refers to the size of the repeating structural units in the metamaterial and influences the mechanical behaviour of the material.

[0077]

[0068] Additionally, properties such as stiffness and density determine how the orthosis responds to pressure and force in different areas.

[0078]

[0069] The metamaterial parameters may be determined using an optimization algorithm or through manual input in a graphical user interface (GUI). The algorithm may be designed to optimize the orthosis for specific goals, such as minimizing pressure on sensitive areas or providing extra support to regions that bear more weight.

[0079]

[0070] In some implementations, these metamaterial parameters are determined for each volumetric element within the 3D representation (these may be referred to as metamaterial unit cell parameters), ensuring precise control over the orthosis’s behaviour in different regions. The method supports continuous variation in these parameters, allowing for smooth transitions between areas of different stiffness or density.

[0080]

[0071] In some embodiments, the method, at box 135, includes receiving calibrated experimental data that provides information about the unit cell structure of the metamaterial. For example, the unit cell may have a gyroid structure. This data can be used to further refine the metamaterial parameters and ensure that the orthosis meets the desired performance characteristics. The calibrated experimental data may be measured experimental data that confirm that a unit cell with a particular unit cell size and wall thickness will produce a specific compressive stiffness, for example. Further, the calibrated experimental data can relate to a given printer / material combination. The specific parameters for this combination can be determined via a calibration study. A parameter set relates to a fabrication setup, with different parameters sets for different printer / material combinations.

[0081]

[0072] In some embodiments, at box 140, determining the metamaterial properties further includes generating an updated 3D representation of the orthosis including the metamaterial parameters and programmable mechanical properties.

[0082] 3D Printing

[0083]

[0073] Once the 3D representation and metamaterial parameters are determined, the method, at box 145, generates printing instructions (that may be saved to an instruction file 215) to fabricate the orthosis using a printing device, such as a 3D printer. In particular, the method generates instructions configured to control a printing device for printing the orthosis according to the 3D representation and the metamaterial parameters. In relevant embodiments, the instructions 215 may be generated from an updated 3D representation of the orthosis.

[0084]

[0074] More specifically, the instructions, when executed by an appropriate device, control the movement and material extrusion parameters of the printing device.

[0085]

[0075] The instructions and instruction file 215 may be optimised for 3D printing to reduce the likelihood of print failure and improve speed of production on the selected 3D printer. To optimise the instructions, the method may include interpolating between volumetric elements of the orthosis. For example, the metamaterial wall thickness at a specific point is determined by mathematical interpolation between the nearest volumetric elements.

[0086]

[0076] These instructions, typically in the form of g-code or other suitable machine- readable code, control various parameters of the printing process.

[0087]

[0077] One of the parameters that can be controlled by the instructions is the tool path, which refers to the route the printer nozzle follows to deposit material. Both the route of the tool path and the number of tool paths can be varied.

[0088]

[0078] Creating multiple toolpaths can be particularly advantageous where the desired wall width exceeds the maximum wall width can be achieved using a single toolpath. These toolpaths are approximately parallel, but will increase in separation (diverge) as the print line width increases.

[0089]

[0079] The extrusion rate, which governs the amount of material extruded during printing, is another parameter that influences the thickness and strength of the width of the printed material line and can be controlled by the instructions.

[0090]

[0080] Varying the extrusion rate by increasing or decreasing material extrusion through the nozzle allows for the control of print line width within a range relative to the size of the nozzle (from approximately 0.75 nozzle widths to 1 .5 nozzle widths, for example).

[0091]

[0081] Additionally, parameters such as layer height and print speed may be useful for controlling the precision and quality of the printed orthosis and therefore can be controlled by the instructions.

[0092]

[0082] In some embodiments, varying print speed and extrusion rate simultaneously may be useful to account for the non-linear relationship between software extrusion and actual, physical extrusion and movement of the printer extruder.

[0083] Further, in some embodiments, material extrusion and toolpath parameters can be related to the desired mechanical properties. As a result, the method can compute smooth transitions between these.

