CN107007341B - Cobalt chromium molybdenum chest waist way of escape nail stick system - Google Patents

Cobalt chromium molybdenum chest waist way of escape nail stick system Download PDF

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Publication number
CN107007341B
CN107007341B CN201710361138.8A CN201710361138A CN107007341B CN 107007341 B CN107007341 B CN 107007341B CN 201710361138 A CN201710361138 A CN 201710361138A CN 107007341 B CN107007341 B CN 107007341B
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screw
rod
nail
orthopedic
cap
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CN107007341A (en
Inventor
许小波
宁宇航
沈嘉桢
蔡宝春
周凯旋
韩雪梅
张小曼
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Zhejiang Dekang Medical Instrument Ltd Co
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Zhejiang Dekang Medical Instrument Ltd Co
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7002Longitudinal elements, e.g. rods
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7032Screws or hooks with U-shaped head or back through which longitudinal rods pass
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61LMETHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/02Inorganic materials
    • A61L31/022Metals or alloys
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61LMETHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials

Abstract

The patent discloses a cobalt chromium molybdenum chest waist way of escape nail stick system, cobalt chromium molybdenum chest waist way of escape nail stick system includes: pedicle screws, orthopedic rods and plugs; different parts are manufactured by adopting a cobalt-chromium-molybdenum material, a titanium alloy material and a pure titanium material, so that the sizes of the parts in the system are reduced under the condition of ensuring the required stress intensity of the system, and the harm to a human body is reduced. Meanwhile, the combination of the system and the vertebra is more stable through the matching structure design of the specific structure, and the using effect is improved.

Description

Cobalt chromium molybdenum chest waist way of escape nail stick system
Technical Field
This patent belongs to medical instrument technical field, particularly relates to a cobalt chromium molybdenum chest waist way of escape nail stick system.
Background
The most common solution for spinal diseases such as thoracolumbar vertebra and the like is spinal internal fixation, and the development in the spinal thoracolumbar internal fixation mode is a common mode in the posterior spinal internal fixation so far.
Spinal posterior internal fixation is usually realized through implanting a nail stick system, and chest waist posterior nail stick system is through fixing one set of system on thoracic vertebra or lumbar vertebrae, and this system is implanted probably can make the implanted segment mobility excessively restrict behind the chest lumbar vertebrae to lead to adjacent segment to degenerate and implant the unreliable or even failure of bone fusion, still probably lead to the system to become invalid because internal stress concentrates too greatly simultaneously, appear phenomenons such as becoming flexible, disconnected nail. The thoracolumbar posterior nail rod system in the prior art is mainly made of titanium alloy and stainless steel, mainly comprises a titanium alloy screw and a titanium alloy orthopedic rod, is based on the consideration of stress factors and combined with the strength problem of the titanium alloy, and the pedicle nails and the orthopedic rods on the market at present are relatively large in size and thick in diameter, so that the integral rigidity of the whole spinal internal fixation system can be ensured, but adverse factors such as too high incisional marks, too interference on the growth of tissues in a body and the like are brought.
Accordingly, there is a need in the art for a nail and rod system that can have greater strength while having a smaller volume.
Disclosure of Invention
This patent is just proposed based on the above-mentioned demand of prior art, and the technical problem that this patent will be solved provides a cobalt chromium molybdenum chest waist way of escape nail stick system, and it has less volume to can improve the intensity of entire system and with the fixed effect of backbone.
In order to solve the above problem, the technical scheme provided by the patent comprises:
a cobalt chromium molybdenum thoracolumbar posterior nail rod system, comprising: pedicle screws, orthopedic rods and plugs; the pedicle screws are used for fixing on the spine, thereby anchoring the whole screw-rod system on the spine; the universal screw and the fixing screw are integrally designed, and the whole universal screw and the fixing screw cannot be obviously deformed and are used for being fixed on corresponding positions of the spine; the universal screw is characterized in that: the nail head, the retainer ring and the nail body; the screw cap is positioned at the top of the whole universal screw and is cylindrical, a first groove is formed in the top of the screw cap, and the first groove penetrates through the diameter direction of the whole screw cap; the first groove is used for accommodating a screw plug, and the wall of the first groove is provided with threads which are matched with the threads arranged on the screw plug, so that the screw plug is allowed to be operably fixed with the screw cap in a thread matching way; the bottom of the nail cap is provided with a first through hole, one end of the first through hole is communicated with the bottom wall of the first groove, the other end of the first through hole penetrates through the bottom of the nail cap, the first through hole is used for accommodating a nail body, and the top end of the nail body comprises a ball head which is accommodated in the first through hole; a check ring is further arranged between the ball head and the first through hole, the check ring is positioned at the top of the ball head and between the top end of the first opening and the ball head, and the position of the ball head in the first through hole is limited from the top of the ball head; the collar is arranged between the bottom of the first through hole and the bottom of the ball head and used for limiting the position of the ball head relative to the nail cap at the lower part of the