Anatomical below-knee prosthetic leg that can be fabricated with a 3D printer

Abstract

The invention relates to an anatomical below-knee prosthetic leg that can be fabricated with a 3D printer, which has a complex geometry optimised according to stress regions by means of structural analyses considering engineering calculations and various loading conditions in daily life with a topology optimization method, for below-knee amputee patients.

Description

[0001] ANATOMICAL BELOW-KNEE PROSTHETIC LEG THAT CAN BE FABRICATED WITH A 3D PRINTER

[0002] Technical Field of the Invention

[0003] The invention relates to an anatomical below-knee prosthetic leg that can be fabricated with a 3D printer, which has a complex geometry optimised according to stress regions by means of structural analyses considering engineering calculations and various loading conditions in daily life with a topology optimization method, for below-knee amputee patients.

[0004] State of the Art

[0005] Below-knee leg prostheses are artificial limbs designed to assist individuals who have lost part or all of the leg below the knee joint. These prostheses help the user regain mobility, perform daily activities more independently, and improve quality of life.

[0006] In cases of limb loss caused by congenital conditions, disease, accident, or various surgical procedures, medical products such as prostheses are utilised in order to fulfil limb functions, reduce the insufficiency of the patient, enable the amputee patient to regain social life, and improve quality of life. With the development of technology, in a market with intense competition and limited resources, high-performance and low-cost designs have gained great importance. There are many different types of leg prostheses available on the market. These prostheses are fabricated with different manufacturing methods according to their types.

[0007] Prostheses are medical devices with freeform shapes that are difficult to produce with conventional machines. Furthermore, optimised constructions exhibit complex geometric features as a result of the reduced materials, since the stress conditions in different regions of the product are taken into consideration. In this way, additive manufacturing has recently become one of the methods applied in the production of below-knee leg prostheses that are difficult to manufacture with conventional methods. In the biomedical field, additive manufacturing methods with different technologies such as fused deposition modelling (FDM), stereolithography (SLA), selective laser sintering (SLS), and electron beam melting (EBM) are widely used.

[0008] Although various proposals and applications have been developed for below-knee prosthetic legs in the state of the art, these developments are not sufficient. Some applications concerning inventions developed for this purpose are given below.

[0009] In the invention disclosed in the application numbered “US5725598A” in the state of the art, a prosthetic leg is described, characterised by a long leg element having an upper connection section functionally fixed to the amputee user’s limb and a lower connection section to which the prosthetic foot can be attached permanently or removably. It is stated that the prosthetic leg, which consists of one or more leg elements made of materials such as carbon fibres, glass fibres, or synthetic fibres, can be replaced with leg and foot prostheses suitably configured to provide size adjustment or different spring rates to fit the size of the amputee person’s leg and foot, or according to the amputee’s stride, height, weight, and activity level.

[0010] In the invention disclosed in the application numbered “GB2559213A” in the state of the art, a prosthetic leg consisting of a large number of parts is described. It is understood that, as a method in the design of the prosthesis, a 3D scan of the tibia to be amputated was performed, and the CAD model of the prosthesis was created. It is stated that the prosthetic leg, having a socket formed by enclosing and fixing a part of the patient’s amputated limb, being coverable with a silicone or latex sheath, and being configured to match the other leg, can be manufactured from a biocompatible material using three-dimensional printing techniques.

[0011] The invention disclosed in the application numbered “US2021121305A1” in the state of the art describes a prosthetic foot device designed to be attached to the patient’s natural limb. The device consists of a socket section, a lateral cylindrical ankle joint, and a foot portion comprising the dorsum, phalanx, sole, and heel parts. The ankle joint has a labyrinth-like internal structure. It is mentioned that the foot portion, being made of flexible Glass Fibre Reinforced Plastic (GFRP) material, can be manufactured as a single piece by means of 3D printing technology.

