Degradable anterior cervical intervertebral fusion fixing system

Abstract

The utility model discloses a degradable anterior cervical interbody fusion fixing system which comprises a fusion cage and a locking screw, the fusion cage is in a wedge shape with a high front part and a low rear part and is provided with an inclined mounting hole, and the locking screw is matched with the inclined mounting hole; wherein the fusion cage is made of degradable magnesium alloy, and the locking screw is made of degradable zinc alloy. According to the degradable anterior cervical interbody fusion fixing system and the application method thereof, the zero-incisura interbody fusion fixing system which is degradable, good in mechanical strength and beneficial to bone tissue growth is provided for anterior cervical intervertebral disc resection decompression fusion.

Description

Technical Field

[0001] This utility model relates to the field of medical devices, and in particular to a biodegradable anterior cervical interbody fusion fixation system. Background Technology

[0002] Anterior cervical discectomy and fusion is a classic surgical procedure for treating degenerative cervical spine diseases. It involves removing part of the intervertebral disc tissue and implanting an intervertebral fusion cage to fuse the upper and lower vertebrae together, achieving decompression and fixation. Currently, most clinically used intervertebral fusion cages are made of non-absorbable materials such as titanium alloy or polyetheretherketone (PEEK). However, non-absorbable fusion cages only provide intervertebral support; they cannot be degraded or absorbed, nor do they induce osteogenic processes.

[0003] Therefore, researchers are dedicated to the development of biodegradable fusion devices. Due to the advantages of magnesium (Mg) and its alloys, such as good biocompatibility, mechanical properties close to human bone, and good osteogenic induction, the development of absorbable magnesium alloy fusion devices has received widespread attention in recent years. However, due to the insufficient mechanical strength of magnesium alloys, biodegradable fusion devices made of magnesium alloys need to be used in conjunction with anterior cervical plates, and are not truly fully biodegradable fusion devices; furthermore, the use of anterior plates leads to a higher incidence of postoperative complications such as foreign body sensation, dysphagia, and degeneration of adjacent segments.

[0004] Unlike traditional anterior cervical fusion cages, the zero-notch interbody fusion fixation system can be accommodated within the decompressed intervertebral space, eliminating the need for anterior vertebral body plate fixation. Screws are inserted obliquely into the superior and inferior vertebral bodies through channels within the fusion cage, giving it biomechanical stability similar to plate systems. The application of the zero-notch interbody fusion fixation system significantly shortens surgical time and can compensate for postoperative problems such as dysphagia and adjacent segment degeneration associated with traditional cervical fusion cages.

[0005] Current research generally agrees that local blood flow and mechanical load are the main factors affecting the degradation of magnesium alloy implants in vivo. Due to the low blood flow in the intervertebral space and the fact that the fusion cage primarily provides mechanical support and experiences relatively low shear stress, it is possible to use lower-strength magnesium alloys in the development of absorbable fusion cages. However, the screws in zero-notch intervertebral fusion fixation systems need to be obliquely inserted into adjacent vertebral bodies through channels within the fusion cage. The screws experience significant shear stress, and the high blood flow within the vertebral bodies leads to rapid degradation of the magnesium screws. Therefore, the relatively low mechanical strength and rapid degradation rate of magnesium alloys cannot meet the requirements for manufacturing such screws.

[0006] In recent years, besides magnesium alloys, zinc (Zn) alloys have also been a research hotspot in the field of biodegradable metallic materials. Zinc is an essential nutrient element for the human body and has good biocompatibility. In terms of osteogenic induction, zinc ions play an important role in promoting bone growth and are an indispensable element for bone metabolism. In addition, compared with magnesium alloys, zinc alloys degrade more slowly but have higher strength. Through alloying and process control, the mechanical strength of zinc alloys can approach that of stainless steel.

[0007] Chinese utility model patent CN 216168114 U discloses a biodegradable zinc alloy fusion device. While the main body of this device is made of zinc alloy, which has strong mechanical stability, its osteoinductive properties are inferior to magnesium alloy, and it degrades slowly and remains in the body for a longer period. Chinese utility model patent CN 217772598 U discloses a cervical spine zero-notch self-locking magnesium alloy interbody fusion device. Both the main body and screws of this device are made of magnesium alloy. Magnesium alloy has good osteogenic properties, but its mechanical strength is insufficient, leading to insufficient initial mechanical strength in the locking screws used in the zero-notch fusion device. Summary of the Invention

[0008] In view of the aforementioned deficiencies in the prior art, the technical problem to be solved by this utility model is that existing anterior cervical interbody fusion fixation systems cannot simultaneously achieve the three aspects of biodegradability, mechanical stability, and good osteogenic induction. This utility model provides a biodegradable anterior cervical interbody fusion fixation system and its application method, offering a biodegradable, mechanically strong, and bone-growth-promoting zero-notch interbody fusion fixation system for anterior cervical discectomy and decompression fusion.

