CN213372407U - Spring type pedicle screw capable of being flexibly fixed from rigid gradual change - Google Patents

Abstract

The utility model discloses a spring type pedicle screw which can be flexibly fixed from rigid gradual change, comprising a pedicle screw, a connecting rod and a screw plug; the screw plug is used for locking and fixing the connecting rod on the pedicle screw which is intersected with the connecting rod, and the connecting rod can be directly pressed down to be locked on the screw seat through the screw plug or pressed down to be locked on the screw seat through a hook frame sleeved outside the screw seat; the lower end of the nail seat of the pedicle nail is connected with the upper end of the nail body by a spring and is restrained into a rigid neutral position state by a stopper made of hard degradable biological materials so as to facilitate the operation of implanting, expanding or pressurizing the screw; with the gradual degradation of the degradable stopper, the fixing mode of the pedicle screw-rod system is gradually changed from an initial rigid fixing mode to a non-rigid fixing mode.

Description

Spring type pedicle screw capable of being flexibly fixed from rigid gradual change

Technical Field

The invention relates to the technical field of medical instruments, in particular to a spring type pedicle screw capable of being flexibly fixed from rigid gradual change.

Background

Currently, pedicle screw and rod fixation systems used in the fields of bone surgery and neurosurgery are mainly divided into two main categories, one is a static pedicle screw which causes a fixed segment to lose any movement, and the fixation is called rigid fixation for short; the other is a dynamic pedicle screw which can make a fixed segment do proper bending and stretching activities, and is called as a dynamic screw for short, and the fixed segment is fixed in a non-rigid way.

The rigid fixation is stronger, which is beneficial to fracture healing and interbody fusion, but the over-strong fixation can lead the fixed segment to generate stress shielding, thus causing the disuse osteoporosis of the vertebra; furthermore, the inner fixing device can generate the phenomena of fatigue fracture, looseness and other protection failures due to the fact that the inner fixing device is excessively dependent on the long-term protection of the inner fixing object; once the loose spine loses the effective support of the pedicle screw, the injury such as osteoporosis fracture and the like can be more easily caused; it is therefore often clinically necessary to intentionally surgically remove the internal fixation device after the bone has healed.

In addition, some injuries need to support the spine by using the pedicle screw rod system in the early operation stage, so that the pressure on the vertebral body and the intervertebral is reduced, the stability of the spine is enhanced along with the healing of an incision, and a fixed segment is expected to have certain flexion and extension activities, namely the fixing strength of the pedicle screw rod system is expected to be reduced, and the degeneration caused by the stress concentration of the adjacent segment is prevented.

In order to prevent adjacent segments from degeneration, non-rigid fixed dynamic nails are produced due to the fact that most of the pedicle screws are not fixed in situ, in the operation process, after all pedicle screws are implanted and the connecting rods are installed, a distractor or a clamping device is often used for distracting or clamping a screw seat of the pedicle screws to drive a screw body in rigid connection with the screw seat to pick up a vertebral body fixed by the pedicle screws, and after adjacent vertebral bodies and intervertebral spaces are opened or closed to a required position, all screw plugs are screwed down to maintain the position and maintain the spinal stability of the fixed segments; however, the dynamic nail with the nail body and the nail seat in a hinged state only acts on the nail seat due to the spreading and pressurizing tool, is influenced by soft tissue resistance of intervertebral discs, ligaments and the like, the front end of the nail body cannot synchronously move in parallel with the nail seat, but temporarily stays in the original position, so that the coaxial relation between the nail seat and the nail body is destroyed, an included angle is formed, only when the spreading or clamping force exerted by the tool continues to act, and the swinging included angle between the nail body and the axis of the nail seat reaches a design limit value, the lower end of the nail body can flip the front edge of the vertebral body to move to generate the spreading or clamping effect, so that the set swinging angle of the dynamic nail is completely lost, the buckling or straightening motion mode in the bending and stretching function is lost, the straightening or buckling amplitude in the opposite direction is doubled, namely, the fixed section can only swing by 0-2 times of the design angle (0-2 times); the two results of the over-exercise range and the under-exercise range violate the original design purpose of the dynamic nail, and have adverse effects on human bodies, so that the advantage performance of the dynamic nail cannot be embodied, and the actual application of the advanced concept of dynamic fixation is seriously influenced.

