Dynamic pedicle screw capable of neutral compression and its limiting tool

Abstract

The present invention aims at the current situation that the existing dynamic pedicle screw-rod fixing system cannot limit the swing between the screw seat and the screw body during surgery, so that the screw seat and the screw body cannot be kept in a coaxial state after the fixed segment is stretched or pressurized, thereby failing to realize the original intention of the device design that the dynamic pedicle screw-rod fixing system still allows the fixed segment to perform flexion and extension activities within a certain range after fixation. The present invention invents a dynamic pedicle screw with a screw seat side wall provided with a slot penetrating the side wall with a wedge-shaped longitudinal section, and a limiting tool that can be wedged into the slot and limit the swing between the screw body and the screw seat by pressing the head of the screw body downward. The present invention can temporarily fix the dynamic nail into a static nail with a rigid connection between the screw body and the screw seat by using the limiting tool during surgery, so that the pedicle screw can be forced in a neutral position to keep the screw body and the screw seat from swinging at an angle, so that after the fixing is completed and the limiting tool is removed, the dynamic fixation effect of the dynamic pedicle screw can be realized to the maximum extent.

Description

Technical Field

[0001] The invention belongs to a human spine internal fixation device and a special installation tool thereof. Background Art

[0002] At present, in orthopedic and neurosurgery, pedicle screw-rod fixation system is often used to perform treatments such as reduction, correction, and fixation on injuries and diseases such as spinal injuries, degeneration, deformity, and pathological changes. During the operation, after completing the implantation of all pedicle screws and installing the connecting rod, a spreader or a clamp is often used to spread or clamp the screw seat of the pedicle screw, and then the screw body (hereinafter referred to as the fixing screw) rigidly connected to the screw seat is driven to lift the vertebra fixed by the pedicle screw, so that the adjacent vertebra and intervertebral space are opened or closed to the desired position, and then all screw plugs are tightened to maintain the position and maintain the spinal stability of the fixed segment. This fixing mode of the pedicle screw-rod fixation system is rigid fixation, and there is no movement function between the fixed spinal segments, and the fixed adjacent vertebrae are in a static state, which is conducive to fracture healing and intervertebral bony fusion. However, this static fixation method is not the most ideal fixation method, nor is it suitable for all patients who need pedicle screw-rod fixation. Therefore, non-rigid fixation theory and corresponding non-rigid fixation pedicle screw-rod fixation systems have gradually emerged, among which dynamic pedicle screws (hereinafter referred to as dynamic screws) with a swingable non-rigid connection between the screw seat and the screw body have also begun to be used clinically; the original intention of the design of this type of "dynamic screw" is that the screw body implanted in the human vertebral body can still swing at a positive or negative angle (±∠) relative to the screw seat and the connecting rod after the connecting rod is locked by the screw plug, so as to maintain the appropriate flexion and extension of the segment fixed by the dynamic screw; but due to the position limitation between the screw seat and the vertebral body during the operation, when the adjacent vertebrae are distracted and clamped, it is impossible to use tools to act directly on the screw body, and it can only be used like the traditional "fixation screw". The tool can only act on the screw seat; this leads to a criticized phenomenon: since the screw body and the screw seat of the dynamic pedicle screw can swing relative to each other, when the tool only acts on the screw seat, affected by the resistance of soft tissues such as the intervertebral disc and ligaments, the front end of the screw body cannot move synchronously and parallel with the screw seat, but temporarily remains in place, so that the coaxial relationship between the screw seat and the screw body is destroyed, and an angle appears; only when the distraction or clamping force applied by the tool continues to act, so that the swing angle between the screw body and the screw seat axis reaches the designed limit value, the lower end of the screw body can provoke the front edge of the vertebral body to move, producing a distraction or clamping effect; in this way, the swing angle set by the dynamic screw will be completely lost, the flexion or extension movement mode in the flexion and extension function is lost, and the extension or flexion amplitude in the opposite direction is doubled, that is, the fixed segment can only swing 0 to 2 times the designed angle (0 to 2*∠). Both excessive and insufficient range of motion go against the original design intention of the dynamic nail and may have adverse effects on the human body. It is impossible to reflect the superior performance of the "dynamic nail" and seriously affects the practical application of the advanced concept of dynamic fixation.

