Degradable anterior cervical interbody fusion fixing system and application method thereof

Abstract

The invention 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] The present invention relates to the field of medical devices, and in particular to a degradable anterior cervical intervertebral fusion fixation system and an application method thereof. Background Art

[0002] Anterior cervical discectomy, decompression and fusion is a classic procedure for the treatment of cervical degenerative diseases. It removes part of the intervertebral disc tissue and implants an intervertebral fusion device to fuse the upper and lower vertebrae together, thereby achieving the effect of decompression and fixation. At present, the intervertebral fusion devices commonly used in clinical practice are mostly made of non-absorbable materials such as titanium alloy or polyetheretherketone. However, non-absorbable fusion devices only play an intervertebral support role, cannot be degraded and absorbed, and have no osteogenesis induction effect.

[0003] Therefore, researchers are committed to the development of degradable fusion devices. Due to the advantages of magnesium (Mg) and its alloys, such as good biosafety, mechanical properties close to human bones, and good osteoinduction, the development of absorbable magnesium alloy fusion devices has received extensive attention in recent years. However, due to the insufficient mechanical strength of magnesium alloys, degradable fusion devices made of magnesium alloys need to be used in conjunction with anterior cervical plates, and are not truly fully degradable fusion devices; and the use of anterior plates leads to a high incidence of complications such as foreign body sensation, dysphagia, and adjacent segment degeneration after surgery.

[0004] Unlike traditional anterior cervical fusion devices, the zero-profile intervertebral fusion fixation system can be accommodated in the intervertebral space after decompression, and no plate is required in front of the vertebral body. The screws are implanted obliquely into the upper and lower vertebral bodies through the channel in the fusion device, giving it similar biomechanical stability as the plate system. The application of the zero-profile intervertebral fusion fixation system significantly shortens the operation time and can make up for the problems of dysphagia and adjacent segment degeneration after traditional cervical fusion devices.

[0005] Current research generally believes that local blood flow and mechanical load are the main factors affecting the degradation of magnesium alloy implants in the body. Since the blood flow in the intervertebral space is low, and the fusion device mainly plays a mechanical support role in the intervertebral space and is subject to less shear stress, it is possible to use low-strength magnesium alloys in the development of absorbable fusion devices. However, the screws of the zero-profile intervertebral fusion fixation system need to be implanted obliquely into the adjacent upper and lower vertebrae through the channel in the fusion device, the shear stress on the screws is large, and the blood flow in the vertebral body is large, and the magnesium screws will degrade rapidly in the vertebral body. Therefore, the relatively low mechanical strength and fast degradation rate of magnesium alloy materials cannot meet the requirements for the preparation of such screws.

[0006] In recent years, in addition to magnesium alloys, zinc (Zn) alloys are also a research hotspot in the field of biodegradable metal materials. Zinc is an essential nutrient for the human body and has good biosafety. 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 have a slower degradation rate but higher strength. Through alloying and preparation process regulation, the mechanical strength of zinc alloys can be close to that of stainless steel.

[0007] Chinese utility model patent CN 216168114 U discloses a degradable zinc alloy fusion device, the main body of which is made of zinc alloy. Although it has strong mechanical stability, the osteoinductivity of zinc alloy is not as good as that of magnesium alloy, and it degrades slowly and remains in the body for a long time. Chinese utility model patent CN 217772598 U discloses a cervical zero-profile self-locking magnesium alloy intervertebral fusion device, the main body and screws of which are made of magnesium alloy. Magnesium alloy has good osteogenic properties, but insufficient mechanical strength. The locking screws used to make zero-profile fusion devices have the problem of insufficient initial mechanical strength. Summary of the invention

[0008] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the existing anterior cervical intervertebral fusion fixation system cannot take into account the three problems of degradability, mechanical stability and good osteoinductive properties at the same time. The present invention provides a degradable anterior cervical intervertebral fusion fixation system and its application method, which provides a zero-notch intervertebral fusion fixation system that is degradable, has good mechanical strength and is conducive to bone tissue growth for anterior cervical discectomy, decompression and fusion.

[0009] To achieve the above-mentioned purpose, the present invention provides a degradable anterior cervical intervertebral fusion fixation system, including a fusion device and a locking screw. The fusion device is wedge-shaped, higher in front and lower in the back, and is provided with an inclined mounting hole. The locking screw cooperates with the inclined mounting hole. The fusion device is made of a degradable magnesium alloy, and the locking screw is made of a degradable zinc alloy.