[0009] To achieve the above objectives, this utility model provides a biodegradable anterior cervical interbody fusion fixation system, including a fusion device and a locking screw. The fusion device is wedge-shaped with a higher front and lower rear, and is provided with an inclined mounting hole. The locking screw cooperates with the inclined mounting hole. The fusion device is made of biodegradable magnesium alloy, and the locking screw is made of biodegradable zinc alloy.

[0010] Furthermore, the front-back direction of the fusion device is consistent with the front-back direction of the human body, the up-down direction of the fusion device is consistent with the up-down direction of the human body, and the left-right direction of the fusion device is consistent with the left-right direction of the human body.

[0011] Furthermore, the height of the leading edge of the fusion device is set to 5-10mm, the wedge angle is set to 3°-7°, the left and right diameters (i.e., the width of the fusion device) are set to 12-18mm, and the front and rear diameters (i.e., the depth of the fusion device) are set to 10-12mm.

[0012] Furthermore, the upper and lower surfaces of the fusion unit are uniformly provided with “∧”-shaped serrated strips, with the bottom surface of the “∧”-shaped serrated strips set on the upper and lower surfaces of the fusion unit and the tip of the serrated strips far away from the upper and lower surfaces of the fusion unit.

[0013] Furthermore, two semi-circular depth limiting teeth are provided on the upper right front edge and the lower left front edge of the fusion unit. The base of the depth limiting teeth is connected to the fusion unit. The upper and lower surfaces of the depth limiting teeth and the fusion unit are approximately perpendicular. The width of the base of the depth limiting teeth is set to 2-4 mm, the height of the depth limiting teeth is set to 1-2 mm, and the thickness of the depth limiting teeth is set to 0.5-1 mm.

[0014] Furthermore, the fusion device includes four inclined mounting holes, which are respectively located in the middle and on the outside of the fusion device. The two inclined mounting holes in the middle are inclined downward and inward, and the two inclined mounting holes on the outside are inclined upward and inward. The angle between the central axis of the mounting hole and the horizontal plane of the human body is set to 30°-45°, and the angle between the central axis of the mounting hole and the sagittal plane of the human body is set to 0°-10°.

[0015] Furthermore, the inclined mounting hole is provided with threads that mate with the locking screw.

[0016] Furthermore, the tip of the locking screw is self-tapping, and the thread of the nut portion at the tail of the locking screw matches the thread of the inclined mounting hole. After being fully screwed in, the nut portion of the locking screw locks together with the inclined mounting hole, preventing the screw from coming loose.

[0017] Furthermore, it also includes a bone graft chamber, which is located in the middle of the fusion unit and occupies 40%-50% of the fusion unit's volume.

[0018] Technical effect

[0019] This invention provides a biodegradable anterior cervical interbody fusion fixation system specifically designed for anterior cervical discectomy and decompression fusion. After implantation, it eliminates the need for a plate at the anterior vertebral body for fixation, reducing the incidence of postoperative complications such as foreign body sensation, dysphagia, and adjacent vertebral disease. Furthermore, the magnesium and zinc ions generated during the degradation of the magnesium and zinc alloys have osteogenic induction effects, enhancing the interbody fusion outcome. In addition, the unique design of the magnesium-zinc screw structure maintains biodegradability while avoiding the problem of insufficient mechanical strength in magnesium alloys, effectively improving the initial stability between the fusion device and the vertebral body.

[0020] The following will further explain the concept, specific structure and technical effects of this utility model in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of this utility model. Attached Figure Description

[0021] Figure 1 This is a frontal structural diagram of the fusion device according to a preferred embodiment of the present invention;

[0022] Figure 2 This is a diagram showing the oblique structure of the fusion device according to a preferred embodiment of the present invention;

[0023] Figure 3 This is a side view of the fusion device according to a preferred embodiment of the present invention;

[0024] Figure 4 This is a cross-sectional view of the fusion device according to a preferred embodiment of the present invention;

[0025] Figure 5 This is a structural diagram of a locking screw according to a preferred embodiment of the present invention;

[0026] Figure 6 This is a perspective view of the assembly structure of the fusion device and locking screw according to a preferred embodiment of this utility model;

[0027] Figure 7 This is a side view of the assembly structure of the fusion device and locking screw according to a preferred embodiment of the present invention;

[0028] Figure 8 This is a structural diagram of a preferred embodiment of the intervertebral fusion fixation system implanted within the intervertebral space.

