An anterior cervical spine internal fixation device

Abstract

The utility model discloses a kind of upper thoracic vertebrae anterior internal fixation devices, including fixed plate, bone screw, pedicle screw and vertebral body nail;Fixed plate both ends are equipped with pedicle nail groove, the outside of each pedicle nail groove of fixed plate is also equipped with vertebral body nail hole, fixed plate both ends are also equipped with bone nail groove along its long direction arrangement;Pedicle screw is fixed using fixed section and enters pedicle nail groove to be combined with fixed screw cap to prevent sliding, enhance the stability of system;The nail head of vertebral body nail is hemispherical structure, and nail head sinks into vertebral body nail hole after installation fastening, not only avoid the interference of nail head leakage to surrounding tissue structure, but also prevent various complications caused by vertebral body nail exit. Bone screw is fixed into bone nail groove when installing and fixes bone block, bone nail groove, in addition to fixing bone block, can also be conveniently used to observe the deep tissue structure of fixed plate, help to judge the placement position of fixed plate, when installing, bone screw can be prevented from automatically sliding out.

Description

Technical Field

[0001] This utility model relates to the field of orthopedic surgical instruments, specifically to anterior thoracic vertebral internal fixation device. Background Technology

[0002] The upper thoracic spine generally refers to T1-T4 (Th1-Th4), a transitional zone between the cervical and thoracic segments of the spine where stress transfers. When certain diseases lead to anterior destruction and vertebral osteoporosis in the upper thoracic spine, simple anterior debridement often necessitates posterior internal fixation to maintain spinal stability. This not only increases surgical time but also raises surgical risks. To achieve one-time anterior decompression and reconstruction of spinal stability, some researchers have proposed a retrograde pedicle screw placement method via the anterior approach to improve the stability of internal fixation and avoid the risks associated with posterior surgery. Therefore, this application proposes an anterior internal fixation device for the upper thoracic spine. Utility Model Content

[0003] In view of the deficiencies in the prior art, the purpose of this utility model is to provide an anterior internal fixation device for the upper thoracic spine, which can be used to reconstruct spinal stability from the front after subtotal resection of the Th2 and / or Th3 vertebrae.

[0004] The technical solution adopted by this utility model is: an anterior fixation device for the upper thoracic spine, including a fixation plate, bone graft screws, a pair of pedicle screws and a pair of vertebral body screws; the fixation plate is provided with pedicle screw grooves at both ends, wherein one pedicle screw groove is arranged along the length of the fixation plate and the other pedicle screw groove is arranged along the width of the fixation plate, and the fixation plate is also provided with vertebral body screw holes on the outer side corresponding to each pedicle screw groove, and a bone graft screw groove is also provided between the two ends of the fixation plate along its length;

[0005] The pedicle screw includes an implantation segment and a fixation segment, with a rotating part between the implantation segment and the fixation segment. A fixing nut is screwed onto the fixation segment. The head of the vertebral screw has a rotating part with a flat, round structure. The tip of the bone graft screw has a self-tapping groove, with the inner diameter of the bone graft screw being smaller than the self-tapping groove and the outer diameter being larger than the self-tapping groove.

[0006] In this technical solution, the fixation plate can conform to the target position of the vertebral body. The fixation plate is equipped with corresponding pedicle screw slots, vertebral screw holes, and bone graft screw slots for installing pedicle screws, vertebral body screws, and bone graft screws. The installation position of the pedicle screws after installation in the pedicle screw slots has a certain adjustment space. By using the fixation section to pass through the pedicle screw slot and use the fixation nut for fixation, slippage can be prevented, enhancing the stability of the system. The vertebral body screw head has a hemispherical rotating structure. After installation and tightening, the screw head sinks into the vertebral body screw hole, which not only avoids the screw head protruding and interfering with the surrounding tissue structure, but also prevents various complications caused by the vertebral body screw coming out. During installation, the bone graft screw is inserted into the bone graft screw slot to fix the bone graft. In addition to fixing the bone graft, the bone graft screw slot can also be used to easily observe the deep tissue structure of the fixation plate, which helps to determine the placement position of the fixation plate. During installation, it can prevent the bone graft screw from automatically slipping out, resulting in higher stability.

