Novel axis pedicle lag screw assembly and internal fixation system

Abstract

The invention provides a novel axis pedicle lag screw assembly and an internal fixation system, and relates to the technical field of fracture surgery equipment. The novel axis pedicle lag screw assembly comprises a lag screw, a first limiting head and a locking assembly, the lag screw comprises a mounting part and a screw rod, the mounting part is fixed to the end of the screw rod, and the screw rod comprises a first threaded section and a second threaded section which are arranged at intervals in the length direction of the screw rod; the first threaded section is located on the side, away from the mounting part, of the second threaded section, and the thread pitch of the first threaded section is larger than that of the second threaded section. The first limiting head is provided with a first hole position for the titanium rod to penetrate through, the mounting part is located in the first limiting head, the locking assembly is in threaded connection with the first limiting head, the titanium rod can be fixed, and the mounting part can be locked in the first limiting head. The lag screw can provide higher holding force, the stability is improved, meanwhile, the fracture is further reset through two-time pressurization, excessive pressurization of the screw is prevented, and the safety is high.

Description

Technical Field

[0001] The invention relates to the technical field of fracture surgical equipment, and in particular to a novel axis pedicle tension screw assembly and an internal fixation system. Background Art

[0002] Hangman fracture, also known as traumatic spondylolisthesis, refers to a fracture between the upper and lower articular processes of the axis under violent action, often accompanied by damage to the surrounding ligaments and intervertebral discs, followed by instability or dislocation of the axis body. It is the second most common upper cervical spine injury after odontoid fracture. The main surgical methods are divided into three categories, namely anterior surgery, posterior surgery, and anterior and posterior combined surgery. Anterior surgery mainly includes anterior discectomy, decompression, fusion and internal fixation of the C2-3 cervical spine. Commonly used posterior surgical methods mainly include posterior C1-3 / C2-3 pedicle screw internal fixation and fusion, C2 pedicle lag screw internal fixation, etc. Since Roy-Camille et al. described the C2-3 posterior screw-plate internal fixation technique, C2-3 posterior internal fixation has become increasingly popular. At present, multiaxial screw and rod fixation technology has been developed and widely used in practice.

[0003] When a Hangman fracture occurs, the C2 vertebra is broken into two parts. In the prior art, a full-thread screw is inserted into the two broken parts of the C2 vertebra to connect the two parts. For some unstable structures, another vertebra needs to be nailed into the C3 vertebra, and a titanium rod is used to connect the screws on the C2 vertebra and the screws on the C3 vertebra. After the unstable C2 vertebra is connected to the C3 vertebra, the stability of the overall structure can be guaranteed.

[0004] The applicant has found that the prior art has at least the following technical problems: when the existing full-thread screw is driven into the C2 vertebral body, when the full-thread screw drills into the posterior arch part of the C2 vertebral body, it will continue to be screwed in, which will produce a certain thrust on the posterior arch part of the C2 vertebral body, and the posterior arch part may fall off from the anterior arch part of the C2 vertebral body, and the vertebral body will be angled, dislocated and unstable. Therefore, in the prior art, the specifications of the full-thread screw are difficult to meet clinical needs; the fixation stability is poor, and the pedicle and lamina behind the fracture are only fixed by pressure, lacking thread grip; insufficient or excessive pressure may cause the fracture reduction to be lost again, and the degree of pressure is mainly determined by the surgeon's experience. Summary of the invention

[0005] The purpose of the present invention is to provide a novel axis pedicle lag screw assembly and internal fixation system to solve the technical problems in the prior art that when the full-thread screw connects the two parts of the C2 vertebral body with fracture, the fixation stability is poor, and the vertebral body is easy to dislocate and unstable. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The novel axis pedicle lag screw assembly provided by the present invention comprises a lag screw, a first stopper head and a locking assembly, wherein:

[0008] The tension screw comprises a mounting portion and a screw rod, wherein the mounting portion is fixed to an end of the screw rod, and the screw rod comprises a first thread segment and a second thread segment arranged at intervals along a length direction thereof, wherein the first thread segment is located on a side of the second thread segment away from the mounting portion, and a pitch of the first thread segment is greater than a pitch of the second thread segment;

[0009] The first limit head is provided with a first hole for the titanium rod to pass through, the mounting portion is located in the first limit head, the locking assembly is threadedly connected to the first limit head, and can fix the titanium rod and lock the mounting portion in the first limit head.

