CN114767247A - Detachable screw for fixing anterior pelvic ring and internal fixing device - Google Patents

Abstract

The invention provides a detachable screw and an internal fixation device for fixing an anterior pelvic ring. The screw comprises a main nail, a nail barrel, a fixing piece and an inner screw; The hole and the second through hole with a diameter larger than the first through hole, the first and second through holes are respectively away from and close to the main nail, the main nail includes a nail tail and a nail rod and is integrally formed, and the nail tail can pass through the second through hole; The inner wall of the first through hole of the nail barrel is provided with an inner thread, and the inner screw is connected with the nail barrel through the inner thread; the fixing member is arranged in the nail barrel and between the nail tail and the inner screw, and the nail tail is retained in the nail by the fixing member In the barrel, the fixing member includes a support portion and a plurality of arc-shaped spring pieces fixed on one end of the support portion close to the nail tail and arranged along the circumferential direction of the support portion. Nail tail. The internal fixation device includes a connecting crossbar and at least two of the above-mentioned screws, and the screws are connected by the connecting crossbar, thereby reducing postoperative discomfort.

Description

Removable screw and internal fixation device for anterior pelvic ring fixation

technical field

The invention relates to the technical field of orthopedic medical devices, in particular to a detachable screw and an internal fixation device for fixing an anterior pelvic ring.

Background technique

Minimally Invasive Anterior Pelvic Ring Internal Fixator (Minimally Invasive Anterior Pelvic Ring Internal Fixator) is generally used clinically for elderly fragile anterior pelvic ring injuries. The most widely used and effective device in this procedure is called the internal fixator (INFIX). The original 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 the best indications. Because the internal fixator is located in front of the lower abdomen and pelvis, patients with thin body 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 has healed, the internal fixator should be removed by a second operation.

At present, the main nail of the internal fixator and the nail cap connecting the crossbar are integrated design, but for some special fractures, the main nail needs to be indwelled for a long time, and the crossbar causes discomfort and needs to be removed early. However, in the early stage after rehabilitation surgery for anterior pelvic ring injury, the degree of pelvic recovery is not sufficient, and the rest of the screws except the main screw are not easily removed.

In view of the problem in the prior art that it is difficult to remove the rest of the main nail for a patient with an internal fixator installed, no effective solution has been proposed yet.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a detachable screw and an internal fixation device for fixing an anterior pelvic ring, which solves the problem in the prior art that it is difficult to remove the rest of the main nail for patients with an internal fixator installed.

For this reason, the present invention provides the following technical solutions:

A first aspect of the present invention provides a detachable screw for fixing an anterior pelvic ring, including: a main nail, a screw barrel, a fixing member and an inner screw;

The through holes in the nail barrel are stepped, including a first through hole and a second through hole that communicate with each other. The first through hole is far away from the main nail, and the second through hole is close to the main nail, so The diameter of the first through hole is larger than the diameter of the second through hole, the main nail includes a nail tail and a nail shaft, the nail tail and the nail shaft are integrally formed, and the nail tail can pass through the second through hole. hole;

The inner wall at the first through hole of the nail barrel is provided with an inner thread, and the inner screw is connected with the nail barrel through the inner thread;

The fixing member is arranged in the nail barrel and is located between the nail tail and the inner screw, the nail tail is retained in the nail barrel by the fixing member, and the fixing member includes a support part and a fixing part. The support portion is close to a plurality of spring pieces at one end of the nail tail, the plurality of spring pieces are arranged along the circumferential direction of the support portion, the spring pieces are arc-shaped, and the arc center of the arc faces the nail tail. The spring piece includes a first state of tightening the nail tail when the inner screw is screwed into the nail barrel and a second state of loosening the nail tail when the inner screw is screwed out of the nail barrel.

Optionally, the threads on the shank include coarse threads and fine threads, the coarse threads are close to the nail tail, and the fine threads are far away from the nail tail.

