CN105496610B - A kind of adjustable anti-hip dislocation artificial semi-pelvis prosthesis - Google Patents

Abstract

The present invention relates to artificial prosthesis technical field, specifically a kind of adjustable anti-hip dislocation artificial semi-pelvis prosthesis, including ilium fixture, acetabular component and pubis fixture, the outer surface of described ilium fixture one end are provided with ilium fixture external screw thread；Ilium end connector is stretched out in the outer surface of the acetabular component, and the outer surface of the ilium end connector is provided with ilium end connector external screw thread；The externally threaded screw thread of ilium fixture is opposite towards screw thread externally threaded with ilium end connector direction.The invention has the advantages that hip mobility is suffered from increase, the prevention of postoperative dislocation of hip joint, prosthese installation and debugging are more flexible in art, reduce operation risk.

Description

An adjustable anti-hip dislocation artificial hemipelvic prosthesis

technical field

The invention relates to the technical field of artificial prostheses, in particular to an adjustable anti-hip dislocation artificial semi-pelvic prosthesis.

Background technique

Pelvic tumors involving the acetabulum often require functional reconstruction after resection. The customized hemipelvic prosthesis reconstruction can achieve early firm fixation, the anatomical continuity of the pelvic ring is well restored, and the length and shape of the limbs are satisfactory. Early weight-bearing requirements and good postoperative hip joint function are ideal reconstruction methods after resection of tumors involving the second area of the pelvis.

However, due to the lack of good soft tissue coverage and restrictive structure of the postoperative hemipelvic prosthetic hip joint, only relying on its own rigid structure, the incidence of postoperative dislocation is extremely high. Therefore, it is necessary to repeatedly adjust the acetabular abduction angle and anteversion angle during the operation. , The operation process is cumbersome, the range of motion of the affected limb of the patient is greatly restricted after the operation, and the occurrence of dislocation is often still unavoidable.

The invention patent with the application number "200810225315.0", the authorized announcement number "CN 101390781 B" and the title "An artificial half pelvic prosthesis" discloses an artificial half pelvic prosthesis, which includes The fixed seat and the spherical cup with artificial acetabular function, it also includes a connecting body and a screw for connecting the fixed seat and the spherical cup; the connecting body is composed of two plate-shaped connecting arms fixed as a whole, Each plate-shaped connecting arm is provided with a bolt through hole matching the screw, and the angle between the axes of the two bolt through-holes is 75°-90°; in the two plate-shaped connecting arms, A plate-shaped connecting arm connects a surface provided with bolts through with a surface of the other plate-shaped connecting arm not provided with bolt-through holes, and the angle between the two surfaces is at least 90°; the connecting body The two plate-shaped connecting arms are respectively connected with the spherical cup and the fixed seat by bolts through the bolt through holes. The positions of the fixed seat fixed on the ilium, the spherical cup with artificial acetabular function, and the connecting body connecting the fixed seat and the spherical cup are fixed. Once implanted, fine-tuning cannot be done.

The invention patent with application number "201010572478.3", application publication number "CN 102008361 A" and title "artificial half pelvic prosthesis for restoring continuity from lumbosacral vertebra to hip joint" discloses an artificial half pelvic prosthesis , comprising a metal acetabular cup and at least two metal rods connected with the metal acetabular cup. For specific use, pedicle screws are first implanted in the vertebral bodies of the sacrum or lower lumbar vertebrae, and then the artificial hemipelvic prosthesis is implanted. The curvature of the metal rod is adjusted so that the metal acetabular cup is close to the normal anatomical position, and then the The principle on the metal rod is that the end of the metal acetabular cup is directly connected to the groove of the pedicle screw through a nut. After reconfirming the position of the artificial hemipelvic prosthesis, the connection of the entire prosthesis can be completed. The metal rod described in this invention patent has no special structure at its end away from the metal acetabular cup, and can be fixedly connected with the pedicle screw after being cut at an appropriate length. Once implanted, fine-tuning cannot be done.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a hemipelvic prosthesis that increases the range of motion of the affected hip, prevents postoperative hip joint dislocation, and is more flexible in the installation and adjustment of the prosthesis during the operation.

