Envelope and method for capturing the contour of an amputation stump

Description

[0001] The invention relates to a method for at least partially capturing the contour of a limb, in which such a covering body is used which has a base body.

[0002] The term "enclosing body" refers in particular to prosthetic liners and bandages that, when applied as intended, at least partially, but preferably completely, enclose a limb or amputation stump. The limb can be an upper limb, i.e., an arm, or a lower limb, i.e., a leg, but also part of the wearer's torso.

[0003] A prosthesis typically has a socket into which the amputation stump is inserted. The socket is usually made of a rigid material, such as a carbon fiber composite. Particularly with leg prostheses used for walking or running, significant forces act on both the socket and the stump. To prevent painful pressure sores, it is crucial that the socket, which is usually custom-made for the user, fits the shape of the stump as precisely as possible. However, this is complicated by the fact that the stump contains both bony components that are particularly sensitive to pressure and therefore need protection, and soft tissues that deform under the stress of walking or standing.For this reason, it is useful to compress the amputation stump, i.e., to apply pressure to it, and to modify it with a suitable mold in order to at least partially capture the shape and contour of the prosthetic socket to be manufactured. This is called pre-compression.

[0004] Several methods for producing a prosthetic socket are known from the prior art. For a long time, the standard method was to take a plaster cast of the amputation stump. This has the advantage that, for example, the orthotist creating the cast can apply pressure to the stump with their hands, thus manipulating its shape to create a functional form. A positive mold of the amputation stump is then made from this negative impression, which is used to manufacture the prosthetic socket. The disadvantage is that the procedure is time-consuming and uncomfortable for the patient, as they have to wait until the plaster has hardened and the cast can be removed from the stump.

[0005] WO 2017 / 011753 A1 describes a method using different sensors. Multiple position sensors and multiple orientation sensors are positioned on the amputation stump, and their measurement data and / or position are recorded, for example, by optical sensors. This occurs sequentially and involves several evaluation steps.

[0006] To achieve uniform pre-compression of the amputation stump during the impression-taking process, various methods are known from the prior art. For example, it has been suggested that the amputation stump be inserted into a container filled with sand. In this way, the patient can apply pressure that corresponds to the pressure that will later occur when standing. This creates a negative impression of the amputation stump in the sand, which can then be used, for example, as a casting material. Alternatively, it has been suggested that the amputation stump be inserted into a flexible membrane inside a water tank, and the water pressure used for pre-compression. Within the water tank, the prepared amputation stump can then be scanned, for example, using an optical scanning method, without contact, and its contour can be captured in this way.

[0007] However, DE 20 2016 001 130 U1 discloses a device that has a retaining ring with a liner attached to it, into which the amputation stump is inserted. The advantage of this device is that the liner, into which the amputation stump is inserted, exerts a pressure distribution on the stump that largely corresponds to that of the actual liner worn inside the prosthetic socket. The amputation stump can then also be scanned using non-contact scanning methods within this liner, which is held by the retaining ring or fastening ring.

[0008] A 2015 press release from the Fraunhofer Institute for Silicate Research ISC states that it is generally possible to integrate strain or pressure sensors made of silicone elastomers into textiles. The statement can be found at https: / / www.isc.fraunhofer.de / de / presse-und-medien / pressearchiv / pressearchiv-2015 / textilintegrierte-drucksensoren.html.

[0009] However, a disadvantage is that the pressure distribution cannot be manually adjusted, as an orthotist would do, for example, with the plaster cast method. Furthermore, scanning the amputation stump, for instance in a water tank, involves considerable equipment-related effort. The invention therefore aims to further develop a liner in such a way that the disadvantages of the prior art are eliminated or at least mitigated.

[0010] The invention solves the stated problem by a method comprising the following steps: Applying a covering body to the limb, wherein the covering body has a base body and at least one sensor which is configured to acquire measurement data from which a distance and / or a relative position between two points in or on the base body can be determined, acquiring measurement data by means of the at least one sensor, determining distances and / or relative positions between two points in or on the base body in an electronic data processing device, wherein a manipulation of a shape of the limb takes place during at least one sub-process of acquiring the measurement data.

