CN115969496A - Detachable expansion screw and internal fixing frame for pelvis front ring - Google Patents

Abstract

The invention provides a detachable expansion screw for a front pelvic ring and an internal fixing frame, which comprise a main screw, a trapezoidal expansion piece, a trapezoidal sliding block and an internal connecting rod; the inside of main nail is equipped with the cavity, and the cavity runs through the axial of main nail, and main nail includes integrated into one piece's nail pole and pin fin, and the tip that the pin fin was kept away from to the nail pole sets up the draw-in groove of the trapezoidal inflation of joint, and trapezoidal slider makes the outside both sides inflation of trapezoidal inflation piece to the nail pole through to the pin fin direction slip in trapezoidal inflation piece, and the one end and the trapezoidal slider of in-connection pole are connected, and the in-connection pole is used for penetrating and carries in the main nail and draw trapezoidal slider to slide. The internal fixing frame comprises a connecting cross rod and at least two screws, and the screws are connected through the connecting cross rod. The trapezoidal expansion piece is arranged at the end part of the main nail far away from the nail head, so that the main nail is expanded in a body, and the stability of the main nail in the body is improved.

Description

Detachable expansion screw and internal fixing frame for pelvis front ring

Technical Field

The invention relates to the technical field of orthopedic medical instruments, in particular to a detachable expansion screw for a pelvis front ring and an internal fixing frame.

Background

Aiming at the fragile old Pelvic Anterior Ring injury, currently, a Minimally Invasive percutaneous Anterior Pelvic Internal fixation (Minimally Invasive Anterior Pelvic Internal Ring Internal fixation) is generally adopted clinically. The most widely used and effective instrument in this procedure is called an internal fixation frame (INFIX).

The internal fixing frame is designed primarily to stabilize the anterior pelvic ring, so that injury of the anterior pelvic ring, including pubic symphysis and pubic ramus fracture, is the best indication. Because the internal fixation frame is located abdomen pelvis the place ahead, subjective uncomfortable sense can appear to the patient of size emaciation, especially to sitting the position, the postoperative usually appears subjective uncomfortable sense and influences daily life, nevertheless should discomfortable sense disappear promptly after taking out the internal fixation frame. Therefore, after the fracture heals, the internal fixation frame should be removed by a secondary operation. However, in some special fractures, the main nail needs to be left in place for a long time, and the other parts such as the connecting cross rod are taken out, so that how to improve the fixing stability of the main nail left in the body becomes a problem to be solved urgently in the clinical medical field.

Disclosure of Invention

In view of the above, the present invention provides a detachable expansion screw for a front pelvic ring and an internal fixation frame, wherein the trapezoidal expansion member is disposed at an end of the main nail far from the head of the main nail, so that the main nail expands in vivo, thereby improving the stability of the main nail in vivo fixation.

Therefore, the invention provides the following technical scheme:

in a first aspect of the invention, a detachable expansion screw for a front pelvis ring is provided, which comprises a main nail, a trapezoidal expansion piece, a trapezoidal sliding block and an inner connecting rod,

the main nail is internally provided with a cavity which penetrates through the axial direction of the main nail, the main nail comprises a nail rod and a nail head which are integrally formed, the end part of the nail rod, which is far away from the nail head, is provided with a clamping groove for clamping the trapezoidal expansion piece, the trapezoidal sliding block enables the trapezoidal expansion piece to expand towards the two sides of the outer part of the nail rod by sliding towards the direction of the nail head in the trapezoidal expansion piece,

one end of the inner connecting rod is connected with the trapezoidal sliding block, and the inner connecting rod is used for penetrating into the main nail and pulling the trapezoidal sliding block to slide.

Furthermore, the end part of the nail rod close to the nail head is provided with an internal thread, the two ends of the internal connecting rod are provided with external threads, the two external threads on the internal connecting rod are in the same direction, one external thread on the internal connecting rod is in threaded connection with the trapezoidal slider, the other external thread on the internal connecting rod is in threaded connection with the internal thread of the nail rod, and the trapezoidal slider is pulled towards the direction of the nail head while the internal connecting rod is screwed into the nail rod.