[0010] Preferably, the length of the first thread segment is greater than the length of the second thread segment.

[0011] Preferably, the mounting portion is a spherical structure, and when the mounting portion is in an unlocked state, it can rotate in a deflectable manner within the first limiting head.

[0012] Preferably, the screw has an axial cavity therein, and the axial cavity is arranged along the central axis of the screw.

[0013] Preferably, the first limiting head comprises a receiving portion and a threaded connection portion, wherein:

[0014] The first hole is opened on the opposite side wall of the accommodating portion and is connected to the accommodating cavity; the accommodating portion has a connected accommodating cavity and a limiting opening, the limiting opening is located at the end of the accommodating portion, the mounting portion is located in the accommodating cavity, and the screw rod passes through the limiting opening, and the limiting opening allows the mounting portion to deflect within a first angle range;

[0015] The threaded connection portion is used for threaded connection with the locking assembly.

[0016] Preferably, a deflection transfer groove is provided on the side wall of the accommodation portion, and the deflection transfer groove is communicated with the limiting opening;

[0017] The deflection transfer groove allows the screw to deflect within a second angular range, which is greater than the first angular range.

[0018] Preferably, the deflection transfer grooves are evenly spaced around the center of the limiting opening;

[0019] The threaded connection portion is provided with an open groove arranged along its axial direction, so that the locking assembly can extend into the threaded connection portion.

[0020] Preferably, the locking assembly comprises a saddle, an external locking head, and an internal locking rod, wherein:

[0021] The saddle is located in the first limiting head, and is provided with a second hole connected to the first hole, and the titanium rod can pass through the first hole and the second hole;

[0022] The outer locking head is threadedly connected to the first limiting head and can abut against the saddle, thereby pushing the saddle against the mounting portion, thereby locking the mounting portion;

[0023] The outer locking head has an inner thread cavity, and at least a portion of the inner locking rod extends into the inner thread cavity and is threadedly connected to the outer locking head to abut against the titanium rod passing through the saddle, thereby locking the titanium rod.

[0024] The present invention also provides an internal fixation system, comprising a titanium rod, a fully threaded screw, a second limit head, and the above-mentioned new axis pedicle tension screw assembly, wherein the titanium rod passes through the first limit head and the second limit head, and the first limit head and the second limit head are both provided with the locking assembly, the locking assembly locks the titanium rod, and the fully threaded screw is drilled into another vertebra adjacent to the fractured vertebra.

[0025] Preferably, the full-thread screw is provided with equidistant thread segments.

[0026] Compared with the prior art, the novel axis pedicle lag screw assembly and internal fixation system provided by the present invention have the following beneficial effects: on the lag screw, since the pitch of the first thread segment is greater than the pitch of the second thread segment, when the first thread segment drills into the posterior arch portion of the C2 vertebral body, the second thread segment is located at the anterior arch portion of the C2 vertebral body, and the lag screw is continuously turned. The advancement length of the first thread segment in the posterior arch portion of the C2 vertebral body is greater than the advancement length of the second thread segment in the anterior arch portion of the C2 vertebral body, and the lag screw will pull the posterior arch portion of the C2 vertebral body toward the anterior arch portion of the C2 vertebral body, achieving a secondary pressurization effect. The locking assembly can lock the titanium rod, thereby improving the stability of the structure.

[0027] The tension screw can provide stronger holding force and increase stability. At the same time, the two compressions can further reduce the fracture and prevent the screw from being over-pressurized, which is highly safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a three-dimensional schematic diagram of a lag screw;

[0030] Figure 2 is a schematic diagram of the cross-sectional structure of a tension screw;

[0031] Figure 3 It is a schematic diagram of the exploded structure of a new axis pedicle lag screw assembly;

[0032] Figure 4 is a schematic diagram of the cross-sectional structure of the internal fixation system;

[0033] Figure 5 It is a three-dimensional structural diagram of the internal fixation system;

[0034] Figure 6 It is an enlarged structural cross-sectional view of the locking assembly locking the titanium rod and the tension screw;

[0035] Figure 7 This is the front view of the internal fixation system on the C2 and C3 vertebrae;

[0036] Figure 8 It is a lateral view of the internal fixation system on the C2 and C3 vertebrae;

[0037] Fig. 9 It is a schematic diagram of the effect of the lag screw in the internal fixation system on the two parts of the C2 vertebral body.

