Lumbar facet fusion fixation device

Abstract

The present application relates to lumbar joint fixation treatment technical field, provide lumbar facet joint fusion fixation device, including two opposite connection titanium plate, joint movement core, transverse extension arm and cortical bone screw, joint movement core includes sliding groove piece and sliding block piece, sliding block piece relative to sliding groove piece in elastic sliding groove slip and swing, extension arm is detachably connected to connection titanium plate, end connection cortical bone screw, the present application forms movable joint structure through sliding groove piece and sliding block piece, retains spinal segment multidirectional physiological activity while stabilizing support, through cortical bone screw, reliable anchoring effect is obtained, the risk of screw loosening or falling out after operation is reduced, the buffer stiffness of elastic sliding groove is designed according to clinical demand, matches the biomechanical demand of different patients, different segment position, prevents segmental micro-motion or misplacement, extension arm and connection titanium plate are detachably connected, when local component failure, can be individually replaced, need not to be taken out as a whole, reduce secondary revision surgical trauma.

Description

Technical Field

[0001] This invention relates to the field of lumbar joint fixation treatment technology, and in particular to a lumbar facet joint fusion fixation device. Background Technology

[0002] The statements herein are provided only as background information in connection with this application and do not necessarily constitute prior art.

[0003] Degenerative lumbar spine diseases (such as lumbar spinal stenosis and lumbar spondylolisthesis) are common and frequently occurring diseases in orthopedics. For patients who do not respond to conservative treatment, posterior lumbar decompression surgery is often required to relieve nerve compression. However, surgery inevitably damages the facet joints on both sides of the responsible segment, leading to decreased spinal stability. Traditional treatment methods use pedicle screw-rod systems for fusion fixation. Although this can restore immediate stability, it sacrifices the normal physiological range of motion of that segment, causing stress to concentrate in adjacent segments, thereby accelerating the degeneration of adjacent segments and triggering new clinical symptoms.

[0004] To address the drawbacks of fusion fixation, the industry has developed artificial facet joint replacement devices, aiming to replace damaged facet joints after decompression, achieving stable yet flexible dynamic stability. For example, existing devices simulate joint movement by implanting a flexible polymer motion core. However, such devices still have shortcomings in practical applications: First, the stiffness of the polymer motion core is limited, making it difficult to accurately match the complex stress requirements of the lumbar spine under different working conditions such as flexion, extension, lateral bending, and rotation, especially its insufficient ability to resist sagittal shear forces, posing a risk of segmental micromotion; Second, the transverse arm used to connect the screws in the device is often designed as a single piece with the main plate, which cannot be flexibly adjusted according to individual anatomical differences such as pedicle spacing and lamina morphology, making it unsuitable for some patients with anatomical abnormalities. Moreover, if a local component is damaged, the entire prosthesis must be removed for repair, resulting in significant trauma; Finally, the single limiting structure designed to prevent excessive joint movement is at risk of breakage or loosening under extreme physical activity or long-term fatigue, posing a safety hazard.

[0005] Therefore, there is an urgent need to develop a new type of lumbar facet joint functional replacement device that can simulate the multidimensional physiological activities of facet joints, has good mechanical support and individualized adaptation capabilities, and has a higher degree of safety redundancy. Summary of the Invention

[0006] This invention aims to solve at least one of the technical problems existing in related technologies. To this end, this invention proposes a lumbar facet joint fusion fixation device that can preserve the physiological range of motion of the spine, provide stable mechanical support, and has good anatomical adaptability and long-term safety.

[0007] A lumbar facet joint fusion fixation device according to an embodiment of the present invention includes a first connecting titanium plate, a second connecting titanium plate, a joint motion core, two sets of extension arms, and cortical bone screws. The first connecting titanium plate and the second connecting titanium plate are disposed opposite to each other. The joint motion core is disposed between the first connecting titanium plate and the second connecting titanium plate. The joint motion core includes a groove and a slider. The first end of the groove is fixed to the first connecting titanium plate, and the second end of the groove forms an elastic groove. The first end of the slider is fixed to the second connecting titanium plate, and the second end of the slider is movably inserted into the elastic groove of the groove. Each set of extension arms includes two transverse extension arms. The two transverse extension arms of one set of extension arms are symmetrically and detachably connected to both sides of the first connecting titanium plate, and the two transverse extension arms of the other set of extension arms are symmetrically and detachably connected to both sides of the second connecting titanium plate. The cortical bone screws are detachably connected to the transverse extension arms and are used for implantation into the cortical bone of the vertebral body.

[0008] According to one embodiment of the present invention, the slide rail includes a slide rail connecting portion and a groove portion, the slide rail connecting portion being fixedly connected to the first connecting titanium plate, the groove portion being connected to the side of the slide rail connecting portion away from the first connecting titanium plate, and the groove portion being formed with the elastic slide rail extending along its axial direction.