Furthermore, an inner screwing hole is formed in the end face, close to the nail head, of the inner connecting rod.

Further, the external thread on the nail rod comprises a fine thread and a coarse thread, the fine thread is close to the nail head, and the coarse thread is far away from the nail head.

Furthermore, a plurality of injection holes are formed in the side wall of one end, far away from the nail head, of the nail rod, and the injection holes are communicated with the cavity.

In a second aspect of the present invention, there is provided an internal fixation frame, which includes a connecting cross bar and at least two detachable expansion screws for the anterior pelvic ring according to the first aspect of the present invention, wherein the main screw is provided with a through hole for the connecting cross bar to pass through, the through hole is closer to the head relative to the inner connecting bar, and the connecting cross bar passes through the through hole to connect the detachable expansion screws for the anterior pelvic ring.

Furthermore, the connecting cross rod locking device further comprises a locking bolt used for locking the connecting cross rod, an internal thread matched with the locking bolt is formed in the nail head, and the locking bolt is screwed into the nail head to lock the connecting cross rod.

Further, the connecting rail includes elastic portions and rigid portions, which are alternately connected.

Further, the elastic part is a spring, and two end parts of the spring are respectively fixedly connected with the rigid part.

The technical scheme of the invention has the following advantages:

the invention provides a detachable expansion screw for a front pelvic ring and an internal fixing frame.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of a detachable expansion screw of the anterior pelvic ring according to the present invention;

FIG. 2 is an exploded view of a detachable expansion screw of the anterior pelvic ring according to the present invention;

FIG. 3 is a longitudinal cross-sectional view of a detachable expansion screw of the anterior pelvic ring according to the present invention;

FIG. 4 is a schematic illustration of the expansion process of a trapezoidal shaped expansion member according to the present invention;

FIG. 5 is a schematic structural view of a primary staple according to the present invention;

FIG. 6 is a schematic structural view of an internal mount according to the present invention;

fig. 7 is a schematic view of the construction of the connecting rail of the present invention.

In the figure, the position of the upper end of the main shaft,

1. a main nail; 11. a nail head; 12. a nail rod; 121. coarse thread; 122. fine thread; 123. an injection hole; 13. a card slot; 2. a trapezoidal expansion member; 3. a trapezoidal slider; 4. an inner connecting rod; 5. connecting the cross bars; 51. an elastic portion; 52. a rigid portion; 6. locking the bolt; 7. a slider; 8. a chute.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present disclosure, the word "exemplary" is used to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is presented to enable any person skilled in the art to make and use the invention. In the following description, details are set forth for the purpose of explanation. It will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known structures and processes are not shown in detail to avoid obscuring the description of the invention with unnecessary detail. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a detachable expansion screw and an internal fixing frame for a pelvis anterior ring, which can be used for postoperative fixation of pelvis anterior ring injury, such as pubis symphysis separation postoperative fixation and pubic ramus fracture postoperative fixation. As shown in fig. 1-3, the detachable expansion screw for the front pelvic ring comprises a main nail 1, a trapezoidal expansion piece 2, a trapezoidal sliding block 3 and an inner connecting rod 4, wherein a cavity is formed in the main nail 1 and penetrates through the main nail 1 in the axial direction, the main nail 1 comprises a nail rod 12 and a nail head 11 which are integrally formed, a clamping groove 13 for clamping the trapezoidal expansion piece 2 is formed in the end part, far away from the nail head 11, of the nail rod 12, and the clamping groove 13 penetrates through the cavity of the nail rod 12 in the radial direction and is communicated with the cavity; trapezoidal inflation piece 2 card is in the draw-in groove, and trapezoidal inflation piece 2 less tip is close to pin fin 11, and trapezoidal slider 3 makes trapezoidal inflation piece 2 expand to the outside both sides of nail pole 12 through sliding to 11 directions of pin fin in trapezoidal inflation piece 2, and the one end and the trapezoidal slider 3 of in-connection pole 4 are connected, and in-connection pole 4 is used for penetrating and carries in the main nail 1 and draw trapezoidal slider 3 to slide. During initial state, trapezoidal expanding piece 2 is in the unexpanded state, the both sides of trapezoidal expanding piece 2 do not expand out the both sides of nail pole 12, the inside of trapezoidal expanding piece 2 is equipped with the gliding trapezoidal cavity of confession trapezoidal slider 3, the opening of trapezoidal cavity sets up trapezoidal expanding piece 2 and keeps away from on the pin fin 11 terminal surface, supply trapezoidal slider 3 to get into inside the trapezoidal cavity, pin fin 11 is kept away from to the great one end of trapezoidal cavity, less one end is close to pin fin 11, set up the hole that supplies in-connection pole 4 to pass on the trapezoidal expanding piece 2 is close to the terminal surface of pin fin 11, make one of them tip of in-connection pole 4 pass this hole and get into in the trapezoidal cavity of trapezoidal expanding piece 2 and be connected with trapezoidal slider 3. When the trapezoidal sliding block 3 is lifted towards the nail head 11 direction, the trapezoidal sliding block 3 slides in the trapezoidal cavity to expand the two side wings of the trapezoidal expansion piece 2 towards the two sides outside the nail rod 12. Further improving the stability of the main nail 1 fixed in the body and reducing the movement of the main nail 1 to the outside when the human body moves.