Optionally, a cavity is provided inside the main nail, and the cavity penetrates the main nail.

Optionally, a side wall of one end of the nail rod away from the nail tail is provided with a plurality of injection holes, and the injection holes communicate with the cavity.

Optionally, the nail shaft is provided with a plurality of receiving grooves along the circumferential direction, and a raised cutting edge is disposed in the receiving groove, and the cutting edge is used to cut the bone when the main nail is rotated.

In a second aspect of the present invention, an internal fixation device is provided, comprising a connecting crossbar and at least two detachable screws for pelvic anterior ring fixation according to any one of the above-mentioned first aspects. The detachable screws fixed by the front ring are connected by the connecting cross bar;

The side wall of the nail barrel away from the main nail is provided with two opposite clamping grooves, the connecting crossbar is inserted into the clamping groove, and the connecting crossbar is fixed on the fixing member and the between the inner screws.

Optionally, a limiting groove is provided on the end surface of the fixing member away from the main nail, and the connecting crossbar is matched with the limiting groove.

Optionally, the connecting crossbar includes an elastic part and a rigid part, and the elastic part and the rigid part are alternately connected.

Optionally, the elastic portion is a spring, and two ends of the spring are respectively fixedly connected to the rigid portion.

The technical scheme of the present invention has the following advantages:

The present invention provides a detachable screw and an internal fixation device for fixing an anterior pelvic ring. The present invention solves the problem in the prior art that it is difficult to remove the rest of the main screw for a patient with an internal fixator installed. In the present invention, the inner screw is used to squeeze the fixing piece, so that the spring plate on the fixing piece is compressed and deformed, and then the tail of the main screw is held tightly, so that the whole screw is firmly fixed at the anterior ring of the pelvis; The inner screw on the detachable screw for ring fixation is taken out, the spring piece on the fixing piece returns to its natural state, and the nail tail of the main nail can be detached from the plurality of spring pieces, so that the detachable screw for pelvic anterior ring fixation can be realized. disassemble. Therefore, when the main nail does not need to be removed, the remaining part of the detachable screw used for the fixation of the anterior pelvic ring except the main nail can be removed to reduce postoperative discomfort of the patient.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

1 is a schematic structural diagram of a detachable screw for fixation of an anterior pelvic ring according to the present invention;

Fig. 2 is the structural schematic diagram of the main nail according to the present invention;

Fig. 3 is the structural representation of the nail barrel according to the present invention;

Fig. 4 is the structural schematic diagram of the fixing member according to the present invention;

5 is a cross-sectional view along the length of the main nail when the fastener according to the present invention is in the first state;

6 is a cross-sectional view along the length of the main nail when the fastener according to the present invention is in a second state;

Fig. 7 is the structural schematic diagram of the main nail provided with cutting edge according to the present invention;

FIG. 8 is a schematic structural diagram of an internal fixation device according to the present invention;

FIG. 9 is a schematic structural diagram of a connecting cross bar according to the present invention.

In the figure,

1. Main nail; 11. Nail tail; 111. Cavity; 12. Nail stem; 121, coarse thread; 122, fine thread; 123, injection hole; 124, receiving groove; 125, cutting edge; 2, nail barrel; 21, internal thread; 22, card slot; 3, fixing part; 31, support part; 32, spring sheet; 33, limit slot; 4, inner screw; 5, connecting cross bar; 51, elastic part; 52 , Rigid part.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " The orientation or positional relationship indicated by "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation shown in the drawings Or the positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined as "first", "second" may expressly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the present invention, the word "exemplary" is used to mean "serving as an example, illustration or illustration". Any embodiment of this disclosure described 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 present invention. In the following description, details are set forth for the purpose of explanation. It will be understood by one of ordinary skill in the art that the present invention may be practiced without the use of these specific details. In other instances, well-known structures and procedures have not been described in detail so as not to obscure the description of the present 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 can be combined with each other as long as they do not conflict with each other.

