Cervical door fixation device

Abstract

The present invention discloses a cervical vertebra open-door fixing device, which belongs to the technical field of orthopedic implants. The cervical vertebra open-door fixing device comprises a tubular body, the interior of the tubular body is used as a bone grafting cavity, the tubular body has a curvature and a first bayonet for clamping the lateral mass end and a second bayonet for clamping the spinous process end are formed at both ends, respectively, and the second bayonet is a plug-in bayonet. The cervical vertebra open-door fixing device of the present invention has good bending resistance, strong ability to maintain the spinal canal structure, and good bone fusion effect by forming bayonet ports at both ends of the tubular body to clamp and connect the lateral mass end and the spinous process end. The present invention is suitable for laminoplasty.

Description

Technical Field

[0001] The invention relates to the technical field of orthopedic implants, in particular to a cervical vertebra open-door fixing device. Background Art

[0002] There are three main internal fixation methods used in single-door cervical surgery: joint capsule suspension, anchoring, and micro-titanium plate-titanium nail internal fixation. With the development of clinical use and research and analysis, it was found that micro-titanium plate-titanium nail internal fixation has better spinal range of motion stability and lower door opening and closing phenomenon than the other two fixation methods.

[0003] The main structure of the micro titanium plate is Z-shaped, and the principle is the same as that of the bone screw plate. The titanium plate is used to maintain the open door state by driving screws into the side block end and the door opening end. The titanium plates on the market have various designs, but the structure is relatively simple, all of which are single-layer plate structures. The maintenance of the spinal canal structure after the screw plate is fixed mainly depends on the bending resistance of the titanium plate. The greater the bending stiffness, the smaller the bending deformation of the titanium plate, and the stronger the ability to maintain the spinal canal structure. However, the single-layer plate structure has inherent deficiencies under the action of bending loads, which are manifested in the following aspects:

[0004] First, the fixation of titanium plates depends on the holding force of screws, which is related to many factors such as bone quality. It is impossible to ensure that the same holding effect can be achieved when different patients and different doctors operate, and it is also impossible to ensure that the bending resistance of titanium plates is maintained at a high level.

[0005] Secondly, the single-layer plate structure has inherent deficiencies in bending resistance. Its thickness is very thin, usually 0.5-0.7mm. Since the calculation formula of bending stiffness is:

[0006] E×I z =E×∫ A y 2 dA

[0007] Where, E is the elastic modulus, I Z is the moment of inertia, A is the area, and y is the distance from the neutral plane in the thickness direction of the titanium plate. The neutral plane is located in the middle section of the titanium plate, so the maximum value of y is 1 / 2 of the thickness of the titanium plate. Since the titanium plates are very thin, no matter how other designs are changed, their bending stiffness values ​​will not increase significantly. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a cervical vertebra door-opening fixing device with good bending resistance.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] A cervical open-door fixation device comprises a tubular body, the interior of which is used as a bone grafting cavity. The tubular body has a curvature and has a first snap-in socket for snapping the lateral mass end and a second snap-in socket for snapping the spinous process end at both ends, wherein the second snap-in socket is a plug-in snap-in socket.

[0011] Furthermore, a spinous process stump limiting plate is provided in the second bayonet.

[0012] Furthermore, the spinous process stump limiting plate is provided with a plurality of through holes.

[0013] Furthermore, the first bayonet is a plug-in bayonet, a side block end limit plate is provided in the first bayonet, and a plurality of through holes are provided on the side block end limit plate;

[0014] Alternatively, the first bayonet is a plug-in bayonet, and a screw mounting hole is provided on a side wall of the first bayonet.

[0015] Furthermore, the first bayonet is a wrap-around bayonet, the end surface of the tubular body serves as a wrap-around side wall of the wrap-around bayonet, and an extension plate serving as another wrap-around side wall of the wrap-around bayonet is provided on the end surface of the tubular body.

