Removable expansion screws and internal fixator for the anterior pelvic ring

Abstract

The present invention provides a detachable expansion screw and internal fixator for the anterior pelvic ring, comprising a main nail, a trapezoidal expansion piece, a trapezoidal slider, and an internal connecting rod; a cavity is provided inside the main nail, and the cavity runs through the axial direction of the main nail; the main nail comprises an integrally formed nail rod and a nail head; a slot for clamping the trapezoidal expansion piece is provided at the end of the nail rod away from the nail head; the trapezoidal slider slides in the trapezoidal expansion piece toward the nail head, causing the trapezoidal expansion piece to expand toward the outer sides of the nail rod; one end of the internal connecting rod is connected to the trapezoidal slider, and the internal connecting rod is used to penetrate into the main nail and pull the trapezoidal slider to slide. The internal fixator comprises a connecting cross bar and at least two of the above-mentioned screws, and the screws are connected by a connecting cross bar. The present invention provides a trapezoidal expansion piece at the end of the main nail away from the nail head, causing it to expand in the body, thereby improving the stability of the main nail fixed in the body.

Description

Technical Field

[0001] The present invention relates to the technical field of orthopedic medical devices, and in particular to a detachable expansion screw and an internal fixator for a pelvic anterior ring. Background Art

[0002] Minimally invasive percutaneous anterior pelvic ring internal fixation (INFIX) is currently the most widely used and effective device in this procedure for elderly patients with fragile anterior pelvic ring injuries.

[0003] The original intention of the design of the internal fixator is to stabilize the anterior pelvic ring, so anterior pelvic ring injuries, including pubic symphysis separation and pubic ramus fractures, are its best indications. Because the internal fixator is located in the lower abdomen in front of the pelvis, thin patients will experience subjective discomfort, especially in the sitting position. Subjective discomfort usually occurs after surgery and affects daily life, but the discomfort disappears after the internal fixator is removed. Therefore, after the fracture heals, a second operation should be performed to remove the internal fixator. However, some special fractures require the main nail to be retained for a long time, and the remaining parts such as the connecting cross bar must be removed. How to improve the fixation stability of the main nail retained in the body has become an urgent problem to be solved in the clinical medical community. Summary of the Invention

[0004] In view of this, the present invention provides a detachable expansion screw and internal fixator for the anterior pelvic ring, which increases the stability of the main screw fixation in the body by arranging a trapezoidal expansion piece at the end of the main screw away from the screw head so that the main screw expands in the body.

[0005] To this end, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a detachable expansion screw for the anterior pelvic ring, comprising a main screw, a trapezoidal expansion member, a trapezoidal slider and an inner connecting rod.

[0007] The main nail is provided with a cavity inside, and the cavity runs through the axial direction of the main nail. The main nail includes an integrally formed nail rod and a nail head. The end of the nail rod away from the nail head is provided with a slot for clamping the trapezoidal expansion member. The trapezoidal slider slides in the trapezoidal expansion member toward the nail head, so that the trapezoidal expansion member expands toward both sides of the outside of the nail rod.

[0008] One end of the inner connecting rod is connected to the trapezoidal slider, and the inner connecting rod is used to penetrate into the main nail to pull the trapezoidal slider to slide.

[0009] Furthermore, the end of the nail rod near the nail head is provided with an internal thread, and both ends of the inner connecting rod are provided with external threads. The two external threads on the inner connecting rod are in the same direction, one of the external threads on the inner connecting rod is threadedly connected to the trapezoidal slider, and the other external thread on the inner connecting rod is threadedly connected to the internal thread of the nail rod. When the inner connecting rod is screwed into the interior of the nail rod, the trapezoidal slider is pulled toward the nail head.

[0010] Furthermore, an inner tightening hole is provided on the end surface of the inner connecting rod close to the nail head.

[0011] Furthermore, the external thread on the nail rod includes 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.

[0012] Furthermore, a side wall of the nail rod at one end away from the nail head is provided with a plurality of injection holes, and the injection holes are communicated with the cavity.

