Multidirectional reinforcing locking system for spinal pedicle screws

Abstract

The present application relates to a kind of multi-directional reinforcing locking system of spinal pedicle screw, including pedicle screw, nail seat, connecting rod and screw plug, the pedicle screw is arranged on nail seat, connecting rod is radially through nail seat and is pressed on the top of pedicle screw above, the screw plug is screwed with nail seat, and screw plug is resisted with connecting rod, its innovation lies in: the screw thread top surface of the screw plug and along its axial direction has the locking protrusion extending upwards, the outer circumferential surface of the locking protrusion and the screw thread outer circumferential surface of screw plug form the continuous envelope locking surface, the envelope locking surface is made of negative locking surface F1, radial limit surface F2, locking inclined surface F3 and axial limit surface F4.The present application can generate multi-directional locking force, strengthen the axial torque between nail seat and screw plug, make product form all-around locking in spinal orthopedic lateral bending and other need high-strength surgery, effectively prevent nail seat from opening, and reduce the risk of screw plug from escaping in locking process.

Description

Technical Field

[0001] This invention relates to a locking system, specifically a multi-directional reinforcing locking system for spinal pedicle screws. Background Technology

[0002] Pedicle screws are core products used in spinal surgery for spinal fixation, correction, and fusion. Their locking effect is crucial to the success of the surgery, directly affecting biomechanical stability, bone fusion success rate, and prevention of postoperative complications. Traditional pedicle screw locking structures have limitations, only suitable for routine surgeries involving a few segments, such as spondylolisthesis and fractures. In long-segment, high-intensity surgeries such as spinal correction and scoliosis, they cannot withstand the high loads and torques during surgery, easily leading to problems such as screw seat opening and screw plug dislodgement, thus failing to meet the locking requirements of the surgery.

[0003] If the locking mechanism between the pedicle screw and the connecting rod fails to provide effective fixation, or if it loses stability postoperatively due to loosening, breakage, fatigue, or other reasons, the consequences include: Internal fixation instability can cause micro-movement or significant misalignment between the screws and connecting rods, resulting in a loss of effective control over the spine and potentially leading to loss of correction, such as recurrence of scoliosis. Fusion failure: Dynamic micromovement can hinder bone healing, causing partial fusion of the grafted area. Patients may experience persistent lower back pain and limited function. Screw loosening or pullout: Inadequate locking increases the shear force on the screw, causing it to loosen or even come out of the vertebral body. This can compress surrounding nerves, blood vessels, or organs, especially in the thoracolumbar region. Increased risk of instrument breakage: Stress concentration at loosened areas can lead to fatigue fracture of screws and connecting rods over time. Nerve or spinal cord injury: Displaced screws or connecting rods may invade the spinal canal, compressing the spinal cord or nerve roots, causing pain, numbness, and decreased muscle strength. The aforementioned complications necessitate secondary surgery to replace or reinforce the internal fixation, increasing patient suffering, costs, and surgical risks, and impacting postoperative recovery quality. This underscores the importance of screw locking in pedicle screw systems. Currently, pedicle screw systems frequently experience the risk of plug dislodgement during locking due to expansion at the screw seat opening. Therefore, it is necessary to design a locking system that strengthens the locking force between the screw seat and the plug, ensuring effective pedicle screw locking. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-directional reinforcing locking system for spinal pedicle screws that can generate multi-directional locking force, strengthen the axial torque between the screw seat and the screw plug, enable the product to form an all-round lock, effectively prevent the screw seat from opening, and reduce the risk of the screw plug coming out during the locking process.

[0005] To achieve the above objectives, the technical solution of this invention is: a multi-directional reinforcing locking system for spinal pedicle screws, comprising a pedicle screw, a screw base, a connecting rod, and a screw plug. The pedicle screw is disposed on the screw base, the connecting rod radially passes through the U-shaped groove of the screw base, and the connecting rod is pressed above the top of the pedicle screw. The screw plug is threadedly connected to the screw base, and the screw plug abuts against the connecting rod. Its innovation lies in: The screw plug has an upwardly extending locking protrusion on the top surface of its thread along its axial direction, and the threaded groove of the screw seat is provided with a relief groove to accommodate the locking protrusion. The outer peripheral surface of the locking protrusion and the outer peripheral surface of the screw plug's thread form a continuous envelope locking surface. The envelope locking surface is composed of a negative locking surface F1, a radial limiting surface F2, a locking inclined surface F3, and an axial limiting surface F4. The inner surface of the locking protrusion forms a negative locking surface F1 that fits against the nail seat, and its top surface forms an axial limiting surface F4 that fits against the nail seat. The outer surface of the screw thread forms a radial limiting surface F2 that fits against the nail seat, and its bottom surface forms a locking inclined surface F3 that fits against the nail seat. The negative locking surface F1 and the extension line of the screw thread's axis form an angle α of less than 90°, which is used to prevent the screw thread from coming out due to the expansion of the nail seat opening and to increase the locking force between the nail seat and the screw thread.