The nail body and the nail seat can not synchronously move in the same direction in real time, so that adjacent intervertebral discs are gradually expanded along with the gradual distance between the nail seats, and a forward angulation trend consistent with that between the nail bodies gradually appears, so that forward flexion fixation is caused; and the adjacent intervertebral parts are compressed along with the gradual approaching of the nail seats, and simultaneously, the trend of backward angulation consistent with the nail bodies gradually appears, so that the backward extension fixation is caused.

However, there is no dynamic nail that can temporarily limit the dynamically connected nail body and nail seat to be relatively fixed in the distraction or compression direction for operation during operation, and there is no pedicle screw-rod fixation system that can provide strong rigid fixation at the early stage of fixation and then automatically convert into non-rigid fixation with relatively weak fixation strength.

In addition, the lower the height of the pedicle screw exposed out of the bone, namely the lower the 'incisure', the less the adverse stimulation to the human body, and most of the existing pedicle screws are 'middle-positioned' type nails which are tightly connected with the screw seat and the screw body into a whole by directly extruding the connecting rod by the screw plug, so the increased incisure on the axis of the screw plug because of the superposition of the connecting rod on the axis of the screw plug can not be reduced; the side-mounted pedicle screw with the application number of 201910494053.6, namely the externally-arranged spring type pedicle screw with the screw plug and the connecting rod arranged in parallel, can greatly reduce cutting marks and thoroughly solve the problem of wire explosion, but has no screw tool interface at the upper end of the screw seat, and is difficult in nail implantation operation.

Based on the actual conditions, the spring type pedicle screw capable of being flexibly fixed from rigid gradual change is provided.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems which need to be solved urgently in clinic, the invention applies and discloses a spring type pedicle screw which can be fixed flexibly from rigidity gradual change by utilizing the characteristics of biological materials such as metal magnesium, magnesium alloy, magnesium-polylactic acid compound, zinc and the like which have certain rigidity and hardness and can be degraded and absorbed in vivo, and comprises a pedicle screw, a connecting rod and a screw plug; the connecting rod is used for being connected in series with the pedicle screws fixed on adjacent vertebrae on the same side of the spine, and the screw plugs are used for locking the connecting rod on the pedicle screws intersected with the connecting rod; the pedicle screw comprises a screw body, a screw seat and a flexible connecting part, wherein the screw body and the screw seat of the pedicle screw are connected through the flexible connecting part, the flexible connecting part is further connected with a degradable stopper for preventing the flexible connecting part from swinging mutually, and along with the gradual degradation of the degradable stopper, the fixing mode of the pedicle screw rod system is gradually changed from initial rigid fixing into a non-rigid fixing mode.

Furthermore, the flexible connecting part comprises a spring, one end of the spring is connected with the nail seat, and the other end of the spring is connected with the nail body.

Furthermore, the degradable stopper is of a threaded tubular structure with a round table-shaped outer surface and an internal thread matched with the thread shape of the outer wall of the spring in an inner cavity, and is embedded in the horn-shaped through hole at the lower end of the nail seat and sleeved on the outer edge of the spring.

In one embodiment, the nail seat is of a hollow structure, the side wall of the upper part of the nail seat is provided with a pair of U-shaped grooves, and the upper end of the inner cavity of the nail seat is provided with internal threads matched with the external threads of the plug screw; the nail seat inner chamber lower part is axial through-hole, axial through-hole upper portion be with spring upper end outside size shape assorted axial through-hole, the axial through-hole lower part be with degradable stopper round platform form appearance assorted loudspeaker form axial through-hole.

In one embodiment, the nail seat is a cylindrical structure which is thin at the top and thick at the bottom, high at the top and short at the bottom and is in transition with an arc surface, and the arc radius of the arc transition surface at the outer edge of the nail seat is consistent with the radius of the connecting rod; the upper end surface of the nail seat is also provided with a nail seat screwdriver interface which is a notch symmetrically arranged on the peripheral wall of the nail seat through the axial center; the nail seat inner chamber lower part is axial through hole, axial through hole upper portion be with the outside big small form assorted internal thread form axial through hole in spring upper end, the axial through hole lower part be with degradable stopper round platform form appearance assorted loudspeaker form axial through hole.

