HK40015304B - Method for manufacturing an orthopaedic insole and product thus obtained - Google Patents

Description

Method for manufacturing an orthopedic insole and product obtained thereby

Object of the Invention

The object of the present invention is a method for manufacturing an orthopedic insole and the product obtained thereby, wherein the upper part of the insole is geometrically deformed to allow production by means of milling or additive manufacturing techniques.

Background

Currently, orthoses are body-adapted supports or another external device (apparatus) for modifying functional or structural aspects of the neuromuscular and skeletal system, according to the definition of the international organization for standardization (ISO).

The term is used to refer to equipment or devices, splints, technical aids and supports used in orthopedic, physical and occupational therapies that correct or facilitate the performance of an action, activity or movement, seeking to save energy and increase safety. They are used to maintain, align or correct deformities and improve the functioning of the locomotor system.

Orthoses differ from prostheses in that they cannot partially or completely replace organs or limbs having physical disabilities, disabilities or psychological disturbances, but take over or enhance their function.

More specifically, insoles, which are elements placed inside shoes and used as interfaces between the foot and the shoe, fall into the field and the purpose of insoles relates to their use as therapeutic measures ranging from the management of diabetes-related neuropathy to the correction of psychological disorders or walking patterns.

There are many types of different orthopedic insoles and manufacturing techniques. Different devices are used according to the type of pathology, although they can be basically classified as rigid insoles with a soft upper lining or insoles made entirely of soft or flexible material.

The insole uses two basic principles to perform its therapeutic action: redistribution of pressure and change in foot orientation during different phases of gait.

The pressure redistribution is achieved by means of adding elements to the upper part of the insole, such as metatarsal tendons, weight loss elements under the calcaneus, fascial adjustment devices, etc. The idea is that when there are points at which a large amount of pressure is exerted during walking, the excess pressure can be reduced by lifting other areas of the insole so that the contact area of the foot increases or decreases the thickness of the area at which the excess pressure is exerted.

The change in walking pattern is accomplished by changing the orientation of the insole, changing the height and geometry of the arch, or inclined planes in different areas, which forces the foot to have different orientations.

The redistribution of the pressure is performed by means of a soft insole or a lining made of a material such as EVA, to which modules or elements having a specific shape are joined. The change in walking pattern can also be performed in insoles made entirely of flexible material, although the use of a rigid base generally provides better results.

In a more general case, the insole may be considered as a "sandwich" or multilayer structure with a rigid base that provides support and allows the orientation of the foot to be changed during different phases of walking, and the process of redistributing pressure is performed on a soft surface.

The insole is typically manufactured by filling a mold of the patient's foot with plaster, subsequently modifying the mold, and performing a series of material thermoforming and sanding steps.

Today, a high percentage of insoles or orthotics are manufactured by means of CAD/CAM technology, wherein design software based on foot geometry and other complementary information allows to obtain 3D geometries, which 3D geometries are to be manufactured by means of additive technology (also known as 3D printing technology).

This type of manufacturing technique is applicable to both rigid insoles (typically ground using a material such as polypropylene) and soft insoles (typically ground from blocks of material such as EVA rubber).

However, it is not possible to manufacture "sandwich" type insoles by means of CAD/CAM technology, in which the process for pressure redistribution is combined with the process of variation of walking pattern.

In the case of the production of lower (rigid) parts by means of CAD/CAM, the pressure redistribution module located on the top must be placed manually in the orthosis production plant. The reason for this is that it is not possible to produce soft insoles or orthotics with 3D geometry on both faces by means of milling.

Some examples that have been expressed at this time include patent ES 2 336 533, which describes the process of capturing images of the sole of a foot by means of a device with elastic membrane fixing and tensioning mechanism, and the double-sided finishing of the insole obtained in this process. The process is characterized by comprising the steps of:

(a) A fixing and tensioning mechanism consisting of two adjustable horizontal rods is arranged on the scanner,

(b) The height and the distance between the horizontal rods are adjusted,

(c) Placing the membrane on a fixture;

(d) Fixing the film by a T-shaped press plate adhered to the horizontal bar;

(e) Adjusting the tension of the film by means of a crank placed on one of the horizontal bars;

(f) Placing a foot on the membrane and taking an image;

(g) The insole is double-sided finished with the surface image given in STL format.

Another example is patent ES 2 021 968, which describes an orthotic insole device for providing proper support to a patient's foot in a shoe, the orthotic insole device being provided with a top surface for contacting the foot and a bottom surface for contacting an insole, the orthotic insole device comprising: a formed unitary orthotic material having a plurality of closely spaced, substantially parallel grooves formed in a top surface thereof to control sliding of the foot relative to the orthotic.