[0006] In the above technical solution, the negative locking surface F1, combined with the axial limiting surface F4, generates an oblique locking force F5 between the nail seat and the screw plug. The oblique locking force F5, together with the included angle α, generates an angular force to prevent the nail seat opening from expanding. The radial limiting surface F2, combined with the locking inclined surface F3, generates a radial locking force F6 between the nail seat and the screw plug. The radial locking force F6, together with the included angle α, generates an angular force to increase the axial torque between the screw plug and the nail seat, thereby improving the locking force.

[0007] In the above technical solution, the included angle α formed by the negative locking surface F1 and the extended line of the screw plug axis is 5°~85°.

[0008] In the above technical solution, the included angle α formed by the negative locking surface F1 and the extended axis of the screw plug is 5°, 10°, or 15°.

[0009] In the above technical solution, the direction of the oblique locking force F5 generated between the nail seat and the screw plug is offset from the axial direction of the nail seat by 30°~50°, and the direction of the radial locking force F6 generated between the nail seat and the screw plug is perpendicular to the axial direction of the nail seat.

[0010] In the above technical solution, a first guide concave surface is provided at the top thread of the nail seat, and a first guide convex surface is provided at the bottom thread of the plug to cooperate with the first guide concave surface, so as to strengthen the thread strength of the bottom thread of the plug and prevent the plug from tilting when screwed into the nail seat and causing damage to the bottom thread.

[0011] In the above technical solution, the nail seat is provided with a flat second guide surface at the opening of the U-shaped groove, which is used to form a guiding fit with the socket of the matching tool.

[0012] In the above technical solution, the ball head of the pedicle screw is set in the inner hole of the screw seat through an intermediate body, the connecting rod abuts in the limiting groove of the intermediate body and is located above the ball head, the outer wall of the intermediate body is provided with a locking boss, and the locking boss is embedded in the limiting groove of the inner hole of the screw seat to prevent the intermediate body from shifting axially.

[0013] In the above technical solution, the ball head and the intermediate body are connected by a concave-convex mating pair, that is, the outer wall of the ball head is provided with a raised key, and the inner wall of the ball hole of the intermediate body is provided with a raised keyway that mates with the raised key, so that the pedicle screw in the locked state increases the meshing and locking force between the screw seat and the intermediate body.

[0014] In the above technical solution, the outer peripheral surface of the nail seat is an eccentric surface, which is offset from the axis of the pedicle screw by 3° to 5°, in order to reduce the volume occupied by the nail seat after implantation and reduce soft tissue irritation.

[0015] The positive effects of this invention are as follows: When using the multi-directional reinforcing locking system of the spinal pedicle screw of this invention, the top surface of the screw thread of the plug has an upwardly extending locking protrusion along its axial direction, and the threaded groove of the screw seat is provided with a relief groove to accommodate the locking protrusion. The outer peripheral surface of the locking protrusion and the outer peripheral surface of the screw thread of the plug form a continuous envelope locking surface. The envelope locking surface is composed of a negative locking surface F1, a radial limiting surface F2, a locking inclined surface F3, and an axial limiting surface F4. The inner surface of the locking protrusion forms a negative locking surface F1 that fits against the nail seat, and its top surface forms an axial limiting surface F4 that fits against the nail seat. The outer surface of the screw thread forms a radial limiting surface F2 that fits against the nail seat, and its bottom surface forms a locking inclined surface F3 that fits against the nail seat. The negative locking surface F1 forms an angle α of less than 90° with the extension line of the screw plug's axis. This is used to prevent the screw plug from coming out due to the expansion of the nail seat opening and to increase the locking force between the nail seat and the screw plug. Therefore, the screw plug and the nail seat described in this invention do not solely rely on threads for engagement. Furthermore, a locking protrusion extends from the top surface of the screw plug's threads, and the inner surface of the locking protrusion forms a negative locking surface F1 that fits against the nail seat. The negative locking surface F1 and the extended axis of the screw plug form an angle α of less than 90°, creating an inward-locking structure between the negative locking surface F1 and the mating surface of the nail seat. This ensures that during the locking process, the screw plug and nail seat form a highly efficient clamping structure, effectively preventing the screw plug from dislodging due to the expansion of the nail seat opening and increasing the locking force between the nail seat and the screw plug. Therefore, the present invention can generate multi-directional locking force, strengthen the axial torque between the nail seat and the screw plug, so that the product forms an all-round lock, effectively prevent the nail seat from opening, and reduce the risk of the screw plug coming out during the locking process.