[0093]

[0084] In another example, a thermal control parameter can be controlled where the gyroid unit cell size could vary smoothly across the material, with the wall thickness varying to ensure uniform mechanical properties, but the changing unit cell dimension could be used to control airflow (e.g. faster flow in smaller cells) and therefore impact the thermal properties. The instruction file 215 is configured to adjust these printing parameters dynamically, ensuring that the orthosis is printed with functionally graded metamaterials. This allows for continuous property variation throughout the structure, ensuring smooth transitions between regions of different stiffness or flexibility.

[0094] Printing the Orthosis

[0095]

[0085] In an optional, additional step, at box 150, a printing device, such as a 3D printer 217 shown in Figure 2, may be operated using the generated instructions to produce the orthosis 219. The 3D printer 217 (or suitable printing device) fabricates the orthosis 219 layer by layer, incorporating the programmable mechanical properties at each stage. The result is a custom orthosis that is tailored to the user’s specific biomechanical and ergonomic requirements.

[0096]

[0086] In some embodiments, the orthosis 219 may be printed by fused filament fabrication.

[0097]

[0087] In one embodiment, the orthosis may comprise an insole or shoe for a foot, although the method is not limited to this application and can be used to design orthoses for other body parts, such as cushions or crash protection devices.

[0088] Embodiments of the invention provide for a multiscale and volumetric representation of the orthosis. This multiscale approach enables the representation of both large-scale features, such as the overall shape and surface contours of the orthosis, and fine-scale features, such as the internal structure and material properties. By capturing details at multiple levels, the method ensures a high degree of customization and precision, allowing the orthosis to meet the biomechanical needs of the user.

[0098]

[0089] In some implementations, the orthosis is represented using continuous functions or parameters stored in a neural network model, allowing for a higher degree of precision in designing functional outputs compared to voxel-based approaches. This continuous representation eliminates the need to discretise for volume element boundaries, facilitating smooth, gradual variations in properties such as stiffness, density, or wall thickness across the orthosis. Neural networks can further enhance this by learning to predict 3D or even 4D mechanical and shape properties of the structure. With training on experimental data, the model can capture relationships between internal metamaterial structure and mechanical behaviour, potentially integrating human gait and force data for a more comprehensive and predictive model that adapts precisely to specific anatomical and functional requirements. The multiscale representation also allows the orthosis to incorporate not only geometric and mechanical properties but also other factors, such as thermal properties and visual characteristics. Thermal properties, such as temperature diffusion, may be relevant in applications requiring heat dissipation or management. Visual characteristics, such as colour or transparency, can be used for aesthetic or functional purposes, such as indicating regions with different stiffness levels. These properties may be derived from other key factors, such as stiffness or elasticity, using algorithms or machine learning models. For instance, mechanical properties could be used as the foundation for determining both visual and thermal properties, allowing the design process to be more efficient and data-driven.

[0099]

[0090] Furthermore, instructions for the printing of the orthosis can be generated directly from a 3D representation. This eliminates the need for computationally inefficient operations creating a lattice structure and slicing this lattice structure. Instructions for printing the orthosis can be generated directly from its representation within this method, eliminating the need to produce a traditional mesh-based 3D model. This is significant because representing the complex internal architecture of a gyroid-based metamaterial, especially one with varying parameters, via a mesh is computationally prohibitive unless the number of vertices is restricted. Additionally, since a mesh approximates the 3D object, its characteristics — such as resolution and accuracy — directly impact the mechanical properties of the final orthosis.

[0100]

[0091] In some embodiments, manufacture can be achieved using low cost fused filament fabrication 3D printing.

[0101]

[0092] Importantly, it is possible to create continuous functionally graded metamaterials that have geometric structures and mechanical properties that vary continuously through the structure.