[0012] In the state of the art, improvements have been made regarding types of prosthetic legs and manufacturing methods. However, problems exist such as prosthetic legs being heavy, costly, short-lived due to the rapid physical development of children in the growth phase, causing sweating in the socket during use, rotational and mechanical problems of multi-part jointed below-knee prostheses, rusting and corrosion, long production and supply times, and limited accessibility of the product. There is a need for affordable, lightweight, and durable prostheses that are topology- optimised to withstand the stresses occurring in loading conditions such as standing, walking, and climbing up and down stairs, and at the same time provide comfortable movement. In the state of the art, since designs that do not comply with the 45-degree rule are fabricated in 3D printing, support structures are created for the construction of roof regions at angles greater than 45 degrees, and these structures are later cleaned while obtaining the final product. These support structures cause both the amount of material and the printing time to increase. In addition, extra labour and time are required for cleaning the structures. For these reasons, there is a need for affordable, lightweight, and durable prostheses that are topology-optimised to withstand the stresses occurring in loading conditions such as standing, walking, and climbing up and down stairs, and at the same time can be fabricated with 3D manufacturing methods suitable for comfortable movement.

[0013] As a result, due to the drawbacks mentioned above and the inadequacy of current solutions regarding the subject matter, a development in the relevant technical field has become necessary.

[0014] The Aim of the Invention

[0015] The most important aim of the invention is to have an optimised engineering design with the required strength for standing, walking, and climbing up and down stairs for below-knee amputee patients. Thus, it can offer lightness and durability together while performing daily activities. Therefore, by means of its optimised design, it is high- strength, lightweight, and low-cost.

[0016] Another aim of the invention is that it consists of a single piece. Thus, since it does not have a joint, it does not cause mechanical rotation problems. Since it does not have a spring, a joint, or any assembly element, additional manufacturing and assembly processes are not required. Furthermore, in this way, problems such as breaking or malfunctioning are not encountered. Another aim of the invention is that it can easily be fabricated in different sizes.

[0017] Another aim of the invention is that, while being fabricated with a 3D printer, it can be manufactured without the need for any support structure, by having a support-free design. Thus, there is no need for more material, cost, time, and labour.

[0018] Another aim of the invention is that, during its design and production, there is no need for three-dimensional scanning processes. Thus, there is no need for time, cost, and qualified personnel. After the order, the patient’s process of obtaining the prosthesis is short and effortless.

[0019] Another aim of the invention is that, when prostheses need to be frequently replaced due to increasing age or other reasons, the cost is low and the size can be prepared within seconds without requiring a redesign process.

[0020] Another aim of the invention is that the socket part has both a wearable feature and a sweat-pore structure that allows air circulation to reduce sweating.

[0021] Description of Drawings

[0022] Figure 1 is the drawing showing the isometric view of the anatomical below -knee prosthetic leg that can be fabricated with a 3D printer, which is the subject of the invention.

[0023] Figure 2 is the drawing showing the front view of the anatomical below-knee prosthetic leg that can be fabricated with a 3D printer, which is the subject of the invention.

[0024] Figure 3 is the drawing showing the side view of the anatomical below-knee prosthetic leg that can be fabricated with a 3D printer, which is the subject of the invention.

[0025] Figure 4 is the drawing showing the rear perspective view of the anatomical below- knee prosthetic leg that can be fabricated with a 3D printer, which is the subject of the invention.

[0026] Figure 5 is the drawing showing the cosmetic-coated view of the anatomical below- knee prosthetic leg that can be fabricated with a 3D printer, which is the subject of the invention. Reference Numbers

[0027] 1. Below-knee prosthetic leg

[0028] 2. Foot

[0029] 3. Ankle

[0030] 4. Heel

[0031] 5. Leg

[0032] 6. Socket

[0033] 7. Leg support structure

[0034] 8. Ankle support structure

[0035] 9. Foot support structure

[0036] 10. Sweat pore

[0037] 11. Cosmetic coating

[0038] Description of the Invention

[0039] The invention relates to an anatomical below-knee prosthetic leg that can be fabricated with a 3D printer, which has a complex geometry optimised according to stress regions by means of structural analyses considering engineering calculations and various loading conditions in daily life with a topology optimization method, for below-knee amputee patients. Furthermore, the invention relates to a comfortable below-knee leg prosthesis, which has the strength to safely withstand the loads occurring in situations such as standing, walking, and climbing up and down stairs, and which facilitates use by means of its lightness in order to improve the quality of life of amputee patients.