In one embodiment, the connecting rod fixing device further comprises a hook frame for fastening the connecting rod, wherein the hook frame comprises a lantern ring and a barb-shaped rod pressing arm which is arranged on the side edge of the lantern ring and extends outwards; the lantern ring is sleeved on the outer edge of the nail seat, and the lower edge of the press rod arm is a press rod cambered surface with the radius consistent with that of the connecting rod; after the hook frame and the nail seat are sleeved, the semi-arc surface of the pressing rod arm and the arc transition surface of the outer edge of the nail seat jointly form a tunnel for accommodating the connecting rod, so that the connecting rod is located on the outer side of the nail seat.

Further, the inner cavity of the hook frame lantern ring is matched with the outer edge of the nail seat; the lantern ring and the press rod arm are of an integrated structure; the pressing rod cambered surface is intersected with the inner cavity of the lantern ring to form a lantern ring gap.

In one embodiment, the upper end of the nail body is free of a nail head, the upper end face is a plane, and the edge of the upper end face of the nail body is also provided with an adaptive groove matched with the shape of the lower end of the spring; the upper end of the spring is in threaded connection with an axially arranged internal thread-shaped through hole at the lower end of the nail seat and is permanently and mechanically fixed, and the lower end of the spring is in adaptive connection with an adaptive groove at the upper end of the nail body and is permanently and mechanically fixed.

In one embodiment, the screw plug comprises an upper cover, a screw plug screwdriver interface is axially arranged in the center of the upper cover of the screw plug, and the lower part of the screw plug is an external thread matched with the internal thread at the upper end of the screw seat.

Furthermore, the degradable stopper is made of a degradable biological material, preferably, the degradable stopper is made of a magnesium metal/polylactic acid composite material which takes magnesium metal with higher elastic modulus and higher degradation speed as an inner core and takes polylactic acid with lower elastic modulus and lower degradation speed as a surface layer.

Advantageous effects

The spring type pedicle screw capable of being flexibly fixed from rigid gradual change can be adopted in a connecting rod side-mounted pedicle screw capable of realizing 'explosion-proof wire' and 'low notch', and can also be adopted in a connecting rod middle-mounted pedicle screw; and the stopper made of degradable hard biological material is used as a limiting device of the dynamic pedicle screw, so that the dynamic pedicle screw is convenient to implant into a body and expand or compress, strong static fixation can be realized at the initial stage of fixation, the limiting device can be gradually converted into dynamic fixation which allows the fixed segment to move moderately in the gradual degradation process, and the dynamic pedicle screw is in a neutral position state during implantation and after expansion or pressurization, so that the dynamic pedicle screw can have mobility in both forward bending and backward stretching directions after degradation of the limiting device, and the dynamic fixation effect of the dynamic pedicle screw rod system can be ensured to the maximum extent.

Drawings

FIG. 1 is a two-dimensional view of the structure and a partial outline effect diagram of the first embodiment;

FIG. 2 is a schematic diagram illustrating an exploded structure of the first embodiment;

FIG. 3 is a two-dimensional schematic of the principles of the present invention;

FIG. 4 is a two-dimensional view of the structure and a partial outline effect diagram of the second embodiment;

FIG. 5 is a schematic view showing the structural decomposition effect of the second embodiment;

wherein: aplug screw 1; a plug screwexternal thread 11; a plugscrew driver interface 12; a screwupper cover 13;

a connecting rod 2;

aspring 3;

anail seat 4;internal threads 41 at the upper end of the nail seat; a stapleholder U-shaped slot 42; a nail seat lower axial throughhole 43;

an internally threaded axial through hole 431; a flared axial through bore 432; a nail seatouter surface 44; nail seat is revolved

Has aninterface 45;

astopper 5; a stopperouter surface 51; astopper cavity 52; a stoppertop surface 53;

anail body 6; a nail body implanting end 61; an adapting groove 62 on the connecting end of the nail body;

ahook frame 7;hook frame collar 71; hook framepress bar arm 72;

an upper connecting section a; an active segment b; a lower connecting section c; swinging the center of sphere O; a vertebral body G;

gap x between vertebral body and bottom of nail seat

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In one embodiment, as shown in fig. 1, 2 and 3, thenail seat 4 is a hollow structure, the upper side wall of the nail seat is provided with a pair ofU-shaped grooves 42, and the upper opening of the inner cavity of the nail seat is provided with aninternal thread 41 matched with thescrew plug 1; the nail seat inner chamber lower part is axial throughhole 43, axial throughhole 43 upper portion be with 3 upper end outside big small shape assorted internal thread form axial through hole 431, axial throughhole 43 lower part be with 5 round platform form appearance assorted loudspeaker form axial through hole 432 of degradable stopper.