[0009] The slider component includes a slider component connecting part and a slider part. The slider component connecting part is fixedly connected to the second connecting titanium plate, and the slider part is connected to the side of the slider component connecting part away from the second connecting titanium plate. The slider part is movably inserted into the elastic groove.

[0010] According to one embodiment of the present invention, both the sliding groove and the sliding block are made of medical-grade titanium alloy / cobalt-chromium alloy. The groove wall of the elastic sliding groove is provided with a spiral through notch so that the groove body of the sliding groove is formed into a spring-like structure.

[0011] According to one embodiment of the present invention, the joint motion core further includes a limiting band, the first end of the limiting band being connected to the outer side of the first end of the sliding groove member, and the second end of the limiting band being connected to the outer side of the first end of the sliding block member.

[0012] A limiting protrusion is formed at the opening of the elastic groove, and the limiting protrusion is attached to the outer peripheral surface of the slider.

[0013] The limiting band and the limiting protrusion are located on the same side of the joint movement core and are used to limit the flexion and extension of the joint movement core.

[0014] According to one embodiment of the present invention, the limiting band is made of ultra-high molecular weight polyethylene, and at least two limiting bands are provided, which are arranged in parallel, for limiting the excessive flexion of the joint motion core.

[0015] According to one embodiment of the present invention, the limiting protrusion is an arc-shaped stop, and the arc-shaped portion of the arc-shaped stop abuts against the outer peripheral surface of the slider portion to limit the overextension of the joint motion core.

[0016] According to one embodiment of the present invention, limiting bosses are provided on both sides of the end of the slider portion near the slider member connecting portion, and the limiting bosses are used to limit the lateral bending angle of the joint motion core.

[0017] According to one embodiment of the present invention, the elastic groove of the groove portion is flat, the shape of the slider portion is adapted to the elastic groove, the slider portion is movably inserted into the groove portion and forms a clearance fit, and the axial rotation limit of the joint motion core is formed by the shape contour of the groove portion and the slider portion.

[0018] According to one embodiment of the present invention, the opposing surfaces of the first connecting titanium plate and the second connecting titanium plate are configured as groove-shaped structures adapted to the shape of the spinous process of the vertebra, and the opposing surfaces of the first connecting titanium plate and the second connecting titanium plate are provided with annular grooves for fixing the sliding groove or the sliding block.

[0019] According to one embodiment of the present invention, the lumbar facet joint fusion fixation device further includes a corrugated elastic shell, which is connected between the first connecting titanium plate and the second connecting titanium plate and wraps around the joint motion core to protect the joint motion core and form an elastic buffer for the joint motion core.

[0020] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The movable joint structure formed by the sliding groove and the sliding block of the present invention enables the device to provide stable support while preserving the physiological range of motion of the spinal segment in multiple directions such as flexion, extension, lateral bending, and rotation, avoiding stress shielding and accelerated degeneration of adjacent segments. Furthermore, compared with existing artificial facet joint devices using polymer motion cores, the sliding groove and the sliding block of the present invention can be made of metal. The elastic groove can be designed with buffer stiffness according to clinical needs, enabling more precise matching of the biomechanical needs of different patients and different segments. The shear resistance of the metal structure is superior to that of polymer materials, effectively preventing segmental micromovement or misalignment. In addition, the lateral extension arm and the connecting titanium plate adopt a split, detachable connection design, allowing for flexible selection of different specifications of extension arms based on individual anatomical differences such as pedicle spacing and lamina morphology, expanding the applicable population range of the device. Moreover, in the event of a malfunction in a local component, the corresponding component can be disassembled and replaced individually without removing the entire prosthesis, reducing the trauma caused by a second revision surgery.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention and are not considered as limitations on this application. Moreover, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0023] Figure 1 This is a schematic structural diagram of the lumbar facet joint fusion fixation device provided by the present invention.

[0024] Figure 2 This is a first-view schematic structural diagram of the lumbar facet joint fusion fixation device including a corrugated elastic shell provided by the present invention.

[0025] Figure 3 This is a second-view schematic structural diagram of the lumbar facet joint fusion fixation device including a corrugated elastic shell provided by the present invention.

[0026] Figure 4 This is a schematic exploded structural diagram of the lumbar facet joint fusion fixation device provided by the present invention.

[0027] Figure 5 This is a schematic structural diagram of the sliding groove component provided by the present invention.

[0028] Figure 6 This is a schematic structural diagram of the slider component provided by the present invention.

[0029] Figure 7 This is a schematic structural diagram of the cortical bone screw provided by the present invention.

[0030] Figure 8 This is a schematic exploded view of the cortical bone screw provided by the present invention.

[0031] Figure 9 This is an isometric structural diagram of the lumbar facet joint fusion fixation device provided by the present invention fixed to the vertebral body.

[0032] Figure 10 This is a schematic diagram of the lateral structure of the lumbar facet joint fusion fixation device provided by the present invention fixed on the vertebral body.

[0033] Figure 11 This is a top-view structural diagram of the lumbar facet joint fusion fixation device provided by the present invention fixed to the vertebral body.

