PROSTHETIC SHELL AND METHOD FOR PRODUCING SUCH A

Description

[0001] The invention relates to a method for manufacturing a prosthetic socket with an open proximal end for receiving an amputation stump, an inner wall, and an outer wall. Prosthetic sockets of this type have long been known in the art and are used for various prostheses and amputations. They serve as a connecting element between the patient's amputation stump and the prosthesis that replaces the amputated body part. Particularly in leg prostheses, the prosthetic sockets are subjected to considerable mechanical stress. This applies to both femoral and tibial sockets.

[0002] To ensure a comfortable fit and the necessary security for the patient, it is essential that the socket is securely positioned on the amputation stump. Several different methods for achieving this are known in the art. Often, a so-called liner is first pulled over the amputation stump before the combination of stump and liner is inserted into the prosthetic socket. The liner can engage with a corresponding recess in the prosthetic socket via a fastening pin, usually located at its distal end. Alternatively, a vacuum is created between the liner and the socket in a sealed volume, thereby securing the socket to the liner and thus to the amputation stump.

[0003] The wearer of the prosthetic socket, who uses the prosthesis for walking, must lift the entire prosthesis, including the socket, and swing it forward during the swing phase of each step. The prosthetic socket must not give the wearer the feeling that the connection between the socket and the residual limb is insecure. At the same time, the prosthetic socket must have a connecting element at its distal end for additional prosthetic components, such as a prosthetic knee or a lower leg with an attached ankle and foot. This connection, established via the connecting element, must also reliably transmit the forces generated during walking and provide the wearer with a secure feeling.

[0004] The various elements of a prosthetic socket are therefore relatively robust to withstand the stresses that occur. This makes the socket particularly heavy, which reduces wearing comfort. Modern prosthetic sockets are often made with carbon fiber composites. These are lightweight yet highly mechanically stable and thus very well suited to meet the requirements of a prosthetic socket. More recently, prosthetic sockets have also been manufactured using additive manufacturing processes, such as 3D printing. This enables new designs and shapes of the prosthetic socket that were not possible with conventional manufacturing methods, such as those using carbon fiber composites.

[0005] WO 2017 / 012888 A1 discloses a manufacturing process for a prosthetic socket in which an inner socket is first produced using a 3D printer. However, the material used is not capable of absorbing and withstanding the mechanical stresses of a prosthetic socket for lower extremity prostheses. Therefore, additional reinforcing elements are applied to the outside of the manufactured inner socket at particularly stressed points to solve this problem. This makes the manufacturing process more complex, however, as it requires several process steps and the use of several different materials.

[0006] From VITALI ANDREA ET AL: "Design and Additive Manufacturing of Lower Limb Prosthetic Socket", VOLUME 11: SYSTEMS, DESIGN, AND COMPLEXITY, November 3, 2017 (2017-11-03), pages 1-8, a manufacturing process for a prosthetic socket is known which also has an inner wall, an outer wall, and support elements arranged between them. However, the positions and directions of the support elements are not determined based on the directions of the forces expected to occur during use.

[0007] The invention is therefore based on the objective of avoiding or at least reducing the disadvantages of the prior art and proposing a method for manufacturing a prosthetic socket that is lightweight and can withstand the loads.

[0008] The invention solves the stated problem by a method for manufacturing a prosthetic socket according to claim 1.

[0009] By incorporating a hollow cavity into the prosthetic socket, weight is reduced, resulting in a lighter prosthetic socket and, consequently, a lighter prosthesis. Simultaneously, the internal element extending through the cavity increases stability. This internal element is integrally formed with the inner wall and is therefore manufactured in the same process step as the respective wall. Preferably, the inner wall, the outer wall, and the at least one internal element are formed integrally.

[0010] The cavity is located between the inner and outer walls and is not the space into which the amputation stump can be received. The cavity is preferably closed, so that there is no connection between its interior and the surrounding environment. The inner wall of the prosthetic socket preferably approximates the shape of the amputation stump to be received. It is essentially cup-shaped, and the prosthetic socket preferably has a closed distal end. The cavity is preferably located distal to the distal end of the inner wall. The at least one cavity is preferably bounded proximally by the inner wall of the prosthetic socket and in all other directions by the outer wall of the prosthetic socket. It may, but need not, be rotationally symmetrical about a longitudinal axis.At the distal end of the prosthetic stem, there is preferably a connecting element for another distal prosthetic component. The portion of the prosthetic stem where this connecting element is located is also part of the outer wall and preferably defines the distal boundary of the at least one cavity. With respect to the cavity, the inner and outer walls each have an inner surface facing the cavity. The at least one internal element is arranged on this inner surface of the respective wall.