[0102] Example 1: Use of Functionally Graded Orthosis to Reduce Tensile Stresses in the Tibialis Posterior

[0103]

[0093] A 50-year-old patient presents with pain located in the posterior-medial ankle. Following a clinical examination, the pain is diagnosed as stage 2 posterior tibial tendon dysfunction (PTTD). Examination reveals a planus foot type, with high forces required to supinate the foot, as indicated by the manual supination resistance test.

[0094] The tibialis posterior, the muscle and tendon commonly involved in PTTD, functions as an invertor of the subtalar joint and a plantarflexor of the ankle joint. PTTD often arises due to morphological or functional changes in the foot that increase pronation moments around the subtalar joint. A mechanical objective of an orthosis in treating PTTD is to counteract these moments by increasing ground reaction forces acting medial to the subtalar joint axis.

[0104]

[0095] Using the methods described herein, the orthosis could be designed to achieve this by increasing the stiffness of the material medial to the subtalar joint axis using a functionally graded metamaterial. By increasing the wall thickness of the metamaterial structure in this region, the stiffness of the orthosis can be enhanced, resulting in increased plantar pressures medial to the subtalar joint axis and promoting increased supination moments.

[0105]

[0096] To facilitate this customization, a graphical user interface (GUI) may be used to allow the clinician to mark the areas on the orthosis where stiffness should be greatest and where it should be lower. The interface would ensure a smooth gradation between these zones to avoid abrupt transitions in stiffness (See Figure 3). The smooth transition of mechanical properties across the orthosis ensures comfort and functionality, with no distinct changes in stiffness between the zones (See Figure 4).

[0106]

[0097] This approach complements existing methods, such as customized foot orthoses based on 3D scans of the patient’s foot, and modifications such as a medial heel skive. The integration of functionally graded metamaterials into the orthosis design enhances the mechanical support provided to the patient, improving treatment outcomes for conditions such as PTTD. Example 2: Use of Functionally Graded Orthosis to Reduce Plantar Pressures at a Site of the Foot at Risk of Diabetes-Related Ulceration

[0107]

[0098] A 55-year-old patient with type 2 diabetes attends for an annual screening. Examination reveals a loss of protective sensation, indicative of peripheral neuropathy, and the presence of peripheral arterial disease. The patient has a history of a previous diabetes-related foot ulcer at the plantar hallux (great toe) and is determined to be at high risk of further ulceration. A plantar pressure examination conducted while the patient is wearing shoes shows elevated pressure at the plantar surface of the 2nd metatarsophalangeal joint (peak pressure: 400 kPa), which corresponds to a region of hyperkeratosis (callus).

[0108]

[0099] In accordance with the International Working Group on the Diabetic Foot Prevention Guideline, appropriate footwear and insoles are recommended to reduce plantar pressure by at least 30%. A functionally graded metamaterial insole is proposed to achieve this reduction.

[0109]

[0100] The stiffness of the metamaterial can be customized based on the plantar pressure map. Regions of the insole that correspond to high plantar pressures (>200 kPa) would be designed using metamaterials of lower stiffness, while areas with lower pressure would utilize higher stiffness metamaterials. This can be done algorithmically, using a set of pressure thresholds and is generally illustrated in Figures 5 and 6. For example, if the pressure exceeds 200 kPa, a metamaterial wall thickness of 0.4 mm would be applied; if the pressure is below 50 kPa, a wall thickness of 1.0 mm would be used (See Figure 5). The stiffness between these areas would be smoothly interpolated to create a gradual transition, minimizing discrete changes in stiffness (See Figure 6).

[0101] Once the insole is designed, the software generates the toolpaths (e.g. , g-code) required for 3D printing the orthosis. An example of these g-code paths is visualized in Figure 7. In this figure, speed is a surrogate for print line width (high speed will print thin lines, low speed will print thick lines). Inset demonstrates the transition between a single wide line and two narrow lines. The expected mechanical effect of the design is to redistribute forces from regions of lower stiffness to areas with higher stiffness, reducing pressure at the at-risk sites. Following manufacturing, the effectiveness of the insole can be assessed by re-measuring plantar pressures to ensure sufficient pressure redistribution.