[0034] Figure label: 1. First connecting titanium plate; 2. Second connecting titanium plate; 3. Sliding groove; 4. Sliding block; 5. Lateral extension arm; 6. Cortical bone screw; 7. Limiting band; 8. Corrugated elastic shell; 31. Slide body connection part; 32. Slide body part; 33. Through notch; 34. Limiting protrusion; 41. Slider connecting part; 42. Slider part; 43. Limiting boss; 61. Screw connector; 62. Spiral plug; 63. Universal mounting base; 64. Screw assembly. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0037] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0038] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" relationship.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] The following is combined with Figures 1 to 11 The lumbar facet joint fusion fixation device of the present invention is described.

[0041] An embodiment of the present invention provides a lumbar facet joint fusion fixation device, combined with Figure 1 and Figure 4As shown, the device includes a first connecting titanium plate 1, a second connecting titanium plate 2, a joint motion core, two sets of extension arms, and four cortical bone screws 6. The first connecting titanium plate 1 and the second connecting titanium plate 2 are arranged opposite each other along the spinal axis and are used to fix the spinous processes of the two vertebrae above and below the diseased segment, respectively. The joint motion core is located between the first connecting titanium plate 1 and the second connecting titanium plate 2 and is the core component that simulates the movement of natural facet joints. The joint motion core specifically includes a groove component 3 and a slider component 4. The first end of the groove component 3 is fixedly connected to the first connecting titanium plate 1, and the second end of the groove component 3 forms an axially extending elastic groove. The first end of the slider component 4 is fixedly connected to the second connecting titanium plate 2. The second end of the slider 4 is movably inserted into the elastic groove of the slide 3, so that the slider 4 can slide and swing relative to the slide 3 within the elastic groove; each set of extension arms includes two lateral extension arms 5, in which the two lateral extension arms 5 of one set of extension arms are symmetrically and detachably connected to the left and right sides of the first connecting titanium plate 1, and the two lateral extension arms 5 of the other set of extension arms are symmetrically and detachably connected to the left and right sides of the second connecting titanium plate 2; each lateral extension arm 5 is detachably connected to a cortical bone screw 6 at its end, the cortical bone screw 6 is used to be implanted into the cortical bone of the corresponding vertebral body, and the high density of the cortical bone layer provides a firm anchoring force.

[0042] After posterior lumbar decompression surgery, the lumbar facet joint fusion fixation device of this embodiment is placed entirely in the lesion segment. The device is anchored in the cortical bone of the upper and lower vertebral bodies using cortical bone screws 6. The lateral extension arm 5 transmits the anchoring force to the first connecting titanium plate 1 and the second connecting titanium plate 2. When the patient performs physiological activities such as lumbar flexion, extension, lateral bending, or rotation, the slider 4 fixed to the second connecting titanium plate 2 slides and deflects relative to the groove 3 fixed to the first connecting titanium plate 1. During this process, the second end of the slider 4 moves within the elastic groove of the groove 3. The elastic groove undergoes controllable elastic deformation due to the force, thereby simulating the cushioning function of a natural facet joint and achieving a stable yet flexible dynamic stabilization effect.

[0043] It is important to understand that this lumbar facet joint fusion fixation device in this embodiment, through the movable joint structure formed by the cooperation of the sliding groove 3 and the sliding block 4, allows the device to provide stable support while preserving the physiological range of motion of the spinal segment in multiple directions such as flexion, extension, lateral bending, and rotation, avoiding stress shielding and accelerated degeneration of adjacent segments. Furthermore, compared to existing artificial facet joint devices using polymer motion cores, the sliding groove 3 and sliding block 4 in this embodiment can be made of metal. The elastic groove can be designed with buffer stiffness according to clinical needs, enabling more precise matching of the biomechanical requirements of different patients and different segments. The shear resistance of the metal structure is superior to that of polymer materials, effectively preventing segmental micromovement or misalignment. In addition, the lateral extension arm 5 and the connecting titanium plate adopt a split, detachable connection design, allowing for flexible selection of different specifications of extension arms based on individual anatomical differences such as pedicle spacing and lamina morphology, expanding the applicable population range of the device. Moreover, in the event of a malfunction in a local component, the corresponding component can be disassembled and replaced individually without removing the entire prosthesis, reducing the trauma caused by a second revision surgery.

[0044] In some specific embodiments, see Figure 5 As shown, the slide 3 has an overall slender structure. The slide 3 includes a slide body connecting part 31 and a groove part 32. The end of the slide 3 closest to the first connecting titanium plate 1 is the slide body connecting part 31. The end face of the slide body connecting part 31 is fixedly connected to the inner side of the first connecting titanium plate 1 by welding, riveting or integral molding. The side of the slide body connecting part 31 away from the first connecting titanium plate 1 extends to form the groove part 32. The groove part 32 has a through or non-through elastic slide along the axial direction. The cross-sectional shape of the elastic slide can be designed according to the required degree of freedom of motion, such as elliptical, flat or rectangular.