ball head; the screw plug is in screwing fit with the screw cap through threads, the orthopedic rod is arranged in a first groove formed in the screw cap, the bottom of the screw plug is in contact with and pressed against the upper half surface of the orthopedic rod along with the gradual screwing of the screw plug, and the lower half surface of the orthopedic rod is in contact with and pressed against the check ring, so that the orthopedic rod is completely locked and locked by the screw plug and the check ring; the screw plug and the screw body are made of titanium alloy, and the hardness is 260HV 10; the orthopedic rod, the nail cap and the clamping ring are made of cobalt-chromium-molybdenum alloy, and the hardness is 40 HRC; the material of the retainer ring is pure titanium, and the hardness is 150HV 10; the cobalt-chromium-molybdenum chest-waist posterior nail rod system is formed into a soft-hard combined system after soft-hard combination of the materials; the nail body comprises a threaded column, the threaded column and the ball head are fixedly arranged, the threaded column and the ball head are integrally formed, the threaded column is also made of titanium alloy, threads are arranged on the threaded column, threads with a first density are arranged on the periphery of the lower portion of the threaded column, threads with a second density are arranged on the periphery of the upper portion of the threaded column, the threads with the second density are larger than the threads with the first density, the length of the first threads corresponds to the cortical layer of the vertebra, and the length of the second threads corresponds to the cortical layer of the vertebra; the bottom end face of the screw plug is provided with at least one protrusion structure protruding downwards, when the screw plug is gradually screwed into the screw cap, the protrusion structure is initially contacted with the orthopedic rod, and the protrusion structure and the upper half face of the orthopedic rod are extruded to generate certain elastic deformation so as to perform a pre-compression function on the orthopedic rod; in the pre-compression state, the orthopedic rod is not locked, so that the angle of the orthopedic rod can be axially adjusted to meet the surgical requirements; and under the condition that the orthopedic rod and the screw cap need to be completely locked, the screw plug is screwed downwards continuously, and when the torque applied to the screw plug reaches the preset torque, the compression is finished, so that the whole compression process of the orthopedic rod is finished.
Preferably, in the locked state, the screw plug and the rod are locked, and the convex structure surface of the screw plug and the upper half surface of the orthopedic rod generate convex and concave coupling plastic deformation, and the deformation can generate a 'plough effect' (after the convex surface of the material surface generates the concave relative to the surface, the coupling contact surface generates plastic flow phenomenon due to extrusion in sliding) when the orthopedic rod receives external force to generate a twisting or axial sliding trend relative to the screw plug), so that the resistance to twisting or sliding is increased, the locking is facilitated, and the connection performance with the orthopedic rod is further improved.
Preferably, the orthopedic rod comprises a straight rod, the straight rod is in a substantially linear shape as a whole, one end of the straight rod is provided with a hexagonal shape, that is, six connected planes are arranged on the outer peripheral surface of one end of the straight rod, an annular gap is arranged in the middle of the hexagonal shape of the end, and the depth of the gap is arranged along the circumferential direction of the orthopedic rod so as to match with a spring steel ball of a surgical instrument to fix the orthopedic rod and the surgical instrument.
This patent is through adopting cobalt chromium molybdenum material, titanium alloy material and pure titanium material to make different parts, has realized having reduced the overall dimension of part in the system under the condition of the required stress intensity of assurance system, can effectively reduce the wound size in the art to a minimal access surgery has reduced the risk in the art, more does benefit to patient's postoperative simultaneously and resumes. Through the matching structure design of the specific structure, the combination of the system and the spine is more stable, and the use effect is improved.
Drawings
FIG. 1 is a schematic view of a cobalt chromium molybdenum thoracolumbar posterior nail and rod system in accordance with an embodiment of the present invention in combination with a spine;
FIG. 2 is a schematic view of the overall structure of a cobalt-chromium-molybdenum thoracolumbar posterior nail rod system according to an embodiment of the present invention;
FIG. 3 is a block diagram of a universal screw according to an embodiment of the present invention;
FIG. 4 is a schematic view of the combination of a screw with a vertebra according to an embodiment of the present invention;
FIG. 5 is a schematic view of the vertebral Cobb angle in an embodiment of the present patent;
FIG. 6 is a schematic view of the bending angle of a physiological bending bar according to an embodiment of the present invention;
FIG. 7 is a schematic view of a physiological bending bar according to an embodiment of the present invention;
FIG. 8 is a schematic structural view of a straight rod according to an embodiment of the present invention;
FIG. 9 is a schematic view of a straight rod in combination with a surgical tool according to an embodiment of the present invention;
FIG. 10 is a schematic structural diagram of a plug screw according to an embodiment of the present invention;
FIG. 11 is a schematic view of the screw plug fracture surface according to the embodiment of the present invention;
FIG. 12 is a comparison of a plug plum blossom groove and a conventional plum blossom groove in the embodiment of the present patent;
FIG. 13 is a comparison of a plug plum blossom groove and a conventional plum blossom groove in an embodiment of the present invention;
FIG. 14 is a comparison of the threads of the end of the plunger of this embodiment of the present patent with the threads of a conventional plunger.