Thenail body 6 is a cylindrical or conical screw screwed into the spine, the upper end of the nail body is free of a nail head, the upper end face is a plane, and the edge of the upper end face of thenail body 6 is also provided with an adapting groove 62 matched with the shape of the lower end of thespring 3.

Thespring 3 is a cylindrical spring with enough rigidity, the upper end of thespring 3 is in threaded connection with an internal thread-shaped through hole 431 which is axially arranged at the lower end of thenail seat 4 and is permanently and mechanically fixed, and the lower end of thespring 3 is in adaptive connection with an adaptive groove 62 at the upper end of the nail body and is permanently and mechanically fixed.

Preferably, thedegradable stopper 5 is a threaded tubular structure with a circular truncated cone-shapedouter surface 51 and an internal thread in aninner cavity 52, wherein the internal thread is matched with the thread shape of the outer wall of the spring, and the threaded tubular structure is embedded in the trumpet-shaped through hole 432 at the lower end of the nail seat and sleeved on the outer edge of thespring 3.

During assembly, thestopper 5 is firstly embedded in the trumpet-shaped axial through hole 432 of thenail seat 4, and thetop surface 53 of the stopper is tightly abutted against the bottom end of the inner cavity 432 of the nail seat; then, one end of thespring 3 is fixedly connected with the upper end of thenail body 6, and the other end of thespring 3 is screwed into and penetrates through thewhole stopper 5 along the internal thread of the stopperinner cavity 52 to reach the internal thread-shaped axial through hole 431 of thenail seat 4, so that the two are tightly welded after being inosculated to be fixedly connected.

During clinical operation, an operator can drive thewhole nail seat 4, thespring 3, thelimiter 5 and thenail body 6 which are connected into a whole by using a matched screwdriver and rotating theU-shaped groove 42 of the nail seat, and the nail body is implanted into the vertebral body of a patient by using the screw thread on the implantation end 61 of the nail body; since it is not necessary to keep an additional position for the active region of the spring, the bottom of thenail holder 4 can be closely attached to the surface of the vertebra G, as shown in the two-dimensional diagrams of FIGS. 1 and 4, and the gap x is less than about 1mm, which is much less incised than the conventional distance of 4-8 mm. Fig. 3 is an enlarged view of a portion M of fig. 1, from which fig. 3 the working principle of the present application can be clearly described; areas a and c shown in fig. 3 are connecting sections at two ends of thespring 3, which are fixedly connected with the internal thread-shaped axial through hole 431 of thenail seat 4 and the adapting groove 62 of thenail body 6 respectively; it was found in development that such a fixed connection, approximately 3/4 turns of the spring, allows for a compromise between notch and connection fixation.

The left side of fig. 3 shows the initial state of the pedicle screw in the invention, because thestopper 5 is a rigid body, wraps and restrains thespring 3, so that the pedicle screw cannot swing, and the whole pedicle screw is in a fixed screw state, thereby facilitating the operation of implantation and distraction or pressurization and avoiding the possibility that the swing angle set by the dynamic screw is partially or even completely lost.

After a controllable period of time, thestopper 5 gradually softens until disappearing, the movable section b gradually empties, and thespring 3 has a certain movable space, so that when the spine G implanted at the nail body implanting end 61 at the middle end of thespring 3 is subjected to external force such as anteflexion and extension of a human body, a swinging angle L can be formed around a swinging spherical center O point of the spine G, namely as shown by the movable section b shown at the right side of fig. 3, thereby solving the technical problem of 'firstly rigidly fixing and then gradually switching into dynamic fixing' required by clinic.

