PROSTHETIC STEM

Description

[0001] The invention relates to a prosthetic shaft having an open proximal end, a distal end with a distal contact surface and a lateral surface extending between the proximal end and the distal end, wherein the effective length of the prosthetic shaft extends from the distal contact surface of the distal end to the proximal end, wherein an effective circumference of the prosthetic shaft runs along the inner surface of the lateral surface.

[0002] Such a prosthetic socket is known, for example, from DE 10 2010 019 843 A1. The prosthetic socket, which is used as part of a prosthesis, has an open proximal end into which an amputation stump is inserted when the prosthesis, of which the prosthesis socket is a part, is to be worn by the wearer of the prosthesis. A prosthetic device, such as a knee joint, a lower leg tube, a prosthetic foot, or another type of prosthesis, is arranged at the closed distal end of the prosthetic socket. Prosthetic sockets are used for both lower extremity and upper extremity prostheses. To ensure particularly good adhesion of the prosthetic socket to the amputation stump and, if necessary, provide padding, the amputation stump is usually encased in a liner made of an elastic material, such as silicone.

[0003] The amputation stump rests against the distal contact surface of the prosthetic socket, with a liner possibly located between the amputation stump and the distal contact surface. The distal contact surface is formed by a separate element or component. The distal end is preferably closed. In this case, the distal contact surface is arranged as a kind of double bottom parallel to the distal end of the socket. The distal end of the prosthetic socket can also be open.

[0004] Particularly in the case of lower extremity prostheses, such as transfemoral or transtibial prostheses, the prosthesis bears the wearer's total weight with every step the wearer takes and is therefore exposed to high mechanical stress. The same applies to the amputation stump located in the prosthetic socket. It is therefore very important that the prosthetic socket is particularly well adapted to the geometric shape of the amputation stump in order to avoid pressure points and thus wounds and pain. The problem is that the shape of the amputation stump is subject to change, particularly in the initial period after the amputation. This is because the muscles located in the amputation stump in particular atrophy due to inactivation, and scars and tissue hardening develop. Over the course of a day, the stump volume also changes due to fluid redistribution in the tissue.

[0005] To accommodate these changes in the volume and shape of the amputation stump, it is known from the prior art to design both the effective circumference of the prosthetic socket and the effective length of the prosthetic socket so that they can be adjusted. DE 10 2010 019 843 A1 features a tensioning device for this purpose, which, for example, has a pull rope or a wire, which can be used to exert tension on the various elements of the prosthetic socket. This also allows the user of the prosthetic socket to adjust the effective circumference of the prosthetic socket themselves. In addition, the socket described therein features an adjustment device with which the effective length of the prosthetic socket, which is also referred to as a sleeve in the prior art, can be adjusted.

[0006] The disadvantage is that, despite the adjustability of the effective length and circumference, the fit of the prosthetic socket can still be adjusted suboptimally by the wearer of the respective prosthesis, causing pain and problems. It is therefore often not possible, or at least not easy, for the user and wearer of a prosthesis to determine whether a decrease in the volume of the amputation stump should be accommodated by reducing the effective circumference, reducing the effective length, or both. The same applies to an increase in the volume of the amputation stump, as occurs over the course of a day. If the wearer of the prosthesis increases the effective circumference of the prosthetic socket, this can counteract the high pressure on the amputation stump caused by the increase in volume and thus provide relief.At the same time, however, this can result in the weight and force distribution within the prosthetic socket being suboptimal, which can lead to pressure sores and pain. Conversely, excessively increasing the effective length of the prosthetic socket can cause the distal end of the amputation stump to lose contact with the inner surface of the distal end of the prosthetic socket. This can also alter the force distribution within the system consisting of the prosthetic socket and amputation stump, leading to pressure sores and pain. There is a particular risk of edema formation at the distal end of the amputation stump.

[0007] US 2019 / 183 663 A1 discloses a prosthetic socket with an actuator, via which the inner circumference of the prosthetic socket can be changed, and a sensor coupled to a control device connected to the actuator, which activates or deactivates it depending on the received sensor signals. US 2019 / 183 663 A1 shows the features of the preamble of claim 1.

[0008] The invention is therefore based on the object of eliminating or at least alleviating the disadvantages of the prior art.