The present invention provides a detachable screw and an internal fixation device for anterior pelvic ring fixation, which can be used for postoperative fixation of anterior pelvic ring injuries, such as post-operative fixation of symphysis pubis separation and post-operative fixation of pubic ramus fractures. Fig. 1 is a schematic structural diagram of a detachable screw for fixing anterior pelvic ring according to the present invention. As shown in Fig. 1 , the detachable screw for fixing anterior pelvic ring includes: a main nail 1, a nail barrel 2, a fixing member 3 and the inner screw 4. Specifically, by connecting the main nail 1, the nail barrel 2, the fixing member 3 and the inner screw 4, a detachable screw for fixing the anterior pelvic ring is formed, and the detachable screw for fixing the anterior pelvic ring is placed in the pelvis Fractures can be effectively immobilized.

As shown in FIG. 2 and FIG. 3 , the through holes in the nail barrel 2 are stepped, including a first through hole and a second through hole that communicate with each other. The first through hole is far away from the main nail 1 , and the second through hole is close to the main nail 1 The diameter of the first through hole is larger than that of the second through hole. The main nail 1 includes a nail tail 11 and a nail shaft 12. The nail tail 11 and the nail shaft 12 are integrally formed, and the nail tail 11 can pass through the second through hole. Specifically, when removing the detachable screw for pelvic anterior ring fixation, since the screw tail 11 can pass through the second through hole, the main screw 1 can be detached from the screw barrel 2 without limitation, in other words, When the main nail 1 is fixed in the bone, the nail barrel 2 is away from the bone along the length of the main nail 1 , the nail tail 11 passes through the first through hole and the second through hole, and the nail cylinder 2 is separated from the nail tail 11 .

The inner wall of the first through hole of the nail barrel 2 is provided with an inner thread 21, and the inner screw 4 is connected with the nail barrel 2 through the inner thread 21; , the nail tail 11 is retained in the nail barrel 2 by the fixing member 3. The fixing member 3 includes a support portion 31 and a plurality of spring pieces 32 fixed on one end of the support portion 31 close to the nail tail 11. The plurality of spring pieces 32 are arranged along the support portion 31. Circumferentially arranged, the spring pieces 32 are arc-shaped, and the arc center of the arc faces the nail tail 11. As shown in FIG. state (as shown in FIG. 5 ) and the second state (as shown in FIG. 6 ) of loosening the nail tail 11 when the inner screw 4 is screwed out of the nail barrel 2 . Specifically, the fixing member 3 is installed into the nail barrel 2, and then the fixing member 3 is restricted in the nail barrel 2 by the inner screw 4. At this time, the inner screw 4 does not press the fixing member 3, and many The spring piece 32 will not be deformed by pressing the nail barrel 2, and the fixing member 3 is in the second state; since the fixing member 3 is in the second state, the nail tail 11 of the main nail 1 can extend into multiple pieces through the second through hole Between the spring pieces 32, at the same time, since the natural length of each spring piece 32 is greater than the length of the nail tail 11, the plurality of spring pieces 32 can wrap the nail tail 11, and at this time the plurality of spring pieces 32 are not held. Tighten the nail tail 11 so that the nail tail 11 can come out from between the plurality of spring pieces 32, and then separate from the nail barrel 2, and then squeeze the fixing member 3 through the inner screw 4, so that the fixing member 3 moves in the direction of the main nail 1, When the plurality of spring pieces 32 are in contact with the bottom wall of the nail barrel 2, the bottom wall of the nail barrel 2 hinders the movement of the fixing member 3, but as the inner screw 4 continues to press the fixing member 3, the plurality of spring pieces 32 are affected by the bottom wall of the nail barrel 2. Due to the action of the wall, the bending of the plurality of spring pieces 32 is intensified, so that the abdomens of the plurality of spring pieces 32 approach the side wall of the nail cylinder 2, and the end of the spring pieces 32 away from the support portion 31 is bent and deformed along the length direction, and then the plurality of spring pieces The end of the 32 away from the support portion 31 is close to the support portion 31, the plurality of spring pieces 32 are holding the nail tail 11 tightly, and the fixing member 3 is in the first state. It is a detachable screw fixed to the anterior ring of the pelvis; moreover, the plurality of spring pieces 32 also fill the gap between the nail barrel 2 and the nail tail 11, so as to prevent the nail tail 11 from shaking in the nail barrel 2, and the fixing is relatively firm. After the detachable screw for fixation of the anterior pelvic ring is placed in the fracture of the patient, when it is necessary to take out the rest except the main nail 1, the inner screw 4 is taken out, and the fixing member 3 moves away from the main nail 1, so that the nail The effect of the bottom wall of the cylinder 2 on the plurality of spring pieces 32 is reduced, and the plurality of spring pieces 32 gradually return to the natural state. Finally, the fixing member 3 returns to the second state, and the nail tail 11 can be disengaged from the plurality of spring pieces 32. In this way, the main nail 1 is retained at the fracture of the patient, and the detachable screw used for the fixation of the anterior pelvis can be removed and taken out.