[0011] The idea according to the invention therefore consists in equipping the sensor in such a way that at least part of the contour of the enclosing body can be determined by elements arranged in the enclosing body, in this case the at least one sensor, or at least corresponding measurement data can be acquired with which this is possible. This significantly reduces the equipment required to detect the contour and also speeds up the process, which is particularly advantageous for the patient.

[0012] Preferably, the sensor has at least one transmitter for a measuring radiation and one receiver for the measuring radiation, arranged such that the measuring radiation emitted by the transmitter is at least partially received by the receiver. In this way, for example, the distance between the transmitter and the receiver can be determined by measuring the time of flight.

[0013] Preferably, a transmitter and a receiver are located at the first point, while a reflector for the measurement radiation is preferably located at the second point. The reflector need not be a separate component, such as a mirror, but can also be an interface between two different materials. This is advantageous, for example, when using ultrasound as the measurement radiation, which is reflected at interfaces. Such an interface exists, for instance, where the material of the base body meets the limb of the wearer or patient. Depending on the measurement radiation used, an interface is characterized by a sufficiently large density difference between the two adjacent materials, a sufficiently large difference in the optical refractive indices of the adjacent materials, or a change in another physical or chemical property at the interface.

[0014] Alternatively, the sensor's transmitter is preferably located at the first point and the receiver at the second point. Measurement radiation emitted by the transmitter reaches the respective receiver at least partially. For example, if the intensity of the received measurement radiation at the receiver is known when the sensor body is in a relaxed state, without being pulled over a limb, such as an amputation stump, the extent to which the material of the base body, in which the measurement radiation travels, has been stretched can be determined from the intensity received in the applied state. The longer the path between the transmitter of the measurement radiation and the receiver, the lower the intensity of the measurement radiation received at the receiver.

[0015] Alternatively or additionally, the travel time of the measurement radiation from the transmitter to the receiver can be determined. The distance between the transmitter and receiver can then be determined, provided the speed at which the measurement radiation propagates is known.

[0016] Alternatively or additionally, the transmitter and receiver are located at the first point, and a reflector for the respective measurement radiation is located at the second point. The operating principles of the measurement are identical; however, twice the path distance is measured, which improves the signal-to-noise ratio.

[0017] Preferably, the measuring radiation is electromagnetic radiation, in particular visible light, radar radiation, and / or X-rays. Especially with X-rays, it is possible to transmit the measuring radiation even through the limb located within the casing, although this may have adverse health effects on the patient. Alternatively or additionally, the measuring radiation can also be magnetic radiation, particularly in the form of an alternating magnetic field. In this case, the transmitter is an electromagnetic coil, i.e., an electrical conductor wound into a coil and subjected to an alternating electric current. This causes the coil acting as the transmitter, also referred to as the transmitting coil, to generate an alternating magnetic field. The receiver preferably comprises at least one receiver coil located within this alternating magnetic field.This results in the induction of an electric current and / or voltage in the receiver coil, which can be measured and depends on the distance between the transmitting coil and the receiver coil. Furthermore, the magnitude and phase of the induced electrical quantity in the receiver coil depend on the orientation of the transmitting coil relative to the receiver coil.

[0018] Therefore, it is advantageous to use several coils, preferably arranged perpendicular to one another, particularly as transmitters. These can be operated simultaneously with alternating current. Depending on the phase relationship between the alternating current of the individual coils, the direction of radiation in which the alternating magnetic field is predominantly emitted can be influenced. It has proven advantageous to generate an alternating magnetic field whose predominant direction varies, preferably cyclically. This results in the magnetic field induced in the receiver coil being minimal whenever the preferred or main transmission direction, in which the magnetic field is emitted with maximum intensity, does not point towards the respective receiver coil of the receiver.

[0019] In this configuration, it is therefore possible to determine the orientation of the receiver coil relative to the transmitter. For this purpose, it is advantageous if the initial orientation, i.e., the orientation of the transmitter relative to the receiver in the unloaded state of the enclosure (i.e., without the limb attached), is known.