[0040] The invention relates to a below-knee prosthetic leg (1 ) for below-knee amputee patients, which is optimised for standing, walking, and climbing up and down stairs; offers lightness and durability together; consists of a single piece; has low labour and production cost; does not require a model mould, a line installation for its production, or machines such as an oven, moulding, or cutting; is suitable for production in small enterprises; can be fabricated with a desktop or industrial type three-dimensional printer; has a design customised for production with 3D printing (additive manufacturing) that does not require support material during three-dimensional printing; has its geometry formed according to anthropometric data; can have its cosmetic coating (11 ) created in the same production process without the need for a separate cosmetic coating; can be used with a shoe; is comfortable and easy to use; has a socket (6) in which the leg is placed, preventing sweating; can be dimensionally changed m illimetrically and prepared within seconds in case of being requested in different sizes; enables direct transition from order to production; and can be supplied by directly producing the product on a 3D printer remotely online in regions where there are no biomedical enterprises.

[0041] The invention relates to a below-knee prosthetic leg (1 ), which comprises a foot (2), being the part below the ankle (3) of the below-knee prosthetic leg (1 ) and enabling contact with the ground; an ankle (3), forming the ankle part of the below-knee prosthesis; a heel (4), located at the rear side of the foot (2) part of the below-knee prosthetic leg (1 ), helping to maintain balance while standing, walking, and climbing up and down stairs; a leg (5), remaining above the ankle (3) of the below-knee prosthetic leg (1 ); a socket (6), which protects the amputee user’s amputated limb, is the part where the amputee user’s leg limb is placed inside the below-knee prosthetic leg (1 ), and provides freedom of movement; a leg support structure (7), which increases the strength of the below-knee prosthetic leg (1 ) in the leg (5) region; an ankle support structure (8), which increases the strength of the below-knee prosthetic leg (1 ) in the ankle (3) region; a foot support structure (9), which increases the strength of the below- knee prosthetic leg (1 ) in the foot (2) region; sweat pores (10), located in the socket (6) and providing air circulation to reduce sweating of the amputee user’s limb; and a cosmetic coating (11 ), which wraps around the outside of the below-knee prosthetic leg (1 ) and has a thin flesh thickness in the form of a human leg.

[0042] The invention is a below-knee prosthetic leg (1 ), which is prepared for use by patients amputated between the knee and the ankle, and is a prosthesis capable of performing daily movements such as standing, walking, and climbing up and down stairs. The below-knee prosthetic leg (1 ) and all components forming the below-knee prosthetic leg (1 ) have geometric forms and angles that can be fabricated without the need for support structures during 3D printing.

[0043] The invention is a below-knee prosthetic leg (1 ), designed to fulfil the functions of patients with lower extremity limb loss, consisting of a single piece, lightweight, and high-strength. The foot (2), ankle (3), heel (4), leg (5), and socket (6) parts constituting the invention are designed as a single piece according to average anthropometric data. With its design, the invention can safely withstand the loads occurring in situations such as standing, walking, and climbing up and down stairs of amputee patients. The invention has a design developed by considering the walking pattern. The invention is of a nature and strength to withstand the stresses occurring in the prosthesis in the phases of initial contact, loading response, midstance, terminal stance, and preswing.

[0044] The below-knee prosthetic leg (1 ) is resistant to the loads that may occur during the daily activities of the person. The invention is designed as a result of structural analysis and optimisation carried out by considering situations such as standing, walking, and climbing stairs. The invention essentially consists of the foot (2), ankle (3), heel (4), leg

[0045] (5), and socket (6) parts. The foot support structures (7), the ankle support structure (8), and the leg support structure (9), which increase the strength resulting from optimisation, are designed to be suitable for production.