[0011] The at least one internal element extends through the at least one cavity. It therefore not only projects into the at least one cavity, but preferably passes completely through it. It preferably connects two walls that surround and define the at least one cavity. It can extend between the inner wall and the outer wall, or connect several positions or locations of a single wall, i.e., the inner wall or the outer wall.

[0012] The at least one internal element is a support element, preferably extending from the inner wall to the outer wall. Such a support element is preferably a strut, a rod, or a bar-like element, and thus has a greater dimension in the longitudinal direction, preferably from the inner wall to the outer wall, than in the other spatial directions. The cross-section can be circular, oval, square, triangular, polygonal, or irregular. A support element can also be arranged between two points or positions of a single wall, i.e., the inner wall or the outer wall, and connect these points or positions. The cross-section can vary along the length of the support element; in particular, the diameter can change, for example, being larger in the area of ​​the connection between the wall and the support element. Of course, the cross-section can also be constant along the length of the support element.

[0013] The at least one support element preferably extends at least also in the proximal-distal direction. The longitudinal direction of the at least one support element thus has at least one component in this direction, with this component preferably being the largest component. In this case, the at least one support element therefore extends further in the proximal-distal direction than in any other direction.

[0014] Preferably, at least 25, preferably at least 100, particularly preferably at least 500 support elements extend into the at least one cavity, several, preferably all, of which extend from the inner wall to the outer wall.

[0015] This allows for an even distribution of the load across the various support elements and further optimizes the stability of the prosthetic socket.

[0016] In a preferred embodiment, at least one support element is positioned perpendicularly to the inner and / or outer wall. Particularly preferably, several, and most preferably all, support elements are positioned perpendicularly to the inner and / or outer wall. This prevents shear moments and tilting moments on the individual support elements that could otherwise occur when the prosthetic socket is subjected to load, for example, during walking. This also increases the stability of the prosthetic socket. As a result, the number and thickness of the support elements can be reduced, thus saving material and weight.

[0017] Preferably, at least one internal element is a partition that divides the cavity into two partial cavities. Preferably, such a partition is arranged exclusively on the outer wall of the prosthetic socket. In contrast to a support element, a partition is preferably planar, meaning it has a greater extent in two mutually perpendicular directions than in the third spatial direction, which is perpendicular to the first two directions. The at least one partition preferably extends in a plane that is substantially perpendicular to the proximal-distal direction. In this case, the at least one partition is preferably arranged exclusively on the inner side of the outer wall.

[0018] Preferably, the at least one separating element has at least one opening that connects the two partial cavities. Particularly preferably, at least one support element extends through this opening.

[0019] In an alternative embodiment of a separating element, the separating element is three-dimensional and therefore not exclusively planar. It can be designed as a hollow tube, a curved surface, or in some other way. By using a separating element with a closed cross-sectional contour, for example, a tube, the at least one cavity is divided into two partial cavities, one of which lies inside and one outside the separating element. The cross-sectional contour can be circular, oval, rectangular, triangular, polygonal, or irregular. It is also possible for the contour to change in shape, size, and / or contour along a longitudinal direction of the separating element thus designed. A separating element designed in this way preferably extends substantially along the proximal-distal direction, so that the partial cavities created by the separating element also extend in this direction.The separating element is preferably arranged between the inner wall in the proximal region of the cavity and the outer wall in the distal region of the cavity.

[0020] In a preferred embodiment, the prosthetic stem has a plurality of partition elements, such that the at least one cavity is subdivided into a plurality of partial cavities. The partition elements preferably run parallel to each other and are particularly preferably planar and extend further preferably perpendicular to the proximal-distal direction. This creates chambers that significantly increase the bending stiffness of the prosthetic stem in this region.