In order to achieve the above object, the present invention provides an adjustable anti-hip dislocation artificial hemi-pelvic prosthesis, including an iliac fixation, an acetabular prosthesis and a pubic fixation,

The outer surface of one end of the ilium fixture is provided with an external thread of the iliac fixture;

The outer surface of the acetabular prosthesis protrudes from the iliac end connector, and the outer surface of the iliac end connector is provided with an iliac end connector external thread;

The thread orientation of the external thread of the ilium fixation member is opposite to that of the external thread of the iliac end connector;

The hemi-pelvic prosthesis also includes an iliac socket connecting the ilium fixture and the ilium end joint, the inner wall of the iliac socket is provided with Down's thread, and one end of the ilium socket is threadedly connected to the iliac fixture , the other end of the ilium joint is threadedly connected to the ilium end connector;

One end of the pubic fixation member is installed on the outer surface of the acetabular prosthesis. The thread orientation of the external thread of the iliac fixture is opposite to the thread orientation of the external thread of the iliac end connector, that is, the external thread of the iliac fixture is a left-handed thread, and the external thread of the iliac end connector is a right-handed thread, It may also be that the external thread of the ilium fixation member is a right-handed thread, and the external thread of the iliac end connector is a left-handed thread. The inner wall of the ilium socket is provided with Down's threads, and the Down's threads are composed of left-handed threads and right-handed threads overlapping and alternately. Thread the ilium fixing part and the ilium end joint to the ilium connecting pipe and tighten them. This connection method replaces the previous use of groove snap fit or multiple screws to directly install the ilium fixture and the acetabular prosthesis. Since the Down's thread has both left-handed and right-handed threads, when subjected to When external forces such as shock and vibration cause loosening of the threaded connection in one direction of rotation, it happens to be the tightening direction of the thread in the other direction of rotation. Therefore, the connection method is tighter, firmer and more stable. In addition, by connecting the iliac crest to the ilium fixture and the ilium end connector, the distance between the ilium and the acetabular prosthesis can be adjusted during the operation, thereby adjusting the position of the center of rotation of the hip joint. The installation and debugging of the prosthesis during operation is more flexible.

Preferably, the acetabular prosthesis includes a metal acetabular cup, a polyethylene liner, a ceramic femoral head and a femoral stem prosthesis, wherein:

The metal acetabular cup, the polyethylene liner and the ceramic femoral head are set sequentially from outside to inside;

The metal acetabular cup is hemispherical, and the inner surface of the metal acetabular cup is covered with a ceramic layer;

The polyethylene liner is hemispherical;

The ceramic femoral head is spherical, and the femoral stem prosthesis is installed on the ceramic femoral head. The inner surface of the metal acetabular cup is a highly polished metal surface, and the inner surface of the metal acetabular cup is covered with a ceramic layer under the joint action of mild press-fitting and negative pressure, so that the ceramic layer of the metal acetabular cup and its inner surface The layers form a tight bond. The polyethylene lining is in the shape of a hemisphere and has two moving surfaces, wherein the outer surface of the polyethylene lining is movably connected with the ceramic layer, and the inner surface is movably connected with the ceramic femoral head. The way the polyethylene liner is matched with the metal acetabular cup and the ceramic femoral head makes the acetabular prosthesis have a double-action structure, which makes the hip joint more flexible, and compared with the existing acetabular prosthesis , The friction interface between the ceramic layer and the polyethylene lining reduces the wear of the prosthesis, avoids the generation of particles caused by metal wear, reduces the incidence of postoperative complications such as prosthesis loosening, and prolongs the service life of the prosthesis. The femoral stem prosthesis is used to drive into the femoral medullary cavity. The metal acetabulum is designed to have an ultra-large diameter greater than 60mm, and the diameter of the ceramic lining and the outer diameter of the polyethylene lining both match the inner diameter of the metal acetabulum. This design can reduce tedious adjustments during the operation and is beneficial Increase the range of motion of the affected hip and prevent postoperative hip dislocation.

Preferably, the ilium fixation piece and the pubic fixation piece are respectively provided with scale bars. According to the position of the scale bar, the iliac crest fixer and the depth at which the ilium crest fixer is screwed into the ilium socket are properly selected, so as to realize the adjustment of the distance between the ilium and the pubic bone.