[0038] In the figure, 1, tension screw; 11, first threaded segment; 12, second threaded segment; 13, mounting portion; 14, axial cavity; 2, first limiting head; 20, accommodating portion; 21, first hole position; 22, limiting opening; 23, deflection transfer groove; 24, threaded connection portion; 3, locking assembly; 31, saddle; 311, second hole position; 32, external locking head; 33, internal locking rod; 4, full-thread screw; 5, titanium rod; 6, second limiting head; 7, C2 vertebra; 8, C3 vertebra. DETAILED DESCRIPTION

[0039] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "length", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the 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 the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0041] The embodiment of the present invention provides a novel axis pedicle tension screw assembly and internal fixation system. The tension screw can provide stronger holding force and increase stability. At the same time, double pressurization can further reduce the fracture and prevent excessive pressurization of the screw, which has high safety.

[0042] Combine the following Figure 1-Figure 9 The technical solution provided by the present invention is described in more detail.

[0043] Embodiment 1:

[0044] like Figure 1-Figure 3 , Fig. 9 As shown, the new axis pedicle tension screw 1 assembly provided by the present invention includes a tension screw 1, a first limit head 2 and a locking assembly 3, wherein: the tension screw 1 includes a mounting portion 13 and a screw rod, the mounting portion 13 is fixed to the end of the screw rod, the screw rod includes a first thread segment 11 and a second thread segment 12 arranged at intervals along its length direction, the first thread segment 11 is located on the side of the second thread segment 12 away from the mounting portion 13, and the pitch of the first thread segment 11 is greater than the pitch of the second thread segment 12; the first limit head 2 is provided with a first hole position 21 for the titanium rod 5 to pass through, the mounting portion 13 is located in the first limit head 2, the locking assembly 3 is threadedly connected to the first limit head 2, and can fix the titanium rod 5, and can lock the mounting portion 13 in the first limit head 2.

[0045] For details, see Figure 1 , Figure 2 and Figure 3As shown, the tension screw 1 of this embodiment has a first thread segment 11 and a second thread segment 12 arranged on the screw rod at intervals, and the first thread segment 11 is located on the side of the second thread segment 12 away from the mounting portion 13, see Fig. 9 As shown, the first thread segment 11 is used to drill into the posterior arch portion (part b in the figure) of the C2 vertebral body 7, and the second thread segment 12 is used to drill into the anterior arch portion (part a in the figure) of the C2 vertebral body 7. When the first thread segment 11 is used to drill into the posterior arch portion of the C2 vertebral body 7, the tension screw 1 is continuously turned, and the length of the first thread segment 11 continuously drilling into the posterior arch portion (part b in the figure) of the C2 vertebral body 7 is greater than the length of the second thread segment 12 drilling into the anterior arch portion (part a in the figure) of the C2 vertebral body 7, which will pull the posterior arch portion (part b in the figure) of the C2 vertebral body 7 toward the anterior arch portion (part a in the figure) of the C2 vertebral body 7. Fig. 9 Direction of arrow shown.

[0046] The tension screw 1 can provide a stronger holding force and increase stability. The double pressurization can further reduce the fracture and prevent the screw from being over-pressurized, which is highly safe.

[0047] In the novel axis pedicle lag screw 1 assembly of this embodiment, since the pitch of the first thread segment 11 is greater than the pitch of the second thread segment 12, when the first thread segment 11 drills into the posterior arch portion of the C2 vertebral body 7, the second thread segment 12 is located at the anterior arch portion of the C2 vertebral body 7, and the lag screw 1 is continuously turned. The advancement length of the first thread segment 11 in the posterior arch portion of the C2 vertebral body 7 is greater than the advancement length of the second thread segment 12 in the anterior arch portion of the C2 vertebral body 7, and the lag screw 1 will pull the posterior arch portion of the C2 vertebral body 7 toward the anterior arch portion of the C2 vertebral body 7, achieving a secondary pressurization effect. The locking assembly 3 can lock the titanium rod 5, thereby improving the stability of the structure.

[0048] As an alternative embodiment, see Figure 2 As shown, there is an axial cavity 14 in the screw, and the axial cavity 14 is arranged along the central axis of the screw.

[0049] Before drilling the lag screw 1, first fix the Kirschner wire into the C2 vertebra 7, and use the axial cavity 14 to insert the Kirschner wire, so as to achieve the fixed-point implantation of the lag screw 1 on the C2 vertebra 7 and prevent the fixed position of the lag screw 1 from deviating from the target position.