[0007] Preferably, the opening width of the bone graft slot in the fixation plate is smaller than the outer diameter of the bone graft screw and larger than the inner diameter of the bone graft screw.

[0008] Preferably, the end face of the fixed section is provided with a first rotating groove for rotating the pedicle screw.

[0009] Preferably, the end face of the fixing nut opposite to the rotating part is provided with an upper annular protrusion, which is adapted to the upper positioning groove provided at the upper opening position of the pedicle screw groove.

[0010] Preferably, the rotating part has a lower annular protrusion on the end face opposite to the fixing nut, and the lower annular protrusion is adapted to the lower positioning groove located at the lower opening of the pedicle screw groove.

[0011] Preferably, the pedicle screw has a length of 32-44 mm, an outer thread diameter of 3.6-6 mm, and an inner thread diameter of 2.8-3.6 mm.

[0012] Preferably, the end face of the rotating part is provided with a second rotating groove for rotating the vertebral nail.

[0013] Preferably, the vertebral nail has a length of 10-24 mm and an outer diameter of 3.5 mm.

[0014] Preferably, the end face of the bone graft screw is provided with a third rotating groove.

[0015] Preferably, the bone graft screw has a length of 12-20 mm and an outer diameter of 4.0 mm.

[0016] The beneficial effects of this utility model are:

[0017] 1. The fixation plate in this invention adopts a curved plate structure to minimize angular structures and prevent cutting effects on surrounding tissues. The axial and longitudinal curvature parameters of the plate are designed based on the characteristics of local anatomical structures to maximize conformity with the vertebral body, which is beneficial to the stability of the internal fixation system combined with the spine.

[0018] 2. In this utility model, the pedicle screw holes in the fixation plate have horizontal and vertical slot designs. The horizontal design allows the fixation plate to move appropriately left and right in the coronal plane; the vertical design allows the fixation plate to move appropriately up and down in the coronal plane. This appropriate left-right and up-down movement ensures that even if the position and orientation of the pedicle screws are slightly off when inserting them, the fixation plate can still be placed. The vertical holes allow for appropriate up-down movement of the pedicle screws. This up-down movement allows for appropriate pressure and expansion of the fixation segment, which helps maintain the physiological kyphosis angle of the fixation segment.

[0019] 3. The pedicle screw groove and bone graft groove of this utility model have a structure that matches the nut (screw), which can prevent the pedicle screw tail or bone graft screw from sliding in the opening groove and enhance the stability of the system.

[0020] 4. The vertebral screw in this invention features a flat, round head design. This design avoids the screw head protruding and interfering with surrounding tissues, and also prevents complications caused by automatic screw withdrawal. The implantation angle of the vertebral screw can be flexibly adjusted; the upper vertebral screw can be tilted upwards and inwards, while the lower vertebral screw can be tilted downwards and inwards. This tilting increases the screw track, thereby increasing the contact area between the screw and bone tissue, and consequently, the screw's holding force. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0022] Figure 1 This is a perspective view of the anterior thoracic vertebral internal fixation device provided in the embodiments of this utility model.

[0023] Figure 2 This is a perspective view of the pedicle screws of the anterior thoracic vertebral internal fixation device provided in the embodiments of this utility model.

[0024] Figure 3 This is a perspective view of the bone graft screws of the anterior thoracic vertebral internal fixation device provided in the embodiments of this utility model.

[0025] Figure 4This is a three-dimensional view of the vertebral body screw of the anterior thoracic vertebral internal fixation device provided in the embodiment of this utility model.

