Lumbar intervertebral fixing device

Abstract

The lumbar intervertebral fixing device comprises a connecting rod and two fasteners, the two fasteners are arranged in a spaced mode and each provided with a screw seat, the connecting rod is connected with the two screw seats, the connecting rod is provided with a stress concentration area, and the stress concentration area is located between the two screw seats. Due to the fact that the stress concentration area is arranged on the connecting rod, compared with an existing common straight connecting rod, the rigidity of the connecting rod is obviously reduced, fixing support needed by the spine can be provided at the initial stage, meanwhile, a good stress environment is provided, the stress shielding effect caused by the too large rigidity of the spine posterior fixing device is avoided, and the spine posterior fixing device is not prone to damage. And the problems of bone mass reduction and the like caused by stress shielding are prevented. When the degree of bone healing is reached, a larger load such as rotation, stooping and jumping can be applied to the connecting rod through strengthening exercise, or the connecting rod is controlled to be broken in time from a stress concentration area in an external auxiliary mode, and a larger range of activity is provided for the lumbar vertebra.

Description

Technical Field

[0001] The utility model relates to the technical field of medical equipment, in particular to a lumbar intervertebral fixation device. Background Art

[0002] Spinal interbody fusion systems are widely used in the field of spinal surgery. In order to accelerate bone fusion after the insertion of spinal implants, an interbody fusion device needs to be implanted during surgery. The interbody fusion device expands the intervertebral space, restores the tension between the annulus fibrosus, the anterior and posterior longitudinal ligaments of the spine, the muscles and the joint capsule, forms a "expansion-compression tension band" effect, and instantly stabilizes the spine, creating conditions for bone grafting and fusion, and reconstruction of the spinal sequence.

[0003] However, there are also some problems with the clinical application of fusion devices. After implantation, the fusion device is usually fixed by driving two pedicle screws on one side into the upper and lower vertebrae respectively, while the traditional connecting rod uses an ordinary cylindrical connecting rod to connect the two pedicle screws on one side. The intervertebral fixation device formed in this way is prone to stress shielding effect, affecting the osteoblastic fusion process, causing delayed vertebral healing, bone loss or osteoporosis in patients. In addition, due to the large rigidity of the straight connecting rod, although it meets the need for immediate stability during surgery, it also greatly limits the patient's lumbar mobility after surgery. Especially after a period of time after the completion of osteoblastic fusion, the internal fixation system loses its fixation significance, and a secondary operation is required to remove the internal fixation system. In view of the problems existing in the current clinical use of intervertebral fusion devices, some solutions have been provided in the prior art, including improvements to the intervertebral fusion device and the screw-rod system. For example, patent document CN217338997U discloses a fixation device for a lumbar intervertebral fusion device. The fusion cage is connected to the upper and lower vertebral bodies through vertebral screws, fusion cage fixing screws, and longitudinal connecting rods. This can limit the movement of the fusion cage to a certain extent, and on the other hand, it reduces the stress at the interface between the fusion cage and the end plate, which helps prevent the end plate collapse caused by excessive interface stress after intervertebral fusion surgery. However, the structural rigidity is relatively large, and the stress shielding effect of the system on the autologous bone is not taken into account, which is not conducive to the bone fusion between the upper and lower vertebrae after surgery.

[0004] In addition, patent document CN217448144U discloses a 3D printed trabecular self-locking intervertebral fusion device. Its elastic modulus is equivalent to that of the human bone structure, which can induce bone growth and promote intervertebral fusion. It can also carry growth factors to promote bone healing. After locking, it can obtain good immediate stability without the need for a nail-rod system. However, this structure of the fusion device limits the range of motion between vertebrae, resulting in the patient still unable to perform normal spinal movements after completing bone reconstruction. Moreover, once the self-locking system fails, the fusion device is at risk of dislocation.

[0005] In this context, how to design an intervertebral fusion system that can meet the immediate stability requirements, retain a certain vertebral mobility for patients after bone reconstruction, and is effective and safe without the need for secondary surgery to remove it is a problem that urgently needs to be solved by existing technologies. Utility Model Content

[0006] The utility model provides a lumbar intervertebral fixation device, which can solve the problems of stress shielding effect of the existing lumbar intervertebral fixation device on autologous bone and restriction of the freedom of movement of the patient's lumbar spine.

[0007] This application provides the following technical solutions:

[0008] A lumbar intervertebral fixation device comprises: a connecting rod and two fasteners, the two fasteners are arranged at intervals, the two fasteners each have a nail seat, the connecting rod connects the two nail seats respectively, the connecting rod has a stress concentration area, and the stress concentration area is located between the two nail seats.