[0013] According to a second aspect of the present invention, an internal fixation frame is provided, comprising a connecting cross bar and at least two detachable expansion screws of 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 being closer to the screw head than the internal connecting rod, and the connecting cross bar passes through the through hole to connect the detachable expansion screws of the anterior pelvic ring.

[0014] Furthermore, it also includes a locking bolt for locking the connecting cross bar. The interior of the nail head is provided with an internal thread matching the locking bolt. The locking bolt is screwed into the nail head to lock the connecting cross bar.

[0015] Furthermore, the connecting cross bar includes an elastic portion and a rigid portion, and the elastic portion and the rigid portion are alternately connected.

[0016] Furthermore, the elastic part is a spring, and two ends of the spring are respectively fixedly connected to the rigid part.

[0017] The technical solution of the present invention has the following advantages:

[0018] The present invention provides a detachable expansion screw for the anterior pelvic ring and an internal fixator. A trapezoidal expansion piece is provided at the end of the main screw away from the screw head, so that the main screw expands in the body, thereby improving the fixation stability of the main screw in the body. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 2. It is a schematic structural diagram of a detachable expansion screw for the anterior pelvic ring according to the present invention;

[0021] Figure 2 is an exploded view of a detachable expansion screw for anterior pelvic ring according to the present invention;

[0022] Figure 3 is a longitudinal sectional view of the detachable expansion screw for the anterior pelvic ring according to the present invention;

[0023] Figure 4 is a schematic diagram of the expansion process of the trapezoidal expansion member according to the present invention;

[0024] Figure 5 is a schematic structural diagram of a main nail according to the present invention;

[0025] Figure 6 is a schematic structural diagram of an internal fixation frame according to the present invention;

[0026] Figure 7 It is a structural schematic diagram of the connecting cross bar of the present invention.

[0027] In the figure,

[0028] 1. Main nail; 11. Nail head; 12. Nail rod; 121. Coarse thread; 122. Fine thread; 123. Injection hole; 13. Slot; 2. Trapezoidal expansion piece; 3. Trapezoidal slider; 4. Inner connecting rod; 5. Connecting cross bar; 51. Elastic part; 52. Rigid part; 6. Locking bolt; 7. Slider; 8. Slide groove. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0031] In the present invention, the word "exemplary" is used to mean "serving as an example, illustration or description". Any embodiment described in the present invention as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the present invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present invention can be implemented without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed herein.

[0032] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The present invention provides a detachable expansion screw and internal fixator for the anterior pelvic ring, which can be used for postoperative fixation of anterior pelvic ring injuries, such as postoperative fixation of pubic symphysis separation and postoperative fixation of pubic ramus fracture. Figure 1-3As shown, the removable expansion screw of the anterior pelvic ring includes a main nail 1, a trapezoidal expansion piece 2, a trapezoidal slider 3 and an inner connecting rod 4. A cavity is provided inside the main nail 1, and the cavity passes through the axial direction of the main nail 1. The main nail 1 includes an integrally formed nail rod 12 and a nail head 11. A slot 13 for clamping the trapezoidal expansion piece 2 is provided at the end of the nail rod 12 away from the nail head 11. The slot 13 passes through the cavity of the nail rod 12 in the radial direction and is connected to the cavity; the trapezoidal expansion piece 2 is clamped in the slot, and the smaller end of the trapezoidal expansion piece 2 is close to the nail head 11. The trapezoidal slider 3 slides in the trapezoidal expansion piece 2 toward the nail head 11 so that the trapezoidal expansion piece 2 expands toward the outer sides of the nail rod 12. One end of the inner connecting rod 4 is connected to the trapezoidal slider 3, and the inner connecting rod 4 is used to penetrate into the main nail 1 and pull the trapezoidal slider 3 to slide. In the initial state, the trapezoidal expansion member 2 is in an unexpanded state, and the two sides of the trapezoidal expansion member 2 have not expanded beyond the two sides of the nail rod 12. The interior of the trapezoidal expansion member 2 is provided with a trapezoidal cavity for the trapezoidal slider 3 to slide. The opening of the trapezoidal cavity is provided on the end surface of the trapezoidal expansion member 2 away from the nail head 11, allowing the trapezoidal slider 3 to enter the interior of the trapezoidal cavity. The larger end of the trapezoidal cavity is away from the nail head 11, and the smaller end is close to the nail head 11. The end surface of the trapezoidal expansion member 2 close to the nail head 11 is provided with a hole for the inner connecting rod 4 to pass through, so that one end of the inner connecting rod 4 passes through the hole and enters the trapezoidal cavity of the trapezoidal expansion member 2 to connect with the trapezoidal slider 3. When the trapezoidal slider 3 is pulled toward the nail head 11, the trapezoidal slider 3 slides within the trapezoidal cavity, pushing the two side wings of the trapezoidal expansion member 2 toward the outside of the nail rod 12. This improves the stability of the main nail 1 fixed in the body and reduces the movement of the main nail 1 outward during human activity.