[0110]

[0102] The use of functionally graded materials in the insole may be complemented by other design features, such as ensuring the orthosis maintains the contour of the foot’s arch, which can be achieved by designing the orthosis from a 3D scan of the patient’s foot. Additional modifications, such as metatarsal domes or similar forefoot padding, may also be incorporated to further reduce pressure at high-risk sites.

[0111]

[0103] Embodiments of the invention allow for the provision of insoles, and other supportive devices, that have engineered stiffness tuned to match existing insole materials, that are not made from metamaterials.

[0112]

[0104] The stiffness of these orthoses can be matched to the stiffness of existing orthoses. However, orthoses created using the methods and systems disclosed herein can also be engineered to dynamically vary the stiffness across the structure to optimise offloading, thereby providing personalised stiffness. The shape of the orthosis can be also be personalised or customised.

[0113]

[0105] It is envisioned that the methods and systems disclosed herein will allow for the rapid production of custom orthoses that are specifically targeted at treating or alleviating pathologies of different body parts, which is in contrast to existing systems that require a technician to hand-mould an orthosis that may need to be iteratively refined until the desired outcome is achieved or require costly CNC milling equipment.

[0114]

[0106] The term orthosis, as used herein, should be understood to include devices and orthoses that include may be patient-matched, adaptable medical devices and custom-made medical devices.

[0115]

[0107] The term functionally graded metamaterial, as used herein, should be understood to refer to a metamaterial with controllable mechanical function, including whereby the properties of the metamaterial can vary spatially, continuously and smoothly throughout the metamaterial structure.

[0116]

[0108] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features.

[0117]

[0109] It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

[0118]

[0110] The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

1. CLAIMS1 . A method for designing an orthosis, the method comprising: obtaining or generating a three-dimensional (3D) representation of an orthosis for a body part from body part data, wherein the 3D representation includes programmable mechanical properties at one or more points on the orthosis; determining metamaterial parameters for the 3D representation of the orthosis based on the programmable mechanical properties; and generating instructions configured to control a 3D printing device for printing the orthosis according to the 3D representation and the metamaterial parameters.

2. The method of claim 1 , wherein the orthosis comprises functionally graded metamaterial.

3. The method of claim 1 or claim 2, wherein the 3D representation of the orthosis includes geometry of the orthosis and / or pressure distribution information associated with the body part.

4. The method of claim 3, wherein the geometry of the orthosis includes surface data.

5. The method of claim 3 or claim 4, wherein the pressure distribution information is obtained or determined from a pressure map.

6. The method of any one of claims 1 to 5, wherein the 3D representation of the orthosis comprises volumetric elements.

7. The method of any one of claim 1 to 5, wherein the 3D representation of the orthosis includes programmable mechanical properties for one or more volumetric elements of the orthosis.

8. The method of any one of claims 1 to 7, wherein the 3D representation of the orthosis includes thermal properties or visual properties or thermal and visual properties.

9. The method of any one of claims 1 to 9, wherein the method includes obtaining or generating a geometric representation of the body part, including geometry of the body part.

10. The method of claim 9, wherein the geometric representation of the body part is generated from one or more of the following: (1 ) one or more images of the body part; and (2) one or more videos of the body part.

11. The method of claim 10, wherein the one or more images may be two- dimensional and / or three-dimensional images.

12. The method of claim 10 or claim 11 , wherein the one or more images may be obtained from or generated by a scanner suitable for or configured to scan the body part.

13. The method of any one of claims 10 to 12, wherein the method includes the step of obtaining and / or capturing the one or more images.

14. The method of claim 1 , wherein the method includes obtaining or generating pressure distribution information associated with the body part.

15. The method of claim 14, wherein the pressure distribution information is obtained from one or more of the following: (1 ) one or more images of the body part; (2) one or more videos of the body part; and (3) a pressure distribution measuring system or device.