[0003] The reasons that affect the surgical effect of the "dynamic nail" and the promotion and application of the "dynamic nail" may be that the developers ignored the fact that most traditional pedicle screw-rod fixation systems adopt a structural form in which the connecting rod is inserted into the U-shaped open groove at the top of the screw seat and locked and fixed by a screw plug, resulting in the lower component being blocked by the upper component and unable to be directly operated. That is, after the connecting rod is inserted, it will hinder tools such as the nail setter from adjusting and controlling the nail body under the connecting rod, making it impossible to temporarily make the flexibly connected nail body and the screw seat become rigidly connected when expanding or pressurizing.

[0004] How to make the dynamic pedicle screw with a central connecting rod to smoothly dilate and clamp adjacent vertebrae during surgery like a "fixed screw" without losing its set swing angle (±∠), so that after the operation, the implanted dynamic pedicle screw can still swing at a certain set angle, thereby fully realizing the medical effect of the dynamic pedicle screw, is a difficult problem that urgently needs to be solved in clinical practice. Summary of the invention

[0005] The present invention discloses the following solutions to the clinical problems that surgical operators urgently need to solve, namely, to continue to use the "centrally placed connecting rod" dynamic pedicle screw that is already familiar to the industry, to be able to freely expand and clamp such dynamic pedicle screw during surgery like using a fixed screw, and to allow the dynamic screw to swing normally at a certain positive or negative angle (±∠) after the surgery.

[0006] First, what needs to be solved is how to bypass or avoid the obstruction of the connecting rod placed in the U-shaped open through groove of the nail seat and the screw plug inserted into the nail seat, and implement the operation and control of the nail body; the technical solution of the present invention is to design the pedicle screw into a pedicle screw with a nail seat and a nail body connected in a non-rigid manner, and then add a common screw plug and a connecting rod to form a dynamic pedicle screw fixing system: the upper opening of the nail seat is provided with an internal thread matching the screw plug, and the upper part of the nail seat is also symmetrically provided with a U-shaped open through groove for receiving the connecting rod; the lower part of the U-shaped open through groove of the nail seat is a ball-shaped inner cavity, and the lower end of the inner cavity is provided with a trumpet-shaped through hole with a small inner diameter and a large outer diameter vertically downward, the nail body passes through the trumpet-shaped through hole at the lower end of the nail seat, the upper end of the nail body is in a hemispherical head shape matching the ball-shaped inner cavity at the lower part of the nail seat, and the diameter of the ball head of the nail seat is larger than the inner opening of the through hole at the lower end of the nail seat The screw body is fixed in the horn-shaped through hole at the lower end of the screw seat. After the connecting rod is installed and the screw plug is tightened, the ball head of the screw body will not be stuck in the ball-shaped inner cavity at the lower part of the screw seat, and the screw body can still rotate and swing at the horn-shaped through hole of the screw seat; during the operation, a limiting tool is required to temporarily fix the non-rigidly connected screw seat and the screw body into a rigid connection; the limiting tool refers to a special tool that can limit the rotation and swing between the screw seat and the screw body of the dynamic pedicle screw; in order to achieve the purpose of the invention, at least one through hole with a wedge-shaped longitudinal section penetrating the side wall of the screw seat and being larger outside and smaller inside is provided at the lower part of the screw seat; the limiting tool must have a wedge-shaped end that matches the shape of the screw seat bayonet, so that the wedge-shaped end can wedge into the inner cavity of the screw seat to squeeze the head of the nail body downward, and together with the ball-shaped inner cavity at the lower part of the screw seat, the ball head of the nail body is locked, so that the nail body cannot rotate and swing at the through hole at the lower end of the screw seat.

[0007] Preferably, one or a pair of through holes with a wedge-shaped longitudinal section, which are larger outside and smaller inside, are processed on the side wall of the lower part of the nail seat. Furthermore, the pair of wedge-shaped through holes are symmetrically distributed on both sides of the nail seat perpendicular to the U-shaped opening through groove on the nail seat, forming a bayonet; the wedge-shaped end of the special tool is inserted into the wedge-shaped through hole on the side wall of the nail seat, i.e., the bayonet, and the head of the nail body pre-installed in the bottom end of the nail seat is pressed down by using its wedge-shaped surface, so that the nail body and the nail seat can be locked into a rigidly connected whole without relative movement, thereby temporarily turning the entire dynamic root arch root nail into a fixed nail. At this time, as long as the traditional spreading or pressurizing tool is used, the vertebral body and intervertebral space can be spread or compressed very conveniently.