[0020] Alternatively or additionally, the measurement radiation can also include sound waves. Ultrasound waves are particularly suitable for this purpose. In this case, too, the transmitter and receiver can be located at two different points, allowing, for example, the one-way distance—that is, the distance between the two points—to be measured using time-of-flight measurements. If the transmitter and receiver of the measurement radiation are located at the same point, a reflector element is preferably positioned at the second point to reflect the measurement radiation. As already mentioned, the reflector element does not need to be a separate component. Even when using sound waves as the measurement radiation, twice the distance can be measured in this way, thus improving the signal-to-noise ratio.

[0021] Advantageously, the enclosure has multiple receivers and / or multiple reflectors. In a preferred embodiment, the enclosure has, for example, only one transmitter for the respective measurement radiation. In this case, however, the enclosure has a plurality, preferably at least 10, more preferably at least 20, and particularly preferably at least 50 or even at least 100 receivers and / or reflectors for the measurement radiation. In this way, the distances of many points, namely the locations of the receivers or reflectors, to the transmitter can be determined. Since the arrangement of the individual receivers or reflectors relative to each other, and in particular the proximity relationships between the components, cannot change without destroying the enclosure, the contour of the enclosure can be determined from the distances to the different points.Alternatively or additionally, the sensor is configured to determine the direction in which the respective receiver and / or reflector are located. This makes it even easier to determine the contour of the prosthetic liner, and thus the contour of the limb under the pressure of the liner, from the measurement data.

[0022] Advantageously, the transmitter is located in the distal area of ​​the liner body, i.e., the closed lower end of a prosthetic liner.

[0023] Preferably, the at least one sensor has a strain gauge with which a distance between two points between which the sensor is located can be determined. The strain gauge is advantageously at least one strain gauge, an electroactive polymer, and / or a fiber Bragg element.

[0024] A strain gauge is a sensor in which the electrical resistance, for example within a metallic conductor, changes when the strain gauge is subjected to strain. From the change in electrical resistance, conclusions can be drawn about the change in strain and thus the distance between the two points at the ends of the strain gauge. An electroactive polymer, often referred to as an artificial muscle, changes its shape and, in particular, its length when an electrical voltage is applied. Conversely, such an electroactive polymer can also be used as a sensor for a change in length, since the change in length of the electroactive polymer generates an electrical voltage.Since the relationship is also known here, the change in the length of the polymer and thus the change in the distance between its two ends can be deduced from the detectable electrical voltage.

[0025] A fiber Bragg element, on the other hand, is an optical component that uses an optical fiber with a core containing a material exhibiting varying refractive indices. These are so-called optical inscribed interference filters. These elements are also strain-sensitive, as the Bragg wavelength, which corresponds to the center wavelength of the filter bandwidth, depends on mechanical strain or stress. Here, too, the known relationship can be used to deduce a change in strain and thus a change in distance.

[0026] InIn a preferred embodiment, the cladding body has a plurality, preferably at least 10, more preferably at least 20, particularly preferably at least 50 or 100 strain sensors, which are arranged in the material of the base body of the cladding body such that they are preferably equidistantly distributed over the limb as soon as the cladding body has been pulled over the limb.

[0027] In this way, too, based on the known proximity relationships between different endpoints of the respective strain sensors, conclusions can be drawn about the contour of the enveloping body from the changed lengths of the strain sensors as soon as the enveloping body has been pulled over the limb.

[0028] Advantageously, at least one of the sensors is a shape sensor. Within the scope of the present invention, a shape sensor is understood to be a sensor that exhibits linear expansion and is capable of providing information not only about its length but also about its geometric shape based on corresponding measurement data. Particularly preferred examples are sensors that, for instance, have several layers of plastics arranged in a sandwich structure. If the contour of such a contour sensor changes, for example, by bending, the individual layers are stretched or compressed to varying degrees, which, for example, leads to a change in the thickness of the sensor's layer stack. This thickness is measured at various points, allowing different bends to be determined.Alternatively or additionally, so-called cable-like shape sensors, such as those offered by TST-inno, can be used. Alternatively or additionally, fiber optic cables designed according to the fiber Bragg principle with a sufficient number of support points can also be used as shape sensors. At least three support points are sufficient, but more are advantageous. The more support points there are and the closer they are arranged, the more accurate the shape detection of the shape sensor designed in this way.