16. The method of claim 9, wherein the geometry of the body part includes surface data.

17. The method of claim 16, wherein the surface data may include surface shape data.

18. The method of any one of claims 9, 10, 16 or 17, wherein the method includes obtaining or generating a geometric representation of an orthosis from the geometric representation of the body part.

19. The method of claim 18, wherein the geometric representation of the orthosis includes geometry of the orthosis.

20. The method of claim 19, wherein the geometric representation of the orthosis comprises a digital mesh file.21 . The method of claim 20, wherein the digital mesh file is a stereolithography file.

22. The method of any one of claims 18 to 21 , wherein the 3D representation of the orthosis is generated from the geometric representation of the orthosis.

23. The method of any one of claims 1 to 22, wherein the programmable mechanical properties are determined from an optimisation model or optimisation algorithm, wherein the optimisation model or optimisation algorithm identifies mechanical properties of a metamaterial to achieve a goal related to the body part.

24. The method of any one of claims 1 to 23, wherein the programmable mechanical properties are input to the 3D representation through a graphical user interface (GUI).

25. The method of claim 7, wherein the programmable mechanical properties are determined for the one or more volumetric elements of the orthosis.

26. The method of claim 25, wherein the programmable mechanical properties are determined for every volumetric element of the orthosis.

27. The method of any one of claims 1 to 26, wherein determining metamaterial parameters within the 3D representation of the orthosis based on the programmable mechanical properties includes determining metamaterial unit cell parameters.

28. The method of claim 25, wherein determining metamaterial parameters within the 3D representation based on the programmable mechanical properties includes determining metamaterial unit cell parameters for each volumetric element of the 3D representation.

29. The method of any one of claims 1 to 28, wherein determining metamaterial parameters within the 3D representation further includes generating an updated 3D representation including the metamaterial parameters and programmable mechanical properties.

30. The method of any one of claims 1 to 29, wherein the programmable mechanical properties include one or more of stiffness, density, elasticity, pressure, force or load distribution, and flexibility.31 . The method of any one of claims 1 to 30, wherein the metamaterial parameters and / or metamaterial unit cell parameters include one or more of wall thickness, unit cell size, unit cell structure, internal lattice design, colour, and thermal properties.

32. The method of any one of claims 1 to 31 , further comprising receiving calibrated experimental data providing a unit cell structure related to the programmable mechanical properties of the orthosis, and determining metamaterial parameters within the 3D representation based on the programmable mechanical properties and the calibrated experimental data.

33. The method of any one of claims 1 to 32, wherein the instructions are generated from the updated 3D representation.

34. The method of claim 33, wherein the instructions comprise an instruction file including g-code or another machine-readable format.

35. The method of claim 34, wherein the instruction file is configured to adjust printing parameters of a printer to provide an orthosis comprising functionally graded metamaterial.

36. The method of claim 35, wherein the printing parameters include one or more of: tool path, number of tool paths, extrusion rate, layer height, print speed, temperature control, and material flow rate, to achieve the programmable mechanical properties across different regions and / or volumetric elements of the orthosis.

37. The method of any one of claims 33 to 36, wherein the instructions, when executed by a printing device, control the printing device to print the orthosis according to the 3D representation and the metamaterial parameters.

38. The method of any one of claims 33 to 37, wherein the instructions are optimised for 3D printing, and generating the instructions includes interpolating between volumetric elements of the orthosis.

39. The method of any one of claims 1 to 38, wherein the orthosis comprises an insole for a foot.

40. The method of any one of claims 33 to 38, further comprising operating the printing device using the instructions to print the orthosis.41 .A system for designing an orthosis, the system comprising:a computer configured to: obtain or generate a three-dimensional (3D) representation of an orthosis for a body part from body part data, wherein the 3D representation includes programmable mechanical properties of the orthosis; determine metamaterial parameters for the 3D representation of the orthosis based on the programmable mechanical properties; and generate instructions configured to control a 3D printing device for printing the orthosis according to the 3D representation and the metamaterial parameters; and a printing device configured to receive the instructions and print the orthosis.

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