An ankle-foot orthosis based on 3D printing and its fabrication method

Abstract

This invention discloses a 3D-printed ankle-foot orthosis and its manufacturing method. The orthosis consists of three parts: a lower leg portion, an Achilles tendon portion, and a foot portion. The lower leg portion conforms to the posterior and lateral sides of the lower leg, the Achilles tendon portion conforms to the posterior and lateral sides of the ankle, and the foot portion conforms to the bottom and sides of the foot. The ankle portion is located on the outside of the entire ankle-foot orthosis. Y-shaped reinforcing structures are provided at stress concentration points on the exterior of the lower leg and Achilles tendon portions. The orthosis with the Y-shaped structure has good fit, light weight, high strength, and good protection. It is easy to wear inside the patient's shoes and boots, solving the problem of insufficient fit in existing orthoses, and realizing the patient's physiological and psychological desire to integrate into society. It also significantly improves the gait of stroke patients.

Description

Technical Field

[0001] This invention belongs to the field of medical rehabilitation device technology, specifically relating to an ankle-foot orthosis based on 3D printing and its manufacturing method. Background Technology

[0002] With the advancement of technology and the rapid development of 3D printing, 3D scanning and reverse engineering have become increasingly widespread. The application of industrial 3D software and the development of products using reverse design have simplified reverse engineering. This provides a strong impetus for the research and application of customized 3D-printed orthotics. By combining existing mechanical analysis techniques with the orthotics' experience and gait analysis equipment, doctors and orthotists can design treatment plans tailored to the patient's gait, enabling precise, customized, and comfortable treatments. However, current limitations in 3D printing technology and materials restrict the development of customized orthotics, leading to defects in their mechanical properties. Furthermore, existing ankle-foot orthotics have long production cycles, complex molding processes, and difficulty in achieving a proper fit for different patients, which can negatively impact patient rehabilitation. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a 3D-printed ankle-foot orthosis and its manufacturing method to solve the problem that existing ankle-foot orthoses are difficult to fit every patient and restrict patient movement.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A 3D-printed ankle-foot orthosis includes a lower leg portion, an Achilles tendon portion, and a foot portion integrally connected from bottom to top; the lower leg portion conforms to the back and side of the lower leg, the Achilles tendon portion conforms to the back and side of the ankle, and the foot portion conforms to the bottom and side of the foot; the ankle is positioned outside the entire ankle-foot orthosis.

[0006] A Y-shaped reinforcing structure is provided on the exterior of both the lower leg and the Achilles tendon. The upper end of the Y-shaped reinforcing structure is located on the exterior of the lower leg, and the lower end of the Y-shaped reinforcing structure is located on the exterior of the Achilles tendon.

[0007] A further improvement of the present invention is that:

[0008] Preferably, the height of the Y-shaped reinforcing structure is 1 / 4 to 1 / 3 of the total height of the calf portion and the Achilles tendon portion.

[0009] Preferably, the Y-shaped reinforcing structure includes a rear support portion and two side support portions, the rear ends of the two side support portions are connected to the upper end of the rear support portion, and the front ends of the two side support portions are respectively located on both sides of the lower leg portion; the height of the front end of the side support portion is higher than the height of the rear end of the side support portion; the lower end of the rear support portion is located outside the Achilles tendon portion.

[0010] Preferably, the front portion of the sole is inclined upwards at 10°-30° relative to the horizontal plane.

[0011] Preferably, the lower leg portion has a weight-reducing hole at its rear.

[0012] Preferably, each side of the lower leg portion has an upper connecting portion and a lower connecting portion at its front end, with the upper connecting portion above the lower connecting portion; the upper side of the foot portion has a bottom connecting portion.

[0013] Each upper and lower connecting part has a connecting hole at its front end; each bottom connecting part has a connecting hole at its upper end.

[0014] A method for manufacturing an ankle-foot orthosis based on 3D printing includes the following steps:

[0015] Step 1: The patient is in a sitting position, so that the midpoints of the patient's ankle, knee, and hip joints are aligned on the same force line.