[0045] See Figure 6 As shown, the overall structure of the slider 4 corresponds to that of the groove 3. The slider 4 includes a slider connecting part 41 and a slider part 42. The end of the slider 4 near the second connecting titanium plate 2 is the slider connecting part 41. The end face of the slider connecting part 41 is fixedly connected to the inner side of the second connecting titanium plate 2. The side of the slider connecting part 41 away from the second connecting titanium plate 2 extends to form the slider part 42. The outer contour of the slider part 42 is adapted to the shape of the elastic groove of the groove part 32, and the slider part 42 is movably inserted into the elastic groove in a clearance fit manner.

[0046] In the specific implementation process, firstly, based on the preoperative imaging measurement results, select appropriate specifications for the first connecting titanium plate 1, the second connecting titanium plate 2, and corresponding sizes for the sliding groove component 3 and the sliding block component 4. The sliding groove connecting part 31 of the sliding groove component 3 is fixed to the annular groove on the inner side of the first connecting titanium plate 1 by press fitting or laser welding. Similarly, the sliding block connecting part 41 of the sliding block component 4 is fixed to the annular groove on the inner side of the second connecting titanium plate 2. Then, the sliding part 42 of the sliding block component 4 is aligned with the elastic sliding groove opening of the sliding groove component 3, and the sliding part 42 is smoothly pushed into the elastic sliding groove, allowing for relative sliding and swinging movement. Subsequently, the assembled joint motion core, along with the first connecting titanium plate 1 and the second connecting titanium plate 2, is installed to the patient's lumbar lesion segment, and overall fixation is completed using cortical bone screws 6 and transverse extension arms 5.

[0047] In one embodiment of the present invention, both the groove component 3 and the slider component 4 are made of medical-grade titanium alloy (such as Ti-6Al-4V) or cobalt-chromium alloy (such as Co-Cr-Mo). These two types of materials possess excellent biocompatibility, high specific strength, good corrosion resistance, and fatigue resistance. Long-term implantation in the body will not cause adverse reactions, and they can withstand the cyclic loads generated by spinal movement. See also Figure 5 As shown, during the processing of the groove body 32, precision machining or laser cutting technology is used to open a spirally extending through notch 33 on the groove wall of the elastic groove. The through notch 33 penetrates the groove wall along the axial direction of the groove body 32 with a spiral trajectory, cutting the originally complete tubular or cylindrical groove wall into a structure with continuous spiral grooves. Thus, the groove body 32 as a whole forms a spring-like structure similar to a compression spring. The geometric parameters such as the helix angle, pitch, notch width, and number of spiral turns of the through notch 33 can be customized according to the target buffer stiffness requirements.

[0048] During implementation, the required buffer stiffness value is first determined based on the patient's bone density, body mass index, expected activity level, and the location of the lesion segment (such as L4-L5 or L5-S1, which have different biomechanical characteristics). This is achieved through finite element analysis or empirical formulas. Then, the specific geometric parameters of the through notch 33 are designed according to this stiffness value: for patients requiring greater buffer stiffness (e.g., those with higher body weight or lower bone density), a smaller pitch and narrower notch width can be designed to increase the overall rigidity of the groove 32; for patients requiring less buffer stiffness (e.g., those with lower body weight or who desire a greater range of motion), a larger pitch and wider notch width can be designed to make the groove 32 more flexible. After machining, the groove 32 undergoes surface polishing and passivation to eliminate stress concentration points and burrs at the notch edges, ensuring that fatigue fracture does not occur during repeated elastic deformation. The machined sliding groove 3 and sliding block 4 are then assembled, with the sliding block 42 inserted into the elastic groove of the groove 32. An appropriate clearance is left between them to ensure smooth relative movement.

[0049] Understandably, this embodiment uses medical-grade titanium alloy or cobalt-chromium alloy instead of traditional polymers as the joint movement core material. This improves the device's shear resistance and fatigue resistance. The high elastic modulus of the metallic material makes the groove 32 less prone to permanent deformation or segmental misalignment when subjected to sagittal shear force and coronal lateral stress of the spine. This ensures long-term consistency of postoperative segmental motion stability and overcomes the problems of elastic decay and abnormal changes in range of motion that polymer materials are prone to. The spiral through-hole 33 enables the groove 32 to achieve structural elasticity, meaning that elastic deformation is mainly provided by the bending deformation of the groove wall's geometry, rather than the stretching of the material's molecular chains. By adjusting geometric parameters such as the pitch, width, and number of turns of the spiral notch, the buffer stiffness can be precisely controlled, allowing for personalized matching for different patients without changing the material formulation or overall dimensions.