FIG. 15 is a cross-sectional profile view of a lower portion of a plug according to an embodiment of the present invention after plastic deformation by a locking extrusion with an upper portion of an orthopedic rod;
FIG. 16 is a graph comparing axial and twist lock capability indices for the three versions of the graph xxx in this patent embodiment;
FIG. 17 is a graph comparing the pull-off resistance of the nut and the shear resistance of the thread of the nut in case 1 and case 3 according to the embodiments of the present invention.
Fig. 18 is a schematic view of the combination of a traceable flag with a nail and rod system according to an embodiment of the present patent.
Detailed Description
The following detailed description of the embodiments of the present patent refers to the accompanying drawings and is only for the purpose of illustrating preferred embodiments of the patent and is not to be construed as limiting the scope of the patent.
As shown in fig. 1, the present embodiment provides a cobalt-chromium-molybdenum thoracolumbar posterior screw-rod system, which comprises a pedicle screw 1, an orthopedic rod 2 and a plug screw 3.
The pedicle screw 1 is used for fixation to the spine, thereby anchoring the entire rod-and-nail system to the spine for fixation and support.
In the present embodiment, the pedicle screw 1 includes two types, one is a universal screw 11 and the other is a fixing screw 12, and the fixing screw 11 is designed as an integral body, and the whole body cannot be significantly deformed and is used for being fixed on the corresponding position of the spine. The universal screw 12 can also be fixed to the spine but part of its components, such as the nut, can rotate relative to the spine to provide a corresponding follow-up function when the spine moves, the arrows in fig. 1 showing the direction of the main stresses in the rod and nail system.
In the present embodiment, the universal screw has a structure as shown in fig. 2 and 3, and in the present embodiment, the universal screw 12 includes: a nail cap 121, a retainer ring 122, a clamping ring 123 and a nail body 124. The nut 121 is located at the top of the whole universal screw, the whole shape of the nut is preferably cylindrical, and a first groove 125 is formed at the top of the nut and arranged in the diameter direction of the whole nut, so that the upper part of the nut has a notch. The first groove 125 is used for accommodating the screw plug 3, and the wall of the first groove is provided with screw threads which are matched with the screw threads arranged on the screw plug 3, so that the screw plug is allowed to be operably fixed with the screw cap in a screw thread matching manner.
First through-hole has been seted up to the bottom of nail cap 121, the one end of first through-hole with the diapire of first groove 125 communicates with each other, the other end of first through-hole will the bottom of nail cap link up, first through-hole is used for holding the nail body, the nail body adopts titanium alloy to make, the top of the nail body includes a bulb the bulb holds in the first through-hole, like this the nail body just can rely on the bulb with cooperation between the nail cap can be to a plurality of directions rotation, just so provides comparatively abundant universal screw's rotation mode. As shown in fig. 3, a retainer ring 122 is further disposed between the ball head and the first through hole, the retainer ring is made of pure titanium, and is located at the top of the ball head, between the top end of the first opening and the ball head, and the position of the ball head in the first through hole is defined from the top of the ball head; the clamping ring 123 is located between the bottom of the first through hole and the bottom of the ball head, and is made of cobalt-chromium-molybdenum alloy and used for limiting the position of the ball head relative to the nail cap at the lower part of the ball head.
In the present embodiment, the material of the screw plug 3 and the nail body 124 is titanium alloy, and the hardness is 260HV 10; the orthopedic rod 2, the nail cap 121 and the clamping ring 123 are made of cobalt-chromium-molybdenum alloy, and the hardness is 40 HRC; the material of the check ring 123 is pure titanium, and the hardness is 150HV 10.
In the process of installing and matching the nail-bar system as shown in fig. 1-2, the screw plug 3, the orthopedic bar 2, the retainer ring 123 and the nail cap 121 (see fig. 2 in detail) are several components which are in contact fit, that is, the screw plug 3 is in screwing fit with the nail cap 121 through threads, the orthopedic bar 2 is placed in a first through groove 125 formed in the nail cap, as the screw plug 3 is screwed in gradually, the bottom of the screw plug is in contact with and pressed against the upper half surface of the orthopedic bar, the lower half surface of the orthopedic bar is in contact with and pressed against the retainer ring, and finally, the screw plug and the retainer ring are realized to lock the orthopedic bar completely. Through test comparison (table 1), on the premise of the same structural design and the same locking torque applied to the screw plug, the axial locking force of the orthopedic rod is the largest in the axial locking resistance of the material combination mode adopted in the test scheme 3.