[0034] An internal thread is provided at the end of the nail rod 12 near the nail head 11, and external threads are provided at both ends of the inner connecting rod 4. The two external threads on the inner connecting rod 4 are in the same direction. One of the external threads on the inner connecting rod 4 is threadedly connected to the trapezoidal slider 3, and the other external thread on the inner connecting rod 4 is threadedly connected to the internal thread of the nail rod 12. When the inner connecting rod 4 is screwed into the interior of the nail rod 12, the trapezoidal slider 3 is pulled toward the nail head 11. When in use, first place the trapezoidal slider 3 into the trapezoidal expansion piece 2, then place the trapezoidal expansion piece 2 into the slot of the main nail 1, and after placing the main nail 1, the trapezoidal expansion piece 2 and the trapezoidal slider 3 in the position to be fixed in the body, screw the inner connecting rod 4 into the main nail 1. During the screwing-in process, the end of the inner connecting rod 4 away from the nail head 11 is first connected to the internal thread on the trapezoidal slider 3, and then continue to screw in the inner connecting rod 4. Due to the limiting effect of the trapezoidal inner cavity on the trapezoidal slider 3, the trapezoidal slider 3 cannot rotate, but is converted to slide along the trapezoidal inner cavity toward the nail head 11, thereby spreading the two side wings of the trapezoidal expansion piece 2.

[0035] In order to facilitate the screwing of the inner connecting rod 4, in some embodiments, an inner screw hole is opened on the end surface of the inner connecting rod 4 near the nail head 11. For example, the inner screw hole is hexagonal, and the inner connecting rod 4 can be screwed using an inner hexagonal wrench, which facilitates the operation during the surgical process.

[0036] like Figure 4 As shown, the trapezoidal expansion member includes two trapezoidal members with openings on the sides, the openings of the two trapezoidal members are opposite, one of the trapezoidal members is nested into the other trapezoidal member from the side opening, and the trapezoidal surfaces of the two trapezoidal members are provided with matching sliders 7 and slide grooves 8. For example, the slider 7 is provided on the inner surface of the trapezoidal surface of the outer trapezoidal member, and the slide groove 8 is provided on the outer surface of the trapezoidal surface of the inner trapezoidal member. The direction of the slide groove 8 is parallel to the radial direction of the main nail. The slider 7 is snapped into the inside of the slide groove 8 and can slide along the slide groove 8. The two ends of the slide groove 8 are closed to prevent the slider 7 from slipping out of the slide groove 8. The slider 7 and slide groove 8 are only provided near the smaller side of the trapezoidal surface (i.e., the side close to the nail head), or matching sliders 7 and slide grooves 8 are provided near both the larger and smaller sides of the trapezoidal surface. In the initial state, the two trapezoidal members overlap. As the trapezoidal slider slides toward the nail head, the trapezoidal slider expands the distance between the two trapezoidal members. The slider 7 and the chute 8 slide relative to each other. Under the guidance of the chute 8, the two trapezoidal members slide to both sides at the same time, causing the trapezoidal expansion member to expand. The more the trapezoidal slider slides toward the nail head, the greater the expansion of the trapezoidal expansion member. Since the ends of the chute 8 are closed, the slider 7 will not slide out of the chute 8. The interior of the trapezoidal expansion member is supported by the trapezoidal slider, and the closed end of the chute 8 acts as a limiter, keeping the trapezoidal expansion member in this expanded state. Moreover, since the inner connecting rod is threadedly connected to the main nail, there is no external human force, and the trapezoidal slider will not slide inside the trapezoidal expansion member, thus achieving a stable expansion support function for the trapezoidal expansion member. Moreover, during the process of the trapezoidal expansion member being expanded, due to the limiting effect of the card slot, the trapezoidal expansion member can only expand toward the two wings.