[0016] Step 2: Scan the patient's legs to obtain data on the shape and size of the patient's legs;

[0017] Step 3: Combining the shape and size data of the patient's legs, reverse processing is performed using T-spline to obtain the three-dimensional curved surface of the patient's legs;

[0018] Step 4: Trim the three-dimensional curved surface. During the trimming process, remove the curved surface above the longitudinal arch curve and the curved surface before the calcaneus at the ankle, so that the ankle joint is exposed outside the three-dimensional curved surface. Extend vertically upward along the curves on both sides of the curved surface at the ankle to below the knee, and remove the curved surface before the curves on both sides of the curved surface to obtain a single curved surface of the ankle-foot orthosis. The edge of the single curved surface is the edge of the target ankle-foot orthosis; the longitudinal arch curve is the curve between the middle of the first metatarsal bone and the calcaneus.

[0019] Step 5: Thicken the single surface to obtain the basic surface body;

[0020] Step 6: Export the STL file of the surface primitive, perform ANSYS mechanical analysis, and determine the position and size of the Y-shaped reinforcement structure, which is located at the stress concentration point at the back of the ankle.

[0021] Step 7: Copy the back side of the surface primitive to obtain the copied surface. Move the copied surface to the back of the surface primitive and trim the copied surface according to the shape and size of the Y-shaped reinforcement structure to obtain the outer surface of the Y-shaped reinforcement structure. Thicken the space between the outer surface of the Y-shaped reinforcement structure and the back side of the Y-shaped reinforcement structure to obtain the Y-shaped reinforcement structure. Obtain the model with the Y-shaped reinforcement structure.

[0022] Step 8: Based on the model with the Y-shaped reinforcement structure, 3D printing is performed using laser sintering curing additive manufacturing to obtain the ankle-foot orthosis.

[0023] Preferably, after step 2, the shape and size data of the patient's legs are processed using Geomagic to obtain a complete STL model.

[0024] Preferably, in step 5, the thickness of the curved surface basic body is 2-3m.

[0025] Preferably, the material for laser sintering and curing is nylon PA12 powder.

[0026] Preferably, the manufactured ankle-foot orthosis undergoes post-processing through grinding.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention discloses a 3D-printed ankle-foot orthosis, which consists of three parts: a lower leg portion, an Achilles tendon portion, and a foot portion. The lower leg portion conforms to the posterior and lateral sides of the lower leg, the Achilles tendon portion conforms to the posterior and lateral sides of the ankle, and the foot portion conforms to the bottom and sides of the foot. The ankle portion is located on the outside of the entire ankle-foot orthosis. Y-shaped reinforcement structures are provided at stress concentration points on the exterior of the lower leg and Achilles tendon portions. The orthosis with this Y-shaped structure offers good fit, light weight, high strength, and good protection. It is easy to wear inside the patient's shoes, solving the problem of insufficient fit in existing orthoses, and fulfilling the patient's physiological and psychological desire for social integration. It also significantly improves the gait of stroke patients.

[0029] Furthermore, the height of the Y-shaped reinforcement structure is limited to ensure that while providing support, it does not restrict patient movement due to excessive strength.

[0030] Furthermore, the Y-shaped reinforcement structure, including rear and side supports, improves support performance.

[0031] Furthermore, the front part of the sole is tilted upward relative to the horizontal plane, and combined with the bandage binding the big toe area, to prevent the patient's orthosis from not fitting properly inside the shoe, resulting in the "three no-fit" phenomenon: the orthosis not fitting the foot, the orthosis not fitting the shoe, etc.

[0032] Furthermore, a weight-reducing hole is provided at the back of the lower leg section to reduce the weight of the entire orthosis.

[0033] Furthermore, a connection hole is provided on the front side of the Achilles tendon section, allowing the entire device to be attached to the patient's foot via Velcro.

[0034] This invention also discloses a method for manufacturing an ankle-foot orthosis based on 3D printing. The orthosis is based on scanning a patient's affected limb and then reverse-engineering it to accommodate different leg sizes, foot shapes, and ankle widths. Mechanical analysis is performed using Anysys software, and corresponding structural reinforcements are implemented for areas of high stress concentration. The most suitable reinforced torsional structure is determined based on extensive experimental data. This addresses the issue of some 3D-printed ankle-foot orthosis breaking during wear due to excessive force at structural points.

