An expandable percutaneous bone cement pedicle screw

Abstract

The present invention discloses a dilatable percutaneous bone cement pedicle screw, which comprises a screw sleeve with a U-shaped groove and a ball head screw; a channel is provided along the central axis of the ball head screw, and an adjusting nut is matched at the proximal end of the channel. The adjusting nut is an internal hexagonal nut with internal threads. Wherein, the head of the adjusting nut can rotate within the channel at the position of the head of the ball head screw, and the outer circle of the adjusting nut is matched with the channel at the position of the shank of the ball head screw; a plurality of through holes are axially formed along the inner edge of the peripheral wall of the adjusting nut; the internal threads of the adjusting nut are matched and connected with the external threads at the proximal end of the dilating shaft arranged in the channel, and the distal end of the dilating shaft is fixedly connected with the distal head of the ball head screw; a plurality of dilating grooves are sequentially arranged along the axial direction on the peripheral wall of the distal part of the ball head screw. The pedicle screw of the present invention can enable the bone cement to be diffusely distributed, avoiding the risks of loosening and slipping of the pedicle screw after surgery; and only one type of screw structure can be used to realize the dilation and compression of the vertebral body screw, which is convenient to operate, saves the operation time, and improves the operation efficiency.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and particularly to a dilatable percutaneous bone cement pedicle screw. Background Art

[0002] At present, percutaneous pedicle screw internal fixation and fusion has become the gold standard for the treatment of lumbar degenerative diseases, with many advantages such as ensuring decompression effect, stabilizing the spine, promoting fusion and early rehabilitation, and is widely used in the treatment of diseases such as lumbar spinal stenosis, lumbar spondylolisthesis, lumbar degenerative scoliosis, lumbar disc herniation, etc. Although the application of percutaneous pedicle screws is very popular, the related complications cannot be ignored: (1) Loosening of the pedicle screw. The loosening of the screw not only poses a potential danger to the surrounding important soft tissues, but also makes the internal fixation prone to failure, thus affecting the instability or re-collapse of the spine; (2) Due to the differences in bone quality among different patients (some patients have obvious osteoporosis), when using percutaneous pedicle screws, an appropriate amount of bone cement also needs to be implanted at the implantation site during the operation to meet the fixation requirements of the percutaneous pedicle screw.

[0003] For existing bone cement screws, equal amounts of radial light holes are mainly arranged between adjacent two threads (at the bottom of the thread) at the distal end of the hollow pedicle screw thread axially to form a necessary passage for the bone cement to overflow into the vertebral body, so that the vertebral body and the pedicle screw are firmly fixed through the bone cement. However, due to the limitation of the pressure during the bone cement injection process and the actual use feedback of this bone cement screw in clinical practice, the bone cement overflowing into the radial light holes only stays and is fixed on the limited local surface of the pedicle thread, and it is impossible to form a large area of bone cement and firmly fix it, thus unable to improve the fixation of the implant in patients with cancellous bone, resulting in the risk of re-loosening of the pedicle screw after surgery.

[0004] Currently, there are mainly two types of pedicle screws according to the implantation method. One is the open pedicle screw (the tail of the screw is relatively short), that is, a large area of the patient's part needs to be exposed during the operation, with large trauma and a high postoperative infection rate; the other is the minimally invasive percutaneous pedicle screw (the tail of the screw is long). Compared with the open surgery, its greatest advantage lies in the small surgical trauma, less bleeding and corresponding inflammation. Therefore, it is very necessary to design a minimally invasive bone cement pedicle screw with a strong fixation effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a dilatable percutaneous bone cement pedicle screw for the deficiencies in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] Provided is a expandable percutaneous bone cement pedicle screw, including a screw sleeve and a ball head screw. The screw sleeve and the ball head screw are rotatably connected in all directions. The screw sleeve has a U-shaped groove. The ball head screw is provided with a channel along the central axis, and the channel is communicated with the U-shaped groove. A regulating nut is matched at the proximal end of the channel. The regulating nut is an internal hexagonal nut with internal threads. Wherein, the head of the regulating nut can rotate in the channel at the position of the head of the ball head screw, and the outer circle of the regulating nut is matched with the channel at the position of the rod of the ball head screw. A plurality of through holes are axially formed along the inner wall of the circumferential wall of the regulating nut. The internal threads of the regulating nut are in threaded connection with the external threads at the proximal end of the expansion shaft arranged in the channel. The distal end of the expansion shaft is fixedly and hermetically connected with the distal end head of the ball head screw. A plurality of expansion grooves are sequentially arranged along the axial direction on the circumferential wall of the distal part of the ball head screw, and the expansion grooves are communicated with the channel.

[0008] Further, the angle at which the screw sleeve and the ball head screw can rotate in all directions is 0-40° circumferentially.

[0009] Further, the connection mode of fixedly and hermetically connecting the distal end of the expansion shaft with the distal end head of the ball head screw is autogenous welding.

[0010] Further, the number of the through holes is 2-4.