The tip that nail pole 12 is close to pin fin 11 is equipped with the internal thread, and the both ends of in-connection pole 4 all are equipped with the external screw thread, and two external screw threads syntropy on the in-connection pole 4, one of them department external screw thread and 3 threaded connection of trapezoidal slider on the in-connection pole 4, another department external screw thread and the internal thread threaded connection of nail pole 12 on the in-connection pole 4, trapezoidal slider 3 is carried to the direction of pin fin 11 to the inside while of in-connection pole 4 precession nail pole 12. When using, put into trapezoidal expansion piece 2 with trapezoidal slider 3 earlier, then put into the draw-in groove of main nail 1 with trapezoidal expansion piece 2, with main nail 1, trapezoidal expansion piece 2 and trapezoidal slider 3 are arranged in internal treating the fixed position after, to main 1 internal screw-in internal connecting rod 4 of nail, at the precession in-process, the internal connecting rod 4 is kept away from the one end on nail head 11 earlier with the interior threaded connection on trapezoidal slider 3, continue precession internal connecting rod 4, because trapezoidal inner chamber is to trapezoidal slider 3's limiting displacement, trapezoidal slider 3 can not rotate, but turn into and slide to 11 directions of nail head along trapezoidal inner chamber, thereby strut the both sides wing of trapezoidal expansion piece 2.

In order to facilitate the screwing of the inner connecting rod 4, in some embodiments, an inner screwing hole is formed on the end surface of the inner connecting rod 4 close to the pin head 11. For example, the internal screwing hole is hexagonal, and the internal connecting rod 4 can be screwed by adopting an internal hexagonal wrench, so that the operation in the surgical process is facilitated.

