A tibial platform

Abstract

After the knee prosthesis using this tibial platform is implanted in the human body, a gap appears between the femoral condyle and the tibial pad due to long-term wear. The compressed elastic component begins to push the first push block to move, thereby lifting the first ascending part located on the upper inclined surface of the first push block. The first ascending part drives the tibial pad to rise. The first push block, pushed by the elastic component, pushes the second push block to move inward along the track. The second push block then pushes the support rod of the second ascending part to move, and the lifted second fixing block further drives the tibial pad to rise. After the tibial pad has been lifted, the pawl in the blocking device engages with the serrations on the second push block, thereby limiting the push block and preventing it from retracting, thus preventing the ascending part from descending, and completing the lifting of the tibial pad. This effectively solves the problem in the prior art where the gap between the femoral condyle and the pad is different after wear on the inner and outer sides of the femoral condyle, leading to accelerated wear.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more specifically, to a tibial platform. Background Technology

[0002] The knee joint is a core joint of the lower limbs and a common site for knee joint diseases among the elderly. These diseases often manifest as joint pain caused by wear and tear or degeneration of the articular cartilage. In clinical treatment, knee resurfacing is one of the most commonly used surgical procedures. This surgery involves removing the worn cartilage and part of the subchondral bone from the surface of the femur and tibia to create a smooth osteotomy surface. Subsequently, a metal prosthesis made of cobalt-chromium-molybdenum alloy is installed in the osteotomy area through direct fixation or bone cement fixation to replace the original damaged bone structure.

[0003] In knee joint prostheses, the portion replacing the femoral side is called the femoral condyle, and the portion replacing the tibial side is called the tibial plateau. A spacer made of ultra-high molecular weight polyethylene is placed between the two to reduce friction and restore normal knee joint function. Currently, in total knee replacement surgery, femoral condyle prostheses are mostly made of medical-grade metal materials (such as stainless steel or cobalt alloy), while the tibial platen is generally made of ultra-high molecular weight polyethylene.

[0004] During the use of a knee prosthesis, the polyethylene spacer will wear down. However, due to differences in individual patient activity patterns, uneven wear may occur between the medial and lateral spacers, leading to inconsistent gaps between the femoral condyle and the spacer. If this problem is not addressed in time, it will exacerbate unilateral wear and shorten the lifespan of the knee prosthesis.

[0005] Therefore, there is an urgent need to design a tibial platform that can intervene in the inconsistency between the inner and outer sides of the spacer, thereby extending the lifespan of the prosthesis. Summary of the Invention

[0006] The main objective of this invention is to provide a tibial platform to solve the problem in the prior art where the gap between the femoral condyle and the spacer is different after the inner and outer sides of the femoral condyle are worn, which leads to accelerated wear.

[0007] To achieve the above objectives, the present invention provides a tibial platform, specifically comprising: a tibial platform including a tibial support, a platform base disposed on the tibial support, a hollow cavity disposed on the platform base, a protrusion disposed inside the hollow cavity, and the protrusion being fixedly connected to the platform base; two tibial pads symmetrically disposed on the hollow cavity, the bottom of the tibial pads also having a first recess and a second recess; and a lifting part disposed inside the hollow cavity, the lifting part comprising: a shell with three openings; an elastic member disposed inside the shell, one end of which is attached to the inner wall of the shell; a first pushing block disposed inside the shell and connected to the elastic member; and a second pushing block disposed inside the shell and connected to the elastic member. The first pushing block is connected as described above, and the second pushing block is further provided with serrations; a blocking device is disposed inside the aforementioned housing, the blocking device includes a slide rail portion, a track is disposed on the slide rail portion, a first fixing block is symmetrically disposed on the slide rail portion, a first rotating shaft is disposed on the first fixing block, the fixing block is connected to the upper part of the rotating block through the aforementioned first rotating shaft, a second rotating shaft is disposed at the lower part of the rotating block, and the rotating block is connected to a pawl through the second rotating shaft; a first rising portion is disposed on the aforementioned first pushing block; a second rising portion is disposed inside the aforementioned track, the second rising portion includes a second fixing block, and a support rod is crosswise disposed at the lower part of the second fixing block, the support rod is connected through a third rotating shaft.

[0008] Furthermore, the hollow cavity on the tibial platform has arc-shaped sides, and the protrusion on the tibial platform is cylindrical. The protrusion is located in the center of the hollow cavity and is fixedly connected to the platform base. Its height is lower than the height of the inner wall of the hollow cavity. The protrusion can be combined with the lifting part to enhance stability.