[0035] Furthermore, considering the SLS PA12 process, the nylon material lacks sufficient strength. Therefore, a reinforced structure is needed to ensure that the nylon used in ankle-foot orthotics will not break. Attached Figure Description

[0036] Figure 1 A schematic diagram of the bones in the human foot.

[0037] Figure 2 This is a rear view of the ankle-foot orthosis of the present invention;

[0038] Figure 3 This is a side view of the ankle-foot orthosis of the present invention;

[0039] Figure 4 This is a schematic diagram of the curved surface edge design of the present invention;

[0040] Figure 5 Simulation diagram for curved surface design;

[0041] (a) is the right view, and (b) is the left view.

[0042] Figure 6 This is a side view of the original leg in Example 1;

[0043] Figure 7 This is a front view of the original leg in Example 1;

[0044] Figure 8 A top view of a worn ankle-foot orthosis;

[0045] Figure 9 A side view of someone wearing an ankle-foot orthosis;

[0046] Figure 10 A biomechanical simulation diagram of wearing an ankle-foot orthosis;

[0047] Wherein: 1-lower leg part; 2-Achilles tendon part; 3-foot part; 4-Y-shaped reinforcement structure; 4-1-rear support part; 4-2-side support part; 5-upper connecting part; 6-lower connecting part; 7-bottom connecting part; 8-weight reduction hole. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings:

[0049] The terms "front," "back," "up," and "down" described below are all based on the normal human body's front, back, up, and down dimensions, such as... Figure 1 As shown, the description of the present invention is based on this benchmark, and will not be repeated hereafter.

[0050] This invention discloses a 3D-printed ankle-foot orthosis and its manufacturing method, specifically including the following steps:

[0051] Step 1: For stroke patients who are unable to lift their legs or whose feet turn inward or outward when lifting their legs, making it impossible to scan and obtain a good leg model and provide a reference for the final alignment of the orthosis, the initial requirement is for the patient to be in an upright sitting position for leg data scanning. When the patient is in a sitting position, the midpoints of the ankle joint, knee joint, and hip joint should be on the same force line to obtain leg data, which provides a digital model reference for the later design and alignment of the orthosis.

[0052] Step 2: Using a 3D scanner, scan the patient's legs from the knees down in their natural standing posture. During the scan, the patient wears flesh-colored elastic stockings to facilitate rapid scanning and avoid scanning difficult-to-access areas, such as the gaps between the toes. This also facilitates the later inversion of the model. The 3D scanner obtains data on the patient's lower legs, ankles, and feet, specifically including dimensions and shape, such as... Figure 6 and Figure 7 As shown.

[0053] Step 3: Import the patient's leg data obtained in Step 2 into Geomagic for data processing to obtain a complete STL model of the patient's leg.

[0054] Step 4: Import the patient's seated leg STL model obtained in Step 3 into Rhino. Use the Rhino plugin T-spline to perform inverse modeling of the patient's legs, obtaining an editable CAD 3D surface model of the patient's legs. Trim the surface, removing surfaces with a longitudinal arch curve greater than 5, such as... Figure 1 The curve before the calcaneus at the ankle is removed, exposing the ankle joint outside the three-dimensional surface. The curve extends vertically upwards along both sides of the ankle surface, down to below the knee, removing the curve before the calcaneus on both sides of the ankle surface, resulting in the following... Figure 4The ankle-foot orthosis shown has a single curved surface, and the edge of the single curved surface is the edge of the target ankle-foot orthosis, such as... Figure 4 The black lines shown are cutting lines, and the longitudinal arch curve is the curve between the middle of the first metatarsal bone and the calcaneus. Then, an upper connecting part 5 and a lower connecting part extend from the front end of both sides of the single curved surface. Each side has an upper connecting part 5 and a connecting part 6 at its front end, and each connecting part also has a connecting hole at its front end. At the upper end of both sides of the bottom of the single curved surface, a bottom connecting hole 7 is provided on each side.