[0016] This invention's multi-directional reinforced locking system for pedicle screws, through structural innovation, generates multi-directional locking force, significantly enhancing the axial torque between the screw seat and the plug, achieving all-around locking of the product, and perfectly adapting to the needs of high-intensity surgeries such as spinal correction and scoliosis. This system firmly fixes the connecting rod to the head of the pedicle screw, preventing relative sliding or rotation, forming a rigid integral structure between the pedicle screw and the connecting rod. This effectively transfers load, restricts spinal segment movement, and creates a stable environment free of micro-motion for the bone graft area, thereby promoting bone fusion. Simultaneously, it effectively prevents the screw seat from opening and reduces the risk of plug dislodgement during the locking process from a structural perspective. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural schematic diagram of a specific embodiment of the present invention; Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 yes Figure 2 A magnified view of a portion (part A); Figure 4 This is a schematic diagram of the initial state of the screw plug of the present invention being screwed onto the nail seat; Figure 5 yes Figure 4 A top-view structural diagram; Figure 6 This is a three-dimensional structural schematic diagram of the screw plug of the present invention; Figure 7 This is a three-dimensional structural diagram of the nail holder of the present invention; Figure 8 This is a schematic diagram of the structure of the present invention when used with its supporting tools. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] like Figure 1 , 2 As shown in Figures 3, 4, 5, 6, 7, and 8, a multi-directional reinforcing locking system for spinal pedicle screws includes a pedicle screw 1, a screw seat 2, a connecting rod 3, and a screw plug 4. The pedicle screw 1 is mounted on the screw seat 2. The connecting rod 3 radially passes through the U-shaped groove of the screw seat 2 and is pressed against the top of the pedicle screw 1. The screw plug 4 is threadedly connected to the screw seat 2 and abuts against the connecting rod 3. The top surface of the screw thread of the plug 4 has an upwardly extending locking protrusion 41 along its axial direction, and the threaded groove of the pin seat 2 is provided with a relief groove 21 for accommodating the locking protrusion 41. The outer peripheral surface of the locking protrusion 41 and the outer peripheral surface of the screw thread of the plug 4 form a continuous envelope locking surface. The envelope locking surface is composed of a negative locking surface F1, a radial limiting surface F2, a locking inclined surface F3, and an axial limiting surface F4. The inner surface of the locking protrusion 41 forms a negative locking surface F1 that fits against the nail seat 2, and its top surface forms an axial limiting surface F4 that fits against the nail seat 2. The outer surface of the screw thread of the plug 4 forms a radial limiting surface F2 that fits against the nail seat 2, and its bottom surface forms a locking inclined surface F3 that fits against the nail seat 2. The negative locking surface F1 and the extended line of the axis of the plug 4 form an angle α of less than 90°, which is used to prevent the plug 4 from falling out due to the expansion of the opening of the nail seat 2, and to increase the locking force between the nail seat 2 and the plug 4.

[0021] Furthermore, such as Figure 2 , 3 As shown, in order to further achieve multi-directional locking, prevent screw locking failure due to the opening of the screw seat, and increase the axial torque between the screw plug and the screw seat to further improve the locking effect, the negative locking surface F1, combined with the axial limiting surface F4, generates an oblique locking force F5 between the screw seat 2 and the screw plug 4. The oblique locking force F5, together with the included angle α, generates an angular force to prevent the opening of the screw seat 2 from expanding. The radial limiting surface F2, combined with the locking inclined surface F3, generates a radial locking force F6 between the screw seat 2 and the screw plug 4. The radial locking force F6, together with the included angle α, generates an angular force to increase the axial torque between the screw plug 4 and the screw seat 2, thereby improving the locking force.

[0022] Furthermore, such as Figure 3 As shown, in order to make the structure more reasonable, the included angle α formed by the negative locking surface F1 and the extended line of the axis of the screw plug 4 is 5°~85°.

[0023] Furthermore, in a preferred embodiment of the present invention, the included angle α formed by the negative locking surface F1 and the extended axis of the screw plug 4 is 5°, or 10°, or 15°.