When the fixing member 3 is in the first state or the natural state, the diameter of the area surrounded by one end of the plurality of spring pieces 32 close to the main nail 1 is slightly smaller than the maximum diameter of the nail tail 11 , but larger than the diameter of the nail shaft 12 . Since the spring pieces 32 have elastic force, when the nail tail 11 is extended from the area enclosed by the ends of the plurality of spring pieces 32 close to the main nail 1 into the space enclosed by the plurality of spring pieces 32, the plurality of spring pieces 32 can move away from One side of the arc center is opened, so that the nail tail 11 extends into the space enclosed by the plurality of spring pieces 32, and because the diameter of the nail rod 12 is smaller than the diameter of the area enclosed by the end of the plurality of spring pieces 32 close to the main nail 1 , the plurality of spring pieces 32 are no longer deformed and return to the initial position, and at this time, the nail tail 11 is in the space enclosed by the plurality of spring pieces 32, and is not easily separated from the fixing member 3 under the condition of no force.

The screws used for pelvic fractures in the prior art have no detachable function, and the main nail and the screw barrel are usually integrally formed, so that when the screws for pelvic fractures are removed, the screw barrel cannot be taken out. In this embodiment, different from the prior art, a detachable screw for fixing the anterior pelvic ring is designed. Since the screw tail 11 of the main nail 1 can pass through the second through hole, the On the premise, take out the nail cylinder 2 and the fixing piece 3, etc. This embodiment solves the problem in the prior art that it is difficult to remove the rest of the main nail 1 for a patient with an internal fixator installed, and reduces postoperative discomfort for the patient.

To illustrate the threads on the shank 12, in some optional embodiments, the threads on the shank 12 include coarse threads 121 and fine threads 122, the coarse threads 121 are close to the nail tail 11, and the fine threads 122 are far from the nail tail 11. Specifically, the coarse thread 121 has high strength and good fixing performance; the fine thread 122 has good sealing performance. Under the premise of not taking anti-loosening measures, the anti-loosening performance of the fine thread 122 is better than that of the coarse thread 121, but the fine thread 122 has better anti-loosening performance. The strength of the thread 122 is low. Therefore, setting the threads on the nail shaft 12 into coarse threads 121 and fine threads 122 can effectively enhance the gripping force of the main nail 1 . Those skilled in the art should know that the coarse thread 121 and the fine thread 122 are not used to limit the present invention, and other types of threads are also within the protection scope of the present invention, for example, the coarse thread 121 A fine thread 122 is provided between.

