Bi-cortical screw for spinal surgery and method of use

Abstract

The present application relates to the field of spinal fixation medical devices, especially a double-head screw for spinal surgery and a use method, which can conveniently separate the main rod side and the auxiliary rod side after the application of correction force is completed. The technical scheme adopted by the present application to solve its technical problems is: the double-head screw for spinal surgery, the double-head screw includes a main rod side and an auxiliary rod side, the bottom of the main rod side is provided with a screw, the main rod side and the auxiliary rod side are connected through a connecting part, the connecting part includes at least one connecting rib, the main rod side and the auxiliary rod side are fixedly connected through the connecting rib, and the connecting rib is a breakable structure. After the application of correction force is completed, the connecting rib is broken, so that the auxiliary rod side and the main rod side are conveniently and quickly separated, the efficiency of the surgery is greatly improved, the space near the spine is also saved, and the pain of the patient is reduced. The present application is especially suitable for use in spinal correction surgery.

Description

Technical Field

[0001] This invention relates to the field of spinal fixation medical devices, and in particular to a double-ended screw for spinal surgery and its method of use. Background Technology

[0002] Double-ended screws are frequently used in spinal deformity correction surgery. Several double-ended screws are sequentially fixed to the spine along its direction. Each double-ended screw consists of a main rod side and an auxiliary rod side. The main rod side connects to a main rod connecting rod, and the auxiliary rod side connects to an auxiliary rod connecting rod. The main rod connecting rod connects the main rod sides of each double-ended screw, forming a complete load-bearing unit. A screw is located at the bottom of the main rod side, used to fix the double-ended screws to the desired position on the patient's spine. After connecting the main rod and auxiliary rod connecting rods, a corrective force is applied to the auxiliary rod connecting rod using an external force-applying tool. This corrective force is transmitted through the auxiliary rod connecting rod and auxiliary rod side to the main rod side and main rod connecting rod. Under this corrective force, the position and angle of the main rod side change, causing the screw at the bottom of the main rod side to apply external force to the spine, repositioning the spine in the corrective direction, thereby correcting the spinal deformity.

[0003] In existing double-ended screw structures, the main rod side and the auxiliary rod side are interconnected and inseparable. After the corrective force is applied, the auxiliary rod side generally loses its purpose. However, because the auxiliary rod side cannot be separated in time, it must remain in the patient's body along with the main rod side after the corrective force is applied. This occupies the already limited space around the patient's spine, leading to limitations in subsequent surgical operation space. Furthermore, the large size of the double-ended screw causes significant pain for the patient. This is especially true for younger or frail patients with weak back muscles; using existing double-ended screws exacerbates these drawbacks.

[0004] Taking patent application CN114711934A, entitled "A Connecting Assembly for a Spinal Orientation Double-Headed Screw," as an example, it discloses a specific structure of a double-headed screw. In this application, the main rod side and the auxiliary rod side are fixedly connected. In actual use, after the corrective force is applied, the main rod side and the auxiliary rod side are fixed together on the patient's spine, thus occupying a large amount of space. Furthermore, the patient's back will have a noticeable bulge after surgery, greatly increasing the patient's pain. Therefore, existing double-headed screws can no longer meet the actual needs of spinal surgery. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a double-ended screw for spinal surgery that allows for convenient separation of the main rod side and the auxiliary rod side after the corrective force is applied, and a method for using it.

[0006] The technical solution adopted by this invention to solve its technical problem is: a double-ended screw for spinal surgery, comprising a main rod side and an auxiliary rod side. A screw is located at the bottom of the main rod side. The main rod side and the auxiliary rod side are connected by a connecting part, which includes at least one connecting rib. The main rod side and the auxiliary rod side are fixedly connected by the connecting rib, which is a breakable structure. In actual use, an external force-applying tool applies a corrective force to the auxiliary rod connecting rod. This corrective force is then transmitted sequentially to the main rod side through the auxiliary rod side and the connecting rib. Under the action of this corrective force, the main rod side undergoes a positional change, and force can also be transmitted to other points on the main rod side through the main rod connecting rod, ultimately achieving the correction and repositioning of the deformed spine. After the spine is corrected to the desired state, the position of the main rod side is fixed. At this time, since the main rod side and the auxiliary rod side are still fixedly connected by the connecting rib, the main rod side and the auxiliary rod side can be separated simply by breaking the connecting rib, thus conveniently achieving the corresponding separation effect. The connecting ribs can be broken by cutting them directly with scissors or by bending the auxiliary rod side; the specific method can be chosen flexibly according to the actual situation. The connecting ribs can be made of the same material as the main rod and auxiliary rod sides. Through reasonable design and selection of the structural strength of the connecting ribs, it is ensured that the connecting ribs can transfer the corrective force from the auxiliary rod side to the main rod side, while also ensuring that the connecting ribs can be easily broken later.