[0021] Preferably, at least one connection for a distal prosthetic component is arranged at a distal end of the prosthetic stem. The connection is preferably located on the outer wall of the prosthetic stem. The distal prosthetic component is, for example, a prosthetic knee, a lower leg tube, or a prosthetic foot, preferably with an artificial ankle joint. Particularly, but not exclusively, with lower leg prosthetic stems, it is advantageous to extend the prosthetic stem distally to such an extent that a prosthetic foot and / or an artificial ankle joint can be directly positioned on the connection. This reduces the number of prosthetic components required and simplifies prosthesis assembly. For example, a separate lower leg tube can be omitted.In the extended area of ​​the prosthesis shaft there is at least one cavity which is further preferably subdivided into several partial cavities or chambers by at least one, but preferably several, separating elements.

[0022] If the prosthetic socket has multiple support elements, imaginary extensions of these elements pass through the connecting element. Preferably, they meet at a single point within the connecting element. In this case, the force transmission from the support elements occurs directly into the connecting element and thus directly into a prosthetic component attached to the connecting element. This also helps to avoid or at least reduce shear moments or tilting moments.

[0023] Preferably, the prosthetic socket is a prosthetic socket for a prosthesis to supply the lower extremity, preferably for a lower leg prosthesis.

[0024] A prosthetic socket of the type described herein preferably has at least one first insert element having a contact surface that corresponds at least partially, but preferably completely, to at least a portion of the inner wall of the prosthetic socket. Such an insert element is also advantageous for other prosthetic sockets that, for example, do not have a cavity and / or an internal element. Therefore, such an insert element, in combination with the features of the preamble of original claim 1, constitutes a separate invention that can be used with or without the features of the prosthetic sockets described herein. An insert element is used when the amputation stump loses volume over time and the original prosthetic socket is no longer optimally adapted to the amputation stump.Then an insert element is manufactured, which must be painstakingly adapted to the desired shape, for example by sanding. This is time-consuming and therefore expensive.

[0025] The present invention simplifies this process. The prosthetic socket is preferably manufactured using an additive manufacturing process, for example, a 3D printing process, so that its contours and shapes are stored electronically. Therefore, a first insert element can be easily produced, particularly also 3D printed, whose contact surface is optimally adapted to the inner wall of the prosthetic socket, preferably its outer surface opposite the inner surface. Preferably, the insert element can be placed over its entire surface against the outer surface of the inner wall of the prosthetic socket. The insert element is thus placed into the cavity provided for receiving the amputation stump. No time-consuming post-processing is necessary. In the desired position, the insert element is bonded to the inner wall of the prosthetic socket or fixed in some other way.Preferably, the insert element then forms a uniform and, in particular, continuous, i.e., stepless, surface with the part of the outside of the inner wall of the prosthesis shaft that is not covered by it.

[0026] Preferably, the prosthetic socket has at least one second insert element with a contact surface that corresponds to the inner wall of the prosthetic socket and / or to a surface of the first insert element opposite the contact surface. The prosthetic socket is preferably supplied with several such insert elements, preferably forming a set. Alternatively or additionally, insert elements with the appropriate material thickness can be custom-made. If a permanent change in volume, particularly a reduction in volume, occurs in the amputation stump, this can be compensated for by selecting one or more suitable insert elements.

[0027] To determine the directions of the forces expected to occur during use, a model of the prosthesis to be manufactured is preferably created, which can be edited in an electronic data processing unit. It is preferably stored in an electronic data storage device. A simulation unit of the electronic data processing unit then uses a stored model to simulate the forces and records their magnitudes and directions. Based on this data, a modeling unit of the electronic data processing unit models the optimal positions and orientations of the required support elements. Additionally, the thickness, cross-section, course, and / or number of support elements can be used as optimization parameters by the

[0028] A modeling unit is used. The electronic data processing unit then transmits control commands to the additive manufacturing system, for example the 3D printer, and controls it in such a way that the modeled prosthetic socket is printed.

[0029] Preferably, the prosthetic socket is manufactured at least partially using additive manufacturing processes, for example using a 3D printer, wherein in particular the at least one support element is manufactured additively, for example printed.

[0030] With the aid of the accompanying figures, some exemplary embodiments of the present invention are explained in more detail below.