[0029] Preferably, the enclosing body has a communication interface through which the measurement data acquired by the at least one sensor can be transmitted to an electronic data processing device, in particular a microprocessor. There, the desired information about the contour of the enclosing body can then be extracted from the measurement data.

[0030] In a preferred embodiment, a corresponding electronic data processing device is already located in or on the base body of the encasing, particularly at its distal end. In this way, only the encasing itself is required to capture the contour of the encasing and thus the contour of the limbs, without the need for additional components and / or other devices. This further reduces the equipment required to determine the contour.

[0031] Preferably, the base body is made of an elastic material. Preferably, the outer body is a prosthetic liner, preferably for a leg prosthesis, lower leg prosthesis, or upper leg prosthesis, wherein the base body is preferably made of a liner material. Liner materials are, in particular, silicone, polyurethane, or TPE, wherein these materials can form the liner material individually or in combination with each other and / or in combination with a textile and / or a surface coating.

[0032] As an alternative to the prosthetic liner, the outer shell can also be a bandage. Using such a bandage, 3D models and 3D patterns for subsequent manufacturing processes, such as CAM (Computer-Aided Manufacturing), can be created using any method that currently employs optical scanners. This includes milling processes as well as additive manufacturing processes, such as 3D printing. Contours and shapes captured by the bandage can also be used for diagnostic purposes, such as comparing two different conditions.

[0033] According to the invention, the shape of the limb is manipulated during at least one sub-process of acquiring the measurement data. This can be done manually or by means of a device.

[0034] Particularly preferably, distances and / or relative positions between at least 10 points, preferably at least 20 points, more preferably at least 50 points, and particularly preferably at least 100 points are determined. The more distances and / or relative positions that can be determined, the more accurate the resulting image of the limb's contour. The individual sensors can be connected in series, in a bus system, or in some other way. Depending on the sensors, they can be controlled simultaneously, sequentially in a specific order, cyclically, or in some other way.

[0035] Preferably, continuous measurement data is acquired. Alternatively, the acquisition of measurement data can be triggered when the casing is deformed from the outside, i.e., in particular when external pressure acts on at least part of the casing.

[0036] With the aid of the accompanying drawings, some exemplary embodiments of the present invention are explained in more detail below. They show: Figures 1 to 4 - different embodiments of a covering body according to an embodiment of the invention as a prosthetic liner and Figures 5 to 8 - different embodiments of a covering body according to an embodiment of the invention as a bandage.

[0037] Figure 1Figure 1 shows a liner body 1 according to a first embodiment of the present invention in the form of a prosthetic liner. It has a base body 2 made of a liner material. Several optical fibers 4 are embedded in the liner material, into which fiber Bragg sensors 6 are incorporated. The optical fibers 4 converge at a distal end 8 of the liner and can be illuminated by an interrogator 10. This preferably occurs sequentially. The individual fiber Bragg sensors 6 exhibit characteristic behavior as optical interference filters. They absorb light of a specific wavelength, this wavelength depending, as already explained, on the strain or mechanical stress of the fiber Bragg sensor 6.In particular, if the individual fiber Bragg sensors 6, which are connected to each other by a single optical fiber 4, are configured differently and exhibit different absorption spectra, they can be interrogated sequentially or even simultaneously. For example, it is advantageous if the fiber Bragg sensors 6 that are closer to the interrogator 10 do not absorb electromagnetic radiation that is absorbed by fiber Bragg sensors 6 that are connected by the same optical fiber 4 but are further away from the interrogator 10. If the fiber Bragg sensors are subjected to mechanical stress or strain, the center frequency, also known as the Bragg frequency, shifts in a known manner, allowing conclusions to be drawn about the strain.Since the order of the individual fiber Bragg sensors 6 along the optical fibers 4 cannot change, the contour of an amputation stump located within the prosthetic liner can also be deduced from the different strains. Figure 1 however, it is not shown.