[0008] That is to say, when the limiting tool is wedged into the slot of the side wall of the nail seat and the ball head of the nail body is squeezed downward, the nail seat and the nail body can form a relatively fixed rigid body like the fixing nail, so that the spine can be stretched or clamped by stretching or clamping the nail seat like the fixing nail; after all fixation is completed, the dynamic fixation function of the dynamic nail can be restored by simply removing the limiting tool.

[0009] Furthermore, the horizontal height of this or this pair of wedge-shaped slots should be adapted to the horizontal position of the ball head of the nail body after assembly, thereby facilitating the operator to use the special tool to place the wedging end of the limiting tool on the tool into the wedge-shaped slot to implement compression and control of the ball head of the nail body.

[0010] In order to enhance the locking effect of the limiting tool on the head of the nail body, preferably, a pressure ring with a spherical socket-shaped lower end surface is provided in the nail seat, and correspondingly, the head of the nail body is set to be a sphere, and the pressure ring is arranged between the connecting rod and the ball head of the nail body, and the two form a spherical matching pair. At this time, the pressure ring is pressed down with the wedge end of the limiting tool, so that the pressure ring and the spherical socket-shaped inner cavity at the bottom of the nail seat can jointly lock the ball head.

[0011] Furthermore, a compression spring or elastic gasket can be arranged in the ball-shaped inner cavity at the lower part of the nail seat to increase the damping between the nail seat and the nail body for easy operation; the compression spring or elastic gasket is located below the pressure ring, and the wedging end of the limiting tool presses down the pressure ring and compresses the compression spring or elastic gasket, so that the pressure ring and the ball-shaped inner cavity at the lower part of the nail seat can jointly lock the ball head.

[0012] Preferably, the circular holes in the cross-sections of the pressure ring and the compression spring or elastic gasket must be able to pass through a screwdriver for twisting the nail body.

[0013] Preferably, the pressure ring and the compression spring or elastic gasket are pre-installed in the ball-shaped inner cavity at the lower part of the nail seat, and a backstop is added to the upper edge of the pressure ring to avoid temporary installation during surgery.

[0014] Furthermore, the components of the dynamic pedicle screw disclosed in the present invention, such as screw plugs, connecting rods, nail bodies, compression rings, springs or elastic gaskets, can basically use the components of traditional dynamic nails, or only require minor changes on the original basis. In this way, R&D costs can be saved and inventory pressure in the production process can be reduced.

[0015] The limiting tool is composed of a wedge end and a base, wherein the shape characteristics of the wedge end should match the wedge-shaped bayonet of the nail seat; the wedge end of the limiting tool, in addition to being wedge-shaped as the first choice, can also be conical, or "cylindrical body + conical head".

[0016] Preferably, the wedging end of the limiting tool is hingedly fixed to the base by a rotating shaft located on the side of its rear end, and the base is in the shape of a hook and can be hooked on the connecting rod; when the wedging end is wedged into the nail seat slot, the hook is hooked on the connecting rod and clamped, the wedging end can also obtain the maximum wedging force at the same time, so that the nail seat and the nail body are transformed into a static nail state with a rigid connection; when the hook is removed from the connecting rod, the wedging end can also easily withdraw from the nail seat slot, so that the nail seat and the nail body are restored to a dynamic nail state that can swing toward each other.

[0017] The limiting tool can also be configured as a lockable clamp-like tool, that is, the nail seat bayonet is symmetrically arranged on the two side walls of the lower part of the nail seat, and the wedging end is hinged into a clamp-like shape with a lockable handle. The nail seat bayonet is wedged from both sides to jointly squeeze the ball head of the nail body downward or to squeeze the ball head of the nail body downward through a pressure ring. After locking the handle, it can generate and maintain an extrusion force sufficient to limit the dynamic nail to a static nail.