[0016] Furthermore, the end surface of the tubular body is provided with a side block end limit plate, and the side block end limit plate is provided with a plurality of through holes.

[0017] Furthermore, the extension plate is provided with screw mounting holes, and / or the extension plate is arc-shaped.

[0018] Furthermore, the inner dimension of the second bayonet gradually decreases from the outside to the inside, and the spinous process stump limiting plate is detachably engaged in the second bayonet.

[0019] Furthermore, the angle between the end surface of the first bayonet and the end surface of the second bayonet is 30-70 degrees.

[0020] Furthermore, the tubular body is provided with an opening extending in the longitudinal direction, so that the cross-section of the tubular body is U-shaped or C-shaped, and the opening is located at the top, bottom or outer side of the tubular body, and a cover plate is provided on the opening.

[0021] The present invention has the following beneficial effects:

[0022] The cervical vertebra open-door fixation device of the present invention has bayonet holes formed at both ends of the tubular body to respectively connect the lateral mass stump and the spinous process stump, has good bending resistance, strong ability to maintain the spinal canal structure, and good bone fusion effect. The present invention is suitable for laminoplasty. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A three-dimensional perspective structural diagram of an embodiment of the cervical vertebrae door-opening fixing device of the present invention;

[0024] Figure 2 for Figure 1 Other angle structural diagrams of the cervical vertebrae open door fixation device shown, wherein (a) is a stereoscopic diagram at one angle, (b) is a stereoscopic diagram at another angle, and (c) is a cross-sectional perspective diagram;

[0025] Figure 3 for Figure 1 The cervical vertebrae open-door fixation device is shown in the use state diagram, wherein (a) is a stereoscopic diagram and (b) is a perspective diagram;

[0026] Figure 4 It is a three-dimensional structural diagram of another embodiment of the cervical vertebra open door fixing device of the present invention;

[0027] Figure 5 for Figure 4 Other angle structural diagrams of the cervical vertebrae open door fixation device shown, wherein (a) is a stereoscopic diagram, (b) is a cross-sectional perspective diagram, and (c) is a perspective diagram;

[0028] Figure 6 for Figure 4 The cervical vertebrae open-door fixation device is shown in the use state diagram, wherein (a) is a stereoscopic diagram and (b) is a perspective diagram;

[0029] Figure 7 for Figure 1 A schematic longitudinal section diagram of a cervical open-door fixation device is shown;

[0030] Figure 8 This is a comparison diagram of the fixation stiffness of the present invention and traditional titanium plate products in single-door surgery. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention provides a cervical vertebrae opening door fixing device, such as Figure 1-6 As shown, it comprises a tubular body 1, wherein:

[0033] The interior of the tubular body 1 is used as a bone graft cavity 2, and the bone graft cavity 2 is used to load materials that induce bone fusion, such as autologous bone, artificial bone powder, artificial bone blocks, etc.;

[0034] The tubular body 1 has a curvature and is formed at both ends with first snap-fitting holes 3, 3' for snap-fitting the side mass end 16 and a second snap-fitting hole 4 for snap-fitting the spinous process (side) end 15;

[0035] Taking into account the structural characteristics of the spinous process stump 15 (relatively slender) and the convenience of connection, the second bayonet 4 is a plug-in bayonet (that is, the spinous process stump 15 is plugged into the second bayonet 4), and the second bayonet 4 is preferably provided with a spinous process stump limiting plate 5 for limiting the insertion depth of the spinous process stump 15. In order not to limit the fusion of the bone graft and the stump, for example, the width of the spinous process stump limiting plate 5 is smaller than the width of the stump surface or the length is smaller than the length of the stump surface, that is, the spinous process stump limiting plate 5 will not completely close the entire second bayonet 4, so as to facilitate the fusion of the bone graft and the stump surface. At the same time, adding the spinous process stump limiting plate 5 can strengthen the clamping strength between the cervical vertebra door fixing device and the spinous process stump 15.

