Method for manufacturing a prosthetic socket

Abstract

The invention relates to a method for manufacturing a prosthetic socket (1) having a proximal opening (2) for receiving an amputation stump, a base body (3) and an inner surface (4), comprising the steps: a) Acquiring an outer surface (5) corresponding to the inner surface (4) of the prosthetic socket (1); b) Creating a positive model (6) with an inner shell (7), an outer shell (8), an interface (9), a cavity (10) and a connection geometry (11) based on the outer surface (5) which corresponds to the inner surface (4) of the prosthesis stem (1); c) Pouring the cavity (10) with a casting compound (12) and allowing it to harden to form a positive mold (13); d) Placing a pull-out part (14) on the positive form (13); e) Shaping a material onto the positive form (13) to obtain the basic body (3); f) Separating the base body (3) from the positive form (13).

Description

[0001] The present invention relates to a method for manufacturing a prosthetic socket comprising a proximal opening for receiving an amputation stump, a base body and an inner surface.

[0002] A prosthetic socket forms the interface between the amputation stump of an amputee and the rest of the prosthesis. While the other components are now predominantly standardized parts that are assembled to fit the amputee, the prosthetic socket remains an individualized component. This individuality arises, among other things, from the varying sizes, shapes, proportions, and internal structures of amputation stumps.

[0003] To manufacture a prosthetic socket, it is first necessary to acquire the desired shape, tailored to the specific amputation stump. This can be achieved by taking a plaster cast and pouring it into a mold. Alternatively, measurements taken at specific points on the stump and calculation of the desired shape based on a standard model are common. Photogrammetry is also used to capture the shape. Regardless of the method used, it is standard practice to refine the shape manually or digitally.

[0004] If the desired shape of the prosthetic socket exists as a digital model, the socket can be manufactured directly using additive manufacturing processes, such as 3D printing. Alternatively, it is common practice to first create a positive mold of the amputation stump with the desired shape using a subtractive manufacturing process and then mold a material onto this positive mold. If the positive mold is obtained by casting a plaster mold, this can be used for the molding process.

[0005] The known methods for directly manufacturing the prosthetic socket or manufacturing it via a positive mold followed by shaping have several disadvantages.

[0006] Firstly, the process of creating a positive mold by pouring a plaster cast involves several manual steps that are prone to errors and can lead to inconsistent results. Furthermore, these steps are time-consuming, and when performed by skilled personnel, they result in high costs. The need to wait for the plaster to harden between steps also prevents a quick production process.

[0007] Manufacturing the positive mold using a subtractive process from a digital model produces consistent results and is fast. However, this method requires a complex and therefore expensive machine. Furthermore, the machine itself, as well as the raw material from which the positive mold is made, requires a significant amount of space. This limits its potential application to production sites with sufficient available floor space.

[0008] Both the method of manufacturing the prosthetic socket using a positive mold and plaster casting, and subtractive manufacturing processes, have limitations in shaping the socket. After the material has been molded to the positive mold, the two must be separated non-destructively. Only small undercuts are possible through forced demolding during this step. Larger undercuts can only be achieved by gradually removing material from the positive mold after molding, which is very time-consuming and therefore expensive.

[0009] When manufacturing a prosthetic socket directly from a digital model using an additive manufacturing process, such as 3D printing, the choice of manufacturing method and material has a significant impact on the socket's strength. Due to the high demands placed on a prosthetic socket, only a few materials and additive manufacturing processes are suitable. The available manufacturing processes require complex machinery. This, combined with the long production time, results in high costs.

[0010] The object of the present invention is to propose a method for decoupling the production of prosthetic sockets from complex process steps that currently require skilled personnel, larger setup areas, or longer production times. Further objects of the present invention are to reduce production costs and to enable undercuts in the shaping process in order to achieve a good fit and thus a high level of wearing comfort for prosthetic sockets.

[0011] The aforementioned problems are solved by the inventive method for manufacturing a prosthetic socket comprising a proximal opening for receiving an amputation stump, a base body, and an inner surface. In the first step of the method, an outer surface corresponding to the inner surface of the prosthetic socket is acquired. In a further step, a positive model is created based on the outer surface corresponding to the inner surface of the prosthetic socket. This model includes an inner shell, an outer shell, an interface, a cavity, and a connection geometry. Based on this model, the cavity is then filled with a casting compound and cured to form a positive mold. In the next step, a die is placed on the positive mold. Finally, a material is molded onto the positive mold to create the base body of the prosthetic socket.In the next step, the basic body is separated from the positive form.

[0012] According to one embodiment of the invention, the inner shell, the outer shell, and the connection geometry, which together form the positive model, are produced as a single, cohesive body. This makes it possible to manufacture the positive model from a single, continuous material composite.

[0013] According to a further embodiment of the invention, the positive model is created at least partially using an additive manufacturing process. This allows for production using a 3D printer, making it cost-effective and requiring no specialized personnel.