[0050] As an alternative embodiment, see Figure 1-Figure 3 As shown, the length of the first thread segment 11 is greater than the length of the second thread segment 12 .

[0051] See also Figure 7-Figure 9As shown, the lag screw 1 is placed behind the C2 vertebral body 7, and can directly compress and fix the fracture site. Specifically, the lag screw 1 is placed in the middle of the C2 vertebral body 7; the lag screw 1 is 22 to 32 mm long, the diameter of the first thread segment 11 is 4 mm, the thread diameter of the second thread segment 12 is 5 mm, the thread length of the first thread segment 11 is 10 mm or 12 mm, the thread length of the second thread segment 12 is 5.75 mm, the pitch of the first thread segment 11 is 1.75 mm, and the thread pitch of the second thread segment 12 is 1.25 mm. The pitch of the first thread segment 11 is greater than the pitch of the second thread segment 12, the thread diameter of the first thread segment 11 is smaller than the thread diameter of the second thread segment 12, and the middle part has no thread, which is a bare rod structure.

[0052] After the tension screw 1 connects the two broken parts of the C2 vertebra 7, for some unstable situations, the full-thread screw 4 is required to be drilled into the adjacent C3 vertebra 8, and the tension screw 1 and the full-thread screw 4 are fixedly connected by the titanium rod 5, so as to ensure the stability of the entire fixed structure.

[0053] However, see Figure 7-Figure 8 As shown, the fracture position of the C2 vertebra 7 is different, and the position where the tension screw 1 is drilled is different. If the mounting portion 13 and the first limit head 2 are always locked, there may be a problem that the titanium rod 5 cannot be installed, and it is difficult to operate when the titanium rod 5 fixes the tension screw 1 and the full-thread screw 4.

[0054] For the above questions, see Figure 1 , Figure 2 and Figure 4 , Figure 5 As shown, the mounting portion 13 is a spherical structure, and when the mounting portion 13 is in an unlocked state, it can rotate in a deflectable manner within the first limit head 2.

[0055] That is, before the locking assembly 3 fixes the titanium rod 5 , the mounting portion 13 is in an unlocked state and can be deflected and rotated in the first limit head 2 , so as to adjust the deflection angle of the tension screw 1 , thereby facilitating the installation of the titanium rod 5 .

[0056] As an optional embodiment, the first limit head 2 includes an accommodating portion 20 and a threaded connection portion 24, wherein: the first hole position 21 is opened on the opposite side wall of the accommodating portion 20 and is connected to the accommodating cavity; the accommodating portion 20 has a connected accommodating cavity and a limit opening 22, the limit opening 22 is located at the end of the accommodating portion 20, the mounting portion 13 is located in the accommodating cavity, and the screw passes through the limit opening 22, the limit opening 22 allows the mounting portion 13 to deflect within a first angle range; the threaded connection portion 24 is used for threaded connection of the locking assembly 3.

[0057] Specifically, the "accommodating cavity" is a cavity in the first limiting head 2 that accommodates the mounting portion 13. Figure 4 and Figure 6 See Figure 5 As shown, the matching structure of the accommodating cavity, the limiting opening 22 and the mounting portion 13 enables the tension screw 1 to rotate in a deflectable manner, thereby adjusting the angle between the first limiting head 2 and the tension screw 1 to facilitate the installation of the titanium rod 5.

[0058] As an alternative embodiment, see Figure 5 As shown, a deflection displacement groove 23 is provided on the side wall of the accommodation portion 20, and the deflection displacement groove 23 is connected to the limit opening 22; the deflection displacement groove 23 allows the screw to deflect within a second angle range, and the second angle range is greater than the first angle range. The deflection displacement grooves 23 are evenly spaced around the center of the limit opening 22.

[0059] The angle groove provides a maximum angle of 84°, and the rest of the limiting opening 22 provides a maximum angle of 34°.

[0060] The structure of the deflection transfer groove 23 can allow the tension screw 1 to deflect and rotate at a larger angle, such as Figure 5 As shown, it is convenient to install the titanium rod 5.

[0061] As an alternative embodiment, see Figure 3 and Figure 4 As shown, the threaded connection part 24 is provided with an open groove arranged along its axial direction, so that the locking assembly 3 can extend into the threaded connection part 24, thereby facilitating the connection between the locking screw and the threaded connection part 24 of the first limit head 2, thereby locking the titanium rod 5 and the mounting part 13.