[0046] The leg support structure (7) is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the leg (5) region. It helps the stresses and deformations occurring in the leg (5) region during standing, walking, and climbing up and down stairs remain at a reasonable level with a lighter design using less material.

[0047] The ankle support structure (8) is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the ankle (3) region. It helps the stresses and deformations occurring in the ankle (3) region during standing, walking, and climbing up and down stairs remain at a reasonable level with a lighter design using less material.

[0048] The foot support structure (9) is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the foot (2) region. It helps the stresses and deformations occurring in the foot (2) region during standing, walking, and climbing up and down stairs remain at a reasonable level with a lighter design using less material.

[0049] The invention does not have any joint and consists of a single piece. There are no rotation problems or mechanical failures arising from joints in the invention. The socket

[0050] (6) has both a wearable feature and sweat pores (10) that allow air circulation to reduce sweating. The invention has a heel (4) design to enable amputee patients to maintain balance more easily while using the prosthesis and to withstand the forces that may disrupt balance in the sagittal axis.

[0051] The invention is designed by taking anthropometric data into account. The stress values of the obtained design provide the optimum model as a result of structural engineering analyses and topology optimisation carried out by considering the loading conditions in users’ daily activities. Therefore, it has a high-strength and lightweight design. In addition, in order for users not to experience balance problems, it has a sole geometry supported by the heel (4).

[0052] The anatomical design of the invention, which is designed according to anthropometric data, both increases its functionality for the person’s daily life activities and provides a cosmetic appearance. The cosmetic coating (11 ) of the product can be manufactured during 3D printing by closing the gap parts in the form of a thin section to enhance the visual appearance.

[0053] The invention is suitable for use with wearable items for the foot, such as shoes and socks. At the heel (4) part, there is a curve above the heel (4) to facilitate wearing shoes. The design that is the subject of the invention has been optimised by considering human activities, but it does not restrict its use for humanoid robots that can perform activities such as standing, walking, and climbing stairs outside of human use.

[0054] The invention is a below-knee prosthetic leg (1 ), consisting of a single piece, capable of damping energy during use, being able to flex within reasonable displacement ranges, and being jointless, therefore having no mechanical rotation problems. The invention has a design suitable for accessories worn on the foot, such as shoes. The socket of the below-knee prosthetic leg has a structure that is both wearable and contains sweat pores (10) allowing air circulation to reduce sweating.

[0055] The invention is resistant to climatic conditions in different geographical regions and is suitable for use in various weather conditions. The prosthesis can be used comfortably in hot and cold weather conditions. Since the material of the invention has low thermal conductivity, it does not undergo rapid temperature changes in hot and cold weather conditions like metal prostheses. The invention is resistant to corrosion by means of its thermoplastic material and does not undergo any rusting during use. The invention is resistant to corrosion due to the material used. As the material of the invention, thermoplastic polyurethane (TPU) is used because of its flexibility and non-slip property. Apart from this, the invention can also be fabricated from thermoplastic materials such as polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), and different materials.

[0056] The invention can easily be fabricated in the desired size or scale m illimetrically. It is manufactured with 3D printing (additive manufacturing) methods and technologies due to many advantages such as the ability to produce complex designs, the absence of a mould requirement, and the direct transition from design to production. For the production of the invention, FDM technology is used, which is the most preferred in the production of polymer material parts and a technology used by many different desktop printer models in addition to industrial types. FDM printers are lower-cost compared to other 3D printer technologies and are easy-to-use devices that do not require special equipment in home or workplace environments. In addition, the product is also suitable for other 3D printing methods and technologies apart from FDM. It can also be manufactured with any production method in different types of 3D printers at the desired size or scale. The invention is designed and fabricated in a way that does not require support structures by taking into account the 45-degree rule for technologies such as FDM. Since there is no need for the use of support material during the production of the invention in 3D printers or additive manufacturing machines, there is no waste of material, labour, or time.

