Method for creating a digital model

Abstract

The invention relates to a method for creating a digital model of a prosthesis shaft for a user (2), the method including the following steps: a) positioning the user (2) on a saddle (6), the saddle (6) having a shaped cushion (18) with a covering in which a plurality of objects are situated, b) applying negative pressure to or increasing negative pressure at the shaped cushion (18), c) removing the user (2) from the saddle (6) and d) scanning at least the part of the saddle that came into contact with the user (2).

Description

[0001] Procedure for creating a digital model

[0002] The invention relates to a method for creating a digital model of a prosthetic socket for a user.

[0003] A prosthetic socket is used to attach a prosthesis, for example for a lower extremity, to an amputation stump. The prosthetic socket usually has a rigid shell made from a composite material such as carbon. This material is lightweight and very robust against mechanical stress. For the user of a prosthetic socket, the best possible fit is extremely important. Prostheses are usually worn continuously for long periods of time and are also subject to considerable stress. This does not only apply to leg prostheses, for example, which are attached to a thigh amputation stump or a below-knee amputation stump. The user of the prosthesis and thus the user of the prosthetic socket is expected to walk, stand, and run on such a prosthesis, so their entire weight must be absorbed and supported by the prosthesis.

[0004] Therefore, great efforts have been made in the state of the art to design the prosthetic socket so that it is as comfortable and pain-free as possible for the user, even during prolonged use and under heavy load. This is often based on an impression, such as a plaster cast, of the amputation stump in order to optimally reproduce the individual shape and contour of the amputation stump. The amputation stump has several bones surrounded by soft tissue. The prosthetic socket's task is to absorb the volume of the stump and distribute the loads that occur when walking and standing among the remaining soft tissue and bones. In this process, the muscles, skin, and bones are compressed and deformed according to the load.In order to best prepare the shape of the prosthetic socket, an impression of an unloaded amputation stump is often not used to manufacture the prosthetic socket, but the amputation stump is deliberately exposed to a load that is as close as possible to the load during use of the prosthesis, which is to be attached to the amputation stump by the prosthetic socket, and in the best case even corresponds to it.

[0005] Various impression techniques are available for subjecting the amputation stump to stress during the impression taking process. The most common method is manual molding using plaster casts. The prosthetist uses special hand movements and targeted deformation of the amputation stump to create the shape and subsequent stress situation in the prosthetic socket. This technique requires a high degree of experience and well-developed manual skills to achieve a high-quality impression. Molding using plaster casts is very complex, as many different areas of the amputation stump are subjected to different pressures simultaneously, depending on the position of the respective area on the amputation stump and the tissue beneath the skin in that area. Furthermore, the curing process of the plaster cast requires very little time.The perineal region and the shaping of the hip bone for the socket edge are particularly problematic due to the wide variety of shapes of the ischial bones. Work descriptions often contain instructions in which individual phalanges of one of the prosthetist's hands are to be pressed against different areas of the ischium with adapted pressure. Taking an impression of the amputation stump with two prosthetists, and thus four hands, is a rarely chosen solution because it is complex. An incorrect impression of the amputation stump can lead to a multiplication of the workload and the number of prosthetic sockets to be manufactured during the subsequent prosthesis fitting process. Technical aids have been developed since the 1960s to simplify manual stump impression taking.Seat rings with functional preparation of the future prosthetic socket edge in circumference-adjusted sizes are intended to standardize the shape-finding process and shorten the learning process for inexperienced prosthetists. Ottobock also offers such a technical aid in its product portfolio with the SitCast impression device. However, all of these existing, preformed seat rings offer only limited prerequisites for the individual design of the socket edge. Because the shapes are standardized and averaged across a group of amputees, the resulting prosthetic sockets must be painstakingly adapted to the individual anatomy of the future prosthesis user. The time saved from taking an impression is thus lost in the adjustment of the prosthetic socket.Experience over the last decades has shown that the interaction of individual hip bone geometry with the necessary force transmission to the prosthetic stem in this area is an unsolved and recurring problem in prosthetic stem fitting.

[0006] In recent years, processes have been developed and introduced that allow the production of a prosthetic socket using additive manufacturing techniques, such as 3D printing. This requires the creation of a digital model of the prosthetic socket that can be used to manufacture the prosthetic socket. 3D processes are only one possible application of such a model.