To illustrate the main nail 1 , in some optional embodiments, a cavity 111 is provided inside the main nail 1 , and the cavity 111 penetrates the main nail 1 . The cavity 111 is provided inside the main nail 1, which can release the pressure at the fracture, so that the fracture can recover better. In addition, the Kirschner wire can pass through the cavity 111 on the main nail 1, and then the main nail 1 can be guided by the Kirschner wire, so that the main nail 1 can be accurately placed in the pelvic fracture, which effectively promotes the fixation of the pelvic fracture by the main nail 1. . Specifically, when guiding through the Kirschner wire, a Kirschner wire is first inserted into the fracture treatment, and then the main nail 1 is passed through the Kirschner wire, and then the detachable screw for fixation of the anterior pelvic ring is inserted into the K-wire. The location of the pin, and finally exit the K-wire.

In order to further illustrate the main nail 1 , in some optional embodiments, a plurality of injection holes 123 are provided on the side wall of the end of the nail shaft 12 away from the nail tail 11 , and the injection holes 123 communicate with the cavity 111 . After the main nail 1 is inserted into the pelvic fracture, bone cement can be injected into the cavity 111 from the tail of the main nail 1, and the bone cement can enter the pelvic fracture through the injection hole 123, which is beneficial to the recovery of the pelvic fracture. At the same time, because the elderly usually suffer from osteoporosis, when a fracture occurs, the degree of bone damage is more serious. By placing bone cement in the main nail 1, the mechanical strength of the main nail 1 can be improved, which is beneficial to the postoperative rehabilitation of fractures.

In other optional embodiments, as shown in FIG. 6 , the nail shaft 12 is provided with a plurality of receiving grooves 124 along the circumferential direction, and the receiving grooves 124 are provided with a raised cutting edge 125, and the cutting edge 125 is used for rotating the main nail At 1, cut the bones. After the main nail 1 is placed in the patient's pelvic fracture for a period of time, the main nail 1 needs to be taken out after the patient's pelvic fracture recovers, and the bones around the main nail 1 are also gradually restored, which hinders the removal of the main nail 1, so that the main nail 1 It is easy to cause damage, and through the action of the cutting edge 125, the bone around the main nail 1 can be cut when the main nail 1 is rotated, and the cut bone debris enters the receiving groove 124, thereby facilitating the removal of the main nail 1, and in When the main nail 1 is taken out, the bone debris is brought out to prevent the main nail 1 from being damaged.

This embodiment also provides an internal fixation device, as shown in FIG. 7 , comprising a connecting cross bar 5 and at least two detachable screws for fixing anterior pelvic ring according to any one of the above-mentioned embodiments. The detachable screws fixed by the ring are connected by connecting cross bars 5 . The internal fixation device is formed by connecting a plurality of detachable screws for fixing the anterior pelvis ring together by using the connecting cross bar 5, which can better fix the fractured bone.

The side wall of the nail barrel 2 away from the main nail 1 is provided with two opposite clamping grooves 22 . Two opposite clamping grooves 22 are provided on the nail barrel 2 , and the clamping grooves 22 are matched with the connecting crossbar 5 , so that the connecting crossbar 5 can be inserted into the card groove 22 . Specifically, the fixing member 3 is installed into the nail barrel 2, the connecting crossbar 5 is inserted into the card slot 22, then the nail tail 11 of the main nail 1 is placed between the plurality of spring pieces 32, and finally the inner screw is screwed in 4. Squeeze and connect the cross bar 5 and the fixing member 3, so that the fixing member 3 is in the first state, and the nail tail 11 is tightly held to form an internal fixing device. After the internal fixation device is placed in the fractured part of the patient, the nail barrel 2, the fixator 3, the internal screw 4 and the connecting rod 5 can be taken out on the premise of retaining the main nail 1, and then without affecting the patient's recovery. Reduce patient discomfort.

To illustrate the fixing member 3 , in some optional embodiments, a limiting groove 33 is provided on the end face of the fixing member 3 away from the main nail 1 , and the connecting crossbar 5 matches the limiting groove 33 . Since the fixing member 3 is provided with a limiting groove 33 matching with the connecting crossbar 5 , the connecting crossbar 5 can be well fixed.

