Pedicle disarticulation lengthening nail

Abstract

The application discloses a pedicle disconnection lengthening nail, which comprises a front nail and a rear nail in sliding connection with the front nail, the outer surfaces of the front nail and the rear nail are provided with self-tapping external threads with equal pitches, a through hole is vertically arranged in the interior of the rear nail, the upper end of the front nail is fixedly connected with an extension column, the upper end of the extension column is fixedly connected with a sliding cross bolt, the lower end of the rear nail is provided with a through sliding groove, the two sides of the sliding cross bolt are respectively located in the two sliding grooves and slide up and down along the sliding grooves, the sliding groove, the extension column and the inner core bolt are arranged, the pedicle is lengthened by screwing the inner core bolt into the extension column, the extension column can swing in the inner cavity of the rear nail at a small amplitude, the lateral bending force caused by the non-parallel entry of the two nails at different times or at the same time is adapted, and the damage to the vertebra is reduced.

Description

Technical Field

[0001] This invention relates to the field of medical surgical instruments, and in particular to a pedicle fracture lengthening screw. Background Technology

[0002] Currently, three minimally invasive surgical methods are relatively mature in the clinical practice for lumbar spinal stenosis: percutaneous screw-rod system implantation, spinous process distraction, and pedicle screw lengthening surgery. Pedicle screw lengthening surgery expands the area of ​​the spinal canal and intervertebral foramen by lengthening the severed pedicle, thereby improving clinical symptoms. It is currently the most widely used procedure in clinical practice. To achieve better lengthening results, the structure of the pedicle screw is crucial. Chinese Patent CN201320764621, "An Improved Pedicle Lengthening Device," and Chinese Patent CN201920527997, "A Bidirectional Lengthening Pedicle Screw: Anterior and Rear Screws," both disclose pedicle screws comprising three parts: anterior screw, rear screw, and core screw. The anterior screw... Both the anterior and posterior screws are screwed to the mandrel. The assembly of the anterior and posterior screws first enters the minimally invasive channel. Then, the screwing in of the mandrel pushes the anterior and posterior screws to separate, thereby separating the pedicles and achieving the lengthening effect. The drawback of this approach is that, because the cross-section of the vertebra is similar to a triangle rather than a straight line, when the pedicle lengthening screws on both sides enter the vertebra and drill to the sides, the screws do not enter parallel but at a certain angle. At this time, the two screws will enter unevenly on both sides of the vertebra due to asynchronous drilling, resulting in a deflection force in a certain direction. When this deflection force is too strong due to the excessive force of one of the lengthening screws, it will damage the pedicle on one side, thus affecting the overall surgical outcome. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a pedicle fracture extension nail to solve the technical problems mentioned in the background art.

[0004] To solve the technical problem, the present invention adopts the following technical solution:

[0005] To solve the technical problem, the present invention adopts the following technical solution:

[0006] A pedicle screw extension pin includes a front screw and a rear screw slidably connected to the front screw. Both the front and rear screws have self-tapping external threads of equal pitch on their outer surfaces. The rear screw has a through-hole running vertically through it. An extension post is fixedly connected to the upper end of the front screw, and a sliding transverse bolt is fixedly connected to the upper end of the extension post. The lower end of the rear screw has a through-groove. The two sides of the sliding transverse bolt are located within the two side grooves and slide vertically along the grooves. The tail end of the rear screw has a first internal hexagonal socket, and the lower end of the first internal hexagonal socket... The device has a first internal thread, and the rear pin also has an inner core bolt for adjusting the extension action of the front pin. The inner core bolt includes a pin tail at the upper end, a second external thread at the lower end of the pin tail for screwing with the first internal thread, and a protrusion at the lower end of the second external thread for pushing the extension column downward. The pin tail has a second internal hexagonal opening inside. When the inner core bolt is tightened into the rear pin, the protrusion can abut against the uppermost end of the extension column and push the extension column downward, thereby realizing the extension of the front pin relative to the rear pin.

[0007] Furthermore, the front screw head has self-tapping threads longitudinally arranged on its outer surface.

[0008] Furthermore, the diameter of the extension post is smaller than the diameter of the rear nail cavity.

[0009] Furthermore, the upper end of the extension column is designed with a rounded head.

[0010] Furthermore, the upper end of the extension column is designed with a rounded head.

[0011] Furthermore, the pitch of the first internal thread is less than the pitch of the self-tapping external threads of the front and rear pins, and the diameter of the first internal hexagon is greater than the diameter of the second internal hexagon.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) By separating the front nail, rear nail and inner core bolt and not directly connecting the inner core bolt to the front nail, the traditional pedicle extension nail is eliminated from the overall assembly method, thus avoiding the problem of vertebral injury that traditional pedicle extension nails are prone to cause.