[0026] Reference numerals in the figures: Fixation plate 100, pedicle screw groove 110, vertebral body screw hole 120, bone graft screw groove 130, bone graft screw 200, third rotating groove 210, pedicle screw 300, implantation segment 310, fixation segment 320, first rotating groove 321, rotating part 330, upper annular protrusion 331, fixing nut 340, lower annular protrusion 341, vertebral body screw 400, rotating part 410, second rotating groove 411. Detailed Implementation

[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0028] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0029] like Figures 1 to 4 As shown in the figure, a specific embodiment of this utility model provides an anterior thoracic vertebral fixation device, including a fixation plate 100, bone graft screws 200, a pair of pedicle screws 300, and a pair of vertebral body screws 400; the fixation plate 100 has pedicle screw grooves 110 at both ends, wherein one pedicle screw groove 110 is arranged along the length of the fixation plate 100 and the other pedicle screw groove 110 is arranged along the width of the fixation plate 100, and the fixation plate 100 also has vertebral body screw holes 120 on the outer side corresponding to each pedicle screw groove 110. The fixation plate 100 is further provided with bone graft slots 130 arranged along its length between its two ends; the pedicle screw 300 includes an implantation section 310 and a fixation section 320, and a rotating part 330 is provided between the implantation section 310 and the fixation section 320; a fixing nut 340 is screwed onto the fixation section 320; the head of the vertebral screw 400 is provided with a rotating part 410 of a flat round structure; the tip of the bone graft screw is provided with a self-tapping groove, the inner diameter of the bone graft screw is smaller than the self-tapping groove, and the outer diameter is larger than the self-tapping groove.

[0030] like Figure 1As shown in the above structure, the fixation plate 100 can fit snugly against the target position of the vertebral body. The fixation plate 100 is provided with pedicle screw grooves 110, vertebral screw holes 120, and bone graft screw grooves 130 for installing pedicle screws 300, vertebral screws 400, and bone graft screws 200. To ensure a more secure and stable fit during use, the fixation plate 100 is designed with certain lateral and longitudinal curvatures. The lateral curvature of the fixation plate 100 mainly depends on the axial curvature of the vertebral body. Since the surface curvatures of the Th1 to Th4 vertebrae in the human body are not consistent, their average values ​​are currently used in the design. To maximize the compatibility between the fixation plate 100 and the vertebral body, the longitudinal curvature of the fixation plate 100 depends on the long and short distances of the corresponding arcs of multiple vertebrae in the sagittal plane. Furthermore, the thickness of the fixation plate 100 should be as thin as possible while still being able to withstand the load and assemble well with the screws. This is because if the fixation plate 100 is too thick, it will cause local forward protrusion, irritating the esophagus and trachea. If the fixation plate 100 is too thin, it will be prone to bending deformation or fatigue fracture due to insufficient strength, resulting in internal fixation failure and related complications. Therefore, in practical applications, the fixation plate 100 is preferably 2.5mm thick, taking into account both the need for details of the fixation plate 100 and screw connection and biomechanical factors.