[0055] As one of the preferred options, an appropriate loosening of 1-2 mm is made according to the patient's ankle, heel, and the ends of the first and fifth metatarsal bones to avoid discomfort caused by compression of the patient's heel, metatarsals, and ankle.

[0056] Step 5: Increase the overall size by 2m to allow for the thickness of the inner lining. Then, based on the offset curved surface, thicken it outward by 3mm to obtain the orthosis without reinforcement structure in the first stage. The basic body is 2-3mm thick, preferably 3mm, to obtain the curved basic body.

[0057] Furthermore, during the lifting process, addressing the patient's toe-turning issue, the doctor analyzes the patient's gait to determine the angle at which the orthosis should be raised around the toes. This, combined with a bandage around the big toe, prevents the orthosis from not fitting snugly into the shoe, resulting in a "three-no-fit" situation (orthosis 2011 - orthosis not fitting snugly into the shoe). See details... Figure 3 The angle α between the distal end of the first metatarsal joint and the front of the foot and the horizontal plane is 10-15°.

[0058] Step 6: Export the surface primitive to STL, import it into ANSYS for mechanical analysis, and based on the mechanical distribution diagram obtained from the analysis, perform targeted reinforcement on areas of stress concentration and high stress (e.g., Figure 10 (As shown) Based on the patient's walking needs, a certain degree of mobility is required for ankle joint twisting. Therefore, it is necessary to reduce the lateral movement restrictions on the Achilles tendon reinforcement structure and determine the specific location of the Y-shaped structure. Generally, this location is located on the Achilles tendon and its upper part. Therefore, the Y-shaped reinforcement structure 4 is set in this part. In the specific design, the location and size of the Y-shaped reinforcement structure 4 will be adjusted according to the different leg sizes of the patient. However, the overall size cannot exceed 1 / 3 of the length from the sole of the foot to the lower part of the knee. The rear support part 4-1 of the Y-shaped reinforcement structure 4 is located on the center line of the tibia, and the side support part 4-2 extends forward along the curvature of the muscle to ensure that the prepared Y-shaped reinforcement structure 4 can provide appropriate support to the leg muscles.

[0059] The specific process of obtaining the Y-shaped reinforcement structure 4 is as follows: The rear side of the surface primitive is copied to obtain the copied surface. The copied surface is moved directly behind the surface primitive. The copied surface is trimmed according to the shape and size of the Y-shaped reinforcement structure 4 to obtain the outer surface of the Y-shaped reinforcement structure 4. The area between the outer surface of the Y-shaped reinforcement structure 4 and the rear side of the Y-shaped reinforcement structure 4 is thickened to obtain the Y-shaped reinforcement structure 4, thus obtaining a model with the Y-shaped reinforcement structure 4. Figure 5 As shown;

[0060] Step 7: Output the STL model with Y-shaped reinforcement structure 4 to the laser sintering and curing 3D printer. Slice the STL model using Magics software and then print it using the laser sintering and curing 3D printer. The material used is nylon PA12 powder.

[0061] Step 8: The orthosis is obtained through SLS printing. The resulting ankle-foot orthosis is relatively rough. Post-processing and polishing are performed to smooth the orthosis, preventing rough areas from damaging the patient's shoes and preventing the lining from failing to adhere or falling off, ultimately affecting the wearability of the orthosis. After polishing, the lining is glued on and bandages are secured, then the orthosis is given to the patient for trial.