[0009] Furthermore, the lifting section consists of two identical parts on the left and right sides, symmetrically arranged inside the hollow cavity. The combined lifting section maintains the same shape and size as the hollow cavity, allowing the entire lifting section to be inserted into the hollow cavity, thus enhancing the overall stability of the tibial plateau.

[0010] Furthermore, the first opening on the side of the outer shell is located in the middle of the side, with a semi-circular bottom that extends upward through the side of the outer shell, but its penetration height does not exceed the top of the outer shell. At the same time, the diameter of the semi-circular bottom of the first opening is the same as the diameter of the aforementioned protrusion, and the penetration height is the same as the height of the aforementioned protrusion. The combined opening of the first openings on the left and right sides of the outer shell allows the protrusion on the platform base to be inserted into it, enhancing stability.

[0011] Furthermore, the elastic component is a compressed spring, and there are two of them symmetrically connected to the first push block. The first push block is shaped like a side-mounted frustum. The elastic component is in contact with the first push block, so the first push block has a tendency to move. The second push block is a cuboid and is fixedly connected to the upper surface of the first push block. When the first push block moves, it can drive the second push block to move.

[0012] Furthermore, the track width is consistent with the width of the second push block, the track height extends through the top of the slide rail, and the length does not exceed the side of the slide rail. Therefore, after the second push block is pushed into the track, it can move along the track to avoid left and right slippage. At the same time, the pawl and the saw teeth mesh with each other to prevent the second push block from being squeezed back, thus playing a limiting function.

[0013] Furthermore, the upper part of the first rising part is a third fixed block, which is in the shape of an inverted trapezoid, and the lower part is a wedge. The bottom surface of the wedge is an inclined surface, parallel to the side surface of the first pushing block. Two sliding shafts are also symmetrically arranged at the bottom of the first rising part, so that the first rising part can be lifted and move smoothly along the inclined surface of the first pushing block after sensing the wear gap.

[0014] Furthermore, the initial height of the top of the first rising part and the second rising part are consistent to maintain the balance of the left and right sides of the pad; the shape of the second opening on the outer shell is consistent with the shape of the second fixing block on the second rising part, and the shape of the third opening is consistent with the shape of the third fixing block on the upper part of the first rising part.

[0015] Furthermore, the shape and size of the first recess on the tibial pad are consistent with the second fixing block on the second rising part, and the shape and size of the second recess are consistent with the third fixing block on the upper part of the first rising part. Since each part is an inverted trapezoid, the combination of the tibial pad and the pushing part can increase friction and thus improve the overall stability.

[0016] According to the technical solution of the present invention, a tibial platform includes a tibial platform, a tibial pad, and a thrusting part. The lower part of the tibial platform is the tibial support, and the upper part is the platform base. The platform base is provided with a hollow cavity and a protrusion. The protrusion can connect with the lifting part to enhance stability. The tibial pad is divided into two identical pads on the inner and outer sides, symmetrically arranged on the hollow cavity. The bottom is provided with a first opening and a second opening to connect with the lifting part. The lifting part is also divided into two parts and symmetrically arranged in the hollow cavity, corresponding one to one of the tibial pads. The lifting part includes a shell, a pushing block, a sliding rail, and an ascending part. The shell is located inside the hollow cavity and is provided with a first opening to accommodate the protrusion on the platform base. A compressed elastic component is connected between the first pushing block and the shell to provide elastic potential energy, so that the first pushing block has a tendency to move, thereby lifting the first ascending part and driving the tibial pad to rise. The first pushing block pushes the second pushing block to move along the track, thereby lifting the second ascending part and driving the tibial pad to rise. The pawl engages with the serrations on the second pushing block to prevent the pushing block from being squeezed back, thereby achieving a stable limiting function.