[0031] like Figure 1 and Figure 2As shown, in this embodiment, the pedicle screw 300, which can be installed in the pedicle screw slot 110, includes an implantation section 310 and a fixation section 320. During installation, the fixation section 320 is inserted into the pedicle screw slot 110. Since the pedicle screw slot 110 is arranged in both longitudinal and transverse directions, the pedicle screw 300 has a certain adjustment space during installation. During fixation, the fixation nut 340 is used to fix it, which can prevent slippage and enhance the stability of the system. The end face of the fixation section 320 is provided with a first rotation groove 321 for rotating the pedicle screw 300. By inserting a fixation tool into the first rotation groove 321, the pedicle screw 300 is rotated and screwed into the target area. The thread pitch of the implantation section 310 of the pedicle screw 300 is 2.0 mm, and it adopts an internal conical thread structure. The inner diameter gradually thickens from the tip to the tail, and the thread depth gradually becomes shallower. This design aims to allow the screw tail to engage more bone, providing better holding force. The thicker screw neck can increase the screw's load-bearing capacity and improve the fatigue resistance of the internal fixation. The fixation section 320, located at the rear end of the implantation section 310, is 3mm long. This section is threadedly matched with the fixing nut 340. Tightening the nut securely connects the fixation plate 100 to the screw. To improve fixation stability, the end face of the fixing nut 340 opposite to the rotating part 330 has an upper annular protrusion 331, which matches the upper positioning groove located at the upper opening of the pedicle screw groove 110. The end face of the rotating part 330 opposite to the fixing nut 340 has a lower annular protrusion 341, which matches the lower positioning groove located at the lower opening of the pedicle screw groove 110. Thus, the upper annular protrusion 331 matches the corresponding upper positioning groove of the fixation plate 100, increasing the contact area between the fixing nut 340 and the fixation plate 100, reducing local stress, and preventing loosening due to wear. Additionally, the lower annular protrusion 341 matches the lower positioning groove to prevent relative sliding between the pedicle screw 300 and the fixing plate 100. In practical applications, the pedicle screw 300 has a length of 32-44mm, a thread outer diameter of 3.6-6mm, and a thread inner diameter of 2.8-3.6mm. The length increases in 2mm increments, including 32mm, 34mm, 36mm, 38mm, 40mm, 42mm, and 44mm, for a total of 7 specifications. The thread outer diameter increases in 0.5mm increments, including 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, and 6.0mm, for a total of 6 specifications. The thread inner diameter includes 2.8mm, 3.0mm, 3.2mm, 3.4mm, and 3.6mm, for a total of 5 specifications.

[0032] like Figure 4As shown, in this embodiment, the vertebral screw 400 is installed in the vertebral screw hole 120. Because the screw head of the vertebral screw 400 has a hemispherical rotating part 410, after installation and tightening, the screw head sinks into the vertebral screw hole 120. This not only prevents the screw head from leaking out and interfering with surrounding tissue structures, but also prevents various complications caused by the vertebral screw 400 coming out. The end face of the rotating part 410 is provided with a second rotating groove 411 for rotating the vertebral screw 400. This groove allows the vertebral screw 400 to be screwed into the installation position using an installation tool. The second rotating groove 411 can be an internal hexagonal hole. In practical applications, the vertebral screw 400 has a length of 10-24 mm and an outer diameter of 3.5 mm; the length increases in 2 mm increments, including 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, and 24 mm, for a total of eight specifications. In addition, the Vertebral Screw 400 uses a fully threaded cancellous bone screw with a pitch of 1.5 mm, a thread depth starting from 0.5 mm, and an external cone angle of 0.8°.

[0033] like Figure 3 As shown, the bone graft screw 200 is inserted into the bone graft slot 130 during installation to fix the bone graft. Besides fixing the bone graft, the bone graft slot 130 also facilitates observation of the deep tissue structure of the fixation plate 100, helping to determine the placement of the fixation plate 100. It also prevents the bone graft screw from slipping out during installation, resulting in higher stability. Simultaneously, the opening width of the bone graft slot 130 of the fixation plate 100 is smaller than the outer diameter of the bone graft screw 200 but larger than its inner diameter. This prevents the bone graft screw from falling out during installation. The end face of the bone graft screw head has a third rotating groove 210, used to screw it into the bone graft with a tool. The bone graft screws are 12-20mm long and 4.0mm in outer diameter, with lengths increasing in 2mm increments: 12mm, 14mm, 16mm, 18mm, and 20mm, a total of five specifications. The vertebral screws used are fully threaded cancellous bone screws.

[0034] In material selection, biomedical implant materials should be chosen, taking into account the compatibility of various properties of the implant material with the human body. Ideal bone internal fixation materials should possess: good biocompatibility and chemical stability; an elastic modulus close to that of bone tissue; high fatigue resistance; high mechanical strength; and non-toxicity and non-carcinogenicity. Titanium alloys are non-toxic, lightweight, high-strength, corrosion-resistant, and have excellent biocompatibility. In particular, their non-magnetic nature does not affect postoperative examinations, making them ideal medical metal materials, currently widely used in clinical practice. Therefore, all components of this internal fixation system are manufactured using medical-grade titanium alloy (Ti-6Al-4V).

