DE102019102071A1 - Arm prosthesis and method of making the same - Google Patents

Abstract

The invention relates to an arm prosthesis comprising a shaft (1) with a proximal end (10) and a distal end (11) and an artificial hand (2) attached to the distal end (11), the shaft (1) being made in an additive process is made of a plastic material and a clamping device is provided, by means of which a radially inward clamping force on the shaft (1) can be generated. A method for producing such an arm prosthesis is also specified.

Description

The invention relates to an arm prosthesis, comprising a shaft with a proximal end and a distal end and an artificial hand attached to the distal end.

Arm prostheses of the type described above are known, for which on the DE 10 2016 201 002 A1 is referred to as an example. They serve to care for a patient who has only one arm stump due to an amputation, for example.

The stem of the prosthetic arm is placed on the amputation stump or put over and fixed over it, although it has already been proposed to manufacture the stem in an additive process based on the 3-D data obtained from the amputation stump.

Arm prosthesis stems are usually funnel-shaped due to the shape of the arm stump, since the arm is usually thicker at the proximal end than at the distal end. This enables the patient to enter the shaft of the prosthetic arm. Due to a frictional contact with a prosthesis liner, which is first applied as an inner layer to the arm stump, the prosthesis shaft sits firmly on the arm stump. Over the course of a day, however, the size of the arm stump changes due to, for example, physical exertion and normal volume fluctuations. These cannot be easily compensated for in the known arm prostheses and there is a risk that the prosthesis wearer will lose the arm prosthesis.

If the prosthetic arm is also designed to be myoelectrical and has sensors that derive electrical signals from the skin of the arm stump and direct it to drive means of an articulated hand that adjoins the arm stump, such volume fluctuations can also result in the sensors no longer operating as desired lie against the skin surface and malfunctions or incorrect controllability of the artificial hand occur.

In addition, it is more common that part of the wrist and / or the bones of the hand were not amputated during the amputation or that the stump of the arm was not approximately conical. In such a case, a thickening remains at the end of the arm stump, which makes it difficult to establish the necessary contact between the prosthesis socket and the arm stump or to tighten the prosthesis socket beyond such an undercut.

The object of the invention is therefore to propose an arm prosthesis of the type mentioned at the outset, which has a significantly improved shaft, which can be adapted precisely and easily to the arm stump even under difficult conditions, and which can be easily and without additional help by the patient. and can be stored and can also be adapted to volume differences occurring during the wearing period.

To achieve the object, the design of an arm prosthesis according to the features of claim 1 is proposed.

A method for producing such arm prostheses is the subject of claim 11.

Advantageous refinements and developments of the invention are the subject of the dependent claims.

The invention proposes that the shaft is made from at least one plastic material in an additive process and a clamping device is provided, by means of which a radially inwardly directed clamping force can be generated on the shaft in order to radially compress the shaft reversibly.

Within the scope of the invention, it is thus possible, in particular in accordance with a 3-dimensional model of the patient's arm stump, to produce a shaft that exactly fits this arm stump in an additive process, which is elastically flexible and in particular elastically expandable, so that the shaft also in the case of a non-tapered arm stump or a thickening at the end of the arm stump can be easily tightened by temporarily widening. The clamping device then generates a desired radially inward clamping force on the regions of the shaft separated by the slot and compresses it radially until the shaft is firmly and precisely seated on the arm stump.

Within the scope of the invention it is provided that the tensioning force that can be carried out by the tensioning device is adjustable and reversible, for example by means of appropriate adjustment means, so that the patient can individually determine the tensioning force himself and can also readjust and also cancel it if volume changes occur during the wearing period, for example if the prosthetic arm should be removed.

According to a proposal of the invention, the shaft, starting from the proximal end, comprises at least one in the longitudinal direction towards the distal end running slot that is open to the proximal end and ends before the distal end. The tensioning force is then exerted on the regions separated from one another by the at least one slot by means of the tensioning device.