[0062] See Figure 2 and Figure 3 The fabricated 3D-printed ankle-foot orthosis specifically comprises a calf portion 1, an Achilles tendon portion 2, and a foot portion 3 integrally connected from bottom to top. Calf portion 1 conforms to the posterior and lateral sides of the calf, Achilles tendon portion 2 conforms to the posterior and lateral sides of the ankle, and foot portion 3 conforms to the bottom and sides of the foot. These three parts are integrally printed without dividing lines; for ease of description, they are divided into three parts. Preferably, the sum of the heights of calf portion 1 and Achilles tendon portion 2 is 360-380 mm. As shown in the figure, calf portion 1 and Achilles tendon portion 2 completely wrap around the posterior part of the patient's calf and Achilles tendon, with a small edge extending from the sides. Foot portion 3 similarly completely wraps around the bottom of the foot, with an edge extending upwards from the sides. Each side of the extended sides of calf portion 1 has an upper connecting portion 5 and a connecting portion 6 at its front, and each connecting portion also has a connecting hole at its front end. The upper ends of both sides of the single curved bottom are each provided with a bottom connecting hole 7. The ankle is positioned outside the entire ankle-foot orthosis, allowing patients to move their ankle bones from side to side while walking. This structure, through a Y-shaped reinforcement structure, provides sufficient support at stress concentration points while not restricting ankle bone movement, thus improving the patient's experience.

[0063] A Y-shaped reinforcing structure is provided on the exterior of both the calf portion and the Achilles tendon portion. The upper end of the Y-shaped reinforcing structure is located on the exterior of the calf portion, and the lower end is located on the exterior of the Achilles tendon portion. The height of the Y-shaped reinforcing structure is 1 / 4 to 1 / 3 of the total height of the calf portion 1 and the Achilles tendon portion 2.

[0064] See Figure 3 The Y-shaped reinforcing structure 4 includes a rear support portion 4-1 and two side support portions 4-2. The rear ends of the two side support portions 4-2 are connected to the upper end of the rear support portion 4-1, and the front ends of the two side support portions 4-2 are respectively located on both sides of the lower leg portion 1. The height of the front ends of the side support portions 4-2 is higher than the height of the rear ends of the side support portions 4-2. The lower end of the rear support portion 4-1 is located outside the Achilles tendon portion 2. The two side support portions 4-2 extend upward along both sides of the muscle to ensure good fit.

[0065] The front portion of the foot part 3 is inclined upwards at 10°-30° relative to the horizontal plane. See Figure 3 The range of α is 10°-30°.

[0066] The lower leg portion 1 has several weight-reducing holes 8 at its rear. These holes are located where stress is not concentrated in the lower leg, so they do not affect the overall support of the orthosis. They also reduce weight and provide good breathability.

[0067] The following description, in conjunction with specific embodiments, provides further details.

[0068] Example

[0069] See Figure 6 and Figure 7 The patient's specific leg dimensions are as follows: calf height 446.74 mm (including the calf portion 1 and the Achilles tendon portion), foot length 269.70 mm, and foot width 96.66 mm. See also... Figure 8 and Figure 9 The Y-shaped reinforcing structure 4 prepared by the model has a total height of 12cm, a total width of 6-8mm for the Y-shaped curved surface, a total height of 380.83mm for the entire orthosis, that is, the height between the upper end of the calf part and the lower end of the Achilles tendon part, and a width of 96.66mm for the widest part of the sole 3.

[0070] During preparation, the base is positioned at the junction of the patient's heel and Achilles tendon, 12cm above the Achilles tendon. A 3mm thickened surface is cut and replicated, creating a Y-shaped curved surface. The cut Y-shaped curved surface is then thickened by 2mm.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A 3D-printed ankle-foot orthosis, characterized in that, It includes a lower leg portion (1), an Achilles tendon portion (2), and a foot portion (3) that are integrally connected from top to bottom; the lower leg portion (1) fits the back and side of the lower leg, the Achilles tendon portion (2) fits the back and side of the ankle, and the foot portion (3) fits the bottom and side of the foot; the ankle is located outside the entire ankle-foot orthosis; A Y-shaped reinforcing structure (4) is provided on the outside of both the lower leg portion (1) and the Achilles tendon portion (2). The upper end of the Y-shaped reinforcing structure (4) is located on the outside of the lower leg portion (1), and the lower end of the Y-shaped reinforcing structure (4) is located on the outside of the Achilles tendon portion (2). The height of the Y-shaped reinforcing structure is 1 / 4 to 1 / 3 of the total height of the calf part (1) and the Achilles tendon part (2); The Y-shaped reinforcing structure (4) includes a rear support part (4-1) and two side support parts (4-2). The rear ends of the two side support parts (4-2) are connected to the upper end of the rear support part (4-1). The front ends of the two side support parts (4-2) are respectively located on both sides of the lower leg part (1). The height of the front end of the side support part (4-2) is higher than the height of the rear end of the side support part (4-2). The lower end of the rear support part (4-1) is located outside the Achilles tendon part (2). The rear support (4-1) of the Y-shaped reinforcing structure (4) is located on the center line of the tibia, and the side support (4-2) extends forward along the curvature of the muscle.