[0007] Instead of a plaster cast, the state of the art proposes capturing and scanning the amputation stump, preferably in a contactless manner. Stationary or mobile scanners, so-called handheld scanners, can be used for this purpose to digitally capture the external contour and shape of the amputation stump and use this data as the basis for the digital model to be created. Scanning the amputation stump under load is problematic, as this load is applied to the amputation stump via mechanical contact, i.e., a separate object. This is also captured during scanning, but is not necessary for creating the digital model and, in the worst case, can even be disruptive. Another problem is capturing areas of the amputation stump that are inaccessible or difficult to access for a scanner.This is the case, for example, for the entry area at the proximal end of a femoral prosthesis stem.

[0008] The invention is therefore based on the object of further developing a method for creating a digital model of a prosthetic socket in such a way that the model is adapted as well as possible to the individual circumstances of the user, even in the load-bearing, proximal area of ​​the prosthetic socket.

[0009] The invention solves the stated problem by a method for creating a digital model of a prosthetic socket for a user, comprising the following steps: a. positioning the user on a saddle, wherein the saddle has a shaped cushion with a shell in which a plurality of objects are located, b. applying or increasing a negative pressure to the shaped cushion, c. removing the user from the saddle, and d. scanning at least the part of the saddle that has come into contact with the user.

[0010] When the user is positioned on the saddle, the saddle comes into contact with a part of the body that is otherwise barely visible or not visible and therefore difficult or even impossible for a scanner to access. This affects, for example, the perineum, the ischial bone, or the ramus ossis ischii, the node on which the body weight rests when sitting. The two ischial tuberosities, the lateral borders of the lower pelvic opening or pelvic outlet, aperture pelvis inferior, can also come into contact with the saddle. Such bony protrusions pose the risk of pressure sores and pain when using the prosthetic socket if the prosthetic socket is not properly fitted and adjusted. The soft tissues surrounding the bones, such as the pelvic floor and hip muscles, are also molded.In the method according to the invention, the user is positioned on the saddle such that at least part of their body weight rests on the saddle and is supported by the saddle. Preferably, the user's entire body weight is transferred to the saddle. This preferably corresponds to the load acting on the body regions that come into contact with the saddle during use of the prosthesis, to which the prosthetic socket to be manufactured belongs.

[0011] The saddle has a shaped cushion containing a plurality of objects. This plurality of objects is, for example, a granulate, preferably a free-flowing granulate. Small glass beads or coffee powder have proven particularly suitable, although in principle any granulate with a similar degree of grinding and similar flowability is suitable. If the saddle's shaped cushion is then subjected to pressure by the user positioned on it, the shaped cushion adapts to the shape of the body part that comes into contact with it. A vacuum source, such as a pump, can then be used to create a vacuum on the shaped cushion, sucking out the air contained in the shaped cushion. This solidifies the objects in the casing of the shaped cushion, making further deformation difficult or impossible.The shaped cushion, and thus also the sleeve, now exhibit an optimal shape for the user's body part that comes into contact with the sleeve. The shaped cushion is maintained in this state. For this purpose, a valve located in an exhaust line between the shaped cushion and the vacuum source can be closed, for example, to prevent air from entering the sleeve of the shaped cushion even when the vacuum source is switched off. Alternatively, the vacuum source can be left switched off, so that it continues to produce negative pressure, which is applied to the shaped cushion and thus to the sleeve.

[0012] In process step b, a negative pressure is applied to the molding cushion or increased if the molding cushion is already subjected to a negative pressure. The negative pressure is then so strong that the air contained in the molding cushion is sucked in, causing the molding cushion to lose its deformability, at least in the area subjected to the negative pressure. Increasing the negative pressure means that the negative pressure is increased, thus reducing the pressure within the molding cushion.

[0013] The user is then removed from the saddle, for example, by standing up. The cushion and thus the cushion cover are then no longer subjected to the user's body. However, since the objects inside the cover are solidified due to the prevailing negative pressure, preventing the flow of air, the cushion and its cover remain in the shape induced by the user's load. In this shape, at least the part of the saddle that came into contact with the user is scanned to ensure the best possible shape.

[0014] Preferably, landmarks are marked on the saddle before scanning. These landmarks preferably correspond to the position of impressions of anatomically prominent areas, such as bony protrusions, on the user's body. These are usually depressions caused by the protruding bony areas and can usually be attributed to at least one bone. In addition, multi-stage preparation of the various chambers of the saddle can visualize changes in the shape of muscles and tendons.