In an alternative embodiment of the invention, it is provided that the shaft is formed from a multiplicity of interwoven ring elements made of the plastic material, which can also be produced additively in this configuration. Such a substrate is similar in structure to a chain mail, but is made of ring elements made of the plastic material and, due to the elastic material properties, can compensate for volume fluctuations in all directions and can also be radially compressed in an adjustable manner by means of the tensioning device.

According to a proposal of the invention, the tensioning device can be formed by a tensioning ratchet fastened on the outside of the shaft and a tensioning rope running around the shaft, the at least one end of which can be adjustably wound on the tensioning ratchet. Such ratchets are known and are used as a tensioning device, for example, in sports shoes such as ski boots and inline skates. Either one end of the tensioning rope is fixed in place and only the other end is variably wound on the tensioning ratchet, or both ends of the tensioning rope are wound equally on the tensioning ratchet.

As a result of the manufacture of the shaft made of a plastic material in accordance with the invention in an additive process, for example 3D printing, according to a further proposal of the invention, the possibility of integrating guide channels for the tensioning rope at least in regions on and / or in the surface of the shaft during the manufacture of the shaft to train. Viewed from the outside of the arm prosthesis according to the invention, the tensioning cables of the tensioning device then run almost completely concealed within the shaft.

In addition, according to a further proposal of the invention, due to the additive manufacturing process, hollow chambers for receiving electrodes, batteries, conductor tracks, actuators or other components can also be integrally introduced into the shaft, which in this way are integrated extremely efficiently and unobtrusively into the prosthetic arm according to the invention.

By using electrically conductive plastic materials, electrically conductive structures for forming electrodes and / or conductor tracks can also be produced directly during the additive manufacturing of the arm prosthesis according to the invention.

Non-slip inserts, such as silicone pads, can also be incorporated into the inner surface of the shaft to prevent the prosthetic arm from slipping.

The shaft of the arm prosthesis according to the invention can be designed, for example, as an inner shaft and an outer shaft, for example in skin-colored coloring, is provided, which is positioned as an outer shell over the inner shaft. It is also conceivable to design such an outer cover in the same way when the arm prosthesis according to the invention is produced using the additive method.

By using a gradient material, i.e. Plastic with different hardness and / or elasticity can also be formed areas of the shaft with different hardness and / or elasticity, although the shaft was manufactured integrally in an additive process. For example, a flexibility that increases from the distal end to the proximal end can be set with such a gradient material. Both the requirements for the anatomical adaptability of the inner shaft and the rigid, shock-resistant and dimensionally stable design of the outer shaft can be taken into account.

According to a further proposal of the invention, the shaft can also have a structure of additively and integrally formed inner and outer layers, the inner and outer layers being connected at the edges or each being designed as a closed layer, so that an air-filled cavity is formed within the shaft , which is delimited by the inner layer, the outer layer and possibly their edge-side connection, in such a way that the inner layer and the outer layer together enclose the air-filled cavity. A multiplicity of elastically deformable support elements are arranged within this cavity, which maintain the cavity between the inner and outer layers and, because of their elastic deformability, enable a corresponding elastically restoring deformation of the inner layer with respect to the rigid or dimensionally stable outer layer serving as an abutment. In addition, air passage openings are formed in the space between the individual support elements, which can be designed, for example, so that when the inner layer and / or the support elements are elastically deformed, the air present in the cavity is temporarily displaced and can escape into other areas of the cavity. Finally, at least one suitable position, preferably in the area of the outer layer, At least one ventilation opening can be provided, through which the air-filled cavity of the shaft communicates with the surrounding atmosphere, so that an air exchange can take place between the cavity and the surrounding atmosphere. By forming the inner and outer layer and / or some or all of the support elements made of plastic material with different properties, the behavior of the shaft formed in this way can be adjusted within wide limits. The structure of such a material is, for example, from DE 20 2017 106 997 U1 known.