Likewise, patent WO/2003/015670 describes an improved method for producing insoles for correcting foot deformities, comprising a series of process steps starting from a previous diagnosis by an expert, including a foot examination for evaluation and, if the patient needs, correcting his somatic defects by means of surgery or by means of corrective insoles after obtaining the diagnosis, for the production of corrective insoles, characterized in that it comprises:

a first step consisting in detailing the patient's footprint, where the print to be corrected has been left, drawing lines on the patient's foot representing the limits that the insole will have to reach, using a non-erasable ink pen, tracing the pattern inside the shoe that the patient normally uses, respectively, cutting it and placing it inside the shoe, then dipping the paper pattern in alcohol and printing the drawing on the sole of the foot on paper in a template-like manner, and asking the patient to put on the shoe again, taking care not to dirty the insole.

-a second step consisting in preparing a corrective insole comprising obtaining again the pattern of the insole on a second sheet of paper, reproducing the parts that have to be corrected, drawing the outlines of said cut shapes on a sheet of resin of thermoformable plastic, and wherein one side is smooth and the other side is a layer of loosely woven fabric, this material serving as reinforcement, producing the bottom of the insole by cutting the outlines of the shapes drawn on the surface of the sheet of thermoformable resin and placing the sheet of thermoformable resin in a kiln to soften it according to the specific temperature of each material, wherein the temperature of the kiln is in the range 35 to 120 ℃ for a period of 2 to 3 minutes;

-a third step, consisting in preparing the patient's foot to receive the chosen thermoformable resin sheet, placing a disposable plastic sock, the patient's sock being separated therefrom as a hygienic measure between the doctor and the patient, in order to perfectly isolate the foot, said element being very simple and economical, in order to then place an insulating sock, the function of which will be to prevent any injury to the patient's sole due to heat, then the hose is connected to a vacuum pump in the sock, the function of which will be to evacuate all the air;

a fourth step consisting in placing the thermoformable resin previously softened in the kiln on the insulated sock so that the resin does not stick to the sock, inserting a paper film between the sock and the softened resin, covering all the elements with a plastic bag and sealing the bag with neoprene tape and fasteners (such as hook and loop or adhesive hook and loop film) until cooling of the resin molded directly on the patient's foot is observed;

a fifth step, consisting in moulding the smoothing and lining of the corrective insole, which consists in sending the latter to a correction workshop for smoothing and lining it, in which the usual tools and machines are used for producing the orthoses in the final finishing, in combination with the respective lightening elements, as the case may be.

None of the above documents solves the problem of obtaining an orthotic insole or orthosis formed by a rigid base and a soft surface with different protrusions to perform the redistribution of pressure.

This is because, according to the current knowledge of the prior art, those insoles which can be formed from a rigid base and a soft upper part (such as the one proposed in the present invention) must contain a 3D shape in their soft base in both their upper and lower parts and must therefore be manufactured by means of double-sided milling to achieve the stated purpose.

However, this solution means that when milling one side, since it is a soft, non-rigid material, the other side may not be machined because the material is not milled but moved by the tool.

Thus, the (previously attempted) method for machining the soft part involves affixing a piece of soft material to the orthosis or rigid part for subsequent milling in a machine tool.

Thus, the lower surface of the soft part takes the shape of the upper surface of the rigid part and only the upper surface of the soft part needs to be milled. In this case, however, it is necessary to know very precisely the position of the orthosis in space and to have a specific fastening system that varies with the shape and size of each foot, so that the manufacture must be carried out practically according to the needs of each user, which turns the obtained insole into a rather expensive product.

Disclosure of Invention

The technical problem solved by the present invention is to realize a corrective insole formed by a rigid base and a soft surface, comprising a series of protuberances to perform the redistribution of the pressure while walking and allowing to produce them by means of milling or additive manufacturing techniques, which allow mass production, reducing the manufacturing costs and subsequently selling the obtained product (insole).

As a result of the manufacturing methods described herein, an orthopedic insole or orthotic can be manufactured by means of machinery found in the prior art, thereby eliminating the need for a workshop with a grinding and bonding system and a stack of parts that do not allow for the manufacturing of weight reducing elements or surface variations for redistributing pressure.

Using such a production model, a sandwich-type orthopaedic insole or orthosis can be manufactured in a shorter time, with more precise positioning of the elements, since it allows the use of 3D modeling techniques available only when the insole is not manufactured by means of a sandwich-type method.