[0050] In one embodiment of the present invention, see Figure 1 As shown, the joint motion core also includes a limiting band 7, which has a predetermined length and tensile strength. The first end of the limiting band 7 is fixedly connected to the outer wall or end face of the first end of the sliding groove 3 (the end near the first connecting titanium plate 1), and the second end of the limiting band 7 is fixedly connected to the outer wall or end face of the first end of the slider 4 (the end near the second connecting titanium plate 2). When the slider 4 slides outward axially relative to the sliding groove 3, the limiting band 7 is gradually straightened and eventually tensioned. When the sliding distance of the slider 4 reaches the natural length of the limiting band 7, the limiting band 7 is fully tensioned, thereby applying a reverse tension force to the slider 4 and preventing the two from continuing to move away from each other, thus limiting the excessive flexion of the joint motion core.

[0051] Meanwhile, a limiting protrusion 34 is formed at the groove opening of the elastic groove (the end of the groove part 32 away from the groove body connecting part 31). The limiting protrusion 34 can be designed as an annular flange, an arc-shaped stop, or a local protrusion. The inner surface contour of the limiting protrusion 34 is adapted to the outer peripheral surface of the slider part 42 and fits tightly against the outer peripheral surface of the slider part 42. When the slider 4 slides inward relative to the groove part 3 along the axial direction to the limit position, the root end face of the slider connecting part 41 or the slider part 42 will abut against the limiting protrusion 34, forming a mechanical block, thereby preventing the two from continuing to approach each other, thus limiting the overextension of the joint movement core.

[0052] Specifically, based on the physiological range of motion of the human lumbar spine (usually flexion of about 40°~50° and extension of about 15°~20°) and the specific geometric dimensions of the device, the maximum allowable sliding distance and the maximum allowable sliding in distance of the slider 4 relative to the groove 3 are calculated. The length of the limiting band 7 is then determined accordingly. The natural length of the limiting band 7 should be slightly greater than or equal to the length of the limiting band 7 after being straightened, corresponding to the maximum allowable sliding distance. The limiting protrusion 34 can be formed by local additive manufacturing, stamping, or welding at the edge of the groove of the groove body 32, or by embedding an independent annular or arc-shaped limiting ring at the groove opening. The protrusion height of the limiting protrusion 34 should ensure that it can reliably abut against the end face of the slider part 42 or the slider connecting part 41, while not interfering with the normal sliding of the slider part 42 within the elastic groove. The close fit between the limiting protrusion 34 and the outer peripheral surface of the slider part 42 also helps maintain the centering position of the slider part 42 within the elastic groove, reducing swaying and deviation during movement. The limiting band 7 and the limiting protrusion 34 are both arranged on the same side of the joint movement core (e.g., the dorsal or ventral side), working together to form a complete limit for the extreme movements in both flexion and extension directions.

[0053] See some specific examples. Figure 1 As shown, the limiting band 7 is made of ultra-high molecular weight polyethylene (UHMWPE). UHMWPE limiting bands exhibit extremely high tensile strength, excellent fatigue resistance, and extremely low creep rate, while also possessing self-lubricating properties and good wear resistance. In specific implementation, at least two limiting bands 7 are provided. All limiting bands 7 are arranged in parallel between the groove 3 and the slider 4. The first ends of the two limiting bands 7 are independently fixed to the left and right sides or the top and bottom sides of the outer side of the first end of the groove 3, respectively. The second ends of the two limiting bands 7 are correspondingly and independently fixed to the corresponding positions on the outer side of the first end of the slider 4. The two limiting bands 7 are parallel to each other and do not intertwine, each independently bearing the tensile load at the buckling limit position.

[0054] Using at least two parallel limiting bands 7 creates a redundant design. Even if one limiting band 7 is damaged or broken due to an accident, the other limiting band can still independently assume the limiting function, temporarily maintaining restraint against excessive buckling. This buys valuable time for patient treatment and revision surgery, improves safety redundancy, and overcomes the serious safety hazard of completely losing buckling limiting protection once a single limiting band fails. The two limiting bands 7 can adopt a symmetrical force-bearing mode with parallel arrangement, so that the tensile load generated during buckling can be evenly distributed on the two limiting bands 7. Compared with a single limiting band bearing the entire load, the dual-band design can reduce the maximum stress and cyclic stress amplitude borne by each limiting band, thereby extending the overall fatigue life.

[0055] In one embodiment of the present invention, see Figure 6 As shown, limiting bosses 43 are symmetrically provided on both sides of the end of the slider part 42 near the slider member connecting part 41 (the root of the slider part 42). The limiting bosses 43 extend radially outward from the outer side wall of the slider part 42, and their protrusion height and axial length are designed according to the required lateral bending limit angle. The limiting bosses 43 can be designed as rectangular blocks, trapezoidal blocks, or irregular shapes with rounded transitions. Their outer surfaces are preferably designed with smooth curved surfaces to reduce stress concentration. When the joint motion core is in the centering position, a predetermined gap is maintained between the two limiting bosses 43 and the edge of the elastic groove opening of the groove part 32. When the slider member 4 bends laterally relative to the groove member 3, the limiting bosses 43 located on the same side of the bending direction will gradually approach and eventually abut against the groove edge of the groove part 32 or the corresponding end face of the groove body connecting part 31, forming a mechanical block, thereby preventing the joint motion core from continuing to bend in that direction, and achieving limitation on the lateral bending angle.