[0031] They show Figure 1 - a schematic representation of a lower leg prosthesis, Figure 2 - a representation from Figure 1Figures 3-6 show a schematic sectional view of the prosthetic socket, Figures 7-8 show schematic representations of an insert element, Figure 9 shows schematic sectional views through the cavity, Figure 10 shows schematic representations of a connecting element, Figure 11 shows a schematic sectional view through a socket with a connecting element, Figure 12 shows a schematic representation of part of a prosthetic socket, Figure 13 shows a schematic sectional view through part of a prosthetic socket with a connecting element, and Figure 14 shows a schematic sectional view along another plane through a prosthetic socket.

[0032] Figure 1Figure 1 shows a schematic representation of a lower leg prosthesis comprising a prosthetic stem 2 with an open proximal end 4 and a closed distal end 6. A connecting element 8 is located at the distal end 6, to which a lower leg tube 10 is attached. A prosthetic foot 12 is located at the lower end of this lower leg tube 10. For determining the position and orientation, a virtual pivot axis 14 for a knee housed in the prosthetic stem 2 was assumed in the illustrated embodiment. This pivot axis 14 was connected on one side to a heel strike point 16 and on the other side to a point 18 where the load is applied during the transition to the swing phase. This results in the maximum load angle.

[0033] Figure 2 shows the representation from Figure 1The prosthetic socket 2 is now shown in a sectional view. It has an inner wall 20 and an outer wall 22, between which a cavity 24 is located. In this cavity 24, a plurality of support elements 26 are arranged in the illustrated embodiment, all of which extend through the cavity 24. Most are arranged with one end on an inner surface of the inner wall 20 and with the opposite end on the inner surface of the outer wall 22. A few, however, extend between two different points on the inner surface of the outer wall 22. It can be seen from the dashed lines 28 that some of the support elements 26 run along these lines 28 and thus enable optimal force transmission during heel strike and toe lift. The remaining support elements 26 have been configured in a similar manner.Different support elements are subjected to maximum loads for different movements and / or in different phases of a gait cycle. These elements are positioned in the optimal direction for force transmission at any given time.

[0034] Figure 3Figure 1 shows a schematic cross-sectional view through another prosthetic stem 2. It also has an inner wall 20 and an outer wall 22, between which a cavity 24 is located. A separating element 30 is present within the cavity, which in the illustrated embodiment has a closed cross-sectional contour. The separating element 30 has a plurality of openings 32, which are shown as small dots. The separating element 30 extends from the inner wall 20 in the proximal region of the cavity 24 to the distal end of the cavity 24, where it terminates at the outer wall 22. This creates two partial cavities 34, one of which is located outside the separating element 30, between the separating element 30 and the outer wall 22. The other partial cavity 24 is located inside the separating element 30.Figure 3 shows that the prosthetic stem 2 has been extended distally, so that the connecting element 8, which in the illustrated embodiment is designed as a pyramid adapter, is shifted further distally. If the... Figure 3 Schematically depicted prosthetic socket 2 for a lower leg prosthesis, as used, for example, in the Figures 1 and 2 As shown, it is no longer necessary to use a separate lower leg tube 10. The extended distal region of the prosthetic stem 2 takes over these functions and, due to the structures within the cavity 24, is able to withstand the occurring loads.

[0035] Figure 4 shows another representation of a prosthetic socket 2 with the inner wall 20, the outer wall 22 and the in Figure 3 The previously shown separating element 30. In addition, the prosthetic socket 2 has Figure 4via a multitude of support elements 26. Some of these support elements 26 extend from the inner wall 20 to the outer wall 22, with some of these support elements 26 passing through the openings 32 in the separating element 30. Some of the support elements 26 run completely within the outer partial cavity 34 and extend from a first point on the outer wall 22 to a second point on the outer wall 22. Most of these support elements 26 extend at least predominantly in a proximal-distal direction.

[0036] Figure 5 Figure 1 shows another schematic representation of a prosthetic stem 2 in a sectional view. This prosthetic stem 2 also has the inner wall 20, the outer wall 22, and the connecting element 8 for a distal prosthetic component. The following also applies to the prosthetic stem 2 shown in Figure 2: Figure 5In the prosthetic stem 2 shown, the distal area is extended, thus eliminating the need for a lower leg tube, for example. Between the inner wall 20 and the outer wall 22 is the cavity 24, which in the illustrated embodiment is divided into five partial cavities 34 by four separating elements 30. The separating elements 30 run parallel to each other and are planar. Unlike the separating element 30 made of Figures 3 and 4 not over a closed cross-sectional contour. The separating elements 30 in Figure 5 Each has an opening 32 through which the adjacent partial cavities 34 are connected to each other.