[0009] The invention solves the stated problem by a prosthetic socket according to the preamble of claim 1, which is characterized in that the prosthetic socket has an electrical control and an adjustment device for the effective length and the effective circumference and has at least one first sensor for detecting a force acting distally on the amputation stump and at least one second sensor for detecting forces acting radially on the amputation stump, the measured values ​​of which are transmitted to the electrical control, wherein the electrical control is set up to control the adjustment device depending on the measured values ​​of both sensors.

[0010] The prosthetic socket according to the invention has an adjustment device with which the effective length and effective circumference of the prosthetic socket can be adjusted and changed. The adjustment device is controlled via the electrical control of the prosthetic socket, which can be, for example, an electronic data processing device. Thus, the effective circumference and effective length can preferably be adjusted to the individual needs of the prosthetic wearer and the current situation of the amputation stump.

[0011] The prosthetic socket has a first sensor for detecting a force acting distally on the amputation stump and at least one second sensor for detecting forces acting radially on the amputation stump. Preferably, the first sensor and / or the second sensor comprise a pressure sensor, a force sensor, a torque sensor and / or a deformation sensor. For the purposes of the present application, a pressure sensor can detect a pressure if conclusions about the prevailing pressure can be drawn from the measured values ​​of the pressure sensor. It is not necessary for the pressure sensor to measure the pressure directly. Accordingly, a force sensor is understood to be any sensor from whose measured data conclusions about a force can be drawn.In the context of the present invention, a moment sensor is any sensor whose measured values ​​allow conclusions to be drawn about a moment, and a deformation sensor is any sensor from whose measured values ​​statements can be made about a deformation of the amputation stump.

[0012] Hydraulic or pneumatic systems, for example, can be used as the first sensor and / or second sensor. In a hydraulic or pneumatic system, for example, the pressure of the hydraulic fluid or gas contained in the hydraulic or pneumatic system is measured. It is a measure of the pressure applied to the system from the outside, for example, by the amputation stump and / or the prosthetic socket. The working medium of a pneumatic system is preferably a compressible gas; the working medium of a hydraulic system is preferably an incompressible fluid, for example, a liquid, preferably hydraulic oil.

[0013] For example, an optical sensor can be used as the first and / or second sensor, which measures the applied pressure using optical measurement. This can be achieved by using a pressure-sensitive element, such as a spring element, which is expanded or compressed to a greater or lesser extent by the amputation stump, or is deformed or deflected in some other way. This expansion, compression, deformation, or deflection can then be detected by the optical sensor.

[0014] A deformation sensor can, for example, be a capacitive and / or resistive sensor. In a capacitive sensor, the outer surface of the amputation stump or a liner placed over it, on the one hand, and the inner surface of the prosthetic socket, on the other, form the two plates of an electrical capacitor. The distance between the two plates thus formed determines the capacitance of the capacitor, which is measured. A change in distance and thus a deformation of the amputation stump changes the capacitance of the capacitor. Thus, the distance can be determined indirectly via the capacitance of the capacitor.

[0015] With a resistive sensor, a deformation of the amputation stump changes the electrical resistance, which is measured. A change in the resistance therefore contains information about a deformation of the amputation stump.

[0016] Alternatively or additionally, a strain gauge or a Hall probe can be used as the first sensor and / or as the second sensor to detect deformation of the amputation stump.

[0017] Alternatively or additionally, a strain gauge can be used as the first sensor and / or the second sensor to detect the deformation of a part of the prosthetic socket's adjustment mechanism. Furthermore, a strain gauge can be used in combination with a load cell to detect the force exerted on the residual limb.

[0018] Regardless of the choice of sensors, it is important that a first sensor and a second sensor are used, the measured values ​​of which are used to control the adjustment device.

[0019] The first sensor and the second sensor send their measured values ​​in the form of measurement signals to the electrical control unit. The electrical control unit is configured to determine, based on these measured values, whether and, if so, how the effective length and circumference of the prosthetic socket need to be adjusted. Furthermore, the electrical control unit is configured to generate control signals and transmit them to the adjustment device. The adjustment device is controlled by the control signals in such a way that the effective length and circumference are adjusted accordingly.

[0020] With a prosthetic socket according to the invention, it is not necessarily necessary for the effective length and the effective circumference to always be changed at the same time. It is entirely possible that in certain situations the electrical control unit detects from the measured values ​​transmitted to it that only one of the two, for example the effective circumference or the effective length, needs to be changed. Regardless of whether the effective length or the effective circumference or both variables need to be changed, the detected distal pressure and the detected radial pressure are input variables on the basis of which the electrical control unit carries out its algorithms and methods and generates the control signals. With a prosthetic socket according to the invention, it is not possible for the electrical control unit to control the adjustment device without both the distal pressure and the radial pressure being detected and transmitted to the electrical control unit.