As can also be seen from the two-dimensional diagram on the right side of fig. 3, it is possible to control the swing angle of the pedicle screw by setting the volume of thestopper 5, i.e., the space of the trumpet-shaped axial through hole 432 of thescrew seat 4, and the diameter of the lower end of thestopper 5 is 1mm larger than the outer diameter of thespring 3, and the swing angle thereof can reach plus or minus 10 degrees; if the spring is in a 'dense spring' form (namely, the wire diameter is equal to the wire distance), the required swinging couple is large; if the cable is in a 'sparse spring' form (namely the wire diameter is smaller than the wire distance), the cable can have a certain impact resistance; in addition, the technical requirements of continuous and deep clinical exploration can be met by adopting technical measures of degradable materials with different wire diameters and different components and the like.

In the second embodiment, as shown in fig. 3, 4 and 5, the invention is composed of a pedicle screw formed by combining a screw seat and a screw body, an attached hook frame, a connecting rod, a screw plug and a degradable stopper; the lower end of thenail seat 4 is connected with the upper end of thenail body 6 through thecylindrical spring 3, thenail seat 4 is shaped like a hollow round nut, the appearance of the nail seat is cylindrical with a thin upper part and a thick lower part, a high upper part and a low lower part, and the nail seat is in a circular arc transition shape, the circular arc transition shape is also a nail seat holding rod arc surface, and the radian radius of the circular arc transition shape is consistent with that of theconnecting rod 2; an opening at the upper part of the inner cavity of the nail seat is provided with aninternal thread 41 matched with thescrew plug 1, the lower part of the inner cavity of the nail seat is provided with an axial throughhole 43, the upper part of the axial throughhole 43 is provided with an internal thread-shaped axial through hole 431 matched with the external shape and size of the upper end of thespring 3, and the lower part of the axial throughhole 43 is provided with a horn-shaped axial through hole 432 matched with the circular truncated cone-shaped appearance of thedegradable stopper 5; the upper end face of thenail seat 4 is provided with a nail seatscrewing tool interface 45, and the nail seatscrewing tool interface 45 is a notch which is formed by symmetrically arranging the peripheral wall of thenail seat 4 through the axis, and preferably two pairs of crossed notches.

Thenail body 6 is a cylindrical or conical screw screwed into the spine, the upper end of the nail body is free of a nail head, the upper end face is a plane, and the edge of the upper end face of thenail body 6 is also provided with an adapting groove 62 matched with the shape of the lower end of thespring 3. Thespring 3 is a cylindrical spring with enough rigidity, the upper end of thespring 3 is in threaded connection with an internal thread-shaped through hole 431 which is axially arranged at the lower end of thenail seat 4 and is permanently and mechanically fixed, and the lower end of thespring 3 is in adaptive connection with an adaptive groove 62 at the upper end of the nail body and is permanently and mechanically fixed.

Preferably, thedegradable stopper 5 is a threaded tubular structure with a circular truncated cone-shapedouter surface 51 and an internal thread in aninner cavity 52, wherein the internal thread is matched with the thread shape of the outer wall of the spring, and the threaded tubular structure is embedded in the trumpet-shaped through hole 432 at the lower end of the nail seat and sleeved on the outer edge of thespring 3.

Thehook frame 7 is provided with alantern ring 71 sleeved on the outer edge of thenail seat 4, and the inner cavity of the lantern ring is matched with the outer edge of thenail seat 4; one side edge of thelantern ring 71 is provided with a barb-shapedpress rod arm 72 which extends outwards, thelantern ring 71 and thepress rod arm 72 are of an integrated structure, the lower edge of thepress rod arm 72 is a press rod arm formed by an approximately semicircular press rod cambered surface with the same radius as that of the connectingrod 2, and preferably, the press rod cambered surface is intersected with the inner cavity of the lantern ring to form a lantern ring notch; after thehook frame 7 is sleeved with thenail seat 4, the small semicircular arc surface of the rod pressing arm and the rod holding arc surface of thenail seat 4 jointly form a tunnel which just holds the connectingrod 2, the connectingrod 2 is placed into the tunnel at the moment, thescrew plug 1 is screwed into theinternal thread 41 at the upper end of thenail seat 4, the connectingrod 2 can be limited to be separated, thescrew plug 1 is screwed, and the connectingrod 2 can be forced to fasten thenail seat 4 through the lantern ring notch while the connectingrod 2 is fastened.