[0036] As another example, Figure 1-6 As shown, although the spinous process stump limiting plate 5 is a structure that closes the second bayonet 4, a plurality of through holes can be provided on the spinous process stump limiting plate 5 to facilitate the connection between the spinous process stump 15 and the bone graft in the bone graft cavity 2.

[0037] During the single-open-door surgery on the cervical spine, the vertebral lamina on one side of the diseased part of the cervical spine is first cut open, and a groove is made on the side of the vertebral lamina gate axis so that the cut vertebral lamina can be slightly rotated around the groove on the side of the gate axis. Then the cervical vertebrae open-door fixing device of the present invention is implanted, so that the side mass broken end 16 is clamped in the first clamping slot 3, 3', and the spinous process broken end 15 is clamped in the second clamping slot 4. Here, the clamping part between the second clamping slot 4 and the spinous process broken end 15 is connected to the tubular body 1 (the four surfaces of the clamping part are integrally formed or fixedly connected with the tubular body), thereby increasing the degree of freedom restriction of the clamping part on the spinous process broken end 15, thereby providing strong support for the vertebral lamina opening, avoiding the closure of the open-door lamina again, maintaining the effect of expanding the spinal canal, and achieving effective decompression inside the spinal canal.

[0038] According to different structural forms of the first bayonet, the present invention may have the following specific embodiments.

[0039] Embodiment 1

[0040] like Figure 1-3 As shown, the first bayonet 3 is also a plug-in bayonet (i.e., the side mass end 16 is plugged into the first bayonet 3), and a side mass end limit plate 6 for limiting the insertion depth of the side mass end 16 is provided in the first bayonet 3, and a plurality of through holes are provided on the side mass end limit plate 6, so as to facilitate the side mass end 16 to be connected with the bone graft growth in the bone graft cavity 2. Here, since the first bayonet 3 and the side mass end 16 are connected to the tubular body 1 at the clamping part (the four surfaces of the clamping part are all integrally formed or fixedly connected with the tubular body), the degree of freedom restriction of the side mass end 16 at the clamping part is increased, and combined with the degree of freedom restriction of the spinous process end 15 by the second bayonet 4, the two sides can be combined to achieve a stable connection of the vertebral plate, avoid the vertebral plate from closing again after opening, maintain the effect of expanding the spinal canal, and achieve effective decompression inside the spinal canal. In addition, this solution does not require the use of screw fixation.

[0041] As an alternative implementation, a screw mounting hole (not shown) may be provided on the side wall of the first bayonet 3 so as to be fixed to the side block end 16 by screws, thereby further improving the fixing strength of the entire device.

[0042] The spinous process end stopper 5 and the lateral mass end stopper 6 are both fixed to the inner wall of the tubular body 1, and can be connected to the inner wall of the tubular body 1 on three sides, two sides or one side, and can be connected in various ways such as integral molding, clamping, welding, etc.

[0043] The spinous process stump limiting plate 5 and the lateral mass stump limiting plate 6 are used to limit the movement of the stump while allowing the bone graft to contact the stump, thereby promoting the fusion of the bone graft. In this embodiment, the tubular body 1, the spinous process stump limiting plate 5 and the lateral mass stump limiting plate 6 together form a bone graft cavity 2.

[0044] It is conceivable that the side block end limit plate 6 can be omitted. After omission, a screw mounting hole can be provided on the side wall of the first bayonet 3 and fixed to the side block end 16 by screws to achieve side block end limit and ensure the fixing strength of the entire device.