[0029] Among them, 1 and 2 are upward-sloping mounting holes, 3 and 4 are downward-sloping mounting holes, 5 and 6 are depth-limiting teeth, 7 is surface serrations, 8 is bone graft chamber, 9 is locking screw, 10 is upper vertebral body, and 11 is lower vertebral body. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0031] In the following description, specific details, such as particular internal procedures and techniques, are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will understand that the present invention may be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of the present invention with unnecessary detail.

[0032] like Figure 1-7As shown, this utility model embodiment provides a biodegradable anterior cervical interbody fusion fixation system, including a fusion device and a locking screw 9. The fusion device is wedge-shaped with a higher front and lower rear, and is provided with an inclined mounting hole. The locking screw 9 cooperates with the inclined mounting hole. The fusion device is made of biodegradable magnesium alloy, and the locking screw 9 is made of biodegradable zinc alloy.

[0033] The fusion device's anterior-posterior direction aligns with the anterior-posterior direction of the human body, its vertical direction aligns with the vertical direction of the human body, and its lateral direction aligns with the lateral direction of the human body. In this embodiment, the height of the anterior edge of the fusion device is set to 5-10 mm, the wedge angle is set to 3°-7°, the lateral diameter (width of the fusion device) is set to 12-18 mm, and the anterior-posterior diameter (depth of the fusion device) is set to 10-12 mm. Different sizes of fusion devices are selected based on the individual size of the intervertebral disc space.

[0034] The fusion device has "∧"-shaped serrated strips 7 evenly distributed on its upper and lower surfaces. The bottom surface of the "∧"-shaped serrated strips 7 is set on the upper and lower surfaces of the fusion device, and the tip is away from the upper and lower surfaces of the fusion device. The "∧"-shaped serrated strips 7 can improve the holding force between the fusion device and the vertebral body and enhance the initial stability.

[0035] The fusion device has two semi-circular depth-limiting teeth, 5 and 6, located on its right anterosuperior edge and left anteroinferior edge. The bases of the depth-limiting teeth 5 and 6 are connected to the fusion device. The upper and lower surfaces of the depth-limiting teeth and the fusion device are approximately perpendicular. The width of the base of the depth-limiting teeth is set to 2-4 mm, the height of the depth-limiting teeth is set to 1-2 mm, and the thickness of the depth-limiting teeth is set to 0.5-1 mm. During use, after the fusion device is implanted into the intervertebral space, the depth-limiting teeth are positioned close to the anterior edge of the vertebral body to prevent the fusion device from being implanted too deeply and thus avoid entering the spinal canal and causing spinal cord injury.

[0036] In this embodiment, the fusion device includes four inclined mounting holes, which are respectively located in the middle and on the outside of the fusion device. The two inclined mounting holes 3 and 4 in the middle are inclined downward and inward, while the two inclined mounting holes 1 and 2 on the outside are inclined upward and inward. The angle between the central axis of the mounting hole and the horizontal plane of the human body (i.e., the upward / downward angle) is set to 30°-45°, and the angle between the central axis of the mounting hole and the sagittal plane of the human body (i.e., the inward angle) is set to 0°-10°.

[0037] The inclined mounting hole is provided with threads that mate with the locking screw.

[0038] The locking screw 9 has a self-tapping tip. The thread of the nut portion at the tail of the locking screw matches the thread of the angled mounting hole. After being fully screwed in, the nut portion of the locking screw locks into the angled mounting hole, preventing the screw from coming loose. The locking screw is made of biodegradable zinc alloy, with a screw diameter of 3.0 mm and three lengths of 12, 14, and 16 mm.

[0039] In this embodiment, the fusion device also includes a bone graft chamber 8, which is located in the middle of the fusion device and occupies 40%-50% of the volume of the fusion device. The bone graft chamber facilitates bone grafting.

[0040] The fusion device in this embodiment of the invention is similar in anatomical shape to the intervertebral space of the human cervical spine. The anterior-posterior direction of the fusion device is consistent with the anterior-posterior direction of the human body, the vertical direction of the fusion device is consistent with the vertical direction of the human body, and the lateral direction of the fusion device is consistent with the lateral direction of the human body. The magnesium alloy fusion device can provide the mechanical support required in the early stage of intervertebral fusion. As time progresses, the magnesium alloy is gradually degraded and absorbed, and eventually the fusion device is completely replaced by bone tissue. At the same time, the magnesium ions generated by the degradation of magnesium alloy can induce bone tissue regeneration and promote intervertebral fusion. The locking screw is made of biodegradable zinc alloy. Zinc alloy degrades more slowly than magnesium but has higher mechanical strength. Therefore, zinc alloy screws can provide better biomechanical stability in the early stage of implantation. The zinc ions generated by the degradation of zinc alloy can also induce new bone formation and promote intervertebral fusion.