The whole connectingrod 2 except the two ends is cylindrical, and can be straight or bent to form a radian. Thescrew plug 1 is provided with anupper cover 13, the center of the upper cover of the screw plug is axially provided with ascrewdriver connector 12, and the lower part of thescrew plug 1 is provided with anexternal thread 11 matched with theinternal thread 41 at the upper end of the screw seat.

Thedegradable stopper 5 is preferably made of a magnesium metal/polylactic acid composite material which takes magnesium metal with higher elastic modulus and higher degradation speed as an inner core and takes polylactic acid with lower elastic modulus and lower degradation speed as a surface layer.

As can be seen from fig. 3, the pedicle screw of the invention is formed by connecting and permanently fixing the upper end and the lower end of thespring 3 with thescrew seat 4 and thescrew body 6 respectively, and the axes of the three parts are superposed, and thescrew body 6 and thescrew seat 4 can swing in all directions by taking thespring 3 as a turning point; when thedegradable limiter 5 is screwed into the lower part of thespring 3 connected with thenail body 6, and the upper end of thespring 3 is screwed with the internal thread-shaped through hole 431 at the lower end of the nail seat and is permanently fixed, the outer surface of thelimiter 5 is completely matched with the shape of the trumpet-shaped through hole 432 at the lower end of the nail seat, and the inner cavity is completely matched with thespring 3, so that thenail body 6 and thenail seat 4 are constrained in a rigid coaxial state, namely a neutral position state, and the nail planting operation is convenient; during operation, after all the pedicle screws are implanted into the spine, the connectingrod 2 is arranged on one side of thescrew seat 4, thehook frame 7 is sleeved into theouter surface 44 of the screw seat, and theexternal threads 11 at the lower end of thescrew plug 1 are screwed into theinternal threads 41 of the screw seat, the connectingrod 2 is hooked and restrained on thescrew seat 4 by the rod pressing arm, and the spine can be easily expanded or pressurized by the pedicle screws which are connected in the rigid neutral position, and the angulation of a fixed segment caused by the angulation of thescrew body 6 and thescrew seat 4 under stress can be avoided; after the expansion and the pressurization are completed, when thescrew plug 1 is screwed down, the pressing rod arm of thehook frame 7 and the screw seat holding rod cambered surface lock the connectingrod 2 together through the downward pressure of the screw plugupper cover 13.

The shape of thedriver interface 45 at the upper end of the saddle is clearly shown in fig. 5, and the pedicle screws can be screwed into the spine by means of thesaddle driver interface 45, which is an important optimization improvement of the patent application No. 201910494053.6.

The two embodiments shown in the present application, i.e. the central connecting rod in fig. 1 and 2, are different from the side connecting rod in fig. 4 and 5 in that: in the former, thescrew plug 1 is screwed to tightly press the connectingrod 2 on theU-shaped groove 42 of the nail seat for fixing; in the latter case, thescrew plug 1 is locked, and thehook frame 7 sleeved on theouter surface 44 of thenail seat 4 is pressed by theupper cover 13, so that the hook frame pressingrod arm 72 and the arc-shaped surface of theouter surface 44 of the nail seat cooperate to fix the connectingrod 2.

And both have in common: the axial throughhole 43 at the lower part of the nail seat inner cavity is split into two parts, namely an internal thread-shaped axial through hole 431 and a horn-shaped axial through hole 432, which correspond to the figure 3 and are a section and a section b; the shape of thelimiter 5 can be a polygonal column shape beneficial to embedding or a revolution body beneficial to processing, and the limiter is preferably designed to be a round table shape in the development process; the inner cavity of the stopper is provided with an internal thread matched with the shape of the spring, and the internal thread on theinner cavity 52 of the stopper must be a continuous internal thread processed together with the internal thread of the internal thread-shaped axial through hole 431 of thenail seat 4. The stopper made of the degradable biological material is made of a magnesium metal/polylactic acid composite material, wherein the magnesium metal with higher elastic modulus and higher degradation speed is used as an inner core, and the polylactic acid with lower elastic modulus and lower degradation speed is used as a surface layer.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. A spring type pedicle screw capable of changing rigidity into flexible fixation is characterized by comprising a pedicle screw, a connecting rod and a screw plug; the connecting rod is used for being connected in series with the pedicle screws fixed on adjacent vertebrae on the same side of the spine, and the screw plugs are used for locking the connecting rod on the pedicle screws intersected with the connecting rod; the pedicle screw comprises a screw body, a screw seat and a flexible connecting part, wherein the screw body and the screw seat of the pedicle screw are connected through the flexible connecting part, the flexible connecting part is also connected with a degradable stopper for preventing the flexible connecting part from swinging mutually, and along with the gradual degradation of the degradable stopper, the fixing mode of the pedicle screw rod system is gradually changed from an initial rigid fixing mode to a non-rigid fixing mode.

2. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 1, wherein the flexible connecting part comprises a spring, one end of the spring is connected with the screw seat, and the other end of the spring is connected with the screw body.

3. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 2, wherein the degradable stopper is a thread tubular structure with a round table-shaped outer surface and an inner cavity provided with an internal thread matched with the thread shape of the outer wall of the spring, is embedded in the trumpet-shaped through hole at the lower end of the screw seat and is sleeved on the outer surface of the outer edge of the spring.

4. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 1 or 2, wherein the screw base is of a hollow structure, the side wall of the upper part of the screw base is provided with a pair of U-shaped grooves, and the upper end of the inner cavity of the screw base is provided with an internal thread matched with the external thread on the screw plug;

the nail seat inner chamber lower part is axial through-hole, axial through-hole upper portion be with spring upper end outside size shape assorted axial through-hole, the axial through-hole lower part be with degradable stopper round platform form appearance assorted loudspeaker form axial through-hole.

5. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 1 or 2, wherein the screw seat is of a cylindrical structure with a thin upper part and a thick lower part, a high upper part and a low lower part and is in transition by an arc surface, and the arc radius of the arc transition surface at the outer edge of the screw seat is consistent with the radius of the connecting rod;

the upper end surface of the nail seat is also provided with a nail seat screwdriver interface which is a notch symmetrically arranged on the peripheral wall of the nail seat through the axial center;

the nail seat inner chamber lower part is axial through hole, axial through hole upper portion be with the outside big small form assorted internal thread form axial through hole in spring upper end, the axial through hole lower part be with degradable stopper round platform form appearance assorted loudspeaker form axial through hole.

6. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 5, further comprising a hook frame for fastening the connecting rod, wherein the hook frame comprises a lantern ring and a barb-shaped rod pressing arm arranged on the side edge of the lantern ring and extending outwards; the lantern ring is sleeved on the outer edge of the nail seat, and the lower edge of the press rod arm is a press rod cambered surface with the radius consistent with that of the connecting rod;

after the hook frame and the nail seat are sleeved, the semi-arc surface of the pressing rod arm and the arc transition surface of the outer edge of the nail seat jointly form a tunnel for accommodating the connecting rod, so that the connecting rod is located on the outer side of the nail seat.

7. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 6, wherein the inner cavity of the lantern ring is matched with the outer edge of the screw seat; the lantern ring and the press rod arm are of an integrated structure; the pressing rod cambered surface is intersected with the inner cavity of the lantern ring to form a lantern ring gap.

8. The spring type pedicle screw capable of being flexibly fixed through gradual change of rigidity according to claim 1 or 3, wherein the degradable stopper is made of a degradable biological material, magnesium metal with higher elastic modulus and higher degradation speed is used as an inner core, and polylactic acid with lower elastic modulus and lower degradation speed is used as a magnesium metal/polylactic acid composite material of a surface layer.

9. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 2, wherein the upper end of the screw body is free of a screw head, the upper end face is a plane, and the edge of the upper end face of the screw body is further provided with an adapting groove matched with the shape of the lower end of the spring; the upper end of the spring is in threaded connection with an axially arranged internal thread-shaped through hole at the lower end of the nail seat and is permanently and mechanically fixed, and the lower end of the spring is in adaptive connection with an adaptive groove at the upper end of the nail body and is permanently and mechanically fixed.

10. The spring type pedicle screw capable of changing rigidity into flexible fixation according to claim 2, wherein the screw plug comprises an upper cover, a screw plug screwdriver interface is axially arranged in the center of the upper cover of the screw plug, and the lower part of the screw plug is provided with external threads matched with the internal threads at the upper end of the screw seat.

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