[0015] In a preferred embodiment, the entire amputation stump is scanned, with the digital model of the prosthetic socket being created at least from the scan of the amputation stump and the scan of the saddle part. Each scan contains a digital representation of the external shape and contour of the respective scanned object. Each scan can be described as a data set that encodes and describes this external shape and contour of the scanned object. In order to link both data sets, it must be known or at least determinable how the two data sets are oriented and arranged relative to one another. It is therefore advantageous if both the scan of the saddle part and the scan of the amputation stump have at least one reference point that is contained in both scans. In this way, the relative orientation and positioning of the two data sets to one another can be determined.In a preferred embodiment, the amputation stump is scanned before the user is removed from the saddle. This allows, for example, a reference point to be present on a tripod or frame where the saddle is also located. When scanning the user's amputation stump while positioned on the saddle, this reference point can be captured in the same way as when scanning the saddle part later.

[0016] The digital data of the prosthetic socket's entry area obtained with the saddle are used for the individual design of the subsequent prosthetic socket edge. Shapes, angles, and dimensions identifiable in the digital data preferably form the basis for a movement- and load-appropriate design of the prosthetic socket model. In this process, compressive, tensile, and torsional forces acting on the amputation stump when the prosthesis is worn are preferably reduced. Furthermore, the amputation stump's mobility function is preferably maintained as comprehensively as possible.

[0017] In one embodiment, digital data of a socket edge of the prosthetic socket are extracted from a database. The socket edge forms the proximal end of the prosthetic socket. The digital data of the socket edge preferably contain information about the entire course of the edge over the entire circumference. Alternatively, in some embodiments, it is sufficient if the digital data only contain information about the course of a portion of the socket edge. This is particularly advantageous if the scan of the saddle part already contains information about a portion of the socket edge. The digital model is preferably created from this socket edge data in addition to the data from the two scans.

[0018] The user should preferably stand when positioned on the saddle. If the prosthetic socket, the digital model of which is to be created, is intended to connect a prosthetic leg to an amputation stump, the user usually has a healthy leg. Depending on the individual loading situation on the user's amputation stump, it may be advantageous for the user to place part of their weight on this leg and not transfer their entire weight onto the saddle. To achieve the best possible design of the socket edge, the saddle should be able to bear as much load as possible. The saddle is preferably mounted on a frame, rack, or other support structure, with the height of the saddle being adjustable.The saddle can thus be adjusted to the exact height required, for example, to keep the user's pelvis in as horizontal a position as possible, which is also advantageous and desirable when the user of the future prosthesis, for whose prosthetic socket a digital model is to be created, is standing and walking. In a further embodiment, the saddle is arranged so that it can be tilted, for example to take into account a tilting of the user's pelvis in order to correct incorrect positions of the hip and / or back. In this way, the load on the body parts that come into contact with the saddle part also corresponds better to the load that occurs when the prosthesis is later used than when the user is sitting on the saddle. This would also be a possible embodiment of the method.

[0019] The shaped cushion preferably has a plurality of chambers which can be separately subjected to negative pressure. Method steps a. and b. are preferably repeated one after the other for different chambers of the shaped cushion. Particularly preferably, steps c. and d. are only carried out once steps a. and b. have been carried out for all chambers. In this way, the entire area of ​​the saddle part with which the user has come into contact can be scanned. Preferably, the user first shifts their weight onto a specific part of the saddle. The corresponding chamber of the shaped cushion is then stabilized by applying negative pressure. The user then assumes a different position and thus shifts their weight onto another area of ​​the shaped cushion. It is irrelevant whether this area was deformed by the previous load on the shaped cushion.It is important, however, that the chamber belonging to this additional area has not yet been subjected to such a strong negative pressure that it cannot be deformed further. This chamber is now also subjected to negative pressure. In this way, individual loading situations can be created for different areas to be molded. In addition to a pure weight shift, the tension of individual muscles or entire muscle groups can also be considered, allowing different activation states and, in particular, the influence of muscles and tendons to be modeled.

[0020] The invention also achieves the stated object by a saddle for use in a method described here, wherein the saddle has at least one shaped cushion with a cover in which a plurality of objects are located.

[0021] Preferably, the sleeve has a connection to which a vacuum source is or can be arranged, so that a vacuum can be applied to the molding cushion. Preferably, the vacuum is applied to the sleeve.

[0022] In a preferred embodiment, the molded cushion has a plurality of chambers, each of which contains a plurality of objects, and which can particularly preferably be separately subjected to a vacuum.

[0023] The shaped cushion is preferably divided into different chambers, allowing for pre-shaping of the cushion. This can be supported by stabilizing elements. This allows for the creation of shaped cushions that deviate from the classic cushion or cylinder shape and are adapted, for example, to the saddle contour or the contact surface.