[0035] In practical use, it is mainly applied after subtotal Th2 and / or Th3 vertebral corpectomy to reconstruct spinal stability from the anterior direction. After subtotal corpectomy, filling material (autologous bone, allogeneic bone, or titanium cage, etc.) is implanted into the bone defect area. Pedicle screws are placed in adjacent vertebrae above and below the subtotal vertebral body: a right pedicle screw is placed anteriorly in the upper vertebral body; a left pedicle screw is placed anteriorly in the lower vertebral body. After the two pedicle screws are placed, the fixation plate is initially positioned according to the corresponding holes, that is, the tails of the two pedicle screws are inserted into the pedicle screw holes of the fixation plate. The position of the fixation plate is adjusted so that it is vertically centered anterior to the vertebral body and fully conforms to the anterior wall of the vertebral body. Based on preoperative imaging data and intraoperative conditions, the fixed segment can be opened or compressed to ensure that the fixed segment is at the physiological Cobb angle of kyphosis. After opening or compression, the opened or compressed state is maintained. Install the matching nuts for the two pedicle screws to initially secure them to the fixation plate. Then, insert the vertebral screws into the two vertebral screw holes respectively. Next, reinforce the entire internal fixation system: tighten the two additional pedicle screw nuts; rotate the locking clips to lock the vertebral screws and prevent them from coming out. If bone graft screws are required, insert them.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. An anterior thoracic vertebral internal fixation device, characterized in that; Includes a fixation plate (100), bone graft screws (200), a pair of pedicle screws (300) and a pair of vertebral body screws (400); The fixation plate (100) has pedicle screw grooves (110) at both ends, one pedicle screw groove (110) is arranged along the length of the fixation plate (100) and the other pedicle screw groove (110) is arranged along the width of the fixation plate (100). The fixation plate (100) also has vertebral body screw holes (120) on the outer side corresponding to each pedicle screw groove (110). The fixation plate (100) also has bone graft screw grooves (130) arranged along its length between the two ends. The pedicle screw (300) includes an implantation segment (310) and a fixation segment (320), with a rotating part (330) between the implantation segment (310) and the fixation segment (320), and a fixing nut (340) screwed onto the fixation segment (320); The head of the vertebral nail (400) is provided with a rotating part (410) with a flat and round structure; The tip of the bone graft screw (200) is provided with a self-tapping groove. The inner diameter of the bone graft screw (200) is smaller than the self-tapping groove, and the outer diameter is larger than the self-tapping groove.

2. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The opening width of the bone graft slot (130) of the fixation plate (100) is smaller than the outer diameter of the bone graft screw (200) and larger than the inner diameter of the bone graft screw.

3. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The end face of the fixed section (320) is provided with a first rotating groove (321) for rotating the pedicle screw (300).

4. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The end face of the fixing nut (340) opposite to the rotating part (330) is provided with an upper annular protrusion (331), which is adapted to the upper positioning groove located at the upper opening position of the pedicle screw groove (110).

5. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The rotating part (330) has a lower annular protrusion (341) on the end face opposite to the fixing nut (340), and the lower annular protrusion (341) is adapted to the lower positioning groove located at the lower opening of the pedicle screw groove (110).

6. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The pedicle screw (300) has a length of 32-44mm, an outer thread diameter of 3.6-6mm, and an inner thread diameter of 2.8-3.6mm.

7. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The end face of the rotating part (410) is provided with a second rotating groove (411) for rotating the vertebral nail (400).

8. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The vertebral nail (400) has a length of 10-24 mm and an outer diameter of 3.5 mm.

9. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The bone graft screw (200) has a third rotating groove (210) on the end face of the screw head.

10. The anterior thoracic vertebral internal fixation device according to claim 1, characterized in that, The bone graft screws are 12-20 mm in length and 4.0 mm in outer diameter.

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