[0062] As an alternative embodiment, see Figure 3-Figure 6 As shown, the locking assembly 3 of this embodiment includes a saddle 31, an outer locking head 32, and an inner locking rod 33, wherein: the saddle 31 is located in the first limit head 2, and is provided with a second hole 311 connected to the first hole 21, and the titanium rod 5 can pass through the first hole 21 and the second hole 311; see Figure 4 and Figure 6 As shown, the external locking head 32 is threadedly connected to the first limit head 2 and can abut against the saddle 31, thereby pushing the saddle 31 to abut against the mounting portion 13, and then locking the mounting portion 13; the external locking head 32 has an internal threaded cavity, at least part of the internal locking rod 33 extends into the internal threaded cavity, and is threadedly connected to the external locking head 32, so as to abut against the titanium rod 5 passing through the saddle 31, and then lock the titanium rod 5.

[0063] Before the locking assembly 3 locks the mounting portion 13, the tension screw 1 can be rotated in a deflectable manner, thereby adjusting the angle between the first limit head 2 and the tension screw 1, so as to facilitate the installation of the titanium rod 5. After the titanium rod 5 is installed, the outer locking head 32 is first threadedly connected to the threaded connection portion 24 of the first limit head 2, see Figure 4 and Figure 6As shown, as shown, the outer locking head 32 is continuously turned, and the outer locking head 32 pushes the saddle 31 to abut against the mounting portion 13 of the tension screw 1, thereby locking the mounting portion 13 of the tension screw 1, and the tension screw 1 cannot continue to deflect compared to the first limit head 2.

[0064] See also Figure 4 and Figure 6 As shown, the inner locking rod 33 is placed in the outer locking head 32 and threadedly connected to the outer locking head 32. The inner locking rod 33 is continuously turned so that the inner locking rod 33 abuts against the titanium rod 5 passing through the saddle 31, thereby locking the titanium rod 5 so that the titanium rod 5 cannot move further.

[0065] Among them, a hexagonal groove can be provided in the inner locking rod 33 to facilitate the inner locking rod 33 to be twisted by tools such as a medical wrench.

[0066] The locking assembly 3 of this embodiment can realize the locking of the tension screw 1 and the titanium rod 5. Specifically, the outer locking head 32 locks the mounting portion 13 of the tension screw 1, and the inner locking rod 33 locks the titanium rod 5.

[0067] In the novel axis pedicle lag screw assembly 1 of the present embodiment, before the locking assembly 3 locks the lag screw 1 and the titanium rod 5, the mounting portion 13 of the lag screw 1 can be deflected and rotated in the first limit head 2, so as to adjust the relative angle between the lag screw 1 and the first limit head 2, such as Fig. 9 As shown, the titanium rod 5 is convenient for connecting the lag screw 1 with the full-thread screw 4, thereby improving the stability of the internal fixation system. When the titanium rod 5 is connected in place, the locking assembly 3 can be used to lock the lag screw 1 and the titanium rod 5, and the lag screw 1 and the titanium rod 5 cannot continue to move, thereby ensuring the stability of the internal fixation system.

[0068] Embodiment 2:

[0069] See also Figure 4-Figure 9 As shown, this embodiment provides an internal fixation system, including a titanium rod 5, a fully threaded screw 4, a second limit head 6, and the above-mentioned new axis pedicle tension screw 1 assembly, the titanium rod 5 passes through the first limit head 2 and the second limit head 6, the first limit head 2 and the second limit head 6 are both provided with a locking assembly 3, the locking assembly 3 locks the titanium rod 5, and the fully threaded screw 4 is drilled into another vertebra adjacent to the fractured vertebra.

[0070] After the tension screw 1 connects the two broken parts of the C2 vertebra 7, for some unstable situations, the full-thread screw 4 is required to be drilled into the adjacent C3 vertebra 8, and the tension screw 1 and the full-thread screw 4 are fixedly connected by the titanium rod 5, so as to ensure the stability of the entire fixed structure.

[0071] In the second limit head 6, except for the structure without the deflection transfer groove 23, the rest of the structure is the same as that of the first limit head 2. The full-thread screw 4 also has the mounting portion 13 structure of the tension screw 1, and the full-thread screw 4 can be deflected within a certain range at the limiting opening 22 of the second limit head 6, so as to adjust the relative angle between the full-thread screw 4 and the second limit head 6, which is convenient for installing the titanium rod 5. After the titanium rod 5 is installed, the locking assembly 3 in the second limit head 6 is used to lock the full-thread screw 4 and the titanium rod 5 to ensure the stability of the structure.