Preferably, the contour of the convex structure of the screw plug is designed into a spherical cambered surface with multi-section arc transition, so that the contact stress with the orthopedic rod is increased, and the locking capability of the screw plug on the orthopedic rod is enhanced. In fig. 1-2, a tiny spherical convex structure is added at the bottom of the screw plug 3, when the tiny convex structure is in pressing contact with the upper half part of the orthopedic rod, stress concentration is caused on the contact area of the two, so that the two contact areas generate plastic deformation, the spherical convex structure of the screw plug is pressed by the cylindrical cambered surface of the orthopedic rod to generate plastic flow, an inverted saddle-shaped (as shown in fig. 15 and an enlarged view) structure is formed, and the cambered surface clamps the orthopedic rod; the orthopedic rod is extruded by the spherical bulge, the surface of the orthopedic rod is subjected to plastic deformation to form a crater structure (shown in figure 15 and an enlarged view), and the crater structure is tightly meshed with the lower surface of the deformed screw plug, so that the resistance of the orthopedic rod when the orthopedic rod slides under the external rotation torque or the axial thrust is increased, and the connection performance of the orthopedic rod and the screw plug is also enhanced.
Preferably, after the spherical bulge at the bottom of the screw plug 3 and the upper half part of the orthopedic rod are extruded and deformed due to locking, the spherical bulge generates plastic flow, the spherical bulge is concave inwards to form an inverted saddle surface, and is meshed with the deformed upper half part of the orthopedic rod, so that the meshing can generate a blocking effect on the rotation of the screw plug, and the blocking effect is similar to the frictional resistance between threads of the screw plug, and the back-rotation looseness of the screw plug can be effectively prevented. The fatigue resistance of the connecting part of the screw plug and the orthopedic rod is enhanced.
The above-mentioned combination locking manner of different materials is the best to use the soft and hard combined system formed by the combination of materials in this embodiment. Because, in spinal orthopedics, the orthopedic rod 2 is a bridge for bearing and transferring spinal load, the high-rigidity orthopedic rod is helpful for maintaining and realizing orthopedic effect, and the high-rigidity material can be properly reduced in diameter (compared with titanium alloy material), cobalt chromium molybdenum is selected as the material; similarly, in order to reduce the volume of the nail head as much as possible and keep the rigidity of the nail head equivalent to that of the nail head made of titanium alloy, the material is selected from cobalt, chromium and molybdenum; furthermore, the screw plug is screwed and matched with the screw cap through threads, if the screw plug is made of pure titanium, the threads are easy to generate elastic and plastic deformation compared with titanium alloy materials under the same locking torque, so that the phenomenon of looseness or slippage between the orthopedic rod and the pedicle screw is caused, and titanium alloy is selected as the material of the screw plug; the retainer ring is used as a transition block for transmitting the locking force between the nail cap and the rod, and has no other additional functional requirements, so that pure titanium is selected as the material of the retainer ring. Meanwhile, in the process of matching the hard material and the soft material, because the hard material has smaller relative deformation and the soft material has larger deformation, the friction force or locking force between the mutually contacted parts can be increased during soft-hard matching, compared with the design of a pure titanium alloy component or the design of a pure cobalt-chromium-molybdenum material, the volume of the part is reduced by adopting a cobalt-chromium-molybdenum material with higher hardness for the part bearing stress in the specific embodiment under the condition of keeping the requirement of strength, and the locking force (comprising axial locking force and torsional locking force, and the test method refers to ASTM F1798) can be increased by adopting a relatively soft material for the part without additional functional requirement, so that the performance of the whole nail rod system is improved.
In conclusion, the locking effect of the combination mode of cobalt chromium molybdenum, titanium alloy and pure titanium is superior to that of the pure cobalt chromium molybdenum material or the pure titanium alloy material. Therefore, in the patent, the screw cap and the orthopedic rod are made of cobalt-chromium-molybdenum materials, the screw plug is made of titanium alloy materials, and the retainer ring is made of pure titanium materials, so that the screw cap and the orthopedic rod have prominent substantive features and remarkable progress.
TABLE 1 comparison of index data of comprehensive locking ability in the presence of various components of the same structure and different materials
Wherein, the index of the comprehensive locking capacity is SQRT (axial locking capacity index) 2+ twist lock capability index 2). Wherein: the axial locking capacity index is axial locking force/full titanium alloy material axial locking force; the twist locking ability index is twist locking force/twist locking force of the all titanium alloy material.
Preferably, the unique material soft and hard matching locking manner of the above scheme 3 not only improves the connection performance of the plug screw and the rod, but also improves the resistance of the tail of the nail 124 pulling out or slipping out of the nail cap 125, hereinafter referred to as the nail cap pull-out force, which is evaluated by the nail cap pull-out resistance index. And the ability of the nut threads to resist shear failure. Hereinafter, the shear resistance index is used for evaluation.
Wherein, the nail cap pull-off resistance index is the nail cap pull-off force test value/the nail cap pull-off force test value of the all-titanium alloy material. The shear resistance index is the critical value of the shear failure of the screw cap thread/the critical value of the shear failure of the screw cap thread made of the all-titanium alloy material.
The results of the tests of scheme 3 were compared with those of scheme 1 and are shown in FIGS. 16 and 17.