[0041] In another preferred embodiment, the surface of the zero-notch magnesium-zinc nail anterior cervical interbody fusion fixation system may be coated with a calcium-phosphorus coating, a micro-arc oxidation coating, or a polymer coating, which can further control its degradation and promote bone tissue growth and interbody fusion.

[0042] like Figure 8 The following steps are shown to explain the method of using a biodegradable anterior cervical interbody fusion fixation system of this utility model:

[0043] Step 1: After the intervertebral disc decompression is completed, the main component of the fusion device is implanted into the intervertebral disc, so that the depth limiting tooth at the front of the fusion device is close to the anterior edge of the vertebral body;

[0044] Step 2: Screw in the matching locking screw through the inclined mounting hole inside the fusion device. The locking screw enters the vertebral body 10 / 11 above / below the fusion device at an angle through the mounting hole until the tail of the locking screw is completely inserted into the mounting hole of the fusion device and completely locked together with the thread inside the mounting hole, thus completing the fixation of the fusion device.

[0045] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A biodegradable anterior cervical interbody fusion fixation system, characterized in that, The fusion cage is wedge-shaped with a higher front and a lower back, and is provided with inclined mounting holes, and the locking screw is matched with the inclined mounting holes.

2. The degradable anterior cervical spine interbody fusion stabilization system of claim 1, wherein, The front-to-back direction of the fusion cage is consistent with the front-to-back direction of the human body, the up-to-down direction of the fusion cage is consistent with the up-to-down direction of the human body, and the left-to-right direction of the fusion cage is consistent with the left-to-right direction of the human body.

3. The degradable anterior cervical spine interbody fusion stabilization system of claim 2, wherein, The height of the front edge of the fusion cage is 5-10 mm, the wedge angle is 3°-7°, the left-to-right diameter, i.e., the width of the fusion cage, is 12-18 mm, and the front-to-back diameter, i.e., the depth of the fusion cage, is 10-12 mm.

4. The degradable anterior cervical spine interbody fusion stabilization system of claim 1, wherein, The upper and lower surfaces of the fusion cage are uniformly provided with "∧"-shaped serrations, the bottom surface of the "∧"-shaped serrations is arranged on the upper and lower surfaces of the fusion cage, and the tip is away from the upper and lower surfaces of the fusion cage.

5. The degradable anterior cervical spine interbody fusion stabilization system of claim 1, wherein, The right front upper edge and the left front lower edge of the fusion cage are provided with two semicircular depth-limiting teeth, the base of the depth-limiting teeth is connected with the fusion cage, the depth-limiting teeth and the upper and lower surfaces of the fusion cage are substantially perpendicular, the width of the base of the depth-limiting teeth is 2-4 mm, the height of the depth-limiting teeth is 1-2 mm, and the thickness of the depth-limiting teeth is 0.5-1 mm.

6. The degradable anterior cervical spine interbody fusion stabilization system of claim 1, wherein, The fusion cage includes four inclined mounting holes arranged at the middle and the outer side of the fusion cage, wherein the two inclined mounting holes at the middle are inclined downward and inward, the two inclined mounting holes at the outer side are inclined upward and inward, the included angle between the central axis of the mounting hole and the horizontal plane of the human body is 30°-45°, and the included angle between the central axis of the mounting hole and the sagittal plane of the human body is 0°-10°.

7. A degradable anterior cervical spine interbody fusion fixation system as in claim 6, wherein, The inclined mounting hole is provided with a thread matched with the locking screw.

8. The degradable anterior cervical spine interbody fusion stabilization system of claim 7, wherein, The tip of the locking screw is self-tapping, the thread of the screw cap portion of the tail of the locking screw matches the thread of the inclined mounting hole, and the screw cap portion of the locking screw is locked with the inclined mounting hole after being completely screwed in, thereby avoiding the locking screw from being removed.

9. The degradable anterior cervical spine interbody fusion stabilization system of claim 1, wherein, The bone grafting cage is also included, which is arranged at the middle of the fusion cage and occupies 40%-50% of the volume of the fusion cage.

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