Preferably, the ilium end joint is composed of an ilium end ear plate and an ilium end support plate, and the ilium end ear plate and the ilium end support plate are respectively provided with through holes, and the first bolt bearing passes through the iliac end The through holes on the ear plate at the bone end and the support plate at the ilium end form a hinged structure. After the truncation data is obtained by the computer before operation, the truncation size may be temporarily fine-tuned to meet special requirements during the operation. At this time, it can be adapted by adjusting the angle between the ear plate at the ilium end and the support plate at the ilium end Size requirements for different patients.

Furthermore, the outer surface of one end of the pubic fixation is provided with external threads of the pubic fixation;

The outer surface of the acetabular prosthesis protrudes from the pubic end joint, and the outer surface of the pubic end joint is provided with external threads of the pubic end joint;

The thread orientation of the external thread of the pubic fixation member is opposite to that of the external thread of the pubic end connector;

The hemipelvic prosthesis also includes a pubic socket connecting the pubic fixation piece and the pubic end joint, the inner wall of the pubic socket is provided with Down's thread, one end of the pubic socket is threaded with the pubic fixing piece, and the pubic socket is threaded. The other end is threadedly connected with the pubic end connector. The thread direction of the external thread of the pubic fixation part is opposite to that of the external thread of the pubic end connector, that is, the external thread of the pubic fixation part is a left-handed thread, and the external thread of the pubic end connector is a right-handed thread. The external thread of the pubic fixation part is a right-handed thread, and the external thread of the pubic end connector is a left-handed thread. The inner wall of the pubic socket is provided with Down's threads, and the Down's threads are composed of left-handed threads and right-handed threads overlapping and alternately. The pubic fixation piece and the pubic end connector are respectively threaded and tightened with the pubic socket. Since Tang's thread has both left-handed and right-handed threads at the same time, when the threaded connection in one direction is loosened due to external forces such as shock and vibration, it happens to be the tightening direction of the thread in the other direction. Therefore, , the connection is tighter, firmer and more stable. In addition, through the connection between the pubic fixation piece and the pubic end joint through the pubic socket, the prosthesis distance between the pubic bone and the acetabular prosthesis can be adjusted during the operation, thereby adjusting the position of the hip joint rotation center, so that the prosthesis Installation and debugging are more flexible.

Preferably, the pubic fixation piece and the pubic end connector are respectively provided with scale bars. According to the gear position of the scale bar, the depth of screwing the pubic fixation piece and the pubic end joint into the pubic tube is properly selected, so as to realize the adjustment of the distance between the ilium and the pubic bone.

Preferably, the pubic end joint is composed of the pubic end ear plate and the pubic end support plate, and the pubic end ear plate and the pubic end support plate are respectively provided with through holes, and the second bolt bearing passes through the pubic end ear plate and the pubic end A hinged structure is formed behind the through holes on the end support plate. After the truncation data is obtained by the computer before operation, the truncation size may be temporarily fine-tuned to meet special requirements during the operation. At this time, the angle between the pubic end ear plate and the pubic end support plate can be adjusted to adapt to different patients. size requirements.

The invention has the beneficial effects of increasing the range of motion of the affected hip, preventing postoperative dislocation of the hip, making the installation and debugging of the prosthesis more flexible during the operation, and reducing the operation risk.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the structural representation of acetabular prosthesis in the present invention;

Fig. 3 is the structural representation of metal acetabular cup in the present invention;

Fig. 4 is a cross-sectional view of the iliac crest socket in the present invention.

in:

1-Iliac Fixation 11-Iliac Fixation External Thread 2-Acetabular Prosthesis

21-Metal cup 22-Ceramic layer 23-Polyethylene lining

24-ceramic femoral head 25-femoral stem prosthesis 3-pubic fixation

31-Pubic Fixation External Thread 4-Iliac End Connector 41-Iliac End Connector External Thread

42-Iliac end ear plate 43-Iliac end support plate 5-Iliac end adapter

51-Down's thread 6-Pubic end connector 61-Pubic end connector external thread

62-Pubic end ear plate 63-Pubic end support plate 7-Pubic bone connection

71-Down's thread 8-First bolt bearing 9-Second bolt bearing

100-scale bar

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

An adjustable anti-hip dislocation artificial hemipelvic prosthesis as shown in Figures 1 and 2, including an iliac crest fixer 1, an acetabular prosthesis 2 and a pubic fixer 3,