[0017] Therefore, the technical solution of this application can address the problem of inconsistent gaps between the inner and outer sides of the pad, thereby extending the lifespan of the prosthesis. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A cross-sectional view of the tibial plateau, tibial pad, and thruster assembly is shown. Figure 2 Anterior view of the tibial plateau is shown; Figure 3 A cross-sectional view of the tibial pad is shown; Figure 4 An overall sectional view of the lifting section is shown; Figure 5 A schematic diagram of the lifting section housing is shown; Figure 6 A schematic diagram of the internal structure of the lifting section is shown; The above-mentioned figures include the following reference numerals: 1. Tibial plateau; 10. Tibial support; 11. Platform base; 12. Hollow cavity; 13. Protrusion; 2. Tibial pad; 20. First recess; 21. Second recess; 3. Lifting part; 30. Outer shell; 31. First opening; 32. Second opening; 33. Third opening; 34. Elastic component; 35. First pushing block; 36. Second pushing block; 360. Serrated edge; 37. Restriction device; 370. Slide rail part; 3700. Track; 371. First fixing block; 3710. First rotating shaft; 372. Rotating block; 3720. Second rotating shaft; 373. Pawl; 38. First rising part; 380. Third fixing block; 381. Wedge; 382. Sliding shaft; 39. Second rising part; 390. Second fixing block; 391. Support rod; 392. Third rotating shaft. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0022] like Figure 1-6 As shown: A tibial platform includes a tibial platform 1, the tibial platform 1 including a tibial support 10, a platform base 11 disposed on the tibial support, a hollow chamber 12 disposed on the platform base 11, a protrusion 13 disposed inside the hollow chamber 12, the protrusion 13 being fixedly connected to the platform base 11; two tibial pads 2 symmetrically disposed on the hollow chamber 12, the bottom of the tibial pads 2 also having a first recess 20 and a second recess 21; and two lifting parts 3 symmetrically disposed inside the hollow chamber 12, the lifting parts 3 including: The outer casing 30 has a first opening 31 on its upper side, the bottom of which is semi-circular and extends upward through the side of the casing, but its penetration height does not exceed the top of the casing. A second opening 32 and a third opening 33 are provided at the top of the casing. An elastic member 34 is disposed inside the outer casing 30, with one end attached to the inner wall of the casing. A first pushing block 35 is disposed inside the outer casing 30 and connected to the elastic member 34. A second pushing block 36 is disposed inside the outer casing and connected to the first pushing block 35, and the second pushing block is also provided with serrations 360. A blocking device 37 is also included. The blocking device is disposed inside the aforementioned housing. The blocking device includes a slide rail portion 370, on which a track 3700 is provided. First fixing blocks 371 are symmetrically arranged on the slide rail portion. A first rotating shaft 3710 is provided on the first fixing block 371. The first fixing block 371 is connected to the upper part of a rotating block 372 via the first rotating shaft 3710. A second rotating shaft 3720 is provided at the lower part of the rotating block 372, and the rotating block 372 is connected to a pawl 373 via the second rotating shaft 3720. A first rising portion 38 is also included. 8 is set on the first pushing block 35. The upper part of the first rising part is a third fixing block 380, which is in the shape of an inverted trapezoid, and the lower part is a wedge 381. The bottom surface of the wedge is an inclined surface, parallel to the inclined surface of the upper part of the first pushing block. Two sliding shafts 382 are also symmetrically arranged at the bottom of the first rising part. The second rising part 39 is set inside the track 3700. The second rising part includes a second fixing block 390 at the top and a support rod 391 arranged crosswise at the lower part of the second fixing block 390. The support rod is connected by a third rotating shaft 392.

[0023] like Figure 1As shown, a tibial platform includes a tibial platform 1, a tibial pad 2, and a lifting part 3. The tibial platform 1 includes a tibial support 10, a platform base 11, a hollow chamber 12, and a protrusion 13. There are two tibial pads symmetrically arranged on the tibial platform 1. There are also two lifting parts 3 symmetrically arranged inside the hollow chamber 12, corresponding one-to-one with the tibial pads 2. The lifting part 3 includes a hollow outer shell 30 and an internal device. The lifting part 3 is connected to the tibial pad 2 through a fixing block extending from the outer shell 30 and realizes the lifting of the tibial pad 2.

[0024] like Figure 2 As shown, the tibial platform 1 includes a tibial support 10, a platform base 11, a hollow chamber 12, and a protrusion 13. The hollow chamber 12 is disposed on the platform base 11, and the protrusion 13 is a cylinder. The protrusion is disposed in the center of the hollow chamber 12 and is fixedly connected to the platform base 11. Its height is lower than the height of the inner wall of the hollow chamber 12.

[0025] like Figure 3 As shown, the upper part of the tibial pad 2 is arc-shaped, and the lower part is provided with a first recess 20 and a second recess 21, both of which are inverted trapezoids, but of different sizes; the shape and size of the first recess 20 are consistent with the second fixing block 390 on the second rising part 39, and the shape and size of the second recess 21 are consistent with the third fixing block 380 on the upper part of the first rising part 38.