[0056] In one embodiment of the present invention, see Figure 5 As shown, the elastic groove of the groove portion 32 has a flat profile in cross-section. Specifically, this flat profile has a pair of relatively long straight edges and a pair of relatively short rounded edges, and is generally racetrack-shaped or elliptical, rather than circular. Correspondingly, see [reference needed]. Figure 6As shown, the cross-sectional shape of the slider part 42 is designed to be a flat profile that matches the elastic groove, forming a clearance fit between them. While maintaining smooth sliding, the clearance between the two is controlled to be as small as possible. Because both the elastic groove and the slider part 42 have flat cross-sections rather than circular cross-sections, the slider part 42 cannot rotate freely around its own axis within the elastic groove. Specifically, when the joint motion core is subjected to axial torque, the flat side of the slider part 42 and the flat inner wall of the elastic groove form a mutually abutting constraint relationship, thereby preventing the slider part 42 from rotating relative to the groove part 32 around the axial direction. The tiny axial rotation angle allowed by this shape fit comes only from the clearance between the two, that is, a very small angle corresponding to a clearance of only tens of micrometers, thus effectively limiting the axial rotation of the joint motion core.

[0057] In one embodiment of the present invention, see Figure 1 or Figure 4 As shown, both the first connecting titanium plate 1 and the second connecting titanium plate 2 are plate-shaped components with a certain thickness and curvature. After implantation, they are respectively attached to the spinous process regions of the upper and lower vertebrae. Specifically, the opposing surfaces of the first connecting titanium plate 1 and the second connecting titanium plate 2 (facing away from the outer surface of the joint motion core) are constructed as groove-shaped structures. The curved shape of the groove is adapted to the anatomical shape of the corresponding vertebral spinous process, presenting an inwardly concave arc surface along the length direction of the spinous process, and also presenting an arc-shaped contour matching the curvature of the spinous process surface along the width direction of the spinous process. This contour-mimicking design allows the connecting titanium plates to form a large-area contact with the surface of the spinous process, achieving bone plate morphology matching. At the same time, the opposing surfaces of the first connecting titanium plate 1 and the second connecting titanium plate 2 (facing the inner surface of the joint motion core) are provided with annular grooves. The contour dimensions of the annular grooves match the end face shape of the sliding groove body connecting part 31 of the sliding groove component 3 or the sliding part connecting part 41 of the sliding block component 4, for accommodating and fixing the end of the sliding groove component 3 or the sliding block component 4.

[0058] In a specific example of the present invention, combined with Figure 7 and Figure 8 As shown, cortical bone screw 6 is a universal cortical bone screw, see [reference]. Figure 8As shown, the universal cortical bone screw includes a screw connector 61, a spiral plug 62, a universal mounting base 63, and a screw portion 64. The upper part of the screw connector 61 has a U-shaped structure with internal threads. The spiral plug 62 has external threads and is screwed into the U-shaped structure of the screw connector 61. The end of the lateral extension arm 5 passes through the U-shaped structure of the screw connector 61 and is pressed and fixed by the spiral plug 62. The bottom of the U-shaped structure of the screw connector 61 has a through hole for installing the universal mounting base 63. The top of the screw portion 64 has a spherical structure and is hinged to the universal mounting base 63, allowing the screw portion 64 to be universally adjustable in orientation and angle. This facilitates the adjustment of the insertion angle of the cortical bone screw 6 by adjusting the head tilt angle and abduction angle of the screw portion 64 when fixing the lumbar facet joint fusion.

[0059] In one embodiment of the present invention, the lumbar facet joint fusion fixation device further includes a bellows elastic housing 8, see [link to previous document]. Figure 2 and Figure 3 As shown, the corrugated elastic outer shell 8 is connected between the first connecting titanium plate 1 and the second connecting titanium plate 2, and wraps around the joint motion core to protect it and provide elastic cushioning. Specifically, the corrugated elastic outer shell 8 is injection molded or blow molded from a high-molecular material (such as polycarbonate polyurethane, medical-grade silicone, or polyurethane elastomer) with good biocompatibility and elasticity. Its overall structure is a stretchable corrugated tube, with alternating annular crests and troughs along the axial direction on the tube wall, giving it good axial expansion and contraction capabilities. The corrugated elastic outer shell 8 completely encloses the joint motion core within its internal cavity. When the patient performs lumbar flexion and extension movements, the slider 4 of the joint motion core slides axially relative to the groove 3, and the corrugated elastic outer shell 8 simultaneously undergoes axial compression or stretching. The corrugated structure adapts to this length change through the elastic deformation of the crests and troughs, always maintaining complete encapsulation of the internal joint motion core.