The external surface of one end of the ilium fixation part 1 is provided with an external thread 11 of the ilium fixation part;

The outer surface of the acetabular prosthesis 2 protrudes from the iliac end joint 4, and the outer surface of the iliac end joint 4 is provided with an iliac end joint external thread 41;

The thread orientation of the external thread 11 of the ilium fixation member is opposite to the thread orientation of the external thread 41 of the ilium end connector;

The hemipelvic prosthesis also includes an ilium connecting piece 5 connecting the ilium fixture 1 and the ilium end joint 4, as shown in Figure 2, the inner wall of the iliac connecting piece 5 is provided with Down's thread 51, the iliac One end of the bone connecting pipe 5 is threadedly connected to the iliac bone fixture 1, and the other end of the iliac bone connecting pipe 5 is threadedly connected to the ilium end connector 4;

One end of the pubic fixation member 3 is installed on the outer surface of the acetabular prosthesis 2 . The thread direction of the external thread 11 of the ilium fixation part is opposite to the thread direction of the external thread 41 of the ilium end connector, that is, the external thread 11 of the ilium fixation part is a left-handed thread, and the external thread 41 of the ilium end connector is For the right-handed thread, the external thread 11 of the iliac crest fixer may be a right-handed thread, and the external thread 41 of the ilium end joint may be a left-handed thread. The inner wall of the ilium socket 5 is provided with Down's thread 51, and the Down's thread 51 is composed of overlapping and alternating left-handed threads and right-handed threads. Screw the ilium fixing part 1 and the ilium end connector 4 to the ilium connecting tube 5 and tighten them respectively. This connection method replaces the previous use of groove snap fit or multiple screws to directly install the ilium fixture 4 and the acetabular prosthesis 2. Since the Down's thread has both left-handed and right-handed threads, When the threaded connection in one direction of rotation is loosened due to external forces such as shock and vibration, it happens to be the tightening direction of the thread in the other direction of rotation. Therefore, the connection method is tighter, firmer and more stable. In addition, by connecting the iliac crest to the ilium fixation piece 1 and the ilium end connector 4 through the ilium connecting tube, the prosthesis distance between the ilium and the acetabular prosthesis 2 can be adjusted during the operation, thereby adjusting the rotation center of the hip joint. The position makes the installation and debugging of the prosthesis more flexible during operation.

Example 2:

An adjustable anti-hip dislocation artificial hemipelvic prosthesis, the rest are the same as in embodiment 1, as shown in Figure 3, the acetabular prosthesis 2 includes a metal acetabular cup 21, a polyethylene liner 23, a ceramic femoral head 24 and a femoral Stem prosthesis 25, wherein:

The metal acetabular cup 21, the polyethylene liner 23 and the ceramic femoral head 24 are set sequentially from outside to inside;

As shown in Figure 4, the metal acetabular cup 21 is in the shape of a hemisphere, and the inner surface of the metal acetabular cup 21 is covered with a ceramic layer 22;

The polyethylene liner 23 is hemispherical;

The ceramic femoral head 24 is spherical, and the femoral stem prosthesis 25 is installed on the ceramic femoral head 24 . As shown in Figures 2 and 3, the acetabular prosthesis 2 and the metal acetabular cup 21 in the acetabular prosthesis 2, the inner surface of the metal acetabular cup 21 is a highly polished metal surface, and the inner surface of the metal acetabular cup 21 is The surface is covered with a ceramic layer 22 under the joint action of mild press-fitting and negative pressure, so that the metal acetabular cup 21 and the ceramic layer 22 on its inner surface form a tight bond. The polyethylene lining 23 is hemispherical and has two moving surfaces, wherein the outer surface of the polyethylene lining 23 is movably connected with the ceramic layer 22 , and the inner surface is movably connected with the ceramic femoral head 24 . The manner in which the polyethylene liner is matched and connected with the metal acetabular cup 21 and the ceramic femoral head 24 makes the acetabular prosthesis 2 have a double-moving structure, which makes the hip joint more flexible, and is more flexible than the existing acetabular prosthesis. Generally speaking, the friction interface between the ceramic layer 22 and the polyethylene lining 23 reduces the wear of the prosthesis, avoids the generation of particles caused by metal wear, reduces the incidence of postoperative complications such as prosthesis loosening, and prolongs the use of the prosthesis. life. The femoral stem prosthesis 25 is used to drive into the femoral medullary cavity. The metal acetabulum 21 is designed to have a super-large diameter greater than 60 mm, and the diameter of the ceramic lining and the outer diameter of the polyethylene lining 23 are both matched with the inner diameter of the metal acetabulum 21. This design can reduce cumbersome adjustments during the operation , which is beneficial to increase the range of motion of the affected hip and prevent postoperative hip dislocation.