[0038] The interrogator 10 queries the individual fiber Bragg sensors 6 and transmits the measurement data to an electronic data processing unit 12, where the actual evaluation takes place.

[0039] Figure 2Figure 1 shows another embodiment of the prosthetic liner 1. A transmitter 14, which emits a measuring radiation, is located in the region of the distal end 8. In the illustrated embodiment, this radiation consists of ultrasound waves. These are reflected by reflectors 16 and travel along the arrows 18 back to the sensor, which also includes a receiver. The measurement data are then transferred to the electronic data processing unit 12 and evaluated.

[0040] The advantage of ultrasound waves lies particularly in the fact that they are coupled into the soft tissue of the amputation stump by the transmitter 14 and propagate within it. It is not necessary to ensure that the ultrasound waves propagate through the liner material, which can be, for example, an elastic silicone material. The transmitter 14 can, for example, transmit continuously or emit its measurement radiation in the form of pulses. A rotating transmitter 14 can also be used, whereby the transmitter 14 itself does not necessarily have to rotate, but rather the emitted measurement radiation is simply directed into different angular ranges, which preferably rotate. The measurement radiation, in this exemplary embodiment the ultrasound radiation, strikes the reflectors 16 and is reflected back by them, reaching the receiver, which is located in Figure 2not shown separately. The distances of the individual reflectors 16 from the transmitter 14 can be determined in this way via time-of-flight measurements. However, a disadvantage is that ultrasound signals in particular can be reflected at interfaces, and bony components of an amputation stump can also generate a signal.

[0041] Figure 3Figure 1 shows another embodiment of the prosthetic liner 1. A transmitting coil is located in the region of the distal end 8. This coil is energized with alternating current and emits an alternating magnetic field 20. This field is also preferably designed to rotate, so that the main transmission direction of the transmitter 14 also changes. Receivers 22, in the form of receiving coils, are located inside the liner material of the base body 2 of the prosthetic liner. These receivers are connected to the distal end 8 via electrical conductors 24. The alternating magnetic field 20 induces an electric current and an electric voltage in the receivers 22, which can be tapped and measured via the electrical conductor 24. The magnitude and phase of the electric current and / or the electric voltage induced in the receivers 22 depend both on the distance of the receivers 22 from the transmitter 14 and on the orientation and direction of the receivers 22 relative to the transmitter 14.This measurement data is transferred to the electronic data processing unit 12 and evaluated there.

[0042] Figure 4 Figure 1 shows another embodiment of the prosthetic liner 1, in which strain sensors in the form of strain gauges 26 are arranged in a grid. In the illustrated embodiment, they form a square grid with intersection points 28, with a strain gauge 26 located between each pair of intersection points 28. This arrangement is enlarged in the right-hand section of the figure. Figure 4 As shown. When the prosthetic liner is pulled over an amputation stump, it stretches in some places more than others, conforming to the shape of the stump. Electrical conductors 24, located in the right part of the Figure 4As shown, the individual intersection points 28 can be subjected to electric current and / or voltage. An electronic data processing unit 12 controls this process. By applying an electric voltage, the strain gauge 26, which lies between the two intersection points 28, is measured, and the resulting measurement signals are evaluated by the electronic data processing unit 12. Since the proximity of the different strain gauges 26 and also the intersection point 28 are known and cannot change, a detailed image of the prosthetic liner's contour can be determined from the knowledge of the respective distances between two adjacent intersection points 28. The denser and closer the mesh, the more detailed and better the image of the contour.