[0021] Preferably, the adjustment device has a movable end element by which the effective length of the prosthetic shaft can be varied, and / or at least one movable circumferential element by which the effective circumference can be varied. The movable end element then preferably forms the distal contact surface.

[0022] InIn a preferred embodiment, changing the effective length and the effective circumference results in a change in the distal pressure and the radial pressure, which leads to a change in the measured values ​​of the two sensors. In this way, a control loop can be created. The electrical control unit preferably accesses an electronic data memory in which target values ​​for the measured values ​​of the two sensors, preferably for the distal pressure and the radial pressure, are stored. The electrical control unit is configured to process this stored target value, for example a stored distal pressure and radial pressure, and the measured values ​​of the sensors in such a way that they are comparable with one another, so that the electrical control unit determines from this comparison whether and in which direction the effective circumference and the effective length need to be changed.

[0023] Preferably, the movable end element forms the distal contact surface of the distal end of the prosthetic stem. To change the effective length of the prosthetic stem, the movable end element is moved toward or away from the open proximal end of the prosthetic stem. To reduce the effective length of the prosthetic stem, the movable end element is moved toward the proximal end of the prosthetic stem. A movement in the opposite direction, i.e., away from the proximal end of the prosthetic stem, leads to an increase in the effective length of the prosthetic stem.

[0024] Preferably, the at least one movable circumferential element is arranged such that it forms at least part of the inner surface of the lateral surface of the prosthetic shaft. Particularly preferably, the at least one movable circumferential element is arranged in a recess in the base body of the prosthetic shaft. InIn this case, the effective circumference of the prosthetic shaft can be reduced particularly easily by moving the at least one movable circumferential element in the recess of the base body of the prosthetic shaft radially inward, i.e., in the direction of the longitudinal axis of the prosthetic shaft, along which the effective length of the prosthetic shaft also extends. To increase the effective circumference of the prosthetic shaft, the at least one movable circumferential element in this embodiment is moved in the opposite direction, i.e., radially outward relative to the longitudinal axis of the prosthetic shaft.

[0025] Alternatively or additionally, the prosthetic socket has several circumferential elements arranged in an overlapping manner, which together form at least part of the effective circumference, but preferably the entire effective circumference of the prosthetic socket. This design is often referred to as a "tulip." In this case, the prosthetic socket preferably has a tensioning device, for example in the form of a tensionable wire or cable, by which the degree of overlap of the various circumferential elements can be adjusted and changed. If the effective circumference of the prosthetic socket is to be reduced in this embodiment, the tension on the wire or cable is increased, and the circumferential elements, which are designed to be movable, are moved so that they overlap one another to a greater extent. This reduces the effective circumference of the prosthetic socket.Conversely, by reducing the tension on the wire under the cable pull, the movable circumferential elements can be moved in such a way that they overlap each other to a lesser extent, thereby increasing the effective circumference of the prosthetic socket. Of course, a combination of the different designs is also possible, for example, several overlapping circumferential elements and at least one circumferential element positioned in a recess of the base body.

[0026] The prosthetic shaft preferably has at least one drive that moves the movable end element. The prosthetic shaft has at least one drive that moves the at least one movable peripheral element. InIn one possible embodiment, the movements are performed by the same drive, so that the prosthetic socket has only a single drive. The drive(s) are part of the adjustment device.

[0027] InIn a preferred embodiment of the prosthetic socket, the first sensor detects a force exerted on the movable end element by an amputation stump inserted into the prosthetic socket. The second sensor detects a force exerted on the movable peripheral element by an amputation stump inserted into the prosthetic socket. The electrical control, preferably an electronic data processing device, is configured to move the adjustment device, for example, the movable end element and / or the at least one movable peripheral element, depending on the measured values ​​of the sensors. Particularly preferably, the values ​​detected by the sensors are compared in the electrical control with a respective target value or a target value range.

[0028] The target values ​​stored in the electrical control system can include both absolute values ​​and desired ratios of the detected forces acting on the amputation stump. The goal is generally to achieve the most even pressure distribution possible from the prosthetic socket to the amputation stump. However, this is subject to user-specific individual fluctuations and is preferably determined and tested for each patient.