[0018] Beneficial Effects

[0019] The present invention bypasses the connecting rod and directly controls the nail body with this innovative thinking, successfully solving the medical problem that the dynamic nail cannot be expanded and clamped in the neutral state, and can effectively avoid the current clinical defects of uncontrollable dynamic swing angle, failure of fixation due to being too large, or static fixation due to being too small, thereby ensuring the quality of surgery, significantly improving the therapeutic effect, and reducing the incidence and degree of surgical complications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the following, the present invention is further explained in conjunction with the accompanying drawings and specific embodiments;

[0021] Figure 1 It is a two-dimensional diagram and a rendering of the present invention;

[0022] Figure 2 It is a technical problem caused by the unimproved existing dynamic nails when they are stretched out;

[0023] Figure 3 is an exploded schematic diagram of the dynamic pedicle screw of the present invention;

[0024] Figure 4 It is a partial enlarged diagram of the working principle of the present invention;

[0025] Figure 5 This is the second embodiment of the dynamic pedicle screw of the present invention;

[0026] Figure 6 It is a two-dimensional diagram of the working principle of the special tool of the present invention;

[0027] Figure 7 It is a three-dimensional effect schematic diagram of the working principle disclosed by the present invention;

[0028] Figure 8 It is a two-dimensional diagram and effect diagram of the second implementation example of the special tool shown in the present invention;

[0029] Fig. 9 The present invention shows several embodiments of the wedge-shaped or tapered bayonet and the matching wedge-shaped or tapered clamp;

[0030] Fig.10 This is the third embodiment of the dynamic pedicle screw of the present invention;

[0031] Wherein: a screw plug 1; a screwdriver insertion hole 11 in the center of the screw plug; an external thread 12 of the screw plug;

[0032] Connecting rod 2; Spring 4;

[0033] Pressing ring 3; pressing ring upper end surface 31; pressing ring inner cavity 32; pressing ring lower end surface 33; pressing ring downward spherical surface 34; nail seat 5; nail seat internal thread 51; nail seat U-shaped opening through groove 52; nail seat inner spherical surface 53; wedge-shaped bayonet 54;

[0034] A downward through hole 55 of the nail seat;

[0035] Nail body 6; upper end surface 61 of the nail body; concave 62 on the end surface of the nail body; tail end 63 of the nail body; hemispherical surface 64 on the nail body;

[0036] Limiting tool 7; wedging end 71; inclined surface 711; bottom surface 712; hook 72; inner side of hook 721; opening spring 73; rotating shaft 74; clamp arm 75;

[0037] In addition: traditional tool G; force during distraction and clamping F; gap X; intervertebral disc Z; DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments; it should be understood that in the description of the present invention, the directions or positional relationships indicated by the terms "left and right", "up and down", etc. are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0039] Figure 1, which are two-dimensional diagrams and effect diagrams of the present invention; it can be seen from the figures that the present invention basically shows two parts: one is the pedicle screw called "dynamic screw" which is currently popular and is formulated based on the "non-rigid fixation" theory, and belongs to the "connecting rod center type", which is characterized in that: the connecting rod 2 and the screw plug 1 are both located directly above the screw body 6; the screw body 6 together with the implanted human vertebral body can swing at a certain angle relative to the screw seat 5 and the connecting rod 2 which have been connected as a whole; the other part is a special tool 7 used as a matching tool.

[0040] During the operation, there is a step to adjust the adjacent vertebrae by expanding and clamping them, such as Figure 2 As shown in the two-dimensional diagram on the right, the usual operation is to use tool G to clamp the connecting rod and move the nail seat. The ideal state is as follows Figure 2 On the left side of the two groups of figures shown, when the nail body and the nail seat are rigidly connected in a coaxial state in the longitudinal section direction of the connecting rod, the nail body can lift the vertebral body to achieve the movement of expansion or clamping, and realize the original design intention of the dynamic nail, swinging at a positive and negative angle (±∠), thereby achieving the medical effect desired by using the dynamic nail; but due to the characteristics of the existing dynamic nail, the nail body can swing relative to the nail seat, and it is impossible to obtain a temporary external force large enough to make the two rigidly connected during expansion or clamping. Therefore, when the force F acts on the nail seat, affected by soft tissues such as the intervertebral disc Z and ligaments, the most likely operation result will be as shown in the effect diagram and the right side of the two-dimensional diagram. The nail seat is driven by the force to move the ball head of the nail body to the left, while the lower end of the nail body temporarily remains in place, that is, the coaxial relationship between the two is destroyed. When the clamping force continues to act, the angle between the nail body and the nail seat axis reaches the limit, and the lower end of the nail body can then provoke the front edge of the vertebral body (the lower end in the figure) to move to the left, producing a clamping effect. In this way, the swing angle set by the dynamic nail will be lost in whole or in part, which results in the criticized reason that "the dynamic nail can only move in the positive direction but not in the negative direction" or even "the dynamic nail cannot move", which is inconsistent with the original intention of using the dynamic nail.