[0010] Furthermore, the front-to-back direction of the fusion device is consistent with the front-to-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 front edge of the fusion device is set to 5-10 mm, the wedge angle is set to 3°-7°, the left-right diameter, ie, the width of the fusion device, is set to 12-18 mm, and the front-back diameter, ie, the depth of the fusion device, is set to 10-12 mm.

[0012] Furthermore, the upper and lower surfaces of the fusion device are evenly provided with "∧"-shaped sawtooth strips, the bottom surfaces of the "∧"-shaped sawtooth strips are provided on the upper and lower surfaces of the fusion device, and the tips are away from the upper and lower surfaces of the fusion device.

[0013] Furthermore, two semicircular depth limiting teeth are provided on the right front upper edge and the left front lower edge of the fusion device. The base of the depth limiting teeth is connected to the fusion device. The upper and lower surfaces of the depth limiting teeth and the fusion device are both roughly vertical structures. The width of the base of the depth limiting teeth is set to 2-4mm, the height of the depth limiting teeth is set to 1-2mm, and the thickness of the depth limiting teeth is set to 0.5-1mm.

[0014] Furthermore, the fusion device includes four inclined mounting holes, which are respectively arranged in the middle and outside of the fusion device, wherein the two middle inclined mounting holes are inclined downward and inward, and the two outer inclined mounting holes are inclined upward and inward, and 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, a thread matching with the locking screw is arranged in the inclined mounting hole.

[0016] Furthermore, the tip of the locking screw is self-tapping, and the thread of the nut part at the tail of the locking screw matches the thread of the inclined mounting hole. After being fully screwed in, the nut part of the locking screw is locked together with the inclined mounting hole to prevent the screw from backing out.

[0017] Furthermore, it also includes a bone grafting bin, which is arranged in the middle of the fusion device and occupies 40%-50% of the volume of the fusion device.

[0018] In a preferred embodiment of the present invention, a method for applying a degradable anterior cervical intervertebral fusion fixation system is provided, comprising the following steps:

[0019] Step 1: After the intervertebral disc decompression is completed, the main part of the fusion device is implanted into the intervertebral disc, so that the depth-limiting teeth in front of the fusion device are close to the front edge of the vertebral body;

[0020] Step 2: Before implanting the locking screw, drill a screw channel in the upper / lower vertebra through the inclined mounting hole, then implant the screw, and screw the matching locking screw through the inclined mounting hole in the fusion device. The locking screw obliquely enters the vertebra above / below the fusion device through the mounting hole until the tail of the locking screw completely enters the mounting hole of the fusion device and is completely locked with the thread in the mounting hole, thus completing the fixation of the fusion device.

[0021] Technical Effects

[0022] The present invention provides a degradable anterior cervical intervertebral fusion fixation system and its application method, which are specifically used for anterior cervical discectomy, decompression and fusion. After implantation, there is no need to place a steel plate at the front edge of the vertebral body for fixation, which can reduce the incidence of complications such as postoperative foreign body sensation, dysphagia and adjacent vertebral disease. At the same time, since the magnesium ions and zinc ions produced by the degradation of magnesium alloys and zinc alloys have an osteoinductive effect, they can enhance the intervertebral fusion effect. In addition, the unique design of the magnesium body zinc nail structure avoids the problem of insufficient mechanical strength of the magnesium alloy while maintaining degradability, and effectively improves the initial stability between the fusion device and the vertebral body.

[0023] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a frontal structural diagram of a fusion device according to a preferred embodiment of the present invention;

[0025] Figure 2 This is an oblique structural diagram of a fusion device according to a preferred embodiment of the present invention;

[0026] Figure 3 is a lateral structural diagram of a fusion device according to a preferred embodiment of the present invention;

[0027] Figure 4 is a cross-sectional view of a fusion device according to a preferred embodiment of the present invention;

[0028] Figure 5 is a structural diagram of a locking screw of a preferred embodiment of the present invention;

[0029] Figure 6 It is an oblique view of the assembly structure of a fusion cage and a locking screw according to a preferred embodiment of the present invention;

[0030] Figure 7 It is a side view of the assembly structure of a fusion cage and a locking screw according to a preferred embodiment of the present invention;

[0031] Figure 8 The present invention is a structural diagram of an intervertebral fusion fixation system implanted in the intervertebral space according to a preferred embodiment of the present invention.