[0037] Figure 6 Another cross-sectional view shows a prosthetic socket 2, which is similar to the one in Figure 5 The prosthetic stem 2 shown is constructed as follows. It also has four separating elements 30 that divide the distal area of ​​the prosthetic stem into partial cavities 34. In addition, the prosthetic stem has in Figure 6 The prosthetic socket 2 shown is supported by a multitude of support elements 26, some of which extend through the openings 32 in the separating element 30. Others extend between two separating elements 30 or run from the inner wall 20 to the outer wall 22.

[0038] Figure 7 Figure 1 schematically shows a prosthetic socket 2 with an insert element 36 manufactured for this prosthetic socket 2. The insert element has a contact surface 38 that corresponds to an outer surface of the inner wall 20 of the prosthetic socket 2, so that the insert element 36 can be positioned with its contact surface 38 fully against the inner wall 20 of the prosthetic socket 2. This accommodates a reduction in the volume of the amputation stump that is to be received in the prosthetic socket 2.

[0039] Figure 8Figure 36 shows three different insert elements 36, each with a different thickness. This is particularly evident at the rim 40. Depending on the degree of volume reduction of the amputation stump, the appropriate insert element 36 can be used. The insert elements 36 are preferably 3D printed, allowing them to be easily adapted to and shaped to fit the inner wall 20 of the prosthetic socket.

[0040] Figure 9 The left part schematically shows a frontal view of a lower leg prosthesis with the prosthetic socket 2, the lower leg tube 10 and the prosthetic foot 12. The right part of the Figure 9Four superimposed cross-sectional views through the prosthetic socket 2 along the dashed lines 42 are shown. Partially complex patterns of support elements 26 and separating elements 30 are visible, although these cannot be distinguished in the illustrations because it is not clear between which two points the internal elements extend. In the four superimposed cross-sectional views, the medial side is on the left, the lateral side on the right, and the frontal side at the bottom.

[0041] Figure 10Figure 1 schematically shows a connection element 8 from two different perspectives. It has a substantially U-shaped form with two legs 44 and an intermediate recess 46. In the embodiment shown, the connection element 8 has four bore holes 48, which are preferably provided with an internal thread. In this way, screws can be fastened in them to attach another connection element, for example a pyramid adapter 50.

[0042] This is in Figure 11As shown, in the distal region of the prosthetic stem 2 shown, there is a slot-shaped recess 52, which is preferably formed integrally with the rest of the prosthetic stem 2. It is therefore preferably not created after the prosthetic stem 2 has been manufactured, for example by means of a milling machine, but rather preferably formed integrally with the rest of the prosthetic stem 2 in an additive manufacturing process. The recess 52 is formed in the distal region of the prosthetic stem 2. Figure 10 The connecting element 8 shown can be inserted into this recess so that the pyramid adapter 50 shown can be screwed on. A stem 54, which transmits the large loads, is positioned in the recess 46 in the connecting element 8, so that the sometimes large mechanical forces, which can occur particularly with leg prostheses, are transmitted.

[0043] Figure 12Figure 1 shows a section of a prosthetic stem 2 and in particular its distal end 6. It has four recesses 56, which are arranged in the corner regions and of which in Figure 12 Two are visible. The connecting means 8 are contained within them in the form of bolts 58. In the illustrated embodiment, the bolts 58 have a slot 60 on their outwardly facing side, so that they can be moved by means of a suitable tool, for example a screwdriver. On a distal side 62 of the prosthesis stem 2 there are four holes 64, into each of which a screw can be inserted, for example to fasten a Figure 12 to attach the pyramid adapter 50 (not shown). The bolts 58 advantageously have a corresponding thread into which the screws can be screwed when the bolt 58 is arranged in the correct position and orientation in the recess 56.

[0044] Figure 13 The situation is shown in a sectional view. Two bolts 58 can be seen, each inserted into a recess 56. They each have a bore 66, which is preferably threaded. Figure 13 However, this is not shown. The screws can be inserted through the holes 64 in the distal side 62 of the prosthesis stem 2, which preferably interact with the thread present on the inner wall of the bore 66 and thus form a Figure 13 to attach adapters not shown, for example a pyramid adapter 50.