[0037] like Figure 5 As shown, in some embodiments, the external threads on the nail shank 12 include a coarse thread 121 and a fine thread 122, with the fine thread 122 121 being closer to the nail head 11 and the coarse thread 121 122 being farther away from the nail head 11. Specifically, the coarse thread 121 has high strength and good fixing performance; the fine thread 122 has good sealing performance. Without taking anti-loosening measures, the fine thread 122 has better anti-loosening performance than the coarse thread 121, but the fine thread 122 has low strength. Therefore, configuring the threads on the nail shank 12 as coarse threads 121 and fine threads 122 can effectively enhance the holding force of the main nail 1. The slot for engaging the trapezoidal expansion member 2 is provided on the coarse thread 121 to ensure fixing strength.

[0038] In some optional embodiments, a cavity is provided inside the main nail 1, which extends axially through the main nail 1. A Kirschner wire can be passed through the cavity on the main nail 1, and then the Kirschner wire is used to guide the main nail 1, so that the main nail 1 can be accurately placed at the pelvic fracture site, effectively promoting the fixation of the pelvic fracture by the main nail 1. Specifically, when using the Kirschner wire for guidance, a Kirschner wire is first inserted into the fracture site, and then the trapezoidal slider 3, the trapezoidal expansion member 2, and the main nail 1 are passed through the Kirschner wire. The detachable expansion screw of the anterior pelvic ring is then placed in the position where the Kirschner wire is located, and finally the Kirschner wire is withdrawn.

[0039] In some optional embodiments, a plurality of injection holes 123 are provided on the sidewall of the end of the nail rod 12 away from the nail head 11, and the injection holes 123 are connected to the cavity. After the main nail 1 is placed in the pelvic fracture, bone cement can be injected into the cavity from the nail head 11 of the main nail 1. The bone cement can enter the pelvic fracture through the injection holes 123, which is beneficial for the recovery of the pelvic fracture. At the same time, because the elderly often suffer from osteoporosis, the degree of bone damage is relatively severe when a fracture occurs. By inserting bone cement into the main nail 1, the mechanical strength of the main nail 1 can be improved, which is beneficial for postoperative recovery of the fracture. The injection holes 123 can be distributed on both sides of the slot.

[0040] This embodiment also provides an internal fixation frame, such as Figure 6 As shown, it includes a connecting crossbar 5 and at least two detachable expansion screws of the pelvic anterior ring according to any one of the above embodiments, and the detachable expansion screws of the pelvic anterior ring are connected by the connecting crossbar 5. The connecting crossbar 55 is used to connect multiple detachable expansion screws of the pelvic anterior ring to form an internal fixator, which can better fix the fractured bones. A through hole for the connecting crossbar 5 to pass through is provided on the main nail 1. The through hole is closer to the nail head 11 than the internal connecting rod 4. The connecting crossbar 5 passes through the through hole to connect the detachable expansion screws of the pelvic anterior ring. The through hole can be set obliquely, forming a certain angle with the axial direction of the main nail 1. The connecting crossbar 5 passes through the through hole at an angle, and the oblique through hole plays a certain limiting role. A limiting thread can be set on the connecting crossbar 5 to increase the friction and limiting force between the connecting crossbar 5 and the main nail 1, making the internal fixator more firmly and stably fixed.