[0041] In order to solve the problem of the nail body being blocked, the present invention makes a new attempt. The screw plug and the connecting rod are bypassed from both sides of the nail seat, and the connecting rod is inserted into the newly arranged slot at the lower part of the nail seat to directly control the nail body in the nail seat cavity, or the nail body under the pressure ring is controlled by moving the pressure ring up and down.

[0042] like Figure 3As shown, the dynamic pedicle screw for correction shown in the present invention has a pressure ring 3, a spring 4, and a nail body 6 assembled in the inner cavity of the nail seat 5 before surgery, and a protruding obstacle is processed in the inner cavity of the nail seat 5 to prevent the pressure ring 3 from being dislodged after assembly; (not shown in the figure); during the surgery, the nail body 6 is first implanted into the vertebral body of the patient, and then the connecting rod 2 is placed on the U-shaped opening through groove 52 of the adjacent nail seat 5, and then a screwdriver is inserted into the screwdriver jack 11 in the center of the screw plug 1, and the connecting rod 2 is preliminarily fixed to the U-shaped opening through groove 52 by using its external thread 12 and the internal thread 51 on the nail seat. At this time, each component of the dynamic pedicle screw is in a relatively movable state.

[0043] At this point in the operation, the adjacent pedicle screws need to be adjusted in position, which is the stage of "opening and clamping" or "rotation correction". Figure 4 Recombination Figure 3 The exploded view shows the improvement of the present invention over the conventional pedicle screw: first, a pair of wedge-shaped bayonet holes 54 are processed in the direction perpendicular to the U-shaped opening through groove 52 of the screw seat 5, and the wedge-shaped bayonet holes 54 are connected to the inner cavity of the screw seat 5 from the outer surface, and the horizontal position is set at a position adapted to the pressure ring 3 assembled in the inner cavity of the screw seat 5, so as to ensure that after the wedging end 71 on the limiting tool 7 enters the wedge-shaped bayonet hole 54, the bottom surface 712 of the wedging end 71 can be located above the upper end surface 31 of the pressure ring 3; then, the wedging end 71 can enter and continue to be horizontally driven by the limiting tool 7, and at the same time, it is also affected by the interaction between the inclined surface 711 and the wedge-shaped or conical bayonet hole 54, and the bottom surface 712 of the wedging end 71 will press the upper end surface 31 of the pressure ring, so that the pressure ring 3 moves downward as a whole, until the lower end surface 33 of the pressure ring presses the upper end surface 61 of the nail body, so that the nail body 6 is coaxial with the screw seat 5, that is, it is in a vertical state with the connecting rod 2.

[0044] Through such operation, the dynamic pedicle screw is switched to be similar to a uniaxial screw. Only by applying force to the screw seat 5, the screw body 6 can move along the axial direction of the connecting rod 2, and can also be rotated and adjusted around the axis without losing its original swing angle.

[0045] The nail body 5 can swing only by relying on the cooperation between the hemispherical surface 64 of the nail body and the inner spherical surface 53 of the nail seat, and the swinging angle is constrained by the diameter of the downward through hole 55 of the nail seat. By setting this diameter, the design requirement of limiting the swinging angle to ±2 to 3 degrees, or ±10 to 12 degrees can be met.

[0046] Figure 5Another embodiment of the dynamic pedicle screw of the present invention, namely, embodiment 2, is that the cooperation between the pressure ring 3 and the nail body 6 is spherical, so that the spring 4 therebetween can be eliminated; it should be particularly noted that: as can be seen from the two-dimensional diagram, the U-shaped opening through groove 52 of the nail seat supports the connecting rod 2 and maintains a gap with the upper end surface 31 of the pressure ring, so that the downward spherical surface 34 of the pressure ring also maintains a gap with the hemispherical surface 64 at the upper end of the nail body, so that the nail body 6 can swing in the inner cavity of the nail seat 5; and once the pressure ring 3 is pressed downward by the wedge-shaped or conical wedging end 71, it will constrain the hemispherical surface 64 and make the nail body 6 unable to swing; according to experiments, such a gap of only 0.5 mm can achieve the purpose.