Throughout the specification and claims, the word "comprise", and variations such as "comprises" and "comprising", is not intended to exclude other technical features, additions, components or steps. Additional objects, advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The following examples and figures are provided for the purpose of illustration and are not intended to limit the invention. Moreover, the present invention covers all possible combinations of the specific and preferred embodiments described herein.

Drawings

The following very briefly describes a series of drawings that help to better understand the invention and that are explicitly associated with the embodiments of said invention as non-limiting examples thereof. In the drawings:

figure 1 shows a schematic view of a method for manufacturing an orthopedic insole;

figure 2 shows a view of the elements forming an insole obtained by means of the method described herein;

fig. 3 shows a view of an orthopedic insole obtained by means of the manufacturing method described herein.

Detailed Description

The drawings illustrate preferred embodiments of the invention. More specifically, for the purposes of the present description, the method for manufacturing an orthopaedic insole comprises a first step 1 of 3D modelling of the insole to be manufactured with a specific geometry and which will ideally be formed by an initially soft upper 10 and a rigid element 11.

A second step 2 of software processing of the "flattened" or modeled raw soft upper part 10 is then carried out, converting the raw soft upper part 10 into a soft element 10a obtained with a perfectly flat lower surface and still maintaining the relative thickness.

To this end, the software uses mathematical models based on finite elements and graphical theory to model soft objects whose lower part is flat, wherein the structure of the flat upper plane is modeled.

This is achieved by performing the calculation using an iterative method based on the resolution of a non-linear system with multiple unknowns, the position of each point of the lower surface being such that they all share the same height (Z-coordinate) and the distance between them on the original three-dimensional position is respected. A number of equations are introduced in the calculation method, where the position of each point represents an unknown and the constraints associated with the known distances between the points represent the equations to be solved. For this purpose, the resolution technique of the nonlinear system of the system of equations is realized by means of a conjugate gradient resolution technique, such as the LSQR method of Stanford university, for example (http:// web.

The method comprises a third step 3 and a fourth step 4, as shown in fig. 3, the third step 3 producing the obtained soft element 10a obtained in the second step 2 by means of milling or additive manufacturing techniques; this fourth step joins the obtained soft element 10a to the rigid element 11 to obtain a sandwich-type insole.

In a preferred embodiment, the insole is formed by a soft element 10a and a rigid element 11, and the rigid element 11 is ideally designed as shown in fig. 2.

The method of machining the original soft upper portion 10 is complicated because it has a curvature at the top and another curvature at the bottom. In a second step, the obtained soft element 10a is obtained, which soft element 10a in turn comprises a flat lower surface, and once the obtained soft element 10a is joined to the rigid element 11, it is possible to obtain the same geometry as the original soft upper 10, since it is formed of soft material, bending and obtaining the same geometry as the original soft upper 10. This can be seen in the image shown in fig. 2, where the dashed lines shown have the same length in the original soft upper part 10 and the obtained soft element 10 a.

Claims (7)

1. A method for manufacturing an orthopedic insole, the method comprising:

-a first step (1) of 3D modelling of a future insole having a specific geometry formed by a superimposed 3D model of an original soft upper (10) and a 3D model of a stiffening element (11), the 3D model of the original soft upper (10) having a variable thickness defined between an upper surface having one curvature and a lower surface having another curvature;

-a second step (2) of flattening, by software processing, the lower surface of the 3D model of the raw soft upper portion (10), so as to make it completely flat and maintain a variable thickness between the lower and upper surfaces, to obtain a flattened 3D model of the soft element (10 a);

-a third step (3) of manufacturing the flattened 3D model of the soft element (10 a) obtained in the second step (2) by means of milling or additive manufacturing techniques; and

-a fourth step (4) of joining the manufactured flattened soft element (10 a) to a rigid element (11) corresponding to a 3D model of said rigid element (11) to obtain a sandwich insole.

2. Method according to claim 1, wherein said flattening is performed by keeping constant the relative distance between points of the lower surface of the 3D model of the original soft upper part (10).

3. The method of claim 2, wherein the software process uses a mathematical model based on finite elements and graph theory.

4. The method of claim 2, wherein the software process uses an iterative approach based on resolution of a nonlinear system with multiple unknowns.

5. The method according to claim 4, wherein the software process comprises defining the positions of points of the lower surface of the 3D model of the raw soft upper part (10) as unknowns, defining the constraints related to the known distances between the points as equations to be solved.

6. The method of claim 5, wherein the equations to be solved are solved by a resolution technique using a non-linear system of equations implemented by means of a conjugate gradient resolution technique.

7. Orthopedic insole obtainable by the method according to any of claims 1 to 6, comprising a soft element (10 a) and a rigid element (11) superimposed so as to form a sandwich insole.