[0045] In this embodiment, the tubular body 1 may be provided with an opening 8 extending in the longitudinal direction, so that the cross section of the tubular body 1 is U-shaped. On the one hand, the opening 8 is used as a bone grafting window to facilitate bone grafting into the bone grafting cavity 2. On the other hand, since the sizes of different vertebral lamina ends are different, the opening 8 can make the tubular body 1 have a certain elasticity, so that the two ends of the tubular body 1 can open a certain angle when the vertebral lamina ends of different sizes are inserted, so that the doctor can smoothly clip it to the vertebral lamina ends. The opening 8 can be located at the top or bottom of the tubular body 1. Figure 1-3 In the illustrated embodiment, the opening 8 is located at the bottom. To prevent the bone graft from falling, a cover plate 9 is provided on the opening 8. In specific implementation, to facilitate the connection of the cover plate 9, a slide groove 81 may be provided on the inner wall of the opening 8, and the cover plate 9 is inserted into the slide groove 81.

[0046] This embodiment 1 has the following beneficial effects:

[0047] (1) The structural design of the tubular body allows more material of the product to be placed away from the neutral axis (such as Figure 7 As shown in the bending stiffness calculation formula, the distance y from the neutral plane z in the thickness direction of the titanium plate is significantly increased compared with the single-layer plate structure in the prior art), and the bending section coefficient can be increased under the same cross-sectional area, thereby greatly increasing the bending stiffness, thereby ensuring the postoperative stability of the lamina and avoiding the phenomenon of re-closing after surgery;

[0048] (2) This design eliminates the need for screw fixation, and there is no need to worry about problems such as unstable screw anchoring leading to unsatisfactory surgical results. It reduces surgical time and risk (the area of ​​the stump is small, and it is easy for the screw to deviate), and avoids secondary surgery to remove the screw.

[0049] (3) The broken end of the lateral mass is inserted into the first slot, and the broken end of the spinous process is inserted into the second slot, thereby preventing the bone graft in the bone graft cavity from falling from both ends;

[0050] (4) In the prior art, the bone graft cavity and the vertebral lamina stump are mostly connected in a separate body. When the bone graft cavity structure is stressed, relative displacement will occur between the bone at the vertebral lamina stump and the bone graft. When the relative displacement of the fractured end is greater than 150 μm, it will lead to bone non-fusion and bone fusion failure. The present invention fixes the bone at the vertebral lamina stump and the bone graft cavity in an integrally formed structure (the clamping parts at both ends are integrally formed with the tubular body), which can provide a stable environment for bone fusion between the bone graft and the stump, so that there will be no relative displacement between the stump and the cervical vertebrae open door fixing device, avoiding excessive micro-movement of the stump and thus bone non-fusion.

[0051] (5) The cervical open-door fixation device of the embodiment of the present invention can be made of materials that are absorbable by the human body, so that after the final bone healing and bone fusion, the effect of no fixation in the body can be achieved, eliminating the problem of traditional implants requiring a second surgery to remove or not being removed for a long time, resulting in broken screws, screw retreat and plate breakage.

[0052] Embodiment 2

[0053] like Figure 4-6 As shown, the first bayonet 3' is a wrap-around bayonet, and the end face of the tubular body 1 serves as a wrap-around side wall of the wrap-around bayonet. An extension plate 7 serving as another wrap-around side wall of the wrap-around bayonet is provided on the end face of the tubular body 1 (that is, the wrap-around bayonet is L-shaped). In this way, due to the matching of the appearance, the side block end 16 can be snapped into the wrap-around bayonet.

[0054] To prevent the bone graft from falling off, the end surface of the tubular body 1 may be provided with a side mass end stopper plate 5 , and the side mass end stopper plate 5 may be provided with a plurality of through holes to facilitate the side mass end 16 to be connected with the bone graft in the bone graft cavity 2 .

[0055] The extension plate 7 may be provided with screw mounting holes 71, and the extension plate 7 may be fixed to the side block end 16 by means of screws, thereby improving the fixing strength of the entire device. The extension plate 7 may be in an arc shape matching the outer surface of the side block end 16, so as to further improve the clamping firmness of the side block end 16 and the first clamping port 3'.