[0024] The saddle is preferably arranged on a holding device. This allows the height at which the saddle is arranged to be adjusted so that the saddle can be positioned for the respective user at a height that allows the user to stand while simultaneously placing a load on the saddle in the manner described above. Particularly preferably, the saddle is adjustable, for example displaceable, in the anterior-posterior direction relative to the holding device. Alternatively or additionally, the shaped cushion is adjustable, for example displaceable, in the anterior-posterior direction relative to the rest of the saddle. Preferably, the saddle and / or the shaped cushion is tiltable about a tilt axis relative to the holding device. The tilt axis preferably runs in a medial-lateral direction. The holding device is, for example, a tripod. The adjustability makes it possible to take the impression for each patient in the optimal position.Furthermore, combined with the elasticity of the molded cushion, it also allows the use of just one or a few different sizes for different patients. This is not possible with previous aids used for molding.

[0025] Preferably, the shaped cushion has a pre-shape that corresponds to the shape of the saddle.

[0026] Preferably, the saddle and / or the shaped cushion can be pivoted relative to the holding device about at least one pivot axis and can be locked in various positions. A locking device is preferably part of the saddle, which can be brought into a released position in which pivoting of the saddle and / or the shaped cushion relative to the holding device is possible, and into a locked position in which the saddle and / or the shaped cushion cannot be pivoted relative to the holding device. Preferably, the at least one pivot axis has a medial-lateral axis and / or an anterior-posterior axis. A medial-lateral axis extends in the medial-lateral direction and an anterior-posterior axis extends in the anterior-posterior direction.

[0027] An embodiment of the present invention is described in more detail below with the aid of the accompanying drawings. They show:

[0028] Figure 1 - three schematic views of a user with and without

[0029] Device according to an embodiment of the present invention.

[0030] Figure 2 - two schematic representations of a basin of a

[0031] User on a saddle

[0032] Figure 3 schematic representations of the saddle, Figures 4a to 4c - a shaped cushion in different views,

[0033] Figures 5a to 5c - a saddle base in different views,

[0034] Figure 6 - a combination of saddle base and shaped cushion in a schematic view and

[0035] Figure 7 - the combination of Figure 6 in a sectional view.

[0036] The left-hand illustration of Figure 1 shows a user 2 who has an amputation stump 4. In the middle illustration, the user 2 is positioned on a saddle 6, which is arranged on a holding device 8, a tripod in the illustrated embodiment. It can be seen that the saddle 6 is arranged between the healthy leg 10 of the user 2 and the amputation stump 4. The saddle 6 also has a backrest 12, which in the illustrated embodiment is designed as a combined backrest for the back and arms of the user 2. This backrest 12 is not necessary for the method according to the present invention, but is advantageous in giving the user a feeling of sufficient security and stability. The right-hand illustration of Figure 1 shows a side view of the user 2. He is in the position also shown in the middle illustration of Figure 1.

[0037] In the state shown in the middle and right illustrations, the user 2 preferably loads the saddle 6 and the shaped cushion contained therein, so that it adapts to the contour of the user 2 at the points and in the areas that come into contact with the saddle 6.

[0038] Figure 2 shows this schematically. A pelvis 14 and a spine 16 are shown schematically, shown in a frontal view in the left-hand illustration of Figure 2 and a side view in the right-hand illustration of Figure 2. Only the shaped cushion 18 of the saddle 6 is shown schematically. Both views show how it adapts to the contours of the loads. After the shaped cushion has adapted to the load, a negative pressure is applied to at least some sections of the shaped cushion, ensuring that it is no longer deformable and retains its assumed shape and form.

[0039] This is shown in Figure 3. In the two left-hand views, the molded cushion 18 is shown in a frontal view corresponding to the left-hand view in Figure 2. In the two right-hand views, the molded cushion 18 is shown in a side view corresponding to the right-hand view in Figure 2.

[0040] In the upper views, the molded cushion 18 is shown in its unloaded form, shape, and contour. In the lower views, the molded cushion 18 is shown in its deformed form, shape, and contour, adapted to the anatomical characteristics of the user 2. In this state, the molded cushion 18 is fed to process step d.

[0041] Figures 4a to 4c show a shaped cushion 18 in a perspective view from the front (Figure 4a), a top view (Figure 4b), and a perspective view from the rear (Figure 4c). In the method according to the invention, the user sits on this shaped cushion 18, which can be covered with a cover, for example made of a textile or a plastic. The majority of objects (not shown) are located within the shaped cushion 18, which are in the form of granules, for example. In the top view of Figure 4b of the shaped cushion 18, two particularly prominent locations are provided with markings 20, which are helpful for later scanning and correspond to particularly anatomically prominent locations on the user.