[0007] Using a breakage tool allows for convenient and labor-saving breakage of the connecting rib. To ensure the tool can break the rib effectively, the following solution can be chosen: the connecting part includes a breakage groove for inserting the tool. This groove is located between the main rod side and the auxiliary rod side, and is formed by the main rod side, the auxiliary rod side, and the connecting rib. In practical use, a pry bar is used as an example. First, one end of the pry bar is inserted into the breakage groove. Since the part of the pry bar inserted into the groove is wrapped and constrained by the main rod side, the auxiliary rod side, and the connecting rib, a lever structure is formed. That is, the support point at the aforementioned constraint point, the part of the pry bar inserted into the groove, and the part of the pry bar outside the groove together constitute the lever structure. Through the leverage effect, gently rotating the pry bar generates sufficient destructive force on the connecting rib, breaking it. It is required that the main rod side and the auxiliary rod side have sufficient strength to prevent deformation of the main rod side and auxiliary rod side before the connecting rib is broken.

[0008] Combining the aforementioned fracture groove structure, it is preferable to have two connecting ribs, arranged opposite each other, forming a closed loop structure with the main rod side, auxiliary rod side, and connecting ribs together. Firstly, the opposite arrangement of the two connecting ribs ensures a more stable connection between the main rod side and the auxiliary rod side, guaranteeing structural stability during the transmission of corrective force. When it is necessary to break the connecting ribs, the external force applied by the breaking tool during rotation, under leverage, is generally sufficient to simultaneously break both connecting ribs, thus facilitating the separation of the main rod side and the auxiliary rod side. This solution effectively balances the overall stability of the double-ended screw during the transmission of corrective force with the ease of subsequent separation of the main rod side and the auxiliary rod side.

[0009] In practical use, to induce structural deformation on the auxiliary rod side during the breaking process of the connecting ribs using the breaking tool, thereby achieving separation of the auxiliary rod side with less effort, the following solution can be selected: a breaking auxiliary groove is provided on the wall surface of the auxiliary rod side near the breaking groove. During the rotation of the breaking tool within the breaking groove, the wall surface of the auxiliary rod side is subjected to corresponding stress. Due to the presence of the breaking auxiliary groove, the wall surface of the auxiliary rod side is more prone to deformation, and the deformed wall surface moves along with the rotating breaking tool, thereby accelerating the torsional failure of the connecting ribs and ultimately achieving the destruction of all connecting ribs. Similarly, the setting of the breaking auxiliary groove here must also ensure the structural stability of the auxiliary rod side during the initial straightening force transmission process, preventing premature failure of the auxiliary rod side due to insufficient strength at the breaking auxiliary groove when straightening force is applied. Generally, a V-shaped cross-sectional shape of the breaking auxiliary groove is preferred.

[0010] Sometimes, due to limited surgical space, it is difficult to use breaking tools such as pry bars for breaking operations. To facilitate the separation of the auxiliary rod side, a breaking groove can be provided at the bottom of the auxiliary rod side 11. In actual use, external force can be applied directly to the auxiliary rod side, causing it to separate into two parts at the breaking groove, thereby removing most of the material from the auxiliary rod side and minimizing the space occupied by the double-ended screw. Generally, a V-shaped cross-sectional shape of the breaking groove is preferred.