[0047] Fig.10 The third embodiment of the present invention is a more streamlined embodiment to adapt to the "low notch" emphasized in clinical practice, that is, the pressure ring 3 and the spring 4 are eliminated, and the wedging end 71 of the limiting tool 7 is directly pressed on the hemispherical surface 64 at the upper end of the nail body. After the limiting tool 7 is withdrawn, an appropriate amount of gap X is left between the hemispherical surface 64 and the cylindrical surface of the connecting rod 2 supported by the U-shaped opening groove 52 of the nail seat, so that the hemispherical surface 64 at the upper end of the nail body and the inner spherical surface 53 of the nail seat are also in a clearance fit, so that the nail body 6 can swing at a certain angle in the inner cavity of the nail seat 5; and this swing, in addition to being constrained by the diameter of the downward through hole 55 of the nail seat, is also related to the gap X. According to experiments, such a gap X is only 0.3 mm, and the notch of the entire third embodiment can be compressed to less than 13.5 mm, which is very popular in clinical practice.

[0048] The basic working principle of the limiting tool of the present invention is Figure 6 Fully explained: Figure 6 Figures a and b in the figure are two states of the limiting tool 7 before and after the action, and the two sides of the center line of Figure c are the top views of Figures a and b respectively; combined with Figure 7 From the effect diagram, it can be known that: when the limiting tool 7 is not in effect, there is a gap X between the lower end surface 33 of the pressure ring and the upper end surface 61 of the nail body; when the operator wedges the wedging end 71 of the limiting tool 7 into the wedge-shaped bayonet 54 of the nail seat 5 and pulls the hook 72, the inner side 721 of the hook will inevitably slide close to the surface of the connecting rod 2 and rotate around the rotating shaft 74, thereby driving the wedge-shaped or conical wedging end 71 to realize its movement trajectory, that is, first move horizontally and enter the inner cavity of the nail seat 5, And it is placed above the pressure ring 3; at the same time, the inclined surface 711 on the wedging end 71 and the wedge-shaped or conical bayonet 54 of the nail seat produce a horizontal and downward movement toward the inner cavity, so that the bottom surface 712 presses against the upper end surface 31 of the pressure ring, and then compresses the nail body 6, which completes the switching between the "dynamic" and "single-axis nails" of the present invention during the operation, and solves the technical problem that the dynamic pedicle screw cannot normally realize its clinical advantages due to the "loss of initial angle" that needs to be solved urgently in clinical practice.

[0049] Figure 1 and Figure 6 b, the two sides of the center line represent the different horizontal heights of the pressing ring 3 in the two states of "dynamic" and "single-axis nail": in the "dynamic" state, the pressing ring 3 is supported by the spring 4 and moves upward, and there is a gap X between the lower end surface 33 of the pressing ring and the upper end surface 61 of the nail body; and when the pressing ring 3 is pressed down by the bottom surface 712 of the wedging end 71 of the limiting tool 7, the pressing ring 3 will move downward, and it is in the "single-axis nail" state; after testing, such a downward movement distance is shorter than Figure 5 The embodiment shown is slightly larger, approximately 0.5 to 1 mm.

[0050] When the operator determines the exact position of the opening or clamping, the screw plug 1 is locked with a screwdriver; since the screw plug 1 is located directly above the nail seat 5, and the hook 72 of the limiting tool is located on one side of the nail seat 5, there is room for the operation of the screwdriver; this also explains the Figure 8 In the second embodiment of the special tool 7 shown, the structural feature of the clamp arm 72 is that the operator holds the upper end of the clamp arm 75, and the limit clamp 71 opens with jaws, and enters the wedge-shaped clamp 54 from both sides of the nail seat 5 at the same time. The operator only needs to release his hand and open the spring 73 to drive the clamp arm 75 around the rotating shaft 74, and use the inclined surface 711 of the wedge-shaped or conical clamp 71 to complete the action of moving the pressure ring 3 downward, and then use a screwdriver to lock the screw plug in an unobstructed state to complete the clinical work.

[0051] The key improvement feature of the present invention is to set wedge-shaped bayonet 54 on both sides of the nail seat and use the wedge end 71 of the limiting tool 7, and the shape features of such bayonet and wedge end are not limited to wedge shape, but can also be conical, or can be a conical wedge end + a cylindrical connecting end. Fig. 9 What is shown are only two of them. Therefore, any modification, equivalent substitution and improvement made by using the contents of the specification and drawings of the present invention should be included in the protection scope of the present invention.