[0009] Furthermore, the connecting rod is configured with a groove which surrounds the connecting rod, and the portion of the connecting rod corresponding to the bottom of the groove is the stress concentration area.

[0010] Furthermore, the groove has a first groove wall and a second groove wall intersecting each other, the intersection of the first groove wall and the second groove wall forms the groove bottom of the groove, and the side of the first groove wall and the second groove wall away from the intersection forms the groove opening of the groove.

[0011] Furthermore, the connecting rod gradually becomes thinner from both ends of the connecting rod to the middle area of ​​the connecting rod, and the thinnest part of the connecting rod is the stress concentration area.

[0012] Furthermore, the connecting rod has a porous section, and the porous section is the stress concentration area.

[0013] Furthermore, a protective cover is sleeved on the connecting rod, the protective cover covers the porous section, two ends of the protective cover are fixed on the connecting rod, and the rigidity of the protective cover is higher than the rigidity of the porous section.

[0014] Furthermore, the connecting rod includes a rod body and two sleeves, the two sleeves are respectively detachably assembled on the two nail seats, the stress concentration area is located on the rod body, both ends of the rod body are respectively inserted into the two sleeves, and the two ends of the rod body can move relative to the two sleeves.

[0015] Furthermore, both ends of the rod body have ball heads, and the two ball heads are respectively inserted into the two sleeves; and / or, the nail seat is constructed with a threaded hole and a side opening that are interconnected, the sleeve extends from the side opening into the threaded hole, and a retaining nut is threadedly connected to the threaded hole, and the sleeve is clamped between the retaining nut and the bottom of the threaded hole.

[0016] Furthermore, the two fasteners each have a nail rod connected to the respective nail seat, and the lengths of the two nail rods are different.

[0017] Furthermore, the length difference between the two nail rods is 1 to 3 mm.

[0018] By adopting the above technical solution, the present application has the following beneficial effects:

[0019] After the patient's lumbar spine is implanted with a fusion device and the fixing device of the present application, since the connecting rod of the present application has a stress concentration area, its stiffness is significantly reduced compared to the existing ordinary straight connecting rod, which can provide the fixed support required by the spine in the early stage, and also provide a relatively good stress environment, avoiding the stress shielding effect caused by the excessive stiffness of the posterior spinal fixation device, preventing the occurrence of problems such as reduced bone mass caused by stress shielding, and better promoting bone fusion. When the patient himself reaches the level of bone healing, a greater load can be applied to the connecting rod through enhanced exercise, such as turning, bending, jumping and other actions, or by external auxiliary application of physical fields, the connecting rod can be controlled to break in the stress concentration area in time, eliminating the restraint on the lumbar spine, providing the lumbar spine with greater mobility, and meeting the needs of daily life. And because the connecting rod can be broken in the patient's body, there is no need for a second surgery to remove the fixing device to ensure the freedom of movement of the lumbar spine, thereby reducing patient trauma and reducing economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are part of this application and are used to provide a further understanding of the utility model. The schematic embodiments of the utility model and their descriptions are used to explain the utility model, but do not constitute an improper limitation of the utility model. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of the structure of a lumbar intervertebral fixation device provided by an embodiment of the utility model;

[0022] Figure 2 A schematic diagram of a connecting rod of a lumbar intervertebral fixation device provided in an embodiment of the utility model;

[0023] Figure 3A side view of a lumbar intervertebral fixation device provided by an embodiment of the utility model;

[0024] Figure 4 An exploded schematic diagram of a lumbar intervertebral fixation device provided by an embodiment of the utility model;

[0025] Figure 5 A schematic diagram of a protective cover mounted on a connecting rod of a lumbar intervertebral fixation device provided by an embodiment of the utility model;

[0026] Figure 6 A schematic diagram of the porous structure adopted by the porous section of the connecting rod of the lumbar intervertebral fixation device provided in an embodiment of the utility model.

[0027] In the figure: 1, connecting rod; 11, rod body; 12, sleeve body; 2, fastener; 21, nail seat; 22, nail rod; 23, retaining nut; 3, groove; 4, protective cover; 5, ball head; 6, threaded hole; 7, side opening; 8, porous structure. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. The following embodiments are used to illustrate the utility model but are not used to limit the scope of the utility model.

[0029] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] See also Figures 1 to 6 As shown, an embodiment of the present application provides a lumbar intervertebral fixation device, including a connecting rod 1 and two fasteners 2, the two fasteners 2 are arranged at an interval, the two fasteners 2 both have a nail seat 21, the connecting rod 1 is respectively connected to the two nail seats 21, the connecting rod 1 has a stress concentration area, and the stress concentration area is located between the two nail seats 21.