As shown in fig. 4, the trapezoidal expanding member includes two trapezoidal members having openings at two side portions, the openings of the two trapezoidal members are opposite to each other, one of the trapezoidal members is nested into the other trapezoidal member from the opening at the side portion, the trapezoidal surfaces of the two trapezoidal members are provided with a sliding block 7 and a sliding groove 8 which are matched with each other, for example, the inner surface of the trapezoidal surface of the external trapezoidal member is provided with the sliding block 7, the outer surface of the trapezoidal surface of the internal trapezoidal member is provided with the sliding groove 8, the direction of the sliding groove 8 is parallel to the radial direction of the main nail, the sliding block 7 is clamped into the sliding groove 8 and can slide along the sliding groove 8, and two ends of the sliding groove 8 are sealed, so as to prevent the sliding block 7 from slipping out of the sliding groove 8. The sliding block 7 and the sliding groove 8 are only arranged near the smaller side (namely the side close to the nail head) of the trapezoidal surface, or the sliding block 7 and the sliding groove 8 which are matched are arranged near the larger side and the smaller side of the trapezoidal surface. During initial state, two trapezoidal components overlap, slide to the pin fin direction along with trapezoidal slider, and trapezoidal slider struts the distance between two trapezoidal components, and slider 7 and 8 relative sliding of spout, under the guide effect of spout 8, two trapezoidal components slide to both sides simultaneously for trapezoidal inflation piece expands. Trapezoidal slider slides towards the pin head direction more, and trapezoidal expanding member expanded degree is bigger, because the tip of spout 8 is confined, slider 7 also can not the roll-off spout 8, and the inside of trapezoidal expanding member is supported by trapezoidal slider, and the blind end of spout 8 plays limiting displacement for trapezoidal expanding member keeps this inflation state. And because the internal connecting rod is in threaded connection with the main nail, no artificial external force is applied, the trapezoidal sliding block cannot slide in the trapezoidal expansion piece, and the stable expansion supporting effect of the trapezoidal expansion piece is realized. And in the process that the trapezoidal expansion piece is propped open, the trapezoidal expansion piece can only expand towards the two side wings due to the limiting effect of the clamping groove.

As shown in FIG. 5, in some embodiments, the external threads on shank 12 include coarse threads 121 and fine threads 122, fine threads 122121 are proximal to head 11, and coarse threads 121122 are distal to head 11. Specifically, the coarse thread 121 has high strength and good fixing performance; the fine thread 122 has good sealing performance, and the fine thread 122 has better anti-loosening performance than the coarse thread 121 on the premise of not taking anti-loosening measures, but the fine thread 122 has low strength. Therefore, providing the screw threads on the shank 12 as the coarse thread 121 and the fine thread 122 can effectively enhance the holding force of the main nail 1. The clamping groove for clamping the trapezoid expansion piece 2 is formed in the position of the coarse thread 121, and fixing strength is guaranteed.

In some optional embodiments, a cavity is arranged inside the main nail 1, the cavity penetrates through the axial direction of the main nail 1, and the kirschner wire can penetrate through the cavity on the main nail 1, so that the main nail 1 can be accurately placed in the pelvic fracture part through the guidance of the kirschner wire, and the fixation of the main nail 1 on the pelvic fracture is effectively promoted. Specifically, when the guiding is performed through the kirschner wire, firstly, one kirschner wire is arranged in the fracture, then the trapezoidal sliding block 3, the trapezoidal expansion piece 2 and the main nail 1 penetrate through the kirschner wire, then the detachable expansion screw of the pelvis front ring is arranged in the position of the kirschner wire, and finally the kirschner wire is withdrawn.

In some alternative embodiments, the side wall of the end of the shank 12 remote from the head 11 is provided with a plurality of injection holes 123, the injection holes 123 communicating with the cavity. After the main nail 1 is placed at the pelvic fracture, bone cement can be injected into the cavity from the nail head 11 of the main nail 1, and the bone cement can enter the pelvic fracture through the injection hole 123, so that the pelvic fracture can be recovered. Meanwhile, since the elderly generally suffer from osteoporosis, the degree of bone damage is severe when bone fracture occurs. Through putting into bone cement in main nail 1, can promote the mechanical strength of main nail 1, be favorable to the postoperative rehabilitation of fracture. The injection holes 123 may be distributed at both sides of the card slot.