[0029] If a detected force on one of the movable elements is, for example, greater than a predetermined target value, the electrical control moves the movable element away from the amputation stump in order to reduce the pressure load. If a detected force on one of the movable elements is, for example, less than a predetermined target value, the electrical control moves the movable element in such a way that the pressure is increased. To do this, the respective movable element is moved, for example, towards the amputation stump. Particularly preferably, both the movable end element and the at least one movable peripheral element are moved accordingly simultaneously. If necessary, however, it is sufficient to move only the end element or only the peripheral element in order to achieve the desired pressure distribution.For this purpose, the electrical control sends control signals to the drive, for example an electric motor, by which the respective element, i.e. the end element and / or the peripheral element, is moved.

[0030] If, for example, the pressure detected at both pressure sensors is lower than the predetermined setpoint for the respective sensor, the electrical control moves the movable end element and / or the at least one movable peripheral element such that the volume within the prosthetic socket decreases. If, however, the pressure detected at both pressure sensors is higher than the predetermined setpoint for the respective sensor, the electrical control moves the movable end element and / or the at least one movable peripheral element such that the volume within the prosthetic socket increases. The range between the first setpoint and the predetermined second setpoint can be referred to and viewed as the setpoint range.

[0031] A coupling of the two movements of the movable end element and the movable peripheral element is preferably achieved by using a mechatronic control system, which includes the electrical control and the at least one drive.

[0032] Particularly preferably, the prosthetic socket has at least one additional sensor, preferably a humidity sensor, a temperature sensor and / or an oxygen saturation sensor, and the electrical control is configured to move the movable end element and / or the movable peripheral element depending on the measured values ​​of the first and second sensors and this at least one additional sensor. Preferably, the humidity sensor is arranged such that it measures the humidity between the prosthetic socket and the amputation stump, preferably between the prosthetic socket and a liner in which the amputation stump is located. If the additional sensor is a temperature sensor, it is preferably arranged such that the temperature is measured within the prosthetic socket, i.e. preferably in the space between the prosthetic socket and the amputation stump.An oxygen saturation sensor is preferably arranged so that it can determine the oxygen saturation of the blood within the amputation stump.

[0033] Preferably, the at least one additional sensor is configured to acquire sensor data from which conclusions can be drawn about the movement state of the wearer of the prosthetic socket. Particularly preferably, the at least one additional sensor comprises at least one inertial sensor, which is preferably configured to determine a spatial position, a speed, and / or an angular change of the prosthetic socket or of a component directly or indirectly connected to the prosthetic socket. For example, the electrical control system can control the adjustment device such that the effective length and / or the effective circumference of the prosthetic socket increase when the wearer of the prosthetic socket is seated. InIn this case, no, or at least no regularly recurring, movements of the prosthetic shaft are detected. The prosthetic shaft is also subjected to less stress, or even no stress at all.

[0034] An embodiment of the present invention is explained in more detail below with the aid of the accompanying figures. It shows Figure 1 - the schematic representation of different parts of a prosthetic socket and Figure 2 - a schematic flow diagram showing the operation of the electrical control system.

[0035] Figure 1shows schematically various components of a prosthetic shaft according to a first embodiment of the present invention. The prosthetic shaft has a base body 2, which has an open proximal end 4 and a distal end 6, which is closed in the embodiment shown. It also has a recess 8, in which a peripheral element 10 is arranged, which is movable relative to the base body 2. At the distal end 6 of the base body 2 there is a movable end element 12, which in Figure 1 shown next to the base body 2. The movable peripheral element 10 is movable along the radial double arrow 14, and the movable end element 12 is movable along the axial double arrow 16. The terms "axial" and "radial" refer to the longitudinal extent of the prosthetic shaft, which extends along the effective length of the prosthetic shaft from the inner surface of the distal end 6 to the proximal end 4.

[0036] In the illustrated embodiment, a distal sensor 18 is arranged at the distal end 6 of the base body 2. This sensor measures an axial pressure or an axial force. This is referred to as the distal force and is the resulting total force on a shaft adapter, which is Figure 1not shown for reasons of clarity. Additional prosthetic elements can be arranged on the socket adapter, for example a prosthetic knee joint in the embodiment shown, a transfemoral prosthesis. A first sensor 20 is positioned on the movable end element 12 and measures the pressure or a force exerted on the distal end of an amputation stump. This pressure is referred to as axial pressure. The prosthetic socket has a second sensor 22, which in the embodiment shown is arranged on the movable peripheral element and measures a radial force or a radial pressure. A ramus pressure sensor 24 measures the force of a bony attachment of the prosthetic socket and is also referred to as a ramus sensor.