[0024] Furthermore, such as Figure 2 As shown, in order to ensure that the screw seat and the screw plug can effectively lock the screw, the direction of the oblique locking force F5 generated between the screw seat 2 and the screw plug 4 is offset from the axial direction of the screw seat 2 by 30°~50°, and the direction of the radial locking force F6 generated between the screw seat 2 and the screw plug 4 is perpendicular to the axial direction of the screw seat 2.

[0025] Furthermore, such as Figure 4 , 5 As shown in Figures 6 and 7, in order to enhance the strength of the screw plug contacting the top thread of the nail seat when the screw plug is screwed into place, and to give the thread at the top of the nail seat better guidance, effectively preventing the screw plug from tilting and damaging the thread during screwing, a first guide concave surface 22 is provided at the top thread of the nail seat 2, and a first guide convex surface 42 is provided at the bottom thread of the screw plug 4 to cooperate with the first guide concave surface 22. This is used to strengthen the thread strength at the bottom of the screw plug 4 and prevent the screw plug 4 from tilting and causing damage to the bottom thread when screwed into the nail seat 2.

[0026] Furthermore, such as Figure 8 As shown, to facilitate easier assembly and connection between the accessory tool and the staple holder, reduce assembly difficulty during clinical use, and shorten surgical operation time, the staple holder 2 has a flat second guide surface 23 at the opening of the U-shaped groove, which is used to guide and cooperate with the insertion port of the accessory tool. The insertion port of the accessory tool 5 has an insertion guide surface 51 that cooperates with the second guide surface 23 for positioning and guidance.

[0027] Furthermore, such as Figure 2 , 4 As shown, in order to improve the bonding force between the pedicle screw head and the screw seat, the ball head 11 of the pedicle screw 1 is set in the inner hole of the screw seat 2 through the intermediate body 5. The connecting rod 3 abuts in the limiting groove of the intermediate body 5 and is located above the ball head 11. The outer wall of the intermediate body 5 is provided with a locking boss, and the locking boss is embedded in the limiting groove of the inner hole of the screw seat 2 to prevent the intermediate body 5 from axially shifting.

[0028] Furthermore, such as Figure 2As shown, in order to achieve a locking force between the pedicle screw, the screw seat, and the intermediate body in the locked state, and to further improve the overall multi-directional locking effect of the system, the ball head 11 and the intermediate body 5 are connected by a concave-convex mating pair. That is, the outer wall of the ball head 11 is provided with a protruding key, and the inner wall of the ball hole of the intermediate body 5 is provided with a protruding keyway that mates with the protruding key. This increases the meshing locking force between the pedicle screw 1, the screw seat 2, and the intermediate body 5 in the locked state.

[0029] Furthermore, such as Figure 5 As shown in the figure, the dotted line on the outermost periphery of the nail seat 2 is the reference plane of the circle, and the inner side is the outermost eccentric surface of the nail seat. The outer periphery of the nail seat 2 is an eccentric surface and is offset towards the center of the circle, and deviates from the axis of the pedicle screw 1 by 3°~5°. This is to reduce the volume occupied by the nail seat 2 after implantation, so that the product can achieve a lower notch, reduce soft tissue irritation, and have positive effects such as facilitating suturing and postoperative rehabilitation.

[0030] The screw plug and rivet seat described in this invention do not solely rely on threads for engagement. Furthermore, a locking protrusion extends from the top surface of the screw plug's threads, and the inner surface of this protrusion forms a negative locking surface F1 that conforms to the rivet seat. The negative locking surface F1 and the extended axis of the screw plug form an angle α less than 90°, creating an inward-locking structure between the negative locking surface F1 and the mating surface of the rivet seat. This ensures that during the locking process, the screw plug and rivet seat form a highly efficient clamping structure, effectively preventing the screw plug from dislodging due to the expansion of the rivet seat opening and increasing the locking force between the rivet seat and the screw plug. Therefore, the present invention can generate multi-directional locking force, strengthen the axial torque between the nail seat and the screw plug, so that the product forms an all-round lock, effectively prevent the nail seat from opening, and reduce the risk of the screw plug coming out during the locking process.

[0031] In summary, the multi-directional reinforcing locking system for pedicle screws of this invention, through structural innovation, can generate multi-directional locking force, significantly enhancing the axial torque between the screw seat and the plug, achieving all-around locking of the product, and perfectly adapting to the needs of high-intensity surgeries such as spinal correction and scoliosis. This system can firmly fix the connecting rod to the head of the pedicle screw, preventing relative sliding or rotation, forming a rigid integral structure between the pedicle screw and the connecting rod. This effectively transfers loads, restricts spinal segment movement, and creates a stable environment free of micro-motion for the bone graft area, thereby promoting bone fusion. Simultaneously, it effectively prevents the screw seat from opening from the structural source and reduces the risk of plug dislodgement during the locking process.