In order to illustrate the connecting crossbar 5, in some optional embodiments, as shown in FIG. 8 , the connecting crossbar 5 includes an elastic part 51 and a rigid part 52, and the elastic part 51 and the rigid part 52 are alternately connected. Specifically, when a plurality of detachable screws for fixing the anterior pelvic ring are connected through the connecting cross bar 5 , the rigid part 52 of the connecting cross bar 5 is clamped in the slot 22 to prevent the connecting cross bar 5 from being separated from the nail barrel 2 . At the same time, the connecting cross bar 5 can be bent by the action of the elastic portion 51 between the two rigid portions 52, and when the internal fixation device is placed, the connecting cross bar 5 can be bent by the action of the elastic portion 51, so that the main nail 1 The screw rod 12 can be screwed into an appropriate position, which can better fix the pelvic fracture.

In order to further illustrate the connecting crossbar 5 , in some optional embodiments, the elastic portion 51 is a spring, and two ends of the spring are respectively fixedly connected to the rigid portion 52 . Through the action of the spring, the connecting cross bar 5 can be bent, which is convenient for the internal fixation device to fix the fracture. Those skilled in the art should know that the elastic portion 51 being a spring is not used to limit the present invention, and the elastic portion 51 made of other structures or materials is also within the protection scope of the present invention, such as a silicone rod and a rod-shaped structure formed by a metal mesh.

In some possible embodiments, the patient's fracture is fixed by an internal fixation device, and the specific process is as follows:

(1) Since the nail tail 11 of the main nail 1 is provided with a hexagonal through hole, the plurality of main nails 1 are respectively driven into the fracture of the patient by a hexagonal wrench matched with the hexagonal through hole;

(2) Put the nail barrel 2 on the nail tail 11 of the main nail 1, and the nail tail 11 enters the nail cylinder 2 through the second through hole;

(3) Install the fixing piece 3 into the nail barrel 2 through the first through hole, squeeze the fixing piece 3 with a little force, and the plurality of spring pieces 32 on the fixing piece 3 squeeze the nail tail 11, so that the plurality of spring pieces 32 The end away from the support portion 31 approaches the inner wall of the nail barrel 2, and as the fixing member 3 moves toward the main nail, the plurality of spring pieces 32 surround the nail tail 11;

(4) The connecting cross bar 5 is placed in the limiting groove 33 of the fixing member 3, and the connecting cross bar 5 is snapped into the two opposite snap grooves 22 on the side wall of the nail cylinder 2;

(5) Screw the inner screw 4 into the nail cylinder through the inner thread 21 provided on the inner wall of the first through hole of the nail cylinder 2, and as the inner screw 4 is screwed in, the inner screw 4 squeezes the connecting cross bar 5, and then squeezes Fixing member 3, the plurality of spring pieces 32 are affected by the bottom wall of the nail barrel 2, and the bending of the plurality of spring pieces 32 is intensified, so that the abdomens of the plurality of spring pieces 32 approach the direction of the side wall of the nail barrel 2, and the spring pieces 32 are far away from the support portion One end of 31 is bent and deformed along the length direction, and then one end of the plurality of spring pieces 32 away from the support portion 31 approaches the support portion 31, and the plurality of spring pieces 32 hold the nail tail 11 tightly until the fixing member 3 is in the first state, and the nail tail is in the first state. 11 is confined within the barrel 2.

In some possible embodiments, by retaining the main nail 1 at the fracture of the patient, and removing the remaining components outside the main nail 1, the specific process is as follows:

(1) Unscrew the inner screw 4 from the inner thread 21, and move the fixing member 3 away from the main nail 1 until the fixing member 3 is in the second state;

(2) Take out the connecting cross bar 5 from the two opposite clamping grooves 22 on the side wall of the nail cylinder 2, and disengage from the limiting groove 33 of the fixing member 3, and then take out the connecting cross bar 5 from the patient;

(3) Pull up the fixing piece 3 with a little force, the multiple spring pieces 32 on the fixing piece 3 are deformed near one end of the main nail, and move toward the side wall of the nail cylinder 2, and the multiple spring pieces 32 close to one end of the main nail are stretched Open, separate from the nail tail 11, and take out the fixing part 3;

(4) Pull out the nail barrel 2 directly.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the present invention, such modifications and variations falling within the scope of the appended claims within the limited range.