Example 3:

An adjustable anti-hip dislocation artificial hemipelvic prosthesis, the rest of which are the same as in Embodiment 2, and the ilium fixation part 1 and the pubic bone fixation part 3 are provided with scale bars 100 respectively. According to the position of the scale bar 100 , the screwing depth of the ilium fixation part 1 and the ilium fixation part 4 into the ilium connection tube 5 is properly selected, so as to realize the adjustment of the distance between the ilium and the pubic part.

The described ilium end joint 4 is made up of the ilium end ear plate 42 and the ilium end support plate 43, and the described ilium end ear plate 42 and the ilium end support plate 43 respectively offer through holes, and the first bolt bearing 8 After passing through the through holes on the ear plate 42 of the ilium end and the support plate 43 of the ilium end, a hinged structure is formed. After the truncation data is obtained by the computer before the operation, the truncation size may be temporarily fine-tuned to meet special requirements during the operation. At this time, the angle between the ear plate 43 at the ilium end and the support plate 44 at the ilium end can be adjusted. To meet the size requirements of different patients.

The outer surface of one end of the pubic fixation 3 is provided with an external thread 31 of the pubic fixation;

The outer surface of the acetabular prosthesis 2 protrudes from the pubic end joint 6, and the outer surface of the pubic end joint 6 is provided with an external thread 61 of the pubic end joint;

The thread orientation of the external thread 31 of the pubic fixation member is opposite to the thread orientation of the external thread 61 of the pubic end joint;

The hemipelvic prosthesis also includes a pubic socket 7 connecting the pubic fixation piece 3 and the pubic end connector 6, the pubic socket 7 has the same structure as the iliac socket 5, and the inner wall of the pubic socket 7 is provided with Down's thread 71, One end of the pubic socket 7 is threaded to the pubic fixation member 3 , and the other end of the pubic socket 7 is threaded to the pubic joint 6 . The thread orientation of the external thread 31 of the pubic fixation member is opposite to that of the external thread 61 of the pubic fixation member, that is, the external thread 31 of the pubic fixation member is a left-handed thread, and the external thread 61 of the pubic end connector is a right-handed thread. It may be that the external thread 31 of the pubic fixation member is a right-handed thread, and the external thread 61 of the pubic end joint is a left-handed thread. The inner wall of the pubic socket 7 is provided with Down's thread 71 , and the Down's thread 71 is composed of overlapping and alternating left-handed threads and right-handed threads. The pubic fixation piece 3 and the pubic end connector 6 are respectively threaded and tightened with the pubic socket 7 . Since Tang's thread has both left-handed and right-handed threads at the same time, when the threaded connection in one direction is loosened due to external forces such as shock and vibration, it happens to be the tightening direction of the thread in the other direction. Therefore, , the connection is tighter, firmer and more stable. In addition, the pubic socket 7 is connected to the pubic fixation piece 3 and the pubic end joint 6 respectively, so that the distance between the pubic bone and the acetabular prosthesis 2 can be adjusted during the operation, thereby adjusting the position of the center of rotation of the hip joint, so that The installation and debugging of the prosthesis during operation is more flexible.

Scale bars 100 are respectively provided on the pubic fixation member 3 and the pubic end joint 6 . According to the gear position of the scale bar 100, the depth at which the pubic fixation member 3 and the pubic end joint 6 are screwed into the pubic socket 7 is properly selected, so as to realize the adjustment of the distance between the ilium and the pubic member.