[0032] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A multi-directional reinforcing locking system for a spinal pedicle screw, comprising a pedicle screw (1), a screw seat (2), a connecting rod (3), and a screw plug (4), wherein the pedicle screw (1) is disposed on the screw seat (2), the connecting rod (3) passes radially through the U-shaped groove of the screw seat (2), and the connecting rod (3) is pressed against the top of the pedicle screw (1), and the screw plug (4) is threadedly connected to the screw seat (2), and the screw plug (4) abuts against the connecting rod (3), characterized in that: The top surface of the screw thread of the plug (4) has an upwardly extending locking protrusion (41) along its axial direction, and the thread groove of the pin seat (2) is provided with a relief groove (21) to accommodate the locking protrusion (41). The outer peripheral surface of the locking protrusion (41) and the outer peripheral surface of the screw thread of the plug (4) form a continuous envelope locking surface. The envelope locking surface is composed of a negative locking surface F1, a radial limiting surface F2, a locking inclined surface F3, and an axial limiting surface F4. The inner side of the locking protrusion (41) forms a negative locking surface F1 that fits against the nail seat (2), and its top surface forms an axial limiting surface F4 that fits against the nail seat (2). The outer side of the screw thread of the plug (4) forms a radial limiting surface F2 that fits against the nail seat (2), and its bottom surface forms a locking inclined surface F3 that fits against the nail seat (2). The negative locking surface F1 and the extension line of the axis of the plug (4) form an angle α of less than 90°, which is used to prevent the plug (4) from coming out due to the expansion of the opening of the nail seat (2) and to increase the locking force between the nail seat (2) and the plug (4).

2. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The negative locking surface F1, combined with the axial limiting surface F4, generates an oblique locking force F5 between the nail seat (2) and the screw plug (4). The oblique locking force F5, together with the included angle α, generates an angular force to prevent the opening of the nail seat (2) from expanding. The radial limiting surface F2, combined with the locking inclined surface F3, generates a radial locking force F6 between the nail seat (2) and the screw plug (4). The radial locking force F6, together with the included angle α, generates an angular force to increase the axial torque between the screw plug (4) and the nail seat (2), thereby increasing the locking force.

3. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The angle α formed by the negative locking surface F1 and the extended axis of the screw plug (4) is 5°~85°.

4. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1 or 3, characterized in that: The angle α formed by the negative locking surface F1 and the extended axis of the screw plug (4) is 5°, 10°, or 15°.

5. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 2, characterized in that: The direction of the oblique locking force F5 generated between the nail seat (2) and the screw plug (4) is offset from the axial direction of the nail seat (2) by 30°~50°, and the direction of the radial locking force F6 generated between the nail seat (2) and the screw plug (4) is perpendicular to the axial direction of the nail seat (2).

6. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The top thread of the nail seat (2) is provided with a first guide concave surface (22), and the bottom thread of the screw plug (4) is provided with a first guide convex surface (42) that cooperates with the first guide concave surface (22). This is used to strengthen the thread strength of the bottom thread of the screw plug (4) and prevent the screw plug (4) from tilting when screwed onto the nail seat (2) and causing damage to the bottom thread.

7. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The nail seat (2) is provided with a flat second guide surface (23) at the opening of the U-shaped groove, which is used to form a guide fit with the socket of the matching tool.

8. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The ball head (11) of the pedicle screw (1) is set in the inner hole of the nail seat (2) through the intermediate body (5). The connecting rod (3) abuts against the limiting groove of the intermediate body (5) and is located above the ball head (11). The outer wall of the intermediate body (5) is provided with a locking boss, and the locking boss is embedded in the limiting groove of the inner hole of the nail seat (2) to prevent the intermediate body (5) from axially shifting.

9. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 8, characterized in that: The ball head (11) and the intermediate body (5) are connected by a convex-concave mating pair. The outer wall of the ball head (11) is provided with a protruding key, and the inner wall of the ball hole of the intermediate body (5) is provided with a protruding keyway that mates with the protruding key, so that the pedicle screw (1) increases the meshing and locking force between the screw seat (2) and the intermediate body (5) when it is locked.

10. The multi-directional reinforcing locking system for spinal pedicle screws according to claim 1, characterized in that: The outer peripheral surface of the nail seat (2) is an eccentric surface, which is 3°~5° away from the axis of the pedicle screw (1) to reduce the volume occupied by the nail seat (2) after implantation and reduce soft tissue irritation.

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