[0032] Among them, 1 and 2 are upward oblique mounting holes, 3 and 4 are downward oblique mounting holes, 5 and 6 are depth limiting teeth, 7 is surface serrations, 8 is a bone graft bin, 9 is a locking screw, 10 is an upper vertebral body, and 11 is an lower vertebral body. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] In the following description, specific details such as specific internal procedures and techniques are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0035] like Figure 1-7 As shown, an embodiment of the present invention provides a degradable anterior cervical intervertebral fusion fixation system, including a fusion device and a locking screw 9. The fusion device is wedge-shaped with a high front and a low back, and is provided with an inclined mounting hole. The locking screw 9 cooperates with the inclined mounting hole. The fusion device is configured to be made of a degradable magnesium alloy, and the locking screw 9 is configured to be made of a degradable zinc alloy.

[0036] The front-to-back direction of the fusion device is consistent with the front-to-back direction of the human body, the upper-lower direction of the fusion device is consistent with the upper-lower 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. In this embodiment, the height of the front edge of the fusion device is set to 5-10 mm, the wedge angle is set to 3°-7°, the left-right diameter, i.e., the width of the fusion device, is set to 12-18 mm, and the front-to-back diameter, i.e., the depth of the fusion device, is set to 10-12 mm. Fusion devices of different specifications are selected according to the size of the personalized intervertebral space.

[0037] The upper and lower surfaces of the fusion device are evenly provided with "∧"-shaped sawtooth strips 7, the bottom surface of which is provided 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 sawtooth strips 7 can improve the holding force between the fusion device and the vertebral body and enhance the initial stability.

[0038] Two semicircular depth limiting teeth 5 and 6 are arranged at the front upper edge on the right side and the front lower edge on the left side of the fusion device. The bases of the depth limiting teeth 5 and 6 are connected to the fusion device. The depth limiting teeth and the upper and lower surfaces of the fusion device are both roughly vertical structures. The width of the base of the depth limiting teeth is set to 2-4mm, the height of the depth limiting teeth is set to 1-2mm, and the thickness of the depth limiting teeth is set to 0.5-1mm. When in use, after the fusion device is implanted in the intervertebral space, the depth limiting teeth are placed close to the front edge of the vertebral body to prevent the fusion device from being implanted too deeply and entering the spinal canal to cause spinal cord injury.

[0039] In this embodiment, the fusion device includes four inclined mounting holes, which are respectively arranged in the middle and outside of the fusion device, among which the two middle inclined mounting holes 3 and 4 are inclined downward and inward, and the two outer inclined mounting holes 1 and 2 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°.

[0040] A thread matched with the locking screw is arranged in the inclined mounting hole.

[0041] The tip of the locking screw 9 is self-tapping, and the thread of the nut part at the tail of the locking screw matches the thread of the inclined mounting hole. After being fully screwed in, the nut part of the locking screw is locked together with the inclined mounting hole to prevent the screw from backing out. The locking screw is made of degradable zinc alloy, the screw diameter is set to 3.0mm, and the screw length has three specifications of 12, 14, and 16mm.

[0042] In this embodiment, the fusion device further comprises a bone grafting chamber 8, which is arranged in the middle of the fusion device and occupies 40%-50% of the volume of the fusion device. The bone grafting chamber is convenient for bone grafting.

[0043] The fusion device in the embodiment of the present invention is similar to the anatomical morphology of the intervertebral space of the human cervical spine. The front-to-back direction of the fusion device is consistent with the front-to-back direction of the human body, the upper-lower direction of the fusion device is consistent with the upper-lower 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. The magnesium alloy fusion device can meet the mechanical support required in the early stage of intervertebral fusion. As time goes by, the magnesium alloy is gradually degraded and absorbed, and finally the fusion device part is completely replaced by bone tissue. At the same time, the magnesium ions produced by the degradation of the magnesium alloy can induce bone tissue regeneration and promote intervertebral fusion. The locking screw is made of a degradable zinc alloy. The degradation rate of the zinc alloy is slower than that of magnesium, but the mechanical strength is high. Therefore, the zinc alloy screw can provide better biomechanical stability in the early stage of implantation. The zinc ions produced by the degradation of the zinc alloy can also induce new bone formation and promote intervertebral fusion.

[0044] In another preferred embodiment, the surface of the zero-profile magnesium zinc nail anterior cervical intervertebral fusion fixation system can be coated with a calcium-phosphorus coating, a micro-arc oxidation coating or a polymer coating, which can further control its degradation and facilitate bone tissue growth and intervertebral fusion.