[0043] The Figures 5 to 8Figures show different embodiments of the casing 1 in the form of a bandage. The bandage functions according to the following. Figure 5 the prosthetic liner according to Figure 3 In the distal region, the transmitting coil, which emits the alternating magnetic field 20, is again shown. Inside the base body 2 are receivers 22, which are connected to a distal end of the bandage via electrical leads 24. The alternating magnetic field 20 induces an electric current and an electric voltage in the receivers 22, which can be tapped and measured via the electrical lead 24.

[0044] The function of the bandage according to Figure 6 corresponds to that of the liner according to Figure 4 . The bandage according to Figure 6It has a network of strain gauges 26 arranged between intersection points 28. Electrical conductors 24, which intersect at the intersection points, allow the individual strain gauges 26 to be supplied with electric current or voltage.

[0045] The function of the bandage according to Figure 7 corresponds to the functionality of the prosthetic liner according to Figure 1 . Fiber Bragg sensors 6 are connected to each other via optical fibers 4, which are joined at a distal end 8.

[0046] The function of the bandage according to Figure 8 corresponds to that of the liner from Figure 2At the distal end 8 is the transmitter 14, which emits the measurement radiation, which in the illustrated embodiment can be, for example, ultrasound waves. These are reflected by reflectors 16, which in the illustrated embodiment represent interfaces between two different materials, along the arrows 18 and directed back to the transmitter. Since the transmitter also includes a receiver, measurement data can be evaluated and transmitted. Reference symbol list

[0047] 1 Enclosing body 2 Base body 4 Fiber optic cable 6 Fiber Bragg sensor 8 Distal end 10 Interrogator 12 Electronic data processing unit 14 Transmitter 16 Reflector 18 Arrow 20 Alternating magnetic field 22 Receiver 24 Electrical conductor 26 Strain gauge 28 Crossover point

Claims

1. A method for at least partially recording a contour of a limb, wherein the method comprises the following steps: - mounting an enveloping body (1) on the limb, o wherein the enveloping body (1) has a base body (2) and at least one sensor (6) that is configured to record measurement data which can be used to determine a distance and / or relative position between two points in or on the base body (2) - recording measurement data by means of the at least one sensor (6), - detecting distances and / or relative positions between two points in or on the base body (2) in an electronic data processing device (12) characterized in that a manipulation of a shape of the limb occurs during at least part of the process of recording the measurement data.

2. The method according to claim 1, characterized in that distances and / or relative positions between at least 10 points, preferably at least 20 points, preferably at least 50 points, especially preferably at least 100 points are detected.

3. The method according to claims 1 or 2, characterized in that the recording of the measurement data is continuous or triggered automatically when the enveloping body is deformed from the outside.

4. The method according to one of the preceding claims, characterized in that the sensor (6) has a transmitter (14) for a measuring radiation and a receiver (22) for the measuring radiation, which are arranged in such a way that measuring radiation emitted by the transmitter (14) is at least partially received by the receiver (22).

5. The method according to one of the preceding claims, characterized in that a transmitter (14) and a receiver (22) are located at the first point, wherein a reflector (16) for the measuring radiation is preferably located at the second point, or that the transmitter (14) is located at the first point and the receiver (22) at the second point.

6. The method according to claim 5, characterized in that the measuring radiation is electromagnetic radiation, in particular visible light, radar radiation and / or X-rays, magnetic radiation, for example in the form of an alternating magnetic field and / or sonic waves, in particular ultrasonic waves.

7. The method according to claims 5 or 6, characterized in that the enveloping device (1) comprises several receivers (22) and / or several reflectors (16).

8. The method according to one of the preceding claims, characterized in that, the at least one sensor (6) comprises a strain sensor, in particular a strain gauge (26), an electroactive polymer and / or a fiber Bragg element.

9. The method according to one of the preceding claims, characterized in that at least one of the sensors (6) is a shape sensor.

10. The method according to one of the preceding claims, characterized in that the enveloping body (1) features a communication interface by means of which the measurement data recorded by the at least one sensor can be transmitted to an electronic data processing device (12), in particular a microprocessor.

11. The method according to one of the preceding claims, characterized in that the base body (2) is made from an elastic material.