The described pubic end joint 6 is made up of the pubic end ear plate 62 and the pubic end support plate 63, and the described pubic end ear plate 62 and the pubic end support plate 63 respectively offer through holes, and the second bolt bearing 9 passes through the pubic end ear The through holes on the plate 62 and the pubic end support plate 63 form a hinged structure behind. After the truncation data is obtained by the computer before the operation, the truncation size may be temporarily fine-tuned to meet special requirements during the operation. At this time, it can be adapted by adjusting the angle between the pubic end ear plate 63 and the pubic end support plate 64 Size requirements for different patients.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments, and those skilled in the art can also make various equivalents without violating the spirit of the present invention. These equivalent modifications or replacements are all included within the scope defined by the claims of the present application.

Claims (7)

1. a kind of adjustable anti-hip dislocation artificial semi-pelvis prosthesis, including ilium fixture (1), acetabular component (2) and pubis are consolidated Determine part (3), it is characterised in that

The outer surface of described ilium fixture (1) one end is provided with ilium fixture external screw thread (11)；

Ilium end connector (4) is stretched out in the outer surface of the acetabular component (2), and the outer surface of the ilium end connector (4) is provided with ilium Epiphysis joint external screw thread (41)；

The screw thread direction of the ilium fixture external screw thread (11) is opposite with the screw thread direction of ilium end connector external screw thread (41)；

The semi-pelvis prosthesis also includes the ilium adapter (5) for connecting the ilium fixture (1) and ilium end connector (4), the ilium The inwall of bone adapter (5) is provided with Tang thread (51), and one end of the ilium adapter (5) is threadedly coupled with ilium fixture (1), The other end of the ilium adapter (5) is threadedly coupled with ilium end connector (4)；

One end of the pubis fixture (3) is arranged on the outer surface of the acetabular component (2).

2. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 1, it is characterised in that the acetabular component (2) metal acetabular cup (21), polyethylene liner (23), ceramic femoral head (24) and type femoral bone end prosthesis (25) are included, wherein：

The metal acetabular cup (21), polyethylene liner (23) and ceramic femoral head (24) are arranged from outside to inside successively；

The metal acetabular cup (21) is in hemisphere planar, and the inner surface of the metal acetabular cup (21) covers ceramic layer (22)；

The polyethylene liner (23) is in hemisphere planar；

The ceramic femoral head (24) is in spherical, and the type femoral bone end prosthesis (25) is installed on the ceramic femoral head (24).

3. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 1, it is characterised in that described ilium is consolidated Determine to be respectively equipped with scale strip (100) on part (1) and pubis fixture (3).

4. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 1, it is characterised in that described ilium end Joint (4) is made up of ilium end otic placode (42) and ilium end supporting plate (43), ilium end otic placode (42) and the support of ilium end Through hole is opened up on plate (43) respectively, the first bolt bearing (8) is passed through on ilium end otic placode (42) and ilium end supporting plate (43) Articulated structure is formed after through hole.

5. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 1, it is characterised in that described pubis is consolidated The outer surface for determining part (3) one end is provided with pubis fixture external screw thread (31)；

Pubis end connector (6) is stretched out in the outer surface of the acetabular component (2), and the outer surface of the pubis end connector (6) is provided with shame Epiphysis joint external screw thread (61)；

The screw thread direction of the pubis fixture external screw thread (31) is opposite with the screw thread direction of pubis end connector external screw thread (61)；

The semi-pelvis prosthesis also includes the pubis adapter (7) for connecting the pubis fixture (3) and pubis end connector (6), the shame The inwall of bone adapter (7) is provided with Tang thread (71), and one end of the pubis adapter (7) is threadedly coupled with pubis fixture (3), The other end of the pubis adapter (7) is threadedly coupled with pubis end connector (6).

6. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 5, it is characterised in that described ilium end Scale strip (100) is respectively equipped with joint (4) and pubis end connector (6).

7. adjustable anti-hip dislocation artificial semi-pelvis prosthesis according to claim 5, it is characterised in that described pubis end Joint (6) is made up of pubis end otic placode (62) and pubis end supporting plate (63), pubis end otic placode (62) and the support of pubis end Through hole is opened up on plate (63) respectively, the second bolt bearing (9) is passed through on pubis end otic placode (62) and pubis end supporting plate (63) Articulated structure is formed after through hole.