[0011] To improve the efficiency of spinal surgery by ensuring a smooth connection between the auxiliary rod and its connecting rod after the main rod and connecting rod are connected, the following approach can be chosen: The auxiliary rod includes a U-shaped opening with a rotatable U-shaped rotating ring inside. The side wall of the U-shaped rotating ring has a rotation limiting groove, and the wall of the auxiliary rod has a rotation limiting hole with a pin inside. One end of the pin is positioned within the rotation limiting groove. In actual connection, due to the complexity of spinal curvature, the auxiliary rod often fails to connect to the main rod after it is fixedly connected to the main rod, due to excessive angular deviation. To achieve a smooth connection between the auxiliary rod and its connecting rod, the connecting rod is often forcibly bent to continuously adjust the angle for connection. This method not only leads to stress concentration and scratches that affect the lifespan of the auxiliary rod and its connecting rod, but also prolongs surgical time and increases intraoperative bleeding. This solution involves placing a U-shaped rotating ring, also U-shaped, within the U-shaped opening on the auxiliary rod side. This allows the U-shaped rotating ring to rotatably fit within the U-shaped opening on the auxiliary rod side, thus satisfying both the need for fixation with the auxiliary rod connecting rod and the required connection angle. Since one end of the pin is positioned within the rotation limiting groove, the pin constrains the movement range of the rotation limiting groove. This restricts the rotation range of the groove, ensuring the U-shaped rotating ring has a certain degree of rotational flexibility and preventing it from detaching from the U-shaped opening.

[0012] Under normal circumstances, the U-shaped rotating ring is always constrained within the U-shaped opening. However, during the breakage of the connecting rib, the auxiliary rod side will be subjected to a large external force, which may cause the U-shaped opening to be pried open. At this time, the U-shaped rotating ring inside the pried-open U-shaped opening is at risk of falling off. Once the U-shaped rotating ring falls off, it may fall directly into the patient's body, causing serious surgical accidents. To prevent the U-shaped rotating ring from falling off from the pried-open U-shaped opening, the following solution can be selected: including an auxiliary rod fastening screw, with a threaded connection between the auxiliary rod fastening screw and the U-shaped rotating ring; including a limiting retaining edge set on the outer edge of the screw head of the auxiliary rod fastening screw, the limiting retaining edge extending downward in a direction perpendicular to the screw head; including an auxiliary rod retaining plate set on the top of the auxiliary rod side, the auxiliary rod retaining plate extending upward along the side wall of the auxiliary rod side, the auxiliary rod retaining plate being engaged within the limiting retaining edge, and the bottom horizontal plane of the limiting retaining edge being lower than the top horizontal plane of the auxiliary rod retaining plate. The limiting clamp can hold the auxiliary rod plate in place, preventing it from moving outwards and thus preventing the U-shaped opening from being pried open. Simultaneously, the threaded connection between the auxiliary rod fastening screw and the U-shaped rotating ring ensures that the U-shaped rotating ring is always constrained by the auxiliary rod fastening screw, preventing it from falling off.

[0013] The method of using the aforementioned double-ended screw includes the following steps: The screw at the bottom of the main rod is positioned at the desired location on the patient's spine. Then, the main rod connecting rod is securely fastened to the main rod side. Next, the auxiliary rod connecting rod is securely fastened to the auxiliary rod side. A corrective force is then applied to the auxiliary rod connecting rod using an external force-applying tool, and this corrective force is transferred to the main rod side via a connecting ligament. After the corrective force is applied, the connecting ligament is broken, separating the main rod side and the auxiliary rod side. This method reduces the space occupied by the double-ended screw near the spine after surgery, allowing for more space for subsequent surgical procedures. It also significantly reduces the postoperative bulge on the back caused by existing double-ended screws.

[0014] The beneficial effects of this invention are as follows: By connecting the main rod side and the auxiliary rod side with a connecting ligament that can be broken according to surgical needs, during the initial application of corrective force, the main rod side and the auxiliary rod side transmit force as a unified whole through the connecting ligament, effectively achieving the application of corrective force and restoring the spine to its normal curvature. After the application of corrective force is completed, the connecting ligament is broken, thereby achieving convenient and rapid separation of the auxiliary rod side and the main rod side, greatly improving the efficiency of the operation, saving space near the spine, and reducing patient pain. This invention is particularly suitable for spinal correction surgery in younger or thinner patients. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention after it is connected with the main rod connecting rod and the auxiliary rod connecting rod.

[0016] Figure 2 This is a schematic diagram of the structure after the main rod side and the auxiliary rod side of the present invention are connected by connecting ribs.

[0017] Figure 3 This is a schematic diagram of the fracture groove of the present invention.

[0018] Figure 4 This is a schematic diagram of the U-shaped rotating ring structure of the present invention.

[0019] Figure 5 This is a side cross-sectional view of the U-shaped rotating ring of the present invention disposed within a U-shaped opening.

[0020] Figure 6 This is a schematic diagram showing the positional relationship between the threaded pin and the rotation limiting groove of the U-shaped rotating ring of the present invention, which is disposed in the U-shaped opening.

[0021] Figure 7 This is a schematic diagram of a double-ended screw in the prior art.