Claims (9)

1. A removable screw for anterior pelvic ring fixation, comprising: the nail comprises a main nail (1), a nail barrel (2), a fixing piece (3) and an inner screw (4);

the through hole in the nail barrel (2) is in a step shape and comprises a first through hole and a second through hole which are communicated with each other, the first through hole is far away from the main nail (1), the second through hole is close to the main nail (1), the diameter of the first through hole is larger than that of the second through hole, the main nail (1) comprises a nail tail (11) and a nail rod (12), the nail tail (11) and the nail rod (12) are integrally formed, and the nail tail (11) can penetrate through the second through hole;

an internal thread (21) is arranged on the inner wall of the first through hole of the nail barrel (2), and the internal screw (4) is connected with the nail barrel (2) through the internal thread (21);

the fixing piece (3) is arranged in the nail barrel (2), and is located the nail tail (11) and between the internal screw (4), will through the fixing piece (3) the nail tail (11) is detained in the nail barrel (2), the fixing piece (3) includes supporting part (31) and fixes a plurality of spring pieces (32) that supporting part (31) is close to nail tail (11) one end, a plurality of spring pieces (32) are followed supporting part (31) circumference is arranged, spring piece (32) are the arc, and curved arc center is towards nail tail (11), a plurality of spring pieces (32) include internal screw (4) screw in the first state of holding closely nail tail (11) when the nail barrel (2) with internal screw (4) screw out the second state of loosening nail tail (11) when the nail barrel (2).

2. The removable screw for anterior pelvic ring fixation according to claim 1, wherein the thread on the shank (12) comprises a coarse thread (121) and a fine thread (122), the coarse thread (121) being proximal to the tail (11) and the fine thread (122) being distal to the tail (11).

3. The removable screw for anterior pelvic fixation according to claim 1, characterised in that the main nail (1) is internally provided with a cavity (111), said cavity (111) extending through the main nail (1).

4. The removable screw for anterior pelvic fixation according to claim 3, characterised in that the lateral wall of the end of the shank (12) remote from the tail (11) is provided with a plurality of injection holes (123), the injection holes (123) communicating with the cavity (111).

5. The detachable screw for anterior pelvic fixation according to claim 1, characterised in that said shank (12) is provided with a plurality of receiving grooves (124) along the circumferential direction, said receiving grooves (124) being provided with a raised cutting edge (125), said cutting edge (125) being adapted to cut the bone when the primary screw (1) is rotated.

6. An internal fixation device, characterized in that it comprises a connecting cross-bar (5) and at least two detachable screws for anterior pelvic ring fixation according to any one of claims 1-5, connected between them by the connecting cross-bar (5);

the nail barrel (2) is far away from the side wall of the main nail (1) and is provided with two opposite clamping grooves (22), the connecting cross rod (5) is clamped into the clamping grooves (22), and the connecting cross rod (5) is fixed between the fixing piece (3) and the inner screw (4).

7. An internal fixation device as claimed in claim 6, characterized in that the end surface of the fixing part (3) remote from the main nail (1) is provided with a limiting groove (33), and the connecting cross bar (5) is matched with the limiting groove (33).

8. An internal fixation device according to claim 6, characterized in that the connecting crossbar (5) comprises elastic portions (51) and rigid portions (52), the elastic portions (51) and the rigid portions (52) being alternately connected.

9. An internal fixation device according to claim 8, wherein the elastic portion (51) is a spring, both ends of which are fixedly connected to the rigid portion (52), respectively.

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