Claims

1. A dynamic pedicle screw capable of neutral pressure and a limiting tool thereof, the dynamic pedicle screw comprising a pedicle screw with a screw seat and a screw body connected in a non-rigid manner, a screw plug attached thereto and a connecting rod, the upper opening of the screw seat being provided with an internal thread matching the screw plug, the upper portion of the screw seat being symmetrically provided with a U-shaped opening through groove for receiving the connecting rod; the lower portion of the U-shaped opening through groove of the screw seat being a ball-shaped inner cavity, the lower end of the inner cavity being provided with a trumpet-shaped through hole with a small inner diameter and a large outer diameter, the nail body passing through the trumpet-shaped through hole at the lower end of the screw seat, The upper end of the nail body is in the shape of a hemispherical head that matches the spherical socket-shaped inner cavity at the lower part of the nail seat. The diameter of the ball head of the nail seat is larger than the inner diameter of the through hole at the lower end of the nail seat. The neck of the nail body is stuck in the trumpet-shaped through hole at the lower end of the nail seat. After installing the connecting rod and tightening the screw plug, the ball head of the nail body will not be stuck in the spherical socket-shaped inner cavity at the lower part of the nail seat, and the nail body can still rotate and swing at the trumpet-shaped through hole of the nail seat; the limiting tool is used to temporarily limit the rotation and swing between the dynamic pedicle screw seat and the nail body during surgical operation; it is characterized in that: The lower part of the nail seat is provided with one or a pair of through holes with a wedge-shaped longitudinal section, which penetrate the side wall of the nail seat and are larger on the outside and smaller on the inside, and the stopper tool has a wedge-shaped end, which matches the shape of the nail seat bayonet and can wedge into the inner cavity of the nail seat to squeeze the head of the nail body downward, so that the nail body cannot rotate or swing at the through hole at the lower end of the nail seat; The wedging end of the limiting tool is hingedly fixed to the base through a rotating shaft located on the side of its rear end, and the base is in the shape of a hook and can be hooked on the connecting rod; when the wedging end is wedged into the nail seat bayonet, the hook is hooked on the connecting rod and clamped, the wedging end can also obtain the maximum wedging force at the same time, so that the nail seat and the nail body are transformed into a static nail state with a rigid connection; when the hook is removed from the connecting rod, the wedging end can also easily withdraw from the nail seat bayonet, so that the nail seat and the nail body are restored to a dynamic nail state that can swing toward each other.

2. A dynamic pedicle screw capable of neutral pressure and a limiting tool thereof according to claim 1, characterized in that: The nail seat bayonet is arranged in the vertical direction of the U-shaped opening through groove, and the wedging end of the limiting tool is located above the ball head of the nail body. After the wedging end is wedged, it just locks the ball head together with the ball-socket-shaped inner cavity at the lower part of the nail seat.

3. A dynamic pedicle screw capable of neutral pressure and a limiting tool thereof according to claim 1, characterized in that A pressure ring with a spherical socket-shaped lower end surface is provided in the nail seat, and the pressure ring is arranged between the connecting rod and the ball head of the nail body. The wedging end of the limiting tool presses down the pressure ring, so that the pressure ring and the spherical socket-shaped inner cavity at the bottom of the nail seat jointly lock the ball head.

4. A dynamic pedicle screw capable of neutral pressure and a limiting tool thereof according to claim 3, characterized in that : A compression spring or elastic gasket is provided in the ball-socket-shaped inner cavity at the lower part of the nail seat, and the compression spring or elastic gasket is located below the pressure ring. The wedging end of the limiting tool presses down the pressure ring and compresses the compression spring or elastic gasket, so that the pressure ring and the ball-socket-shaped inner cavity at the lower part of the nail seat jointly lock the ball head.

5. A dynamic pedicle screw capable of neutral pressure and a limiting tool thereof according to claim 1, characterized in that There are two nail seat snap-ons, which are symmetrically distributed on the two side walls of the lower part of the nail seat. The wedging ends are hinged into a clamp shape with a handle that can be locked. They are wedged into the nail seat snap-ons from both sides, and can jointly squeeze the ball head of the nail body downward or squeeze the ball head of the nail body downward through a pressure ring. After the handle is buckled, it can generate and maintain an extrusion force sufficient to limit the dynamic nail to a static nail.

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