[0022] The markings in the diagram are as follows: Double-ended screw 1, Auxiliary rod side 11, Auxiliary rod fastening screw 111, Threaded pin 112, Rotation limiting hole 113, U-shaped opening 114, Main rod side 12, Main rod fastening screw 122, Main rod side inner wall 123, Main rod U-shaped opening 124, Breaking groove 13, Connecting rib 14, Auxiliary rod breaking groove 141, Breaking auxiliary groove 142, Screw 2, Screw head 21, Thread 22, Main rod connecting rod 3, Auxiliary rod connecting rod 4, U-shaped rotating ring 5, Spherical base 51, Arc-shaped wall 52, Rotation guide surface 53, Rotation limiting groove 54, Rotation tangent 55. Detailed Implementation

[0023] like Figures 1 to 6 The double-ended screw 1 shown includes a main rod side 12 and an auxiliary rod side 11. A screw hole is provided at the bottom of the main rod side 12. After the thread 22 passes through the screw hole, the screw head 21, being larger than the screw hole, is positioned at the bottom of the main rod side 12. Generally, the angle of the screw 2 has a certain range of adjustment to accommodate complex application scenarios in spinal correction. The main rod side 12 is securely connected to the main rod connecting rod 3 via a main rod fastening screw 122, while the auxiliary rod side 11 is fixedly connected to the auxiliary rod connecting rod 4. In actual use, the screw 2 is fixedly placed on the spine and serves as the basis for the double-ended screw 1 to transmit corrective force to the spine. After the double-ended screw 1 is arranged, a corrective force is applied to the auxiliary rod connecting rod 4 using an external force-applying tool. Upon receiving the external force, i.e., the corrective force, the auxiliary rod connecting rod 4 transmits this corrective force through the auxiliary rod side 11 to the connecting ligament 14, and further to the main rod side 12 and the spine, thereby completing the correction and adjustment of the spinal curve.

[0024] like Figures 1 to 3 The diagram shows a specific structural form of the break groove 13. The break groove 13 is formed by the side walls of the main rod side 12 and the auxiliary rod side 11, as well as the upper and lower connecting ribs 14, thus creating a closed through-groove structure. In actual design, since the break groove 13 needs to be used with a corresponding breaking tool, the cross-sectional shape of the break groove 13 can be designed to match the cross-sectional shape of the part of the breaking tool inserted into the break groove 13, thereby ensuring a good fit between them. During subsequent breaking operations, a stable and sufficient lever driving force can be generated to ensure the destruction of the two connecting ribs 14. Conventional pry bars or levers can be used as breaking tools. Of course, if space is limited during actual operation, scissors or other tools can be used to directly cut the two connecting ribs 14.

[0025] A breakage auxiliary groove 142 is provided on the wall surface of the auxiliary rod side 11 near the breakage groove 13, so as to... Figure 3As shown, the cross-sectional shape of the breakage auxiliary groove 142 is V-shaped. The breakage auxiliary groove 142 designed here allows for a matching deformation during the torsion process of the breakage tool. Specifically, the wall surface of the auxiliary rod side 11 is first bent and deformed by the breakage tool at the breakage auxiliary groove 142. The deformed wall surface of the auxiliary rod side 11 then rotates around the connecting rib 14 under the drive of the breakage tool, thereby accelerating the breakage of the connecting rib 14 and making the separation of the auxiliary rod side 11 easier and smoother. Of course, both the design of the breakage auxiliary groove 142 and the selection of the connecting rib 14 must ensure the overall structural strength of the main rod side 12 and the auxiliary rod side 11 during the initial transmission of the corrective force. The connection structure between the main rod side 12 and the auxiliary rod side 11 must not be damaged during the initial transmission of the corrective force. Based on the same design concept, such as... Figure 3 As shown, a stylus breakage groove 141 can be further provided at the bottom of the stylus side 11. By breaking the stylus at the stylus breakage groove 141, most of the material of the stylus side 11 can be separated, minimizing the volume of the double-ended screw 1 after surgery.

[0026] A U-shaped rotating ring 5 is provided inside the U-shaped opening 114 on the auxiliary rod side 11. The U-shaped rotating ring 5 can rotate within a certain range to adapt to the overlap angle with the auxiliary rod connecting rod 4 and to achieve connection with the auxiliary rod connecting rod 4. The bottom of the U-shaped rotating ring 5 is a spherical base 51, which is set at the bottom inside the U-shaped opening 114. Since the volume of the spherical base 51 is larger than the volume of a hemisphere of the same diameter, the spherical base 51 can be snapped into place at the bottom inside the U-shaped opening 114, thereby forming a ball-and-socket connection structure.