The present embodiment further provides an internal fixation frame, as shown in fig. 6, comprising a connecting cross bar 5 and at least two detachable expansion screws of the anterior pelvic ring according to any one of the above embodiments, wherein the detachable expansion screws of the anterior pelvic ring are connected with each other through the connecting cross bar 5. The connecting cross rod 55 is utilized to connect a plurality of detachable expansion screws of the front pelvic ring together to form an internal fixing frame, which can play a better role in fixing fractured bones. The main nail 1 is provided with a through hole for the connecting cross rod 5 to pass through, the through hole is closer to the nail head 11 relative to the inner connecting rod 4, and the connecting cross rod 5 passes through the through hole to connect the detachable expansion screw of the pelvis front ring. The through hole can the slant setting, is certain contained angle with the axial of main nail 1, connects horizontal pole 5 slope and passes the through hole, and the slant through hole plays certain limiting displacement. Can set up spacing screw thread on connecting horizontal pole 5, increase frictional force and the spacing power between connecting horizontal pole 5 and the main nail 1 for the internal fixation frame is fixed more firmly and stable.

The conventional internal fixation frame uses two detachable expansion screws of the anterior pelvic ring and a connecting cross bar 5.

In some embodiments, the internal fixing frame further comprises a locking bolt 6 for locking the connecting cross rod 5, the nail head 11 is internally provided with an internal thread matched with the locking bolt 6, and the locking bolt 6 is screwed into the nail head 11 to lock the connecting cross rod 5. After the connecting cross rod 5 is inserted into the through hole in the main nail 1, the locking bolt 6 is screwed into the nail head 11, so that the end part of the locking bolt 6 is tightly pressed on the connecting cross rod 5, and the firmness and the stability of the fixing of the internal fixing frame are further improved.

An inner angle screwing hole can be formed in the end face of the locking bolt 6, the locking bolt 6 is screwed into the inner angle screwing hole through an inner angle wrench, the end face of the locking bolt 6 can be flush with the end face of the nail head 11, and discomfort of a patient is reduced.

In some alternative embodiments, as shown in fig. 7, the connecting rail 5 comprises elastic portions 51 and rigid portions 52, the elastic portions 51 and the rigid portions 52 being alternately connected. Specifically, when a plurality of detachable expansion screws for the anterior pelvic ring are connected by the connecting cross bar 5, the rigid portion 52 of the connecting cross bar 5 is snapped into the through hole of the main nail 1. Meanwhile, the cross rod 5 can be connected in a bending mode through the elastic part 51 between the two rigid parts 52, and then when the internal fixing frame is placed in, the cross rod 5 is connected in a bending mode, so that the placing and connecting functions of the cross rod 5 are facilitated, and a better fixing effect on pelvic fracture can be achieved.

The elastic portion 51 is a spring, and both ends of the spring are fixedly connected to the rigid portions 52, respectively. The connecting cross rod 5 can be bent under the action of the spring, so that the internal fixing frame can fix the fracture part conveniently. It will be appreciated by those skilled in the art that the spring 51 is not limited to the present invention, and the spring 51 formed by other structures or materials, such as a silicone rod and a rod-shaped structure formed by a metal mesh, is also within the scope of the present invention.

In some possible embodiments, the fracture of the patient is fixed by the internal fixing frame by the following specific processes:

(1) The trapezoidal sliding block 3 is placed into the trapezoidal expansion piece 2, then the trapezoidal expansion piece 2 is clamped in the clamping groove of the main nail 1, the two side wings of the trapezoidal expansion piece 2 do not protrude out of the main nail 1, and the main nail 1, the trapezoidal expansion piece 2 and the trapezoidal sliding block 3 are placed into the fracture of a patient together;

(2) After the inner connecting rod 4 is screwed into the main nail 1 and the end part of the inner connecting rod 4 is connected with the trapezoidal sliding block 3, an inner angle wrench is continuously used for screwing the inner connecting rod 4 into the main nail 1, the trapezoidal sliding block 3 slides in the trapezoidal expansion piece 2 towards the nail head 11, and the two side wings of the trapezoidal expansion piece 2 expand and are supported to the two outer sides of the main nail 1;

(3) After two or more main nails 1 are fixed at the fracture of a patient, the connecting cross rods 5 sequentially penetrate through the through holes of the main nails 1 and connect the expansion screws;

(4) The locking bolt 6 is screwed into the nail head 11 of the main nail 1 by using an inner angle wrench until the end part of the locking bolt 6 positioned in the main nail 1 is propped against the connecting cross rod 5, so that the connecting cross rod 5 is compressed.