[0072] As an alternative embodiment, see Figure 4 and Figure 5 As shown, equidistant thread segments are arranged on the full-thread screw 4. Specifically, the full-thread screw 4 has a diameter of 3.5-4.5 mm and a length of 16-32 mm.

[0073] See also Figure 7-Figure 9 As shown, the midpoint of the outer upper quadrant of the lateral mass of the C3 vertebra 8 is used as the needle insertion point. After placing the full-thread screw 4 on the C3 vertebra, the titanium rod 5 is connected. After adjusting to an appropriate angle, the lag screw 1 and the full-thread screw 4 are locked to fix the angle. First, the full-thread screw 4 is locked inside the Sorbonne, and then the lag screw 1 is locked inside the locking rod 33 to further reduce the fracture.

[0074] In the description of this specification, specific features, structures or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A novel axis pedicle lag screw assembly, characterized in that: It includes a tension screw, a first limit head and a locking assembly, wherein: The tension screw comprises a mounting portion and a screw rod, wherein the mounting portion is fixed to an end of the screw rod, and the screw rod comprises a first thread segment and a second thread segment arranged at intervals along a length direction thereof, wherein the first thread segment is located on a side of the second thread segment away from the mounting portion, and a pitch of the first thread segment is greater than a pitch of the second thread segment; The first limit head is provided with a first hole for the titanium rod to pass through, the mounting portion is located in the first limit head, the locking assembly is threadedly connected to the first limit head, and can fix the titanium rod and lock the mounting portion in the first limit head.

2. The novel axis pedicle lag screw assembly according to claim 1, characterized in that: The length of the first thread segment is greater than the length of the second thread segment.

3. The novel axis pedicle lag screw assembly according to claim 1, characterized in that: The mounting portion is a spherical structure, and when in an unlocked state, the mounting portion can be deflectably rotated within the first limiting head.

4. The novel axis pedicle lag screw assembly according to claim 1, characterized in that: The screw rod has an axial cavity therein, and the axial cavity is arranged along the central axis of the screw rod.

5. The novel axis pedicle lag screw assembly according to claim 1, characterized in that: The first limiting head comprises a receiving portion and a threaded connection portion, wherein: The first hole is opened on the opposite side wall of the accommodating portion and is connected to the accommodating cavity; the accommodating portion has a connected accommodating cavity and a limiting opening, the limiting opening is located at the end of the accommodating portion, the mounting portion is located in the accommodating cavity, and the screw rod passes through the limiting opening, and the limiting opening allows the mounting portion to deflect within a first angle range; The threaded connection portion is used for threaded connection with the locking assembly.

6. The novel axis pedicle lag screw assembly according to claim 5, characterized in that: A deflection transfer groove is provided on the side wall of the accommodation portion, and the deflection transfer groove is communicated with the limiting opening; The deflection transfer groove allows the screw to deflect within a second angular range, which is greater than the first angular range.

7. The novel axis pedicle lag screw assembly according to claim 6, characterized in that: The deflection transfer grooves are evenly spaced around the center of the limit opening; The threaded connection portion is provided with an open groove arranged along its axial direction, so that the locking assembly can extend into the threaded connection portion.

8. The novel axis pedicle lag screw assembly according to claim 1, characterized in that: The locking assembly comprises a saddle, an outer locking head, and an inner locking rod, wherein: The saddle is located in the first limiting head, and is provided with a second hole connected to the first hole, and the titanium rod can pass through the first hole and the second hole; The outer locking head is threadedly connected to the first limiting head and can abut against the saddle, thereby pushing the saddle against the mounting portion, thereby locking the mounting portion; The outer locking head has an inner thread cavity, and at least a portion of the inner locking rod extends into the inner thread cavity and is threadedly connected to the outer locking head to abut against the titanium rod passing through the saddle, thereby locking the titanium rod.

9. An internal fixation system, characterized in that: It includes a titanium rod, a fully threaded screw, a second limit head, and a new axis pedicle tension screw assembly as described in any one of claims 1 to 8, wherein the titanium rod passes through the first limit head and the second limit head, and the first limit head and the second limit head are both provided with the locking assembly, the locking assembly locks the titanium rod, and the fully threaded screw is drilled into another vertebra adjacent to the fractured vertebra.

10. The internal fixation system according to claim 9, characterized in that: The full-thread screw is provided with equidistant thread segments.

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