[0045] Figure 14Figure 1 shows another cross-sectional view through the prosthetic stem 2 parallel to the distal side 62 of the prosthetic stem 2. The four bolts 58 are each inserted into one of the recesses 56 and, as already described, have the slot 60 so that their alignment and orientation relative to the rest of the prosthetic stem 2, and in particular relative to the holes 64 on the distal side 62 of the prosthetic stem 2, can be adjusted. Preferably, the desired position is very easy to reach, for example, by adjusting the slot 60 as shown in Figure 1. Figure 14 The bolts are arranged vertically. Each bolt 58 has the bore 66, which is aligned with the bores shown in the diagram by rotating the bolts 58 about their longitudinal axis. Figure 14 The screws (not shown) can be inserted into the holes 64 on the distal side 62 of the prosthesis stem 2, so that the screws (not shown) can be screwed in to attach an adapter, in particular a pyramid adapter 50. Reference symbol list:

[0046] 2 Prosthetic stem 4 Proximal end 6 Distal end 8 Connecting element 10 Lower leg tube 12 Prosthetic foot 14 Virtual pivot axis 16 Heel strike point 18 Position 20 Inner wall 22 Outer wall 24 Cavity 26 Support element 28 Dashed line 30 Separating element 32 Opening 34 Partial cavity 36 Insertion element 38 Contact surface 40 Rim 42 Dashed line 44 Leg 46 Recess 48 Borehole 50 Pyramid adapter 52 Recess 54 Trunk 56 Recess 58 Bolt 60 Slot 62 Distal side 64 Hole 66 Borehole

Claims

1. A method for producing a prosthesis socket (2) with - an open proximal end (4) for accommodating an amputation stump, - an inner wall and - an outer wall, wherein at least one cavity (24) is arranged between the inner wall and the outer wall, through which at least one internal element extends, the at least one internal element being designed as a single piece with the inner wall and / or outer wall, wherein at least one internal element is a support element (26), and wherein in said method - the directions of the forces expected to occur during use of the prosthesis socket are determined, - on the basis of these directions, the positions and directions of the at least one support element (26) are determined, and - on the basis of these positions and directions of the support elements (26) the prosthesis socket (2) is produced.

2. The method according to claim 1, characterized in that the prosthesis socket (2) is at least partially produced by means of an additive manufacturing process, wherein the at least one support element (26) in particular is produced in the additive manufacturing process.

3. The method according to claim 1 or 2, characterized in that the support element (26) extends from the inner wall to the outer wall.

4. The method according to one of the preceding claims, characterized in that at least 25, preferably at least 100, especially preferably at least 500 support elements extend in the at least one cavity from the inner wall to the outer wall.

5. The method according to one of the preceding claims, characterized in that at least one support element (26), preferably a plurality of support elements (26), is perpendicular to the inner wall and / or perpendicular to the outer wall.

6. The method according to one of the preceding claims, characterized in that the at least one internal element is a partition element (30) that divides the cavity (24) into two partial cavities (34) and is preferably arranged only on the outer wall.

7. The method according to claim 6, characterized in that the at least one partition element (30) has at least one opening that connects the two partial cavities (34).

8. The method according to claim 7, characterized in that at least one support element (26) extends through the at least one opening of the at least one partition element (30).

9. The method according to one of the claims 6 to 8, characterized in that a plurality of internal elements are partition elements (30) that preferably run parallel to each other.

10. The method according to one of the preceding claims, characterized in that a connection means (8) for a distal prosthesis component is arranged on the distal end (6) of the prosthesis socket (2) and imaginary extensions of a plurality of support elements (26) in the connection means (8) preferably meet at one point within the connection means (8).

11. The method according to one of the preceding claims, characterized in that the prosthesis socket (2) is a prosthesis socket for a prosthesis for treating a lower limb, preferably a lower leg prosthesis.

12. The method according to one of the preceding claims, characterized in that the prosthesis socket (2) comprises at least a first insert element (36) that has a contact surface (38) which is designed to correspond to the inner wall of the prosthesis socket.

13. The method according to claim 12, characterized in that the prosthesis socket (2) has at least a second insert element (36) that features a contact surface (38), which is designed to correspond to the inner wall of the prosthesis socket and / or a surface of the first insert element (36) that is opposite the contact surface (38).