In a first step, the method for producing such an arm prosthesis comprises the creation of a three-dimensional digital model of the patient's arm stump to be supplied, which can be achieved, for example, using known digitization methods, such as a strip light scanner. Before this, the points for the later position of the sensors on the muscles are marked, the edge course of the shaft is marked and the positions of the batteries or other components are indicated. The digital scan created in this way can then be digitally modeled on the screen.

Following these preparatory actions, a digital CAD construction of the three-dimensional model of the prosthetic arm and, in particular, of the individual shaft can be carried out in a suitable CAD system using the present virtual model. The positions of electrodes, batteries, conductor tracks, actuators, other components as well as any slots provided are determined here or taken from the previous definitions and likewise stored in the three-dimensional model.

The arm prosthesis can then be produced in an additive process from a plastic material in accordance with the 3-dimensional model, the defined guide channels for the tensioning cable and the hollow chambers for receiving electrodes, batteries, conductor tracks and or actuators being integrally introduced or electrodes and or conductor tracks are generated directly in the additive manufacturing process by using electrically conductive materials.

Due to the design of the shaft provided according to the invention, the frequently occurring volume fluctuations can be compensated for by readjusting the tensioning device and slipping of the shaft can thus be prevented. After the prosthesis wearer has tightened the shaft in the open state, he can tighten the shaft to a good fit using the tensioning device. In the course of a day, the natural reduction in volume of the arm stump can be compensated for by further closing the shaft. This also ensures the functionality of the myoelectric prosthesis, since the sensors are pressed against the assigned muscles. It is also possible to prevent slipping by compression in advance.

• 1 eine erfindungsgemäße Armprothese in perspektivischer Darstellung;
• 2 den Schaft der Armprothese gemäß 1 in weiteren Einzelheiten.

Further refinements and details of the prosthetic arm according to the invention are explained in more detail below with reference to the drawing illustrating an exemplary embodiment. Show it:

• 1 an arm prosthesis according to the invention in a perspective view;
• 2nd the stem of the prosthetic arm 1 in more detail.

From the 1 is a prosthetic arm 1 evident that over a shaft 1 with a proximal end 10th and distal end 11 and one to the distal end 11 attached art hand 2nd disposes.

The shaft 1 is made in an additive process from a suitable plastic, for example PA 12, whereby its design was carried out exactly in accordance with a previously created 3-dimensional scan of the arm stump on which the shaft is placed 1 is raised.

Starting from the proximal end 10th and are also open to this in the longitudinal direction to the distal end 11 slits running towards it 12th provided, in diametrically opposite areas, as shown in the detailed illustration 2nd evident. However, the slots end at approximately 4/5 of the total length of the shaft 1 before the distal end 11 .

Through the slots 12th becomes the shaft 1 in two in the area of the distal end 11 interconnected half-shells divided and can thus be easily widened when tightening on the arm stump, not shown. The half-shells are then held in a suitable position on the shaft by a clamping device 1 arranged ratchet 13 fixed on the ends of a tension rope 14 adjustable and reversibly releasably wound. After putting on the shaft, it is possible to operate the ratchet 13 and shortening the circumferential tension rope 14 to exert a radially inward clamping force, which is the temporary expansion of the shaft 1 picks it up and fixes it on the arm stump with the desired tension. This tensioning force can easily be readjusted by the user in the course of the wearing period. For removing the shaft 1 becomes the ratchet 13 loosened, so that a renewed expansion of the shaft 1 is possible.

As in more detail from the 2nd can be seen, the chip ropes or that with its two ends to the ratchet 13 guided single tension rope 14 in guide channels 17th performed as a result of the additive manufacturing of the shaft 1 are integrally incorporated on or in the surface of the shaft and already during the construction of the shaft 1 be determined and taken into account.