[0041] The commonly used internal fixator can be made of two detachable expansion screws of the pelvic anterior ring and a connecting cross bar 5.

[0042] In some embodiments, the internal fixator further includes a locking bolt 6 for locking the connecting crossbar 5. The nail head 11 has an internal thread that matches the locking bolt 6. The locking bolt 6 is screwed into the nail head 11 to lock the connecting crossbar 5. After the connecting crossbar 5 is inserted into the through hole of the main nail 1, the locking bolt 6 is screwed into the nail head 11 so that the end of the locking bolt 6 is pressed against the connecting crossbar 5, further improving the securement and stability of the internal fixator.

[0043] An inner angle screw-in hole can also be provided on the end face of the locking bolt 6. By inserting an inner angle wrench into the inner angle screw-in hole and rotating the locking bolt 6, the end face of the locking bolt 6 can be flush with the end face of the nail head 11, reducing the patient's discomfort.

[0044] In some optional embodiments, such as Figure 7 As shown, the connecting crossbar 5 includes an elastic portion 51 and a rigid portion 52, which are alternately connected. Specifically, when connecting multiple pelvic anterior ring removable expansion screws via the connecting crossbar 5, the rigid portion 52 of the connecting crossbar 5 engages with the through-hole of the main screw 1. Simultaneously, the elastic portion 51 between the two rigid portions 52 bends the connecting crossbar 5, further bending it when inserted into the internal fixator. This facilitates the insertion and connection of the connecting crossbar 5, providing better fixation for pelvic fractures.

[0045] The elastic portion 51 is a spring, with its two ends fixedly connected to the rigid portion 52. The springs bend the connecting crossbar 5, facilitating fixation of the fracture by the internal fixator. Those skilled in the art will appreciate that the fact that the elastic portion 51 is a spring does not limit the present invention; elastic portions 51 constructed of other structures or materials are also within the scope of protection of the present invention, such as silicone rods and rod-like structures formed from metal mesh.

[0046] In some possible embodiments, the patient's fracture is fixed using an internal fixator, and the specific process is as follows:

[0047] (1) Place the trapezoidal slider 3 into the trapezoidal expansion member 2, then clamp the trapezoidal expansion member 2 into the clamping groove of the main nail 1. At this time, the two side wings of the trapezoidal expansion member 2 do not protrude outside the main nail 1. Place the main nail 1, trapezoidal expansion member 2 and trapezoidal slider 3 together into the patient's fracture site;

[0048] (2) Screw the inner connecting rod 4 into the main nail 1. After the end of the inner connecting rod 4 is connected to the trapezoidal slider 3, continue to use the inner angle wrench to screw the inner connecting rod 4 into the main nail 1. The trapezoidal slider 3 slides in the trapezoidal expansion member 2 toward the nail head 11. The two side wings of the trapezoidal expansion member 2 expand and support the main nail 1 on both sides.

[0049] (3) After two or more main nails 1 are fixed to the patient's fracture site, the connecting cross bars 5 are sequentially passed through the through holes of the main nails 1 to connect the expansion screws;

[0050] (4) Use an internal angle wrench to screw the locking bolt 6 into the nail head 11 of the main nail 1 until the end of the locking bolt 6 located inside the main nail 1 rests on the connecting cross bar 5, thereby tightening the connecting cross bar 5.

[0051] In some possible embodiments, the main nail 1 is retained at the patient's fracture site, and the remaining components other than the main nail 1 are removed. The specific process is as follows:

[0052] (1) Unscrew the locking bolt 6 from the nail head 11 of the main nail 1;

[0053] (2) The connecting cross bar 5 is bent and removed from the through hole of the main nail 1, and then the connecting cross bar 55 is removed from the patient's body, so that the main nail 1 is retained at the patient's fracture site.