[0060] Understandably, the corrugated elastic shell 8, encasing the joint motion core, forms a reliable physical barrier, preventing surrounding soft tissues (such as the dura mater, nerve roots, and adipose tissue) from ingrowing into or embedding into the joint motion core's movement space. This avoids serious complications such as pain, limited mobility, and even nerve damage caused by soft tissue impingement. The corrugated elastic shell 8 itself is made of elastic material and has a corrugated structure, allowing it to deform synchronously with the joint motion core's expansion and contraction. It does not restrict or hinder the normal range of motion of the joint motion core, providing protection without sacrificing mobility. Furthermore, the corrugated elastic shell 8 provides additional, evenly distributed elastic assistance force during joint motion core movement. When the joint motion core is compressed, the corrugated shell is compressed, generating a rebound force that assists in the joint motion core's reset and buffers axial impact loads. This synergistic effect with the elastic deformation of the metal spring-like joint helps to share and buffer the dynamic loads generated by spinal movement, reducing the stress on the joint motion core and contributing to extending the overall lifespan of the device.

[0061] The following combination Figure 9 , Figure 10 and Figure 11 This invention specifically describes the fixation of the lumbar facet joint fusion fixation device on the vertebral structure. (In conjunction with...) Figure 9 and Figure 10 As shown, after the posterior lumbar decompression surgery, the pedicle projection position and screw entry point of the lesion segment (such as L4~L5 or L5~S1) are determined according to the preoperative imaging measurement results. The lumbar facet joint fusion fixation device of the present invention is then placed into the lesion segment. The first connecting titanium plate 1 and the second connecting titanium plate 2 are respectively attached to the spinous process regions of the two vertebrae above and below the lesion segment. Their opposing surface structures are groove-shaped structures adapted to the shape of the spinous process of the vertebral body, which can form a large area of ​​contact with the surface of the spinous process, achieve bone plate morphology matching, and enhance the initial stability after implantation. Two sets of transverse extension arms 5 are symmetrically connected to the two sides of the first connecting titanium plate 1 and the second connecting titanium plate 2, and extend outward in the transverse direction. The end of each transverse extension arm 5 is connected to a cortical bone screw 6 through a detachable structure. The cortical bone screw 6 is implanted into the cortical bone of the corresponding vertebral body along the preset screw track, and the entire device is firmly anchored to the spinal motion segment.

[0062] Specifically, in combination Figure 10 and Figure 11As shown, the insertion point of the cortical bone screw 6 is located at the intersection of a vertical line passing through the center of the superior articular process and a horizontal line 1 mm below the lower edge of the transverse process. Regarding the insertion angle, there is no significant difference from the L1 to L5 segments of the vertebral joint. The preferred insertion angle of the cortical bone screw 6 on the vertebral body is: head tilt angle 8°~9° and abduction angle 25°~26°. The cortical bone screw 6, implanted according to the screw track, contacts and passes through four cortical bone points during its traversal of the vertebral body, thereby forming a sufficient and multi-point mechanical engagement between the screw thread and the high-density area of ​​the cortical bone. Since the cortical bone layer has a much higher density and mechanical strength than cancellous bone, this fixation method with multiple cortical bone contacts allows the cortical bone screw 6 to exhibit significantly better pull-out force, holding force, and shear resistance than traditional pedicle screws in terms of biomechanical properties.

[0063] It is important to understand that traditional pedicle screw techniques involve insertion along the anatomical axis of the pedicle, relying primarily on the holding effect of the vertebral cancellous bone on the screw for fixation. In cases of osteoporosis, the mechanical properties of cancellous bone are significantly reduced, often leading to a relatively higher rate of fixation failure. Currently, to address this issue in clinical practice, it is often necessary to adopt auxiliary methods such as increasing the fixation segment, using HOOK reinforcement, expansion screws, HA-coated screws, or cement-reinforced screws. However, these methods inevitably bring new clinical challenges such as increased trauma, accelerated degeneration of adjacent segments, and increased difficulty in revision surgery. To address this deficiency, the lumbar facet joint fusion fixation device of the present invention uses a cortical bone screw 6. The cortical bone screw 6 can use existing universal cortical bone screw products, and its specifications (including diameter, length, etc.) can be flexibly selected according to the patient's preoperative imaging measurement results and the specific situation during the operation. The cortical bone screw 6 can achieve stable fixation in patients with osteoporosis without additional reinforcement measures, which can effectively avoid the above-mentioned defects, improve the applicability of the device and the long-term fixation success rate. Especially for patients with osteoporosis, because cortical bone has a higher density and strength than cancellous bone, even if bone quality declines, the cortical bone screw 6 can still achieve a reliable anchoring effect, which can reduce the risk of screw loosening or dislodgement after surgery.

[0064] After the four cortical bone screws 6 in two sets are fixed to the bilateral cortical bone regions of the upper and lower vertebral bodies, the transverse extension arm 5 stably transmits the anchoring force of the screws to the first connecting titanium plate 1 and the second connecting titanium plate 2. Then, the articular motion core realizes the movable connection between the upper and lower connecting titanium plates, ultimately providing reliable fixation while preserving the physiological range of motion of the spinal segment. The transverse extension arm 5 and the cortical bone screws 6 adopt a detachable connection structure (such as a threaded interface or a snap-fit ​​interface). On the one hand, it is convenient to select an appropriate length of extension arm and screw for matching during the operation. On the other hand, if local components are found to be loose or damaged during postoperative follow-up, the corresponding cortical bone screw 6 or transverse extension arm 5 can be removed and replaced separately without removing the entire prosthesis, thereby reducing the trauma and difficulty of secondary revision surgery.