As shown in fig. 3, the nail body further includes a threaded column fixedly disposed with the ball head, preferably, the threaded column is integrally formed with the ball body, the threaded column is also made of titanium alloy, and a bottom end of the threaded column preferably includes a tip end through which implantation into a vertebra can be facilitated. In this embodiment, the threaded post has a double-thread configuration. Namely, the periphery of the lower part of the threaded column is provided with threads with a first density, the periphery of the upper part of the threaded column is provided with threads with a second density, and the threads with the second density are larger than the threads with the first density. Preferably, the second density, i.e. the number of threads per unit length, is twice the first density. The double-thread design can increase the bone volume on the one hand and facilitate the screwing in of the screw on the other hand.
As shown in fig. 4, the design of the combined screw thread is specially designed by considering the existence of two kinds of bone layers in the pedicle of the human body, wherein in the cortical bone layer 4, the screw and the bone take friction as a main fixing form, and in the cancellous bone layer 5, the screw and the bone take shearing as a main fixing form.
In the cortical bone layer, the threads are designed into small-pitch double-thread threads, so that the contact area between the threads and the cortical bone is increased, namely the friction force between the screw and a bone is increased, and the holding force of the screw is increased; in the cancellous bone layer, the thread is designed as a large-pitch single-thread, a larger bone accommodating space is formed between two teeth of the thread, namely, the bone capacity of cancellous bone between the teeth of the thread is increased, so that the part has larger shear resistance, and the holding force of the screw is increased.
In the present embodiment, the fixing screw also includes a nut and a nut body, and the nut body are integrally formed or fixedly connected. The screw cap is provided with a groove-shaped structure which is the same as the first groove of the universal screw, and the screw body can adopt a double-thread structure which is the same as the universal screw. For reasons of space, this embodiment will not be described in detail.
As shown in fig. 2, the cross-sectional bottoms of the first grooves of the universal screw and the fixing screw are formed in a circular arc shape, which is designed to facilitate the screw to be engaged with an orthopedic rod. The manner in which the screw engages the orthopedic rod is shown in figure 3.
In the figure, the orthopedic rod 2 is partially housed at the bottom of the first groove 125, is arranged substantially perpendicular to the screws used to fix the entire nail-rod system to the spine, and is mainly used to achieve an orthopedic of the spine by the rigidity of the rod body. The orthopedic rod is positioned outside the spine, is fixed with the screw and is fixed on the spine, and simultaneously realizes the orthopedic to the spine by using the rigidity and the shape of the orthopedic rod.
In this embodiment, the orthopedic rods include a straight rod 21 and a physiologically curved rod 22. The straight bar 21 has a substantially straight shape as a whole, and the physiological bending bar has a certain curvature.
In the embodiment, the physiological bending rod is mainly used for spinal column orthopedic surgery and is used for restoring the normal physiological curvature of the spinal column, in medicine, the severity degree of the spinal column lateral bending is mostly evaluated through the angle of the lateral bending of the spinal column segment, the measurement of the angle of the spinal column lateral bending is measured by using a Cobb angle, as shown in fig. 5, the pre-bending radian of the physiological bending rod is designed according to the data of the Cobb angle, the length of the pre-bending radian is consistent with the length of the spinal column segment to be orthopedic, an angle α formed by intersecting extension lines in the tangential directions of two ends of the physiological bending rod is consistent with the Cobb angle, for example, the same angle can be used adaptively, or an angle which is easy to match with the Cobb angle is used adaptively, as shown in fig. 6, and a series of physiological bending rods are designed according to the intrinsic physiological curvature of the thoracic vertebra and the lumbar vertebra to cover the requirements of different groups and different segments for orthopedic.
In the specific embodiment, the physiological bending rod has a predetermined bending degree, and compared with a common straight rod, the physiological bending pre-bending rod can maximize the contact area between the implant and the spine, can play a certain effect on maintaining the physiological bending degree, and can achieve a satisfactory propping effect on the compressed vertebral body after the operation. As shown in fig. 7, the physiological bending rod is provided with two grooves on the outer peripheral surface of one end, the depth direction of the grooves is arranged along the diameter direction of the physiological bending rod, and the grooves are designed to ensure the effective action of the rotating force under the condition of applying the rotating force and the axial translation force to the end of the physiological bending rod, so as to avoid the occurrence of slipping, improve the convenience in the use process and the accuracy of conveying to a preset position. The other end part of the physiological bending rod is provided with a conical end, and the conical end is arranged for the purpose of adopting minimally invasive surgery, namely adopting a wound as small as possible; as little as possible to strip the tissue at the implantation site, the muscle, the ligament, etc.) the tapered design of the end can facilitate the implantation of the orthopedic rod, reduce irritation to the tissue muscle around the implantation site, reduce the traction to the ligament, the nerve, and thereby reduce the injury to the patient.