[0014] According to a further embodiment of the invention, when the casting compound is poured into the cavity, it completely fills the cavity, which is spatially delimited by the inner shell, the outer shell, the connection geometry, and the interface. This allows the positive model, oriented with the interface facing upwards, to be filled from above with a flowable casting compound, with the interface being the only opening. This creates the advantageous possibility of using inexpensive and widely available materials, such as plaster, as the casting compound.

[0015] According to a further embodiment of the invention, the outer shell of the positive mold is at least partially removed after the cavity has been filled and the casting compound has hardened, and before the material is formed onto the positive mold. This allows the forming to take place on the material of the hardened casting compound. An advantage is gained if the hardened material of the casting compound has better properties for forming the material than the material of the outer shell. For example, if a 3D printing process using thermoplastic polymer and gypsum as the casting compound is used to create the positive model, then the hardened gypsum is more resistant to heat than the thermoplastic polymer, which can be advantageous when forming the material.

[0016] According to a further embodiment of the invention, the material is formed using a thermoplastic material: By heating the thermoplastic material above a certain temperature, it becomes easily deformable. This allows the heated and deformable thermoplastic material to be easily formed onto the positive model and, upon cooling, retains the shape of the outer surface of the positive mold, thus creating the basic body of the prosthetic socket.

[0017] According to a further embodiment of the invention, the base body is separated from the positive mold by a force applied to the pull-out part in a pulling direction. The pull-out part allows the applied force to be easily transferred to the positive mold. This enables the positive mold to be separated from the base body in a quick and simple step. The pull-out part can be reusable.

[0018] According to a further embodiment of the invention, when the base body is separated from the positive mold, the positive mold collapses, thereby overcoming at least one undercut. This allows the shape of the positive mold, and consequently the shape of the positive model, to have one or more undercuts. The outer surface of the positive model can thus be optimally adapted to the shape of the amputation stump. This achieves the best possible fit and therefore a high level of wearing comfort for the prosthetic socket.

[0019] According to a further embodiment of the invention, the extractor is positioned on the positive mold in such a way that it does not come into contact with the material during the molding process. This ensures that the shape of the extractor is not reflected in the shape of the molded material and thus not in the shape of the prosthetic socket's base body. The shape of the extractor can therefore be optimized for its functionality.

[0020] According to a further embodiment of the invention, the extracting part is covered by a lid, which forms part of the positive mold, during the molding process. This ensures that the material does not come into contact with the extracting part during molding. Advantageously, the lid can be designed so that its outer shape follows the outer surface of the positive model. Since the lid is a separate part and therefore removable, the extracting part can be easily positioned on the positive mold.

[0021] According to a further embodiment of the invention, when the base body is separated from the positive mold, the cover remains connected to the base body and is positioned in a device via an interface geometry in the cover in a known or calculable relative position and orientation to at least one connecting piece. This allows one or more connecting pieces to be attached to the base body in a defined position and orientation. The connecting pieces can serve to connect the prosthetic socket to further orthopedic attachments. Due to the known or calculable relative position and orientation, the orthopedic attachments can be connected to the prosthetic socket in such a way that a deviation from the norm in the position of the amputation stump can be at least partially compensated for.

[0022] According to a further embodiment of the invention, the lid has a connecting element by which the lid is separated from the base body by a tensile force on the connecting element. This allows the lid to be detached from the base body quickly and easily when it is no longer needed for placement in a device. The connecting element can advantageously be designed as an internal thread.

[0023] Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. These show: Fig. 1. A cross-sectional view of a prosthetic socket; Fig. 2 a sectional view of a positive model; Fig. 3 a sectional view of a positive mold with an extract part and lid.

[0024] Fig. Figure 1 shows a sectional view of a prosthetic socket 1, which has a proximal opening 2, a base body 3, an inner surface 4, and a connecting piece 19. The inner surface 4 is part of the base body. The proximal opening 2 results from the shape of the base body 3. In the illustrated embodiment, the connecting piece 19 is connected to the base body 3 via a connecting element. In another embodiment, the connecting piece 19 can be connected directly to the base body 3. Different designs of the connecting element allow for various positions between the base body 3 and the connecting piece 19. If the position of the amputation stump deviates from the standard position, this can be at least partially compensated for by an advantageous position between the base body 3 and the connecting piece 19.

[0025] Fig. Figure 2 shows a sectional view of a positive model 6, which has an outer surface 5, an inner shell 7, an outer shell 8, an interface 9, a cavity 10, and a connection geometry 11. The outer surface 5 is part of the outer shell 8 and corresponds to the inner surface 4 in Figure 2. Fig. 1. The cavity 10 is spatially delimited by the inner shell 7, the outer shell 8, the connection geometry 11 and the interface 9.

[0026] In the illustrated embodiment, the inner shell 7, the outer shell 8, and the connecting geometry 11 form a single, continuous body that can be produced in one step. For this purpose, an additive manufacturing process can be used, for example. The positive model 6 can be designed such that an additive manufacturing process can create the shape without the need for support material. For this purpose, the connecting geometry 11 and the inner shell 7 are designed with steeply upward-sloping surfaces.