[0065] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A lumbar facet joint fusion fixation device, characterized in that, include: A first connecting titanium plate (1) and a second connecting titanium plate (2) are arranged opposite to each other. The joint motion core is disposed between the first connecting titanium plate (1) and the second connecting titanium plate (2). The joint motion core includes a sliding groove (3) and a sliding block (4). The first end of the sliding groove (3) is fixed to the first connecting titanium plate (1), and the second end of the sliding groove (3) forms an elastic groove. The first end of the sliding block (4) is fixed to the second connecting titanium plate (2), and the second end of the sliding block (4) is movably inserted into the elastic groove of the sliding groove (3). Two sets of extension arms, each set of extension arms including two lateral extension arms (5), wherein the two lateral extension arms (5) of one set of extension arms are symmetrically and detachably connected to both sides of the first connecting titanium plate (1), and the two lateral extension arms (5) of the other set of extension arms are symmetrically and detachably connected to both sides of the second connecting titanium plate (2). A cortical bone screw (6) is detachably connected to the transverse extension arm (5) for implantation into the cortical bone of the vertebral body.

2. The lumbar facet joint fusion fixation device according to claim 1, characterized in that, The slide rail (3) includes a slide rail body connecting part (31) and a groove part (32). The slide rail body connecting part (31) is fixedly connected to the first connecting titanium plate (1). The groove part (32) is connected to the side of the slide rail body connecting part (31) away from the first connecting titanium plate (1). The groove part (32) forms the elastic slide rail extending along its axial direction. The slider (4) includes a slider connecting part (41) and a slider part (42). The slider connecting part (41) is fixedly connected to the second connecting titanium plate (2). The slider part (42) is connected to the side of the slider connecting part (41) away from the second connecting titanium plate (2). The slider part (42) is movably inserted into the elastic groove.

3. The lumbar facet joint fusion fixation device according to claim 2, characterized in that, Both the slide rail (3) and the slider (4) are made of medical titanium alloy / cobalt chromium alloy. The elastic slide rail has a spiral through notch (33) on its groove wall so that the groove part (32) of the slide rail (3) is formed into a spring-like structure.

4. The lumbar facet joint fusion fixation device according to claim 3, characterized in that, The joint motion core also includes a limiting band (7), the first end of which is connected to the outside of the first end of the sliding groove (3), and the second end of which is connected to the outside of the first end of the sliding block (4). A limiting protrusion (34) is formed at the opening of the elastic groove, and the limiting protrusion (34) fits against the outer peripheral surface of the slider (42). The limiting band (7) and the limiting protrusion (34) are located on the same side of the joint movement core and are used to limit the flexion and extension of the joint movement core.

5. The lumbar facet joint fusion fixation device according to claim 4, characterized in that, The limiting band (7) is made of ultra-high molecular weight polyethylene. At least two limiting bands (7) are provided, and they are arranged in parallel to limit the excessive flexion of the joint movement core.

6. The lumbar facet joint fusion fixation device according to claim 4, characterized in that, The limiting protrusion (34) is an arc-shaped stop, and the arc-shaped part of the arc-shaped stop abuts against the outer peripheral surface of the slider part (42) to limit the overextension of the joint motion core.

7. The lumbar facet joint fusion fixation device according to claim 3, characterized in that, The slider part (42) is provided with limiting bosses (43) on both sides of the end near the slider connecting part (41). The limiting bosses (43) are used to limit the lateral bending angle of the joint motion core.

8. The lumbar facet joint fusion fixation device according to claim 3, characterized in that, The elastic groove of the groove part (32) is flat, and the shape of the slider part (42) is adapted to the elastic groove. The slider part (42) and the groove part (32) are movably inserted and form a gap fit. The shape contour of the groove part (32) and the slider part (42) forms an axial rotation limit for the joint motion core.

9. The lumbar facet joint fusion fixation device according to any one of claims 1 to 8, characterized in that, The surfaces of the first connecting titanium plate (1) and the second connecting titanium plate (2) facing away from each other are formed into groove-shaped structures adapted to the shape of the spinous process of the vertebra. The surfaces of the first connecting titanium plate (1) and the second connecting titanium plate (2) facing each other are provided with annular grooves for fixing the sliding groove (3) or the sliding block (4).

10. The lumbar facet joint fusion fixation device according to any one of claims 1 to 8, characterized in that, The lumbar facet joint fusion fixation device also includes a corrugated elastic shell (8), which is connected between the first connecting titanium plate (1) and the second connecting titanium plate (2) and is wrapped around the joint motion core to protect the joint motion core and form an elastic buffer for the joint motion core.

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