[0054] In the process of unscrewing the locking bolt 6 and pulling out the connecting cross bar 5, the expansion limiting effect of the trapezoidal expansion member 2 reduces the possibility of sliding and slipping of the main nail 1, thereby improving the fixing stability of the main nail 1.

[0055] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A detachable expansion screw for the anterior pelvic ring, characterized in that: It comprises a main nail (1), a trapezoidal expansion member (2), a trapezoidal slider (3) and an inner connecting rod (4), The main nail (1) is provided with a cavity inside, and the cavity passes through the axial direction of the main nail (1). The main nail (1) comprises an integrally formed nail rod (12) and a nail head (11). The end of the nail rod (12) away from the nail head (11) is provided with a slot (13) for clamping the trapezoidal expansion member (2). The trapezoidal slider (3) slides in the trapezoidal expansion member (2) toward the nail head (11), so that the trapezoidal expansion member (2) expands toward both sides of the outside of the nail rod (12). The trapezoidal expansion member (2) includes two trapezoidal members with openings on the sides, 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 side opening, a slider (7) is provided on the inner surface of the trapezoidal surface of the outer trapezoidal member, and a slide groove (8) is provided on the outer surface of the trapezoidal surface of the inner trapezoidal member, the direction of the slide groove (8) is parallel to the radial direction of the main nail (1), the slider (7) is snapped into the inside of the slide groove (8) and can slide along the slide groove (8), and the two ends of the slide groove (8) are closed to prevent the slider (7) from slipping out of the slide groove (8). One end of the inner connecting rod (4) is connected to the trapezoidal slider (3), and the inner connecting rod (4) is used to penetrate into the main nail (1) to pull the trapezoidal slider (3) to slide.

2. The detachable expansion screw for the anterior pelvic ring according to claim 1, characterized in that: The end of the nail rod (12) near the nail head (11) is provided with an internal thread, and both ends of the inner connecting rod (4) are provided with external threads. The two external threads on the inner connecting rod (4) are in the same direction. One of the external threads on the inner connecting rod (4) is threadedly connected to the trapezoidal slider (3), and the other external thread on the inner connecting rod (4) is threadedly connected to the internal thread of the nail rod (12). When the inner connecting rod (4) is screwed into the interior of the nail rod (12), the trapezoidal slider (3) is pulled toward the nail head (11).

3. The detachable expansion screw for the anterior pelvic ring according to claim 2, characterized in that: An inner tightening hole is provided on the end surface of the inner connecting rod (4) close to the nail head (11).

4. The detachable expansion screw for the anterior pelvic ring according to claim 1, characterized in that: The external thread on the nail rod (12) comprises a fine thread (122) and a coarse thread (121), wherein the fine thread (122) is close to the nail head (11) and the coarse thread (121) is far away from the nail head (11).

5. The detachable expansion screw for the anterior pelvic ring according to claim 1, characterized in that: A plurality of injection holes (123) are provided on the side wall of one end of the nail rod (12) away from the nail head (11), and the injection holes (123) are communicated with the cavity.

6. An internal fixator, characterized in that: The invention 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, wherein the main nail (1) is provided with a through hole for the connecting cross bar (5) to pass through, and the through hole is closer to the nail head (11) than the inner connecting rod (4), and the connecting cross bar (5) passes through the through hole to connect the detachable expansion screws for the anterior pelvic ring.

7. The internal fixator according to claim 6, characterized in that: It also includes a locking bolt (6) for locking the connecting cross bar (5), and the interior of the nail head (11) is provided with an internal thread matching the locking bolt (6), and the locking bolt (6) is screwed into the nail head (11) to lock the connecting cross bar (5).

8. The internal fixator according to claim 6 or 7, characterized in that: The connecting cross bar (5) comprises an elastic portion (51) and a rigid portion (52), and the elastic portion (51) and the rigid portion (52) are alternately connected.

9. The internal fixator according to claim 8, characterized in that: The elastic part (51) is a spring, and the two ends of the spring are respectively fixedly connected to the rigid part (52).

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