[0037] Figure 2shows schematically how the individual data or measured values ​​recorded by the individual sensors can be used. The aim is to achieve the best possible selection of the effective length x axial and the effective circumference x circ , which can be changed and adjusted by moving the movable end element 12 and the movable circumferential element 10. These form the target configuration 26. For this purpose, the measured values ​​S circ of the second pressure sensor 22, S Ramus of the ramus pressure sensor 24, S dist of the distal pressure sensor 18 and S axial of the first pressure sensor 20 are fed to an electrical control 28. In the embodiment shown, additional data D ext are also input, for example from external sensors located in Figure 1 are not shown, and / or, for example, manual user specifications are taken into account and also passed on to the electrical control 28.

[0038] The electrical control unit 28 calculates values ​​for the effective circumference x circ and the effective length x axial of the prosthetic shaft from the data and measured values ​​provided to it and controls a drive for the respective adjustment device to adjust these values. As a result, the measured values ​​of the various sensors and thus the input values ​​provided to the electrical control unit 28 change until the target configuration 26, which contains, for example, target values ​​for the individual measured variables, is reached. List of reference symbols

[0039] 2Main body 4Proximal end 6Distal end 8Recess 10Circumferential element 12End element 14Radial double arrow 16Axial double arrow 18Distal sensor 20First sensor 22Second sensor 24Ramus pressure sensor 26Target configuration 28Electrical control

Claims

1. A prosthetic socket that comprises - an open proximal end (4), - a distal end (6) with a distal contact surface and - a lateral surface that extends between the proximal end (4) and the distal end (6), wherein an effective length of the prosthetic socket extends from the distal contact surface of the distal end (6) to the proximal end (4), wherein an effective circumference of the prosthetic socket extends along the inner surface of the lateral surface, characterized in that the prosthetic socket comprises an electrical control unit and an adjustment device for adjusting the effective length and the effective circumference, and at least one first sensor (20) for detecting a force acting distally on the amputation stump and at least one second sensor (22) for detecting forces acting radially on the amputation stump, the measured values of which are transmitted to the electrical control unit, the electrical control unit being configured to control the adjustment device according to the measured values of both sensors (20, 22).

2. The prosthetic socket according to claim 1, characterized in that the first sensor (20) and / or the second sensor (22) comprises a pressure sensor, a force sensor, a torque sensor and / or a deformation sensor.

3. The prosthetic socket according to claim 1 or 2, characterized in that the adjustment device comprises a moveable end element (12), by means of which the effective length can be changed, and / or at least one moveable circumferential element (10), by means of which the effective circumference can be changed.

4. The prosthetic socket according to claim 3, characterized in that the moveable end element (12) forms the distal contact surface of the distal end (6).

5. The prosthetic socket according to claim 3 or 4, characterized in that the at least one moveable circumferential element (12) forms at least part of the inner surface of the lateral surface.

6. The prosthetic socket according to one of the preceding claims, characterized in that the at least one circumferential element (10) is arranged in a recess (8) of a base body (2) of the prosthetic socket.

7. The prosthetic socket according to one of the preceding claims, characterized in that the first pressure sensor (20) is configured and arranged to measure a pressure exerted on the moveable end element (12) by an amputation stump inserted into the prosthetic socket and / or the second pressure sensor (22) is configured and arranged to measure a pressure exerted on the at least one moveable circumferential element (10) by an amputation stump inserted into the prosthetic socket.

8. The prosthetic socket according to claim 7, characterized in that the prosthetic socket has at least one additional sensor, preferably a moisture sensor, a temperature sensor and / or an oxygen saturation sensor, and the electrical control unit (28) is configured to move the moveable end element (12) and / or the at least one moveable circumferential element (10) depending on the measured values of the at least one additional sensor.

9. The prosthetic socket according to claim 8, characterized in that the at least one additional sensor is configured to detect sensor data from which conclusions can be drawn about the state of movement of the wearer of the prosthetic socket.

10. The prosthetic socket according to claim 9, characterized in that the at least one additional sensor has at least one inertial sensor that is preferably configured to determine a spatial position, a speed and / or a change in the angle of the prosthetic socket or of a component directly or indirectly connected to the prosthetic socket.