[0026] like Figure 4 As shown in the cross-sectional view of the lifting part 3, it includes a housing 30 with a first opening 31, a second opening 32, and a third opening 33. An elastic member 34 is a compressed spring, one end of which is connected to the inner wall of the side of the housing 30, and the other end is fixedly connected to the first pushing block 35. The first pushing block 35 is fixedly connected to the second pushing block 36. The second pushing block 36 has serrations 360. The second pushing block 36 is placed in the slide rail 370 within the blocking device 37 and slides within the track 3700 on the slide rail 370 to prevent unnecessary left and right movement of the pushing block. The blocking device 37 also has a pawl 373, which meshes with the serrations 360 to limit the second pushing block 36 and prevent it from retracting. On the first pushing block 35... A first rising section 38 is provided, which includes a third fixing block 380, a wedge 381, and a sliding shaft 382. The third fixing block 380 can extend from the third opening 33 on the outer shell 30 and engage with the second recess 21 on the tibial pad 2. A second rising section 39 is provided inside the track 3700, which includes a second fixing block 390, a cross-arranged support rod 391, and a third rotating shaft 392. The second fixing block 390 can extend from the second opening 32 on the outer shell 30 and engage with the first recess 20 on the tibial pad 2.

[0027] like Figure 5As shown, the outer shell 30 in the lifting part 3 is half the size of the hollow cavity 12. The first opening 31 on the side of the outer shell 30 is located in the middle of the side. The bottom surface of the first opening 31 is semi-circular and extends upward through the side of the outer shell, but its penetration height does not exceed the top of the outer shell. At the same time, the diameter of the semi-circular bottom surface of the first opening 31 is the same as the diameter of the aforementioned protrusion 13, and the penetration height is the same as the height of the aforementioned protrusion 13. The outer shell 30 is also provided with a second opening 32 and a third opening 33.

[0028] like Figure 6 As shown, the lifting part 3 includes an elastic component 34, a first pushing part 35, a second pushing part 36, a blocking device 37, a first rising part 38, and a second rising part 39. The elastic component 34 is a compressed spring, and there are two of them, symmetrically arranged and connected to the first pushing part 35. The first pushing part 35 is a side-mounted frustum connected to the elastic component 34. The first rising part 38 is placed on the upper side. The first rising part 38 includes an inverted trapezoidal third fixing block 380 and a wedge 381. The bottom surface of the wedge 381 is an inclined surface, parallel to the upper inclined surface of the first pushing block 35. Two sliding shafts are also symmetrically arranged at the bottom of the first rising part 38. The first pushing block 35 is connected and fixed to the second pushing block 36. The second pushing block 36 is provided with... The slide rail 370 has a serrated edge 360 ​​and a second pusher block 36 that extends into the slide rail 370 and can slide. The slide rail 370 is also symmetrically provided with a first fixing block 371, which is connected to a rotating block 372 via a first rotating shaft 3710. The rotating block 372 is connected to a pawl 373 via a second rotating shaft 3720. The slide rail is also provided with a second rising part 39, which includes an inverted trapezoidal second fixing block 390 and a support rod 391 that is cross-arranged under the second fixing block 390. The support rod 391 is hinged via a third rotating shaft 392. The second rising part 39 is in contact with the second pusher block 36. The initial height of the top of the first rising part 38 and the second rising part 39 is consistent.

[0029] When using this invention, the specific technical effects brought about by the embodiments are as follows: After the knee joint prosthesis of this tibial platform is implanted into the human body, due to the long-term wear of the femoral condyle and the tibial pad, a gap appears between them. The compressed elastic component begins to push the first pushing block to move, thereby lifting the first rising part located on the upper inclined surface of the first pushing block. The first rising part drives the tibial pad to rise. The first pushing block, pushed by the elastic component, pushes the second pushing block to move inward to the track. The second pushing block then pushes the support rod of the second rising part to move. The lifted second fixing block then drives the tibial pad to rise. After the tibial pad is lifted, the pawl in the blocking device engages with the serration on the second pushing block, thereby limiting the pushing block and preventing it from retracting, thus avoiding the rising part from descending, thereby completing the lifting of the tibial pad.

[0030] In summary, by providing a lifting part between the tibial plateau and the tibial pad, the present invention can lift the tibial pad when a gap is created between the femoral condyle and the tibial pad due to wear, automatically compensating for the gap height, so that the tibial pad and the femoral condyle remain in contact, and avoids inconsistent heights of the pads on both sides.