[0056] In this embodiment, the tubular body 1 may be provided with an opening 8 extending in the longitudinal direction, so that the cross section of the tubular body 1 is C-shaped. On the one hand, the opening 8 is used as a bone grafting window to facilitate bone grafting into the bone grafting cavity 2. On the other hand, since the sizes of different vertebral lamina ends are different, the opening 8 can make the tubular body 1 have a certain elasticity, so that the two end clamps of the tubular body 1 can open a certain angle when clamping vertebral lamina ends of different sizes, so that it is convenient for doctors to clamp it to the vertebral lamina ends smoothly. The opening 8 is located on the outer side of the tubular body 1. At this time, the tubular body 1 itself can prevent the bone graft from falling, so there is no need to set an additional cover plate on the opening 8.

[0057] The second embodiment has the following beneficial effects:

[0058] (1) The structural design of the tubular body allows more material to be placed away from the neutral axis (reference Figure 7 , the distance y between the titanium plate thickness direction and the neutral plane z in the bending stiffness calculation formula is significantly increased compared with the single-layer plate structure in the prior art), and the bending section coefficient can be increased under the same cross-sectional area, thereby greatly increasing the bending stiffness, thereby ensuring the postoperative stability of the lamina and avoiding the phenomenon of re-closing after surgery;

[0059] (2) Although screws can be used, when the tubular body, the lateral mass end stop plate and the spinous process end stop plate are made of absorbable materials, a second surgery is not required to remove the screws; in the prior art, in order to ensure the connection strength, the plate body must be made of non-absorbable material, so a second surgery is still required to remove the screws;

[0060] (3) The spinous process stump extends into the second slot, and there is a lateral mass stump stopper at the lateral mass stump, thereby preventing the bone graft from falling off from both ends;

[0061] (4) In the prior art, the bone graft cavity and the vertebral lamina stump are mostly connected in a separate body. When the bone graft cavity structure is stressed, relative displacement will occur between the bone at the vertebral lamina stump and the bone graft. When the relative displacement of the fractured end is greater than 150 μm, it will lead to bone non-fusion and bone fusion failure. The present invention fixes the bone at the vertebral lamina stump and the bone graft cavity in an integrally formed structure (the clamping parts at both ends are integrally formed with the tubular body), which can provide a stable environment for bone fusion between the bone graft and the stump, so that relative displacement will not occur between the stump and the cervical vertebrae open door fixing device, thereby avoiding excessive micro-movement of the stump and resulting in bone non-fusion;

[0062] (5) When this structure is made of materials that can be absorbed by the human body, the effect of no fixation in the body can be achieved after bone healing and bone fusion, eliminating the problem of traditional implants requiring a second surgery to remove or not being removed for a long time, resulting in broken screws, screw retreat, and plate breakage.

[0063] In addition, it should be noted that the cervical vertebra open-door fixation device of the embodiment of the present invention can be designed into multiple specifications for use according to the sizes of different vertebral plates.

[0064] In summary, the cervical vertebra open-door fixation device of the present invention has good bending resistance, strong ability to maintain the spinal canal structure, and good bone fusion effect by forming bayonet holes at both ends of the tubular body to respectively connect the lateral mass stump and the spinous process stump. The cervical vertebra open-door fixation device of the present invention is suitable for single-door cervical surgery, and can also be used for double-door cervical surgery under special circumstances.

[0065] In the embodiment of the present invention, the inner size of the second bayonet 4 is preferably gradually reduced from the outside to the inside to improve the clamping strength, and the spinous process stump stopper plate 5 is preferably detachably clamped in the second bayonet 4. In this way, the spinous process stump stopper plate 5 can be made into a variety of different specifications. During the operation, according to the size of the patient's vertebral plate opening and the depth of the spinous process stump 15 inserted into the bayonet, the spinous process stump stopper plate 5 of appropriate specifications is selected to be clamped in the second opening 4. In order to further improve the clamping strength, the inner walls of the first bayonet 3, 3' and the second bayonet 4 can be provided with an inverted tooth structure that increases friction and prevents retreat, such as Figure 2 As shown in (a) by reference numeral 41.