[0045] like Figure 8 As shown, in a preferred embodiment of the present invention, a method for applying a degradable anterior cervical intervertebral fusion fixation system is provided, comprising the following steps:

[0046] Step 1: After the intervertebral disc decompression is completed, the main part of the fusion device is implanted into the intervertebral disc, so that the depth-limiting teeth in front of the fusion device are close to the front edge of the vertebral body;

[0047] Step 2: Before implanting the locking screw, drill a screw channel in the upper / lower vertebra through the inclined mounting hole, then implant the screw, and screw the matching locking screw through the inclined mounting hole in the fusion device. The locking screw obliquely enters the 10 / 11 vertebrae above / below the fusion device through the mounting hole until the tail of the locking screw completely enters the mounting hole of the fusion device and is completely locked with the thread in the mounting hole, thus completing the fixation of the fusion device.

[0048] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A degradable anterior cervical interbody fusion fixation system, characterized in that: It includes a fusion device and a locking screw. The fusion device is wedge-shaped with a high front and a low back, and is provided with an inclined mounting hole. The locking screw cooperates with the inclined mounting hole. The fusion device is configured to be made of a degradable magnesium alloy, and the locking screw is configured to be made of a degradable zinc alloy.

2. A degradable anterior cervical interbody fusion fixation system as claimed in claim 1, characterized in that: The front-to-back direction of the fusion device is consistent with the front-to-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.

3. A degradable anterior cervical interbody fusion fixation system as claimed in claim 2, characterized in that: The height of the front edge of the fusion device is set to 5-10 mm, the wedge angle is set to 3°-7°, the left-right diameter, i.e., the width of the fusion device, is set to 12-18 mm, and the front-back diameter, i.e., the depth of the fusion device, is set to 10-12 mm.

4. The degradable anterior cervical interbody fusion fixation system according to claim 1, characterized in that: The upper and lower surfaces of the fusion device are evenly provided with "∧"-shaped sawtooth strips, the bottom surfaces of the "∧"-shaped sawtooth strips are arranged on the upper and lower surfaces of the fusion device, and the tips are away from the upper and lower surfaces of the fusion device.

5. The degradable anterior cervical interbody fusion fixation system according to claim 1, characterized in that: Two semicircular depth limiting teeth are provided on the right front upper edge and the left front lower edge of the fusion device. The base of the depth limiting teeth is connected to the fusion device. The depth limiting teeth and the upper and lower surfaces of the fusion device are both roughly vertical structures. The width of the base of the depth limiting teeth is set to 2-4mm, the height of the depth limiting teeth is set to 1-2mm, and the thickness of the depth limiting teeth is set to 0.5-1mm.

6. The degradable anterior cervical interbody fusion fixation system according to claim 1, characterized in that: The fusion device includes four inclined mounting holes, which are respectively arranged in the middle and outside of the fusion device, wherein the two middle inclined mounting holes are inclined downward and inward, and the two outer inclined mounting holes 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°.

7. A degradable anterior cervical interbody fusion fixation system as claimed in claim 6, characterized in that: A thread matching the locking screw is arranged in the inclined mounting hole.

8. The degradable anterior cervical interbody fusion fixation system according to claim 7, characterized in that: The tip of the locking screw is self-tapping, and the thread of the nut part at the tail of the locking screw matches the thread of the inclined mounting hole. After being fully screwed in, the nut part of the locking screw is locked together with the inclined mounting hole to prevent the screw from backing out.

9. The degradable anterior cervical interbody fusion fixation system according to claim 1, characterized in that: It also includes a bone grafting bin, which is arranged in the middle of the fusion device and occupies 40%-50% of the volume of the fusion device.

10. A method for using the degradable anterior cervical intervertebral fusion fixation system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: After the intervertebral disc decompression is completed, the main part of the fusion device is implanted into the intervertebral disc, so that the depth-limiting teeth in front of the fusion device are close to the front edge of the vertebral body; Step 2: Before implanting the locking screw, drill a screw channel in the upper / lower vertebra through the inclined mounting hole, then implant the screw, and screw the matching locking screw through the inclined mounting hole in the fusion device. The locking screw obliquely enters the vertebra above / below the fusion device through the mounting hole until the tail of the locking screw completely enters the mounting hole of the fusion device and is completely locked with the thread in the mounting hole, thus completing the fixation of the fusion device.

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