In the present embodiment, the orthopedic rod, whether a straight rod or a physiological bending rod, is made of cobalt-chromium-molybdenum alloy, the orthopedic rod mainly bears the stress of the spine, and therefore needs to maintain sufficient strength, and under the material of unit volume, the cobalt-chromium-molybdenum alloy has higher strength, so that the cobalt-chromium-molybdenum system adopts 4.75mm cobalt-chromium-molybdenum rods for orthopedic rod titanium alloy rods with diameters of 5.5, 6.0 and 6.35mm in the prior art, that is, the cobalt-chromium-molybdenum system can have the mechanical properties of the titanium alloy rods with diameters of not less than 5.5mm, and has a smaller volume and a smaller occupied space in the body, thereby greatly reducing the influence of the implant on the tissues in the body.
As shown in fig. 8, in the present embodiment, one end of the straight rod 21 of the orthopedic rod is further provided with a hexagonal head 211, that is, six connected flat surfaces are provided on the outer peripheral surface of one end of the straight rod. In the prior art, when the scoliosis orthopedic operation is performed by using the orthopedic rods arranged on the common circumferential surface, the scoliosis deformity is corrected by using the rotation of the orthopedic rods, and if the common orthopedic rods are used, the rotating rods can slip; in the embodiment, the hexagonal end design can ensure that the rotating force can be effectively applied to the orthopedic rod due to the non-smooth design of the six surfaces when the orthopedic rod is rotated, so that the rod is ensured to stably rotate and an ideal orthopedic state is achieved. Furthermore, in the present embodiment, an annular notch 212 is disposed in the middle of the hexagonal end, the depth of the notch is disposed along the circumferential direction of the orthopedic rod, and the notch is used in conjunction with a surgical instrument, that is, when the surgical instrument is used in conjunction with the orthopedic rod to perform orthopedic surgery, for example, when the surgical instrument is combined with the hexagonal structure of the orthopedic rod, the surgical instrument and the orthopedic rod can be locked by means of the steel ball and the spring in conjunction with the notch, so as to ensure that the connection between the instrument and the orthopedic rod is completely locked during the surgical procedure, and ensure the stability of use during the surgical procedure, and the combination principle is shown in fig. 9. Can ensure that the surgical instrument is stably matched with the hexagonal rod and prevent the surgical instrument from slipping off from the hexagonal end of the orthopedic rod. This is illustrated in fig. 9 as one way only, and other ways are possible, such as a snap lock with a ball and spring.
As shown in fig. 3, in the nail rod system of the present embodiment, the orthopedic rod is disposed on the nail cap of the screw, and during the operation, the placed orthopedic rod needs to be pre-compressed to ensure that the orthopedic rod and the screw have a certain relative fixed relationship, so as to maintain the stability of the orthopedic rod in the subsequent operation. For this purpose, in the present exemplary embodiment, a screw plug is provided for pressing the orthopedic rod in the nut.
The structure of the plug screw 3 is shown in fig. 10, and in the present embodiment, the plug screw is made of a titanium alloy material and has a hardness of 260HV 10.
In this embodiment, the plug screw is generally cylindrical, threads are disposed on the circumference of the circumference, and the threads on the plunger are matched with the threads on the inner wall of the first groove of the screw cap, so that the plug screw is selected from the opening of the first groove into the first groove of the screw from top to bottom. The orthopedic rod is accommodated at the bottom of the groove, and when the screw plug is screwed in from top to bottom, a downward pressure for pressing the orthopedic rod to the nail head is gradually applied, so that the orthopedic rod is held in the nail head.
In the embodiment, the bottom end face of the screw plug is provided with at least one downward protruding convex structure, when the screw plug is gradually selected into the screw cap, the convex structure is initially contacted with the orthopedic rod to play a role of pre-compression on the orthopedic rod; due to the structural shape of the protrusion, when the orthopedic rod is in a pre-compression state, the initial contact area between the protrusion structure and the orthopedic rod is small, so that plastic deformation is easy to generate, and the orthopedic rod can be initially locked and has certain adjustability so as to meet the pre-compression requirement in the operation process; in the subsequent process, when the orthopedic rod and the screw cap need to be completely locked, the screw plug is screwed downwards, the orthopedic rod is made of titanium alloy and made of cobalt-chromium-molybdenum material, so that the hardness of the orthopedic rod is greater than that of the screw plug, when the force applied to the screw plug reaches a preset breaking force, the convex structure of the screw plug breaks and deforms, and finally the whole compression process of the orthopedic rod is completed.
The shape, the size and the number of the protruding structures on the bottom end face of the screw plug can be correspondingly determined according to the size and the specification of the screw plug and the specification of the orthopedic rod, so that the screw plug and the orthopedic rod with different specifications can achieve the optimal locking state.
Furthermore, considering that the reduction screw in the pedicle screw, the self-breaking screw plug, the reduction screw plug and the like need to be broken or twisted during the operation, the design of the corresponding fracture section is needed to ensure the quantitative breaking or twisting force, and accordingly, a plurality of different fracture sections are designed to ensure the accurate fracture force and the flat fracture section, so as to minimize the influence of the fracture gap of the product on the tissues in the body. The fracture surface is designed based on the thinned outer wall, but in order to improve the accuracy of the fracture force and the flatness of the fracture surface, various preferred fracture surface designs are provided in the present embodiment as shown in fig. 11.