[0014] (2) By setting up a sliding groove, an extension column, and an inner core bolt, the extension column can be screwed into the inner core to extend the pedicle. At the same time, the extension column can swing slightly within the cavity of the posterior nail to adapt to the lateral bending force caused by the two nails not entering at the same time or simultaneously and not parallel, thereby reducing damage to the vertebrae. Attached Figure Description

[0015] Figure 1 : An exploded view of the overall structure of this invention patent;

[0016] Figure 2Schematic diagram of the overall structure of this invention patent Figure 2 ;

[0017] Figure 3 : Cross-sectional view of the overall structure of this invention patent;

[0018] Figure 4 : Cross-sectional view of the rear nail structure of this invention patent;

[0019] Figure 5 : Schematic diagram of the inner core bolt structure of this invention patent;

[0020] Figure 6 : Schematic diagram of the first internal hexagonal structure of this invention patent;

[0021] Figure 7 : Schematic diagram of the front nail and extension post structure of this invention patent;

[0022] Figure 8 : Schematic diagram of the anterior and posterior screws of this invention acting on the vertebra before vertebral lengthening;

[0023] Figure 9 This invention patent is illustrated in the diagram of the anterior and posterior nails acting on the vertebra after vertebral lengthening.

[0024] In the diagram: 1-front pin, 2-rear pin, 3-rear pin inner cavity, 4-extension post, 5-sliding transverse bolt, 6-slide groove, 7-first internal hexagon, 8-first internal thread, 9-inner core bolt, 10-second external thread, 11-protruding post, 12-second internal hexagon, 13-self-tapping thread, 14-self-tapping external thread. Detailed Implementation

[0025] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0026] refer to Figures 1 to 7This invention discloses a pedicle fracture extension screw, comprising a front screw 1 and a rear screw 2 slidably connected to the front screw 1. Both the front screw 1 and the rear screw 2 have external threads 14 of equal pitch for self-tapping. The rear screw 2 has a through-hole cavity 3. An extension post 4 is fixedly connected to the upper end of the front screw 1, and a sliding transverse bolt 5 is fixedly connected to the upper end of the extension post 4. The lower end of the rear screw 2 has a through-hole groove 6 located on the screw arm of the rear screw 2, with symmetrical grooves on both sides. The sliding transverse bolt 5 is a transverse bolt passing through the upper end of the extension post 4, with protruding ends. The protruding bolt bodies on both sides of the sliding transverse bolt 5 are respectively located in the two side grooves 6 and can slide up and down along the grooves 6. The rear nail 2 has a first internal hexagon 7 at its tail end, and a first internal thread 8 at its lower end. The rear nail 2 also has an inner core bolt 9 for adjusting the extension action of the front nail 1. The inner core bolt 9 includes a nail tail 15 at the upper end and a second external thread 10 at the lower end of the nail tail 15 for screwing with the first internal thread 8, and a protruding post 11 at the lower end of the second external thread 10 for pushing the extension post 4 downward. The nail tail 15 has a second internal hexagon 12 that opens upward inside. The protruding post 11 can abut against the uppermost end of the extension post 4 and push the extension post 4 downward during the tightening of the inner core bolt 9 into the rear nail 2, thereby realizing the extension of the front nail 1 relative to the rear nail 2.

[0027] Preferably, the front nail 1 has a self-tapping tooth 13 longitudinally arranged on the outer surface of the nail head. The self-tapping tooth 13 is a corner notch tooth, which is formed by the tapping tooth wheel entering perpendicular to the nail body axis to cut. After reaching a certain depth, the self-tapping tooth 13 is formed by cutting from the side of the nail body perpendicular to the first cutting surface. The purpose is to increase the cutting force and prevent slippage when drilling into the vertebra.

[0028] Preferably, the diameter of the extension post 4 is smaller than the diameter of the inner cavity 3 of the rear nail. With this configuration, the side of the extension post 4 can easily slide up and down in the inner cavity 3 of the rear nail. At the same time, the outer diameter of the nail tail 15 of the inner core spiral is just equal to the inner diameter of the first internal hexagon 7 on the tail pin. During the process of the inner core spiral being tightened into the inner cavity 3 of the rear nail along the first internal thread 8, the protrusion 11 will push the extension post 4 to move downward. When the sliding bolt 5 just reaches the lowest end of the slide groove 6, the uppermost end of the inner core spiral is flush with the uppermost end of the tail nail and just fits into the internal hexagon of the tail nail.