2. The ankle-foot orthosis based on 3D printing according to claim 1, characterized in that, The front part of the foot part (3) is inclined upwards at 10°-30° relative to the horizontal plane.

3. The ankle-foot orthosis based on 3D printing according to claim 1, characterized in that, The lower leg portion (1) is provided with a weight-reducing hole (8) at the rear.

4. The ankle-foot orthosis based on 3D printing according to claim 1, characterized in that, The lower leg portion (1) has an upper connecting portion (5) and a lower connecting portion (6) at the front end of each side, with the upper connecting portion (5) above the lower connecting portion (6); the foot portion (3) has a bottom connecting portion (7) at the upper end of its side. Each upper connecting part (5) and lower connecting part (6) has a connecting hole at its front end; each bottom connecting part (7) has a connecting hole at its upper end.

5. A method for manufacturing a 3D-printed ankle-foot orthosis as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: The patient is in a sitting position, so that the midpoints of the patient's ankle, knee, and hip joints are aligned on the same force line. Step 2: Scan the patient's legs to obtain data on the shape and size of the patient's legs; Step 3: Combining the shape and size data of the patient's legs, reverse processing is performed using T-spline to obtain the three-dimensional curved surface of the patient's legs; Step 4, trim the three-dimensional curved surface. During the trimming process, remove the curved surface above the longitudinal arch curve (5) and the curved surface before the calcaneus at the ankle, so that the ankle joint is exposed outside the three-dimensional curved surface. Extend vertically upward along the curves on both sides of the curved surface at the ankle, extending to below the knee. Remove the curved surface before the curves on both sides of the curved surface to obtain the single curved surface of the ankle-foot orthosis. The edge of the single curved surface is the edge of the target ankle-foot orthosis. The longitudinal arch curve is the curve between the middle of the first metatarsal bone and the calcaneus. Step 5: Thicken the single surface to obtain the basic surface body; Step 6: Export the STL file of the surface primitive, perform ANSYS mechanical analysis, and determine the position and size of the Y-shaped reinforcement structure (4). The Y-shaped reinforcement structure (4) is located at the stress concentration point at the back of the ankle. Step 7: Copy the rear side of the surface primitive to obtain the copied surface. Move the copied surface to the rear of the surface primitive and cut the copied surface according to the shape and size of the Y-shaped reinforcement structure (4) to obtain the outer surface of the Y-shaped reinforcement structure (4). Thicken the area between the outer surface of the Y-shaped reinforcement structure (4) and the rear side of the Y-shaped reinforcement structure (4) to obtain the Y-shaped reinforcement structure (4). Obtain the model with the Y-shaped reinforcement structure (4). Step 8: Based on the model of the Y-shaped reinforcing structure (4), 3D printing is performed using laser sintering solidification additive manufacturing to obtain an ankle-foot orthosis.

6. The method for manufacturing an ankle-foot orthosis based on 3D printing according to claim 5, characterized in that, After step 2, the shape and size data of the patient's legs are processed using Geomagic to obtain a complete STL model; In step 5, the thickness of the curved surface basic body is 2-3m.

7. A method for manufacturing an ankle-foot orthosis based on 3D printing according to claim 5, characterized in that, The material that is laser-sintered and solidified is nylon PA12 powder.

8. A method for manufacturing an ankle-foot orthosis based on 3D printing according to claim 5, characterized in that, The manufactured ankle-foot orthosis undergoes post-processing through grinding.

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