The self-breaking screw plug and the reset screw plug need to be twisted off in the operation, the twisting force is a fixed value, and further, the locking force between the screw cap and the orthopedic rod by the screw plug is ensured to be a fixed value from the determined twisting force value, so that the final locking state of the screw rod system is ensured to be in a basically same state after the screw rod system is implanted, the problems of inconsistent locking force, unlocking of the screw plug and other human factors caused by the human factors are avoided, and the safety of the product after the implantation is ensured. Meanwhile, considering the smoothness of the fracture, combining the fracture characteristic of the titanium alloy material, designing the notch structure, wherein the condition that the fracture of the notch structure needs to be met is as follows: in the plane stress state, the notch strength is:
Figure BDA0001300408680000111
wherein K tIs the stress concentration coefficient, σ bNFor breaking strength, σ fThe breaking strength, ε, of a smooth specimen fThe breaking strain of the smooth specimen. According to the Hart-Smith method, K tThe values are related to the thickness, width, and cut radius of curvature of the notched portion, etc., and accurate strength selection is achieved through reasonable parameter matching. In addition, the stress state of the root of the notch is changed from a pure plane stress state to a three-way stress state, the stress state enables the crack initiation and the crack propagation of the material to be limited in a certain plane, and the straight fracture appearance is easier to form. The relevant validation tests showed results consistent with theoretical analysis.
Furthermore, the top of the screw plug is provided with a groove with a hexagonal or quincunx section, because the screw plug needs to apply a rotating force to gradually press the screw plug onto the orthopedic rod, the groove is used for screwing the screw plug downwards by using a tool. In the prior art, the whole of the groove is vertically arranged, and the cross-sectional shapes and the sizes of different positions of the groove are approximately the same. The groove with the cross section shape sometimes cannot ensure the centering between the tool and the groove in use, namely, the tool and the groove can shake relatively in the installation process, slight angle difference often has great influence in the process of spinal surgery, so that if the tool and the groove shake relatively, the stress direction of a screw is inclined in the nailing process, the screw installation cannot reach the expected installation position, and the performance of the whole screw rod system is influenced rigidly. In order to solve the above problem, in the present embodiment, as shown in fig. 12, it is preferable that the recess of the plug tip is provided as a tapered groove, that is, the diameter of the notch in the cross section of the recess is gradually reduced from top to bottom, so that when a tapered screwdriver or the like having the same shape as the tapered groove is fitted, the tool and the plug are automatically centered due to the guiding action of the tapered surface, and the axial coaxiality of the driver and the screw can be ensured, so that the problem of incorrect screw mounting position can be avoided.
At present, hexagonal grooves, quincunx grooves and other tool grooves used for transmitting torque on the market are all cylindrical, screws and the like can be screwed by using corresponding hexagonal and quincunx screwdrivers, but the tool grooves have the defect that the centering property cannot be guaranteed between the tools and the grooves, namely, in the installation process, the tools and the grooves can shake relatively to influence the use.
In the embodiment, the tool groove in the screw matched with the screwdriver is used, the problem that the axis of the screw and the axis of the tool are not coaxial in use occurs, the stress direction of the screw is skewed in the nailing process, the screw cannot be installed at the expected installation position, and in order to solve the problem, the conical tool groove is provided and has self-centering property, when the screwdriver is matched with the tool groove in the screw, the axis of the screwdriver and the axis of the screw can be ensured to be coaxial due to the self-centering property of the conical surface, and therefore the problem that the installation position of the screw is incorrect can be solved, for example, as shown in fig. 13.
More preferably, as shown in fig. 14, the bottom end of the plug screw thread terminates with a blunt tip that tapers away from the stud relative to a conventional threaded tip. With a blunt tip, at the end of the thread, there is a direct truncation, as shown in fig. 14. The thread design of the non-blunt-end screw plug has natural transition from no thread to some thread, and during the transition, the tooth form of some threads is not complete and weak, and slight dislocation can easily cause the deformation of the tooth form during screwing, thereby causing unsmooth screwing of the screw plug and the possibility of installation of wrong teeth. The screw plug with the blunt thread design can avoid the problems. Through the design of thread trimming, the bottom diameter of the external thread on the plug screw is exposed, so that when the plug screw is screwed into the internal thread of the screw cap, the exposed internal diameter of the thread can ensure the centering installation of the thread, the correct embedding between thread teeth is ensured, the problem of thread pairing error can not occur, and with the help of the design, the screw plug screw is screwed into the screw cap more quickly, and the installation is smoother.
More preferably, the nail system of the present embodiment further comprises an identification module attached to the nail system.
At present, all marks for the internal implant system are on a product body, such as marking on the product and the like, so as to determine which specification and batch the product belongs to, but the product for the internal implant system is small in size, so that the marking is smaller, and the identification of the product is very troublesome in the actual operation process.