[0011] Further, the number of the expansion grooves is 4-6, and they are symmetrically arranged in pairs in the middle and far parts of the rod of the ball head screw.

[0012] Further, the gap between the channel and the expansion shaft, and the through holes and the expansion grooves form a bone cement channel.

[0013] Further, the external threads of the ball head screw are single double-thread or double four-thread.

[0014] Further, the diameter of the channel at the position of the rod of the ball head screw gradually increases from the proximal end to the distal end.

[0015] Adopting the above technical solutions, compared with the prior art, the present invention has the following technical effects:

[0016] The expandable percutaneous bone cement pedicle screw of the present invention can make the bone cement be diffusely distributed in the nail body and the vertebral body, and solves the problem that the injection of the bone cement cannot be implemented or the injection is incomplete due to excessive resistance during the implantation of the bone cement, promotes the firm fixation of the pedicle screw on the vertebral body through the bone cement, and avoids the risk of loosening and slipping of the pedicle screw after surgery due to non-diffuse implantation of the bone cement.

[0017] The expandable percutaneous bone cement pedicle screw of the present invention can realize the expansion and compression of the vertebral body screw only through a screw of one structure, and can selectively implement the function of whether to expand according to the bone quality of the vertebral body of different patients; at the same time, bone cement can be implanted after expansion, which is convenient to operate, saves the operation time and improves the operation efficiency.

[0018] The expandable percutaneous bone cement pedicle screw of the present invention can also restore the expanded vertebral body screw to the original unexpanded external structure after the pedicle screw is expanded and before the bone cement is implanted, which makes the operation process of the surgery more flexible. Description of the Drawings

[0019] Figure 1 It is a schematic cross-sectional view of the expandable percutaneous bone cement pedicle screw of the present invention;

[0020] Figure 2 It is a partial enlarged view of the expandable percutaneous bone cement pedicle screw of the present invention;

[0021] Figure 3 It is a schematic structural view of the adjusting nut of the present invention;

[0022] Figure 4 It is a preoperative effect diagram of the expandable percutaneous bone cement pedicle screw of the present invention;

[0023] Figure 5 It is a postoperative effect diagram of the expandable percutaneous bone cement pedicle screw of the present invention. Detailed Embodiments

[0024] The present invention will be further described below in conjunction with the drawings and specific embodiments, but it is not intended to limit the present invention.

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] As used in the present invention, the proximal end refers to the end close to the surgeon, and the distal end refers to the end far from the surgeon.

[0027] Such as Figures 1 - 3As shown in the figure, this embodiment provides a deployable percutaneous bone cement pedicle screw, which includes a screw sleeve 1 and a ball head screw 2. The screw sleeve 1 and the ball head screw 2 are connected in a universal rotatable manner. The screw sleeve 1 has a U-shaped groove 11. The ball head screw 2 is provided with a channel 21 along its central axis, and the channel 21 communicates with the U-shaped groove 11. A regulating nut 3 is matched at the proximal end of the channel 21. The regulating nut 3 is an internal hexagonal nut with internal threads. Among them, the head of the regulating nut 3 can rotate within the channel 21 at the position of the head of the ball head screw 2, and the outer circle of the regulating nut 3 is matched with the channel 21 at the position of the rod of the ball head screw 2. A plurality of through holes 31 are axially opened along the inner wall of the circumferential wall of the regulating nut 3. The internal threads of the regulating nut 3 are matched and connected with the external threads at the proximal end of the expansion shaft 4 arranged in the channel 21. The distal end of the expansion shaft 4 is fixedly and hermetically connected to the distal head of the ball head screw 2. A plurality of expansion grooves 22 are sequentially arranged along the axial direction on the circumferential wall of the distal part of the ball head screw 2, and the expansion grooves 22 communicate with the channel 21.

[0028] The deployable percutaneous bone cement pedicle screw of the present invention can enable the bone cement to be diffusely distributed in the vertebral body, and solves the problem that the injection of bone cement cannot be implemented or the injection is incomplete due to excessive resistance during the placement of the bone cement, promotes the firm fixation of the pedicle screw on the vertebral body through the bone cement, and avoids the risk of loosening and slipping of the pedicle screw after surgery due to non-diffuse placement of the bone cement.

[0029] In the present invention, the gap between the channel 21 and the expansion shaft 4, as well as the through holes 31 and the expansion grooves 22 form a bone cement channel. Preferably, the number of the through holes 31 is 2-4. The diameter of the channel 21 at the position of the rod of the ball head screw 2 gradually increases from the proximal end to the distal end, so that the gap between the channel 21 and the expansion shaft 4 gradually increases. During the process of implementing the placement of the bone cement, the resistance of the bone cement placement can be greatly reduced.

[0030] As a preferred embodiment, the angle at which the screw sleeve 1 and the ball head screw 2 of the present invention can rotate universally is 0-40° circumferentially. The low-profile fracture groove design of the screw sleeve 1 is beneficial to the suture of the surgery.