[0066] In order to better clamp the spinous process stump 15 and the lateral mass stump 16 at the same time, the curvature of the tubular body 1 is preferably designed so that the angle between the end surface of the first bayonet 3, 3' and the end surface of the second bayonet 4 is 30-70 degrees, preferably 45-60 degrees, wherein the curvature of the spinous process stump connection end (i.e., the second bayonet 4) is preferably parallel to the anatomical left-right direction, such as Figure 3 (b) and Figure 6 As shown in (b).

[0067] In order to better verify the anti-bending effect of the cervical door-opening fixation device of the embodiment of the present invention, the simulation method is used to compare the present invention with the traditional titanium plate product. The material property of the titanium alloy is an elastic modulus of 110Gpa, and the elastic modulus of the material of this design is 4Gpa, which is the average elastic modulus of the absorbable polylactic acid material. The same load under the worst working condition (i.e. perpendicular to the door closing direction) is applied respectively, and the immediate postoperative deformation resistance of the bone and implant structure as a whole is compared, and the stress on the bone and the implant is compared to illustrate the performance of the product of the present invention. The loading load is 100N. After comparison, it is found that Figure 8 The results show that the stiffness of the invention in the direction of door closing is 4532.7N / mm, while the stiffness of the traditional titanium plate is 3861.7N / mm. The design of the invention has better anti-deformation ability, that is, greater bending stiffness; when the same force is loaded, the stress on the bone is significantly less than the stress of the traditional titanium plate, and the stress on the implant is also significantly less than the stress on the traditional titanium plate. The above results show that the invention has better fixing performance than traditional titanium plate products and is conducive to the initial stability of bone tissue.

[0068] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cervical vertebrae door-opening fixing device, characterized in that: It comprises a tubular body, the interior of the tubular body is used as a bone graft cavity, the tubular body has a curvature and has a first bayonet for clamping the side mass end and a second bayonet for clamping the spinous process end at both ends, and the second bayonet is a plug-in bayonet; The angle between the end face of the first bayonet and the end face of the second bayonet is 30-70 degrees, and the curvature of the second bayonet is parallel to the anatomical left-right direction; a spinous process stump limiting plate is provided in the second bayonet, and a plurality of through holes are provided on the spinous process stump limiting plate; The tubular body is provided with an opening extending along the longitudinal direction, so that the cross-section of the tubular body is U-shaped, the opening is located at the top or bottom of the tubular body, and a cover plate is provided on the opening; or, the tubular body is provided with an opening extending along the longitudinal direction, so that the cross-section of the tubular body is C-shaped, the opening is located on the outer side of the tubular body, and no cover plate is provided on the opening.

2. The cervical vertebrae door-opening fixing device according to claim 1, characterized in that: The first bayonet is a plug-in bayonet, a side block end limit plate is provided in the first bayonet, and a plurality of through holes are provided on the side block end limit plate; Alternatively, the first bayonet is a plug-in bayonet, and a screw mounting hole is provided on a side wall of the first bayonet.

3. The cervical vertebrae door-opening fixing device according to claim 1, characterized in that: The first bayonet is a wraparound bayonet, the end surface of the tubular body serves as a wraparound side wall of the wraparound bayonet, and an extension plate serving as another wraparound side wall of the wraparound bayonet is provided on the end surface of the tubular body.

4. The cervical vertebrae door-opening fixing device according to claim 3, characterized in that: The end surface of the tubular body is provided with a side block end limit plate, and the side block end limit plate is provided with a plurality of through holes.

5. The cervical vertebrae door-opening fixing device according to claim 3, characterized in that: The extension plate is provided with screw mounting holes, and / or the extension plate is arc-shaped.

6. The cervical vertebrae door-opening fixing device according to claim 1, characterized in that: The inner dimension of the second bayonet gradually decreases from the outside to the inside, and the spinous process stump limiting plate is detachably engaged in the second bayonet.

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