[0031] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0032] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0033] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tibial plateau, characterized in that, include: Tibial platform (1), the tibial platform includes a tibial support (10), a platform base (11) is provided on the tibial support, and a hollow cavity (12) and a protrusion (13) are provided on the platform base. Tibial pad (2), the tibial pad is symmetrically arranged on the hollow chamber (12) above, and the bottom of the tibial pad is also provided with a first recess (20) and a second recess (21). The lifting section (3), symmetrically arranged inside the hollow chamber (12), includes: The outer casing (30) has a first opening (31) on its side and a second opening (32) and a third opening (33) on its top. An elastic component (34) is symmetrically arranged inside the outer shell (30), with one end attached to the inner wall of the outer shell (30). The first pushing block (35) is disposed inside the outer casing (30) and is connected to the elastic member (34). The second push block (36) is disposed inside the outer casing (30) and connected to the first push block (35). The second push block is provided with serrations (360). The blocking device (37) includes a slide rail (370) with a track (3700) on it. The slide rail is located inside the outer casing (30). A first fixing block (371) is symmetrically arranged on the slide rail. A first rotating shaft (3710) is provided on the first fixing block. The first fixing block is connected to the upper part of a rotating block (372) via the first rotating shaft (3710). A second rotating shaft (3720) is provided at the lower part of the rotating block. The rotating block is connected to a pawl (373) via the second rotating shaft (3720). The first rising part (38) is disposed on the first pushing block (35), and the bottom surface of the first rising part is an inclined surface. The second rising part (39) is disposed inside the track (3700). The second rising part includes a second fixing block (390) and a support rod (391) which is intersected and disposed at the lower part of the second fixing block (390). The support rod is connected by a third rotating shaft (392).

2. The tibial plateau according to claim 1, characterized in that, The hollow cavity (12) on the tibial platform (1) has arc-shaped sides. The protrusion on the tibial platform (1) is cylindrical. The protrusion is located in the center of the hollow cavity (12) and is fixedly connected to the platform base (11). Its height is lower than the height of the inner wall of the hollow cavity.

3. The tibial plateau according to claim 1, characterized in that, The lifting part (3) is symmetrically arranged inside the hollow cavity (12), and the combined lifting part has the same shape and size as the hollow cavity (12).

4. The tibial plateau according to claim 1, characterized in that, The first opening (31) on the side of the outer shell (30) is located in the middle of the side. The bottom surface of the first opening (31) is semi-circular and penetrates the side of the outer shell from bottom to top, but its penetration height does not exceed the top of the outer shell. At the same time, the diameter of the semi-circular bottom surface of the first opening (31) is the same as the diameter of the protrusion (13) and the penetration height is the same as the height of the protrusion.

5. A tibial plateau according to claim 1, characterized in that, The elastic component (34) is a compressed spring. There are two of them and they are symmetrically connected to the first push block (35). The first push block (35) is a side-mounted truncated pyramid. The elastic component is in contact with the first push block. The second push block (36) is a cuboid and is connected and fixed to the first push block.

6. A tibial plateau according to claim 1, characterized in that, The width of the track (3700) is the same as the width of the second push block (36) mentioned above. The height of the track extends through the top of the slide rail (370) and the length does not exceed the side of the slide rail (370). The pawl (373) and the saw teeth (360) mesh with each other.

7. A tibial plateau according to claim 1, characterized in that, The upper part of the first rising part (38) is a third fixed block (380), which is in the shape of an inverted trapezoid, and the lower part is a wedge (381). The bottom surface of the wedge (381) is an inclined surface, which is parallel to the upper inclined surface of the first pushing block (35). Two sliding shafts (382) are also symmetrically arranged at the bottom of the first rising part (38).

8. A tibial plateau according to claim 1, characterized in that, The first rising part (38) and the second rising part (39) have the same initial height at the top. The shape of the second opening (32) on the outer shell (30) is the same as the shape of the second fixing block (390) on the second rising part (39). The shape of the third opening (33) is the same as the shape of the third fixing block (380) on the upper part of the first rising part (38).

9. A tibial plateau according to claim 1, characterized in that, The shape and size of the first recess (20) on the tibial pad (2) are consistent with the second fixing block (390) on the second rising part (39), and the shape and size of the second recess (21) are consistent with the third fixing block (380) on the upper part of the first rising part (38).

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