[0029] Preferably, the upper end of the extension column 4 is designed with a round head. With this design, the upper end of the extension nail can swing slightly within the rear nail cavity 3, thereby causing the entire front nail 1 to swing slightly relative to the tail nail. This can solve the problem mentioned in the technical problem that the two nails are not parallel after entering the vertebra, which can easily lead to excessive force on one side and damage to the vertebra.

[0030] Preferably, the pitch of the first internal thread 8 is less than the pitch of the self-tapping external threads 14 of the front screw 1 and the rear screw 2. Preferably, the diameter of the first internal hexagon 7 is greater than the diameter of the second internal hexagon 8.

[0031] The assembly principle of this invention is as follows: First, insert the extension post into the inner cavity of the upper end of the front pin. Then, through the fixing holes at both ends of the inner cavity of the front pin, and the corresponding circular holes at the lower end of the extension post, fix the extension post and the front pin together with the fixing bolts. Next, insert the upper end of the extension post into the inner cavity of the rear pin. The upper end of the extension post also has a circular hole through which the sliding bolt passes. Leave a portion of both ends of the sliding bolt symmetrically and let them pass through the groove, so that the sliding bolt is locked in the groove. Finally, screw the inner core bolt into the upper end of the tail pin to complete the assembly.

[0032] The operating principle of this invention: (See reference) Figure 8 and Figure 9 Based on the assembly principle described above, when using this pedicle screw extension screw in surgery, first drill a channel at the designated location on the vertebra with a small drill bit. Then, remove the extension screw and take out the inner core bolt. Align the screw head of the front screw with the channel and use a hex screw with the matching first internal hex socket to drill into the first internal hex socket on the tail screw. Drill the entire extension screw into the channel of the vertebra until it reaches the depth where separation is possible. Then, replace it with a hex screw with the matching second internal hex socket and screw the inner core bolt into the second internal thread 8 located in the inner cavity of the tail screw. Through the tightening action of the screw, the inner core bolt is drilled into the lower end of the tail screw. When the protrusion contacts the top of the extension post, continue to tighten the inner core bolt to make the extension post continue to move downwards, because the purpose at this time is to sever the pedicle screw. The pedicle is the central axis of the vertebral column. The anterior screw is drilled into the lower end of the pedicle, while the posterior screw remains at the upper end. After the pedicle is severed using surgical instruments, it can be lengthened to achieve the surgical goal. However, because the cross-section of the vertebra is neither perfectly oriented nor rectangular, the two screws do not enter the vertebrae parallel to each other. This imbalance or asynchronous screwing can cause stress on one side, resulting in a folding force. Traditional lengthening screws are integral and cannot be easily moved slightly, which can easily damage one side of the vertebra. The lengthening screw of this invention, however, has a groove and an extension post, allowing for slight movement of the anterior screw, thus avoiding the aforementioned technical problems that could lead to vertebral damage.

[0033] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A pedicle fracture extension screw, comprising a front screw and a rear screw slidably connected to the front screw, wherein both the front and rear screws have self-tapping external threads of equal pitch on their outer surfaces, characterized in that: The rear pin has a through hole running vertically through it. An extension post is fixedly connected to the upper end of the front pin. A sliding bolt is fixedly connected to the upper end of the extension post. The lower end of the rear pin has a through groove. The two sides of the sliding bolt are located in the two side grooves and slide up and down along the grooves. The tail end of the rear pin has a first internal hexagonal socket with a first internal thread at the lower end. The rear pin also has an inner core bolt for adjusting the extension action of the front pin. The inner core bolt includes a pin tail at the upper end, a second external thread at the lower end of the pin tail for screwing with the first internal thread, and a protrusion at the lower end of the second external thread for pushing the extension post downward. The pin tail has an upward opening with a second internal hexagonal socket. When the inner core bolt is tightened into the rear pin, the protrusion can abut against the uppermost end of the extension post and push the extension post downward, thereby achieving the extension of the front pin relative to the rear pin.

2. The pedicle screw extension method according to claim 1, characterized in that: The front screw head has self-tapping threads longitudinally arranged on its outer surface.

3. The pedicle screw extension method according to claim 1, characterized in that: The diameter of the extension post is smaller than the diameter of the inner cavity of the rear nail.

4. The pedicle fracture extension nail according to claim 2, characterized in that: The upper end of the extension column is designed with a rounded head.

5. The pedicle screw extension method according to claim 1, characterized in that: The pitch of the first internal thread is less than the pitch of the self-tapping external threads of the front and rear pins, and the diameter of the first internal hexagon is greater than the diameter of the second internal hexagon.

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