Similarly, the shaft is preferably produced in an additive process 1 also cavities for receiving electrodes 15 , a battery compartment 16 incorporated to hold rechargeable batteries or batteries as well as conductor tracks (not shown), so that the prosthetic arm can be myoelectrically designed and thus the artificial hand 2nd according to the on the sensors 15 current pulses tapped from the skin surface can be moved. Associated drive motors can also be provided in corresponding cavities. Finally, when using electrically conductive materials for the additive manufacturing process, it is also possible to add integrally integrally conductor tracks, sensors and the like directly during the manufacture of the shaft. The material is given locally conductive properties during the manufacturing process. In the same way, other properties, for example mechanical, thermally conductive / insulating, hydrophobic / hydrophilic, can be influenced locally or globally via the chemical composition. A method according to, for example, is suitable as an additive manufacturing method WO 2018/022034 A1 and WO 2018/017096 A1 .

The above-described arm prosthesis is thus maximally individualized in a simple manner and thus manufactured with the greatest fit and can be easily put on and taken off using the slits provided in the shaft, even with difficult geometry of the arm stump, and can easily be applied to the arm stump when it is in place due to the tension force exerted to be adapted to individual feelings and changed circumstances.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016201002 A1 [0002]
• DE 202017106997 U1 [0023]
• WO 2018/022034 A1 [0034]
• WO 2018/017096 A1 [0034]

Claims (12)

Arm prosthesis, comprising a shaft (1) with a proximal end (10) and a distal end (11) and an artificial hand (2) attached to the distal end (11), characterized in that the shaft (1) is made of at least one additive method is made of a plastic material and a clamping device is provided, by means of which a radially inward adjustable clamping force can be generated on the shaft (1) in order to radially compress the shaft (1) reversibly. Prosthetic arm after Claim 1 , characterized in that, starting from the proximal end (11), the shaft (1) has at least one slot (12) running in the longitudinal direction towards the distal end (11), which is open towards the proximal end (10) and in front of the distal end (11) ends and by means of the clamping device the clamping force can be exerted on the areas separated from one another by the at least one slot (12). Prosthetic arm after Claim 1 , characterized in that the shaft (1) is formed from a plurality of interwoven ring elements made of the plastic material. Arm prosthesis according to one of the Claims 1 to 3rd , characterized in that the shaft is shaped according to a three-dimensional model. Arm prosthesis according to one of the Claims 1 to 4th , characterized in that the shaft (1) is formed in several layers from the same or different plastic materials or from a gradient material with areas of different hardness and / or elasticity. Arm prosthesis according to one of the Claims 1 to 5 , characterized in that the tensioning device is formed by a tensioning ratchet (13) fastened on the outside of the shaft (1) and a tensioning rope (14) running around the shaft (1), the end of which can be wound up adjustably on the tensioning ratchet (14). Prosthetic arm after Claim 6 , characterized in that guide channels (17) for the tensioning cable (14) are integrally formed at least in regions on and / or in the surface of the shaft (1). Arm prosthesis according to one of the Claims 1 to 7 , characterized in that hollow chambers for receiving electrodes (15), batteries, conductor tracks and / or actuators are integrally introduced into the shaft (1). Arm prosthesis according to one of the Claims 1 to 8th , characterized in that electrically conductive structures for forming electrodes and / or conductor tracks are additively integrated in the shaft (1). Arm prosthesis according to one of the Claims 1 to 9 , characterized in that the shaft (1) is designed as an inner shaft and an outer shaft is provided which can be positioned as an outer shell over the inner shaft. Method for producing an arm prosthesis according to one of the preceding claims, comprising creating a digital three-dimensional model of a patient's arm stump to be supplied and determining the edge profile of the shaft (1) as well as the position of the clamping device and construction of a three-dimensional model in a CAD system and subsequent production the prosthetic arm according to the three-dimensional model in an additive process made of a plastic material. Procedure according to Claim 11 , characterized in that before or during the construction of the three-dimensional model, positions of electrodes, batteries, conductor tracks, actuators and / or slots (12) are also determined and stored in the three-dimensional model.

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