The utility model provides an outside identification system among the concrete embodiment of this patent for the retrospection of implant, give every implant product promptly and all pair corresponding tablet of marking, will mark tablet and product integration, detachably fixes on the nail stick system, realize the integration, if so need trace back the product then only need look over mark the tablet can, mark the information record on the tablet and can use sign such as digit, figure, for example two-dimensional code, bar code etc. utilize it to pair the scanning instrument scan can obtain all relevant information of required this product. A sign and nail rod system product integration example is shown in fig. 18.
Although the location communication principle and the embodiment in this embodiment have been described in detail, the technical details that are not mentioned in this embodiment can be implemented by the techniques known in the art, and thus are not listed.
However, it is obvious to those skilled in the art that the embodiments and the application range can be changed according to the idea of the patent embodiments; therefore, all modifications, deletions, or substitutions of elements in this embodiment are intended to be included within the scope of this patent. In view of the above, the contents of this specification should not be interpreted as limiting the scope of protection of this patent.

Claims (1)

1. A cobalt chromium molybdenum thoracolumbar posterior nail rod system, comprising: pedicle screws, orthopedic rods and plugs;
the pedicle screws are used for fixing on the spine, thereby anchoring the whole screw-rod system on the spine; the pedicle screw comprises a universal screw and a fixing screw, and the fixing screw is designed in an integrated manner, cannot be obviously deformed integrally and is used for being fixed on a corresponding position of a vertebra; the universal screw is characterized in that: the nail head, the retainer ring and the nail body; the screw cap is positioned at the top of the whole universal screw and is cylindrical, a first groove is formed in the top of the screw cap, and the first groove penetrates through the diameter direction of the whole screw cap; the first groove is used for accommodating a screw plug, and the wall of the first groove is provided with threads which are matched with the threads arranged on the screw plug, so that the screw plug is allowed to be operably fixed with the screw cap in a thread matching way;
the bottom of the nail cap is provided with a first through hole, one end of the first through hole is communicated with the bottom wall of the first groove, the other end of the first through hole penetrates through the bottom of the nail cap, the first through hole is used for accommodating a nail body, the top end of the nail body comprises a ball head, and the ball head is accommodated in the first through hole; a check ring is further arranged between the ball head and the first through hole, the check ring is positioned at the top of the ball head and between the top end of the first through hole and the ball head, and the position of the ball head in the first through hole is limited from the top of the ball head; the collar is arranged between the bottom of the first through hole and the bottom of the ball head and used for limiting the position of the ball head relative to the nail cap at the lower part of the ball head; the screw plug is in screwing fit with the screw cap through threads, the orthopedic rod is arranged in a first groove formed in the screw cap, the bottom of the screw plug is in contact with and pressed against the upper half surface of the orthopedic rod along with the gradual screwing of the screw plug, and the lower half surface of the orthopedic rod is in contact with and pressed against the check ring, so that the orthopedic rod is completely locked and locked by the screw plug and the check ring;
the method is characterized in that:
the orthopedic rod comprises a straight rod and a bent rod; one end of the orthopedic rod is fixedly connected to the screw cap of the fixing screw, and the other end of the orthopedic rod is fixedly connected to the screw cap of the universal screw;
the screw plug and the screw body are made of titanium alloy, and the hardness is 260HV 10; the orthopedic rod, the nail cap and the clamping ring are made of cobalt-chromium-molybdenum alloy, and the hardness is 40 HRC; the material of the retainer ring is pure titanium, and the hardness is 150HV 10; the cobalt-chromium-molybdenum chest-waist posterior nail rod system is formed into a soft-hard combined system after soft-hard combination of the materials;
the nail body comprises a threaded column, the threaded column and the ball head are fixedly arranged, the threaded column and the ball head are integrally formed, the threaded column is also made of titanium alloy, threads are arranged on the threaded column, threads with a first density are arranged on the periphery of the lower portion of the threaded column, threads with a second density are arranged on the periphery of the upper portion of the threaded column, the thread density of the second density is larger than that of the threads with the first density, the length of the threads with the first density corresponds to a vertebra cancellous bone layer, and the length of the threads with the second density corresponds to a vertebra cortical bone layer;
the bottom end face of the screw plug is provided with at least one protruding structure protruding downwards, and when the screw plug is gradually screwed into the screw cap, the protruding structure is initially in contact with the orthopedic rod to achieve the function of pre-pressing the orthopedic rod; the device has adjustability so as to meet the pre-compression requirement in the operation process; and under the condition that the orthopedic rod and the screw cap need to be completely locked, the screw plug is screwed downwards continuously, and when the force applied to the screw plug reaches a preset breaking force, the convex structure of the screw plug is plastically deformed, so that the whole pressing process of the orthopedic rod is completed.
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Denomination of invention: A Cobalt Chromium Molybdenum Thoracic and Lumbar Posterior Screw Rod System

Effective date of registration: 20230529

Granted publication date: 20200211

Pledgee: Agricultural Bank of China Limited by Share Ltd. South Lake branch

Pledgor: ZHEJIANG DECANS MEDICAL INSTRUMENT CO.,LTD.

Registration number: Y2023980042207