[0031] As a preferred embodiment, the connection method of fixedly and hermetically connecting the distal end of the expansion shaft 4 to the distal head of the ball head screw 2 is self-fusion welding.

[0032] As a preferred embodiment, the number of the expansion grooves 22 is 4-6, and they are symmetrically arranged in pairs in the middle and far parts of the rod of the ball head screw 2. When the pedicle screw is in the expanded state, the expansion grooves 22 are expanded into an oval or a rhombus, which is more beneficial to the diffuse distribution of the bone cement in the vertebral body.

[0033] As a preferred embodiment, the external threads of the ball head screw 2 are single-double or double-four-thread threads, which improves the surgical implantation time and at the same time increases its contact area with the vertebral body and the pedicle.

[0034] The working principle of the percutaneous bone cement pedicle screw of the present invention is as follows:

[0035] The operator can select expandable percutaneous bone cement pedicle screws of suitable specifications and implant them in the vertebral body. When the expansion function is needed, the operator rotates the adjusting nut 3 clockwise with the hexagonal screwdriver. After the distal end surface of the head of the adjusting nut 3 contacts the end surface of the connection between the head of the ball stud 2 and the rod of the ball stud 2, it continues to rotate clockwise; since the adjusting nut 3 is threadedly matched with the expansion shaft 4, continuing to rotate the adjusting nut 3 clockwise will apply the same direction of rotational force to the expansion shaft 4; and since the distal end of the expansion shaft 4 and the distal end of the ball stud 2 are self-meltingly welded, the expansion shaft 4 is caused to contact the hexagonal bottom of the ball stud 2 due to the threaded end surface of the adjusting nut 3, so that the effective distance of the expansion shaft 4 inside the ball stud 2 is shortened, causing the expansion groove 22 from the distal end to the proximal end of the ball stud 2 to be expanded and deformed in sequence (such as Figure 5 shown).

[0036] After all the expansion slots 22 are expanded, the rotation of the adjusting nut 3 is stopped. Since the adjusting nut 3 is threadedly matched with the expansion shaft 4, the expanded state is maintained.

[0037] Then, a bone cement injection device is used to inject bone cement through the through hole 31 and the bone cement channel formed by the gap between the channel 21 and the expansion shaft 4, so that the bone cement is placed in the expansion groove 22 of the ball stud 2 after expansion deformation and the vertebral body to achieve diffuse filling of bone cement.

[0038] As a preferred embodiment, before bone cement is injected, when the vertebral nail needs to be removed due to clinical operation reasons or wrong specification selection, the ball nail 2 is in the expanded state and cannot be removed. At this time, the adjusting nut 3 can be pushed toward the distal end by a hexagonal screwdriver and rotated counterclockwise to restore the ball nail 2 to the unexpanded state, and then it can be removed.

[0039] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. An expandable percutaneous bone cement pedicle screw, comprising a screw sleeve (1) and a ball head screw (2), wherein the screw sleeve (1) and the ball head screw (2) are rotatably connected in all directions, and the screw sleeve (1) has a U-shaped groove (11). Characterized in that the ball head screw (2) is provided with a channel (21) along the central axis, and the channel (21) communicates with the U-shaped groove (11); a regulating nut (3) is matched at the proximal end of the channel (21), and the regulating nut (3) is an internal hexagonal nut with internal threads. Wherein, the head of the regulating nut (3) can rotate in the channel (21) at the head position of the ball head screw (2), and the outer circle of the regulating nut (3) matches the channel (21) at the rod position of the ball head screw (2); a plurality of through holes (31) are axially formed along the inner wall of the circumferential wall of the regulating nut (3); the internal threads of the regulating nut (3) are in threaded connection with the external threads at the proximal end of an expansion shaft (4) arranged in the channel (21), and the distal end of the expansion shaft (4) is fixedly and hermetically connected to the distal head of the ball head screw (2); a plurality of expansion grooves (22) are sequentially arranged along the axial direction on the circumferential wall of the distal part of the ball head screw (2), and the expansion grooves (22) communicate with the channel (21).

2. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the angle at which the screw sleeve (1) and the ball head screw (2) can rotate in all directions is 0-40° circumferentially.

3. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the connection mode of the distal end of the expansion shaft (4) fixedly and hermetically connected to the distal head of the ball head screw (2) is autogenous welding.

4. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the number of the through holes (31) is 2-4.

5. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the number of the expansion grooves (22) is 4-6, and they are symmetrically arranged in pairs in the middle and far parts of the rod of the ball head screw (2).

6. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the gap between the channel (21) and the expansion shaft (4), and the through holes (31) and the expansion grooves (22) form a bone cement channel.

7. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the external threads of the ball head screw (2) are single double-thread or double four-thread.

8. The expandable percutaneous bone cement pedicle screw according to claim 1, Characterized in that the diameter of the channel (21) at the rod position of the ball head screw (2) gradually increases from the proximal end to the distal end.

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