[0057] Since the invention can be manufactured with a 3D printer or an additive manufacturing machine, its supply is easy. A company or institution that owns the 3D model of the prosthesis can dimension the prosthesis model within seconds according to the amputated leg measurements of the user and easily make it ready for production for any patient. As new prostheses are needed according to the constantly changing measurements of children in the growth phase, this need can be met more frequently, at low cost, and easily, since it can be adjusted m illimetrically in a simple manner and is low-cost.

[0058] The invention does not need to be redesigned in three dimensions for different patients. No 3D modelling program is used for dimensioning the model or changing its scale for patients. Personnel with knowledge of 3D modelling are not required for the production of the model. When the model is to be fabricated for different patients, the model scale can be changed with paid or free slicing software available on the market for 3D printers, and it can be made ready for production within seconds. From the order of the product, it can be fabricated and delivered to the user within 1-2 days (depending on the features of the printer). Apart from the use of a 3D printer in the manufacture of the prosthesis, qualified personnel are not required. If desired, the prosthesis can be manufactured at any place where the user is located with a 3D printer through a remote internet connection. Since the invention can be manufactured with an online connection, it can be easily supplied for people living in different geographies who have limited access to prostheses. A company or institution that owns the prosthesis model can store and protect the prosthesis design electronically, and it can be fabricated on its own 3D printer or on a remote online 3D printer. It can be fabricated in small enterprises with a desktop or industrial type three-dimensional printer. Direct transition from order to production can be achieved, and the supply can be carried out by direct production of the product on a 3D printer remotely online at the customer’s location, except for delivery by cargo in regions where there is no biomedical enterprise.

Claims

CLAIMS1. The invention is a below-knee prosthetic leg (1 ), comprising;- a foot (2), being the part below the ankle (3) and enabling contact with the ground,- an ankle (3), forming the ankle part of the below-knee prosthesis,- a heel (4), located at the rear side of the foot (2) part of the below-knee prosthetic leg (1 ), helping to maintain balance during standing, walking, and climbing up and down stairs,- a socket (5), in which the leg is placed, being wearable and having sweat pores (10) on it to prevent sweating,- a leg support structure (7), which is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the leg (5) region,- an ankle support structure (8), which is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the ankle (3) region,- a foot support structure (9), which is the support structure that increases the strength of the below-knee prosthetic leg (1 ) in the foot (2) region,- sweat pores (10), located in the socket (6) and providing air circulation to reduce sweating of the amputee user’s limb, and- a cosmetic coating (11 ), which wraps around the outside of the below-knee prosthetic leg (1 ) and has a thin flesh thickness in the form of a human leg.

2. The below-knee prosthetic leg (1 ) according to claim 1 , comprising a heel (4), which has a curve on it to facilitate wearing shoes, and enables amputee patients to maintain balance during prosthesis use and to withstand forces that may disrupt balance in the sagittal axis.

3. The below-knee prosthetic leg (1 ) according to claim 1 , comprising a leg (5), which remains above the ankle (3) of the below-knee prosthetic leg (1 ), and a socket (6), which protects the amputee user’s amputated limb, is the part where the amputee user’s leg limb is placed inside the below-knee prosthetic leg (1 ), and provides freedom of movement.

4. The below-knee prosthetic leg (1 ) according to claim 1 , comprising a leg support structure (7), which is the structure supporting the stresses and deformationsoccurring in the leg (5) region during standing, walking, and climbing up and down stairs.

5. The below-knee prosthetic leg (1) according to claim 1 , comprising an ankle support structure (8), which is the structure supporting the stresses and deformations occurring in the ankle (3) region during standing, walking, and climbing up and down stairs.

6. The below-knee prosthetic leg (1 ) according to claim 1 , comprising a foot support structure (9), which is the structure supporting the stresses and deformations occurring in the foot (2) region during standing, walking, and climbing up and down stairs.

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