[0027] Fig. Figure 3 shows a cross-sectional view of a positive form 13, which is in Fig. The positive form 13, shown in Figure 2, comprises the outer surface 5, inner shell 7, outer shell 8, and interface 9, and contains a casting compound 12. The positive form 13 is obtained by pouring the cavity 10 of the positive model 6 from this compound. Fig. 2 with a casting compound 12 and subsequent hardening. The outer surface 5 remains part of the outer shell 8 and corresponds to the inner surface 4 in Fig. 1. In the illustrated embodiment, the hardened casting compound 12 fills the cavity 10. Fig. 2 is completely removed. Therefore, in the section view, the connection geometry 11 is removed. Fig. 2 not visible.

[0028] In this example, a pull-out part 14 is already positioned on the positive mold 13. Advantageously, the positive model 6, which forms the positive mold through pouring and curing, is already designed to accommodate a pull-out part 14. In the illustrated embodiment, the pull-out part 14 is covered by a lid 17, which includes an interface geometry 18 and a connecting element 20. This prevents the material from coming into contact with the pull-out part 14 when it is molded onto the positive mold. During molding, the base body 3 is formed from Fig. 1 with the inner surface 4, which corresponds to the outer surface 5. Since the extension part 14 is covered, it does not affect the shape of the base body 3.

[0029] By applying a force to the extractor part 14 in a tensile direction 15 after the material has been formed against the positive mold 13, the base body 3 separates from the positive mold. In the illustrated embodiment with a thin wall thickness of the casting compound 12 between the inner shell 7 and outer shell 8 in the area of ​​at least one undercut 16, the positive mold 13 can collapse during separation, thus overcoming the undercut 16. This collapse can be facilitated by an equidistant slope between the inner shell 7 and the outer shell 8.

[0030] If the cover 17 bonds to the base body 3 during the material forming process and remains connected even after separation, the cover 17, with its interface geometry 18, can be used to position the bonded base body 3 together with the cover 17 in a fixture relative to a connecting piece 19, in order to subsequently connect the connecting piece 19 to the base body 3, for example. The cover 17 can later be separated from the base body 3 by a tensile force on the connecting element 20. Reference symbol list 1 prosthetic socket 2 Proximal opening 3 basic shapes 4 interior surface 5 Outdoor area 6 Positive Model 7 Inner shell 8 Outer shell 9 Interface 10 Cavity 11 Connection geometry 12 Casting compound 13 Positive form 14 Excerpt 15 Direction of travel 16 Undercut 17 lids 18 Interface geometry 19 connector 20 connecting element

Claims

[1] Method for manufacturing a prosthetic socket (1) comprising a proximal opening (2) for receiving an amputation stump, a base body (3) and an inner surface (4), comprising the steps: a) Acquiring an outer surface (5) corresponding to the inner surface (4) of the prosthetic socket (1); b) Creating a positive model (6) with an inner shell (7), an outer shell (8), an interface (9), a cavity (10) and a connection geometry (11) based on the outer surface (5) which corresponds to the inner surface (4) of the prosthesis stem (1); c) Pouring the cavity (10) with a casting compound (12) and allowing it to harden to form a positive mold (13); d) Placing a pull-out part (14) on the positive form (13); e) Shaping a material onto the positive form (13) to obtain the basic body (3); f) Separating the base body (3) from the positive form (13). [2] Method according to claim 1, characterized by , that when creating the positive model the inner shell (7), the outer shell (8) and the connection geometry (11) are created as a single, connected body. [3] Method according to claim 1 or 2, characterized by , that the creation of the positive model (6) is carried out at least partially using an additive manufacturing process. [4] Method according to any of the preceding claims, characterized by , that when pouring the cavity (10) the casting compound (12) completely fills the cavity (10) and the cavity (10) is spatially delimited by the inner shell (7), the outer shell (8), the connection geometry (11) and the interface (9). [5] Method according to any of the preceding claims, characterized by, that after the cavity (10) has been filled and the casting compound (12) has hardened and before the material has been molded onto the positive mold (13) the outer shell (8) of the positive mold (13) is at least partially removed. [6] Method according to any of the preceding claims, characterized by that the material is shaped using thermoplastic material. [7] Method according to any of the preceding claims, characterized by , that the separation of the base body (3) from the positive form (13) is effected by a force applied to the extension part (14) in a pulling direction (15). [8] Method according to any of the preceding claims, characterized by , that when the base body (3) is separated from the positive form (13) the positive form (13) collapses and at least one undercut (16) is overcome. [9] Method according to any of the preceding claims, characterized by, that the placement of the extract part (14) on the positive form (13) is carried out in such a way that the extract part (14) does not come into contact with the material when the material is formed. [10] Method according to claim 9, characterized by , that when shaping the material, the extract part (14) is covered by a lid (17) which forms part of the positive form (13). [11] Method according to claim 10, characterized by , that when the base body (3) is separated from the positive form (13) the cover (17) remains connected to the base body (3) and is placed in a device, in a known or calculable relative position and orientation to at least one connecting piece (19) via an interface geometry (18) in the cover (17). [12] Method according to claim 11, characterized by, that the lid (17) has a connecting element (20) by which the lid (17) is separated from the base body (3) by a tensile force on the connecting element (20).

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