[0027] The rotation range of the U-shaped rotating ring 5 depends on the range of motion of the rotating limiting groove 54. The range of motion of the rotating limiting groove 54 is ultimately constrained by the threaded pin 112. Since one end of the threaded pin 112 is always located within the rotating limiting groove 54, when the rotating limiting groove 54 moves to the point where its side wall contacts the threaded pin 112, it is constrained and restricted by the threaded pin 112, thus preventing it from moving in the original direction. This is the structural basis for controlling the rotation range of the U-shaped rotating ring 5. Furthermore, since one end of the threaded pin 112 is located within the rotating limiting groove 54, there are gaps between the threaded pin 112 and the rotating limiting groove 54 in both the horizontal and vertical directions. These gaps constitute the movement space of the rotating limiting groove 54. This allows the range of motion of the rotating limiting groove 54 to have both horizontal and vertical directions, as well as combinations of these two directions. However, the range of motion of the rotating limiting groove 54 is always limited by the rectangular boundary.

[0028] If the U-shaped opening 114 on the auxiliary rod side 11 does not deform, the U-shaped rotating ring 5 can always remain within the U-shaped opening 114. For example... Figure 3As shown, when the connecting rib 14 is damaged, the wall surface at the broken auxiliary groove 142 will deform, causing the U-shaped opening 114 to open. This creates a risk that the U-shaped rotating ring 5 will fall out of the U-shaped opening 114. By designing the limiting retaining edge 115 and the auxiliary rod retaining plate 116, the auxiliary rod fastening screw 111, which is threadedly connected to the U-shaped rotating ring 5, can constrain and limit the gradually opening U-shaped opening 114, preventing the U-shaped opening 114 from opening too large during the aforementioned deformation process, thus preventing the U-shaped rotating ring 5 from falling out.

Claims

1. A double-ended screw for spinal surgery, the double-ended screw (1) comprising a main rod side (12) and an auxiliary rod side (11), wherein a screw (2) is provided at the bottom of the main rod side (12), and the main rod side (12) and the auxiliary rod side (11) are connected by a connecting part, characterized in that: The connecting part includes at least one connecting rib (14), and the main rod side (12) and the auxiliary rod side (11) are fixedly connected by the connecting rib (14). The connecting rib is a breakable structure. The connecting part includes a breaking groove (13) for inserting a breaking tool, the breaking groove (13) being disposed between the main rod side (12) and the auxiliary rod side (11); The connecting ribs (14) are two in number and are arranged opposite to each other. The main rod side (12), the auxiliary rod side (11) and the connecting ribs (14) together form a closed loop structure, which is a break groove (13). A breakage auxiliary groove (142) is provided on the wall surface of the auxiliary rod side (11) near the breakage groove (13). The cross-sectional shape of the breakage auxiliary groove (142) is V-shaped; A breakage groove (141) is provided at the bottom of the auxiliary rod side (11); The cross-sectional shape of the auxiliary rod breakage groove (141) is V-shaped.

2. The double-ended screw for spinal surgery as described in claim 1, characterized in that: The auxiliary rod side (11) includes a U-shaped opening (114), and a rotatable U-shaped rotating ring (5) is provided in the U-shaped opening (114). The side wall of the U-shaped rotating ring (5) is provided with a rotation limiting groove (54). The wall surface of the auxiliary rod side (11) is provided with a rotation limiting hole (113). A pin is provided in the rotation limiting hole (113), and one end of the pin is provided in the rotation limiting groove (54).

3. The double-ended screw for spinal surgery as described in claim 2, characterized in that: It includes an auxiliary rod fastening screw (111), which is threadedly connected to a U-shaped rotating ring (5). It includes a limiting retaining edge (115) located on the outer edge of the screw head of the auxiliary rod fastening screw (111), which extends downward in a direction perpendicular to the screw head. It also includes an auxiliary rod retaining plate (116) located on the top of the auxiliary rod side (11), which extends upward along the side wall of the auxiliary rod side (11). The auxiliary rod retaining plate (116) is engaged within the limiting retaining edge (115), and the bottom of the limiting retaining edge (115) is lower than the top of the auxiliary rod retaining plate (116).

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