In some possible embodiments, by keeping the main nail 1 at the fracture of the patient and removing the rest of the main nail 1, the following process is implemented:

(1) Screwing out the locking bolt 6 from the nail head 11 of the main nail 1;

(2) The main nail 1 is retained at the fracture site of the patient by taking the connecting rail 5 out of the through hole of the main nail 1 by bending the connecting rail 5, and then taking the connecting rail 55 out of the patient.

In the process of screwing out the locking bolt 6 and pulling out the connecting cross rod 5, due to the expansion limiting effect of the trapezoidal expansion piece 2, the possibility of sliding and slipping of the main nail 1 is reduced, and the fixing stability of the main nail 1 is improved.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims (9)

1. A detachable expansion screw for a front pelvic ring is characterized by comprising a main nail (1), a trapezoidal expansion piece (2), a trapezoidal sliding block (3) and an inner connecting rod (4),

the interior of the main nail (1) is provided with a cavity, the cavity penetrates through the axial direction of the main nail (1), the main nail (1) comprises a nail rod (12) and a nail head (11) which are integrally formed, the end part, far away from the nail head (11), of the nail rod (12) is provided with a clamping groove (13) for clamping the trapezoidal expansion piece (2), the trapezoidal sliding block (3) slides towards the direction of the nail head (11) in the trapezoidal expansion piece (2) to enable the trapezoidal expansion piece (2) to expand towards the two outer sides of the nail rod (12),

one end of the inner connecting rod (4) is connected with the trapezoidal sliding block (3), and the inner connecting rod (4) is used for penetrating into the main nail (1) and pulling the trapezoidal sliding block (3) to slide.

2. The detachable expansion screw for anterior pelvic ring according to claim 1, wherein the end of the screw rod (12) near the screw head (11) is provided with an internal thread, both ends of the internal connection rod (4) are provided with external threads, the two external threads on the internal connection rod (4) are in the same direction, one external thread on the internal connection rod (4) is in threaded connection with the trapezoidal slider (3), the other external thread on the internal connection rod (4) is in threaded connection with the internal thread on the screw rod (12), and the internal connection rod (4) is screwed into the screw rod (12) and simultaneously pulls the trapezoidal slider (3) towards the screw head (11).

3. The detachable expansion screw of anterior pelvic ring according to claim 2, characterized in that the inner connecting rod (4) has an inner screwed hole on its end face near the head (11).

4. The detachable expansion screw of anterior pelvic ring according to claim 1, characterized in that the external thread on the shank (12) comprises a fine thread (122) and a coarse thread (121), the fine thread being close to the head (11) and the coarse thread (121) being remote from the head (11).

5. The detachable expansion screw of anterior pelvic ring according to claim 1, characterized in that the side wall of the end of the shank (12) remote from the head (11) is provided with a plurality of injection holes (123), the injection holes (123) communicating with the cavity.

6. Internal fixator, characterized in that it comprises a connecting cross-bar (5) and at least two detachable expansion screws for the anterior pelvic ring according to any one of claims 1 to 5, said main nail (1) being provided with a through hole for the passage of said connecting cross-bar (5), said through hole being closer to said head (11) than to said internal connecting bar (4), said connecting cross-bar (5) passing through said through hole to connect said detachable expansion screws for the anterior pelvic ring.

7. The internal fixation frame as claimed in claim 6, further comprising a locking bolt (6) for locking the connecting cross bar (5), wherein the nail head (11) is internally provided with an internal thread matching with the locking bolt (6), and the locking bolt (6) is screwed into the nail head (11) to lock the connecting cross bar (5).

8. Internal mount according to claim 6 or 7, characterized in that the connecting rail (5) comprises elastic parts (51) and rigid parts (52), the elastic parts (51) and the rigid parts (52) being alternately connected.

9. Internal mount according to claim 8, characterized in that the elastic part (51) is a spring, the two ends of which are fixedly connected with the rigid part (52), respectively.

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