[0042] In particularly preferred embodiments, the shaped cushion is divided into several, preferably up to four, different and particularly preferably individually evacuatable sections. A division approximately along the midline into four quadrants is particularly suitable. This makes it possible to use the affected side in each case or to also use the shaped cushion for bilaterally amputees. When divided into a frontal and a dorsal section, it is possible, for example, to first position the patient in an upright sitting position on the saddle, of which the shaped cushion is a part, and then to evacuate the dorsal section, but preferably not the frontal section. This leads to a particularly good impression of the ischium in the area of ​​the elliptical marking 20.The patient is then positioned on the saddle, preferably in a forward-bent position, and the frontal portion is then evacuated, which leads to a particularly good impression of the adductor tendon.

[0043] Figures 5a to 5c show a saddle base 22 in a perspective view from the front (Figure 5a), a top view (Figure 5b), and a perspective view from the rear (Figure 5c). In the illustrated embodiment, the saddle base 22 is arranged between the molded cushion 18 and a holding device (not shown) and is preferably configured to be adjusted, in particular shifted and / or pivoted, relative to this holding device.

[0044] Figure 6 shows the combination of the shaped cushion 18 and the saddle base 22. Figure ? shows the combination in a sectional view. It can be seen that the saddle base 22 has several receiving openings on its underside, through which it can be connected to an element of a holding device, which is not shown, however. The sectional view of the shaped cushion 18 shows that the cavity 24 is significantly thicker, particularly in the posterior region, than in the anterior region. This allows the geometric shape and form of the shaped cushion to be adapted particularly well to the anatomical shape of the user.

[0045] List of reference symbols

[0046] 2 users

[0047] 4 Amputation stump 6 Saddle

[0048] 8 Holding device

[0049] 10 healthy leg

[0050] 12 backrest

[0051] 14 Pelvis 16 Spine

[0052] 18 shaped cushions

[0053] 20 Marking

[0054] 22 Saddle base

Claims

Patent claims 1. A method for creating a digital model of a prosthetic socket for a user (2), the method comprising the following steps: a. positioning the user (2) on a saddle (6), the saddle (6) having a shaped cushion (18) with a shell in which a plurality of objects are located, b. applying or increasing a negative pressure to the shaped cushion (18), c. removing the user (2) from the saddle (6), and d. scanning at least the part of the saddle that has come into contact with the user (2).

2. Method according to claim 1, characterized in that before scanning, orientation points are marked on the saddle part, which preferably correspond to the position of impressions of anatomically prominent parts of the user (2).

3. Method according to claim 1 or 2, characterized in that the amputation stump (4) is scanned and the digital model is created at least also from the scan of the amputation stump (4) and the scan of the saddle part.

4. Method according to claim 3, characterized in that digital data of a shaft edge are taken from a database and the digital model is additionally created from these data of a shaft edge.

5. Method according to one of the preceding claims, characterized in that the user (2) is standing when positioned on the saddle (6).

6. Method according to one of the preceding claims, characterized in that the molding cushion (18) has a plurality of chambers which can be separately subjected to a negative pressure, and steps a. and b. are carried out successively for the chambers, wherein preferably steps c. and d. are only carried out when steps a. and b. have been carried out for all chambers.

7. Saddle (6) for use in a method according to one of the preceding claims, characterized in that the saddle (6) has at least one shaped cushion (18) with a cover in which a plurality of objects are located.

8. Saddle (6) according to claim 7, characterized in that the cover has a connection to which a vacuum source is or can be arranged so that a vacuum can be applied to the molded cushion.

9. Saddle (6) according to claim 7 or 8, characterized in that the shaped cushion (18) has a plurality of chambers, in each of which a plurality of objects are located and which can be separately subjected to a negative pressure.

10. Saddle (6) according to one of claims 7 to 9, characterized in that the saddle (6) is arranged on a holding device, wherein the saddle (6) and / or the shaped cushion (18) is adjustable in the anterior-posterior direction relative to the holding device.

11. Saddle according to one of claims 7 to 10, characterized in that the shaped cushion (18) has a pre-shape which corresponds to the shape of the saddle (6).

12. Saddle (6) according to one of claims 7 to 11, characterized in that the saddle (6) and / or the shaped cushion (18) can be pivoted relative to the holding device about at least one pivot axis and can be locked in different positions, wherein the at least one pivot axis preferably has a medial-lateral axis and / or an anterior-posterior axis.

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