[0032] In the above scheme, since the traditional straight connecting rod has a large rigidity, after the implant, the stress of the vertebral part will be transmitted through the connecting rod, which can provide immediate stability in the early stage of the operation. However, during the bone fusion process, the rigidity of the connecting rod will not be dynamically adjusted to adapt to the body's bone reconstruction process, which will cause the stress to be transmitted along the posterior spine, and the transmission effect of the force on the anterior column of the spine will be weakened. Due to the lack of certain stress stimulation between the vertebrae, the bone fusion effect is not good. Even if the bone reconstruction process can be completed normally, the patient's lumbar spine is restricted by the internal fixation system and cannot resume normal activities, and a second operation is required to remove it. After the patient's lumbar spine is implanted with a fusion device and the fixing device of the present application, since the connecting rod 1 of the present application has a stress concentration area, its rigidity is significantly reduced compared to the existing ordinary straight connecting rod, which can provide the required fixed support for the spine in the early stage, and also provide a relatively good stress environment, avoiding the stress shielding effect caused by the excessive rigidity of the posterior spine fixation device, preventing the occurrence of problems such as bone loss caused by stress shielding, and better promoting bone fusion. When the patient reaches the degree of bone healing, a greater load can be applied to the connecting rod 1 through strengthening exercises, such as turning, bending, jumping and other movements, or by external auxiliary application of physical fields, the connecting rod 1 can be controlled to break in the stress concentration area in time, eliminating the restraint on the lumbar spine, providing the lumbar spine with greater mobility, and meeting the needs of daily life. Moreover, because the connecting rod 1 can be broken in the patient's body, there is no need for a second surgery to remove the fixation device to ensure the freedom of movement of the lumbar spine, thereby reducing patient trauma and reducing economic costs.

[0033] As a first embodiment of the stress concentration area in the connecting rod 1 , the connecting rod 1 gradually becomes thinner from both ends of the connecting rod 1 to the middle area of ​​the connecting rod 1 , and the thinnest part of the connecting rod 1 is the stress concentration area.

[0034] In the above scheme, because the thinnest part of the connecting rod 1 is the most fragile and easy to break, the thinnest part of the connecting rod 1 is the stress concentration area. The connecting rod 1 adopts this structure of thick ends and thin middle, which is a relatively simple design method for the emergence of stress concentration areas, and its processing and manufacturing are also relatively simple. Among them, from the two ends of the connecting rod 1 to the middle area of ​​the connecting rod 1, the connecting rod 1 gradually becomes thinner, which means that the diameter of the connecting rod 1 gradually decreases. The thinnest part of the connecting rod 1 is also the area with the smallest diameter of the connecting rod 1. Of course, the thinnest part is as far as possible in the middle position of the length direction of the connecting rod 1.

[0035] See also Figure 2 and Figure 4 As shown, as the second embodiment of the stress concentration area of ​​the connecting rod 1, a groove 3 is constructed on the connecting rod 1 around itself, and the part of the connecting rod 1 corresponding to the bottom of the groove 3 is the stress concentration area.

[0036] In the above scheme, by constructing the groove 3 on the connecting rod 1, the portion corresponding to the bottom of the groove 3 is the area with the smallest diameter on the connecting rod 1, which is most likely to break, and naturally forms a stress concentration area of ​​the connecting rod 1. This is also a relatively simple design method. Of course, the groove 3 is located in the middle of the length direction of the connecting rod 1 as much as possible. Further, on the basis of the first embodiment, the groove 3 can also be constructed at the thinnest part of the connecting rod 1, that is, the connecting rod 1 is thick at both ends and thin in the middle, so that it is easier to form a stress concentration area.

[0037] Specifically, the groove 3 has a first groove wall and a second groove wall intersecting each other, the intersection of the first groove wall and the second groove wall forms the groove bottom of the groove 3, and the side of the first groove wall and the second groove wall away from the intersection forms the groove opening of the groove 3.

[0038] In the above scheme, the first groove wall and the second groove wall intersect so that the groove 3 is a V-shaped groove. Preferably, the angle formed between the first groove wall and the second groove wall is 60°, that is, the sharp angle at the bottom of the V-shaped groove is a sharp angle of 60°, and the depth of the V-shaped groove is 1mm, and the diameter of the connecting rod 1 corresponding to the deepest part of the V-shaped groove is 1mm. According to fatigue analysis theory, there is a stronger stress concentration at the tip of the V-shaped groove, so there is stress concentration in the middle of the connecting rod 1, and the diameter of the material at the V-shaped groove is small, the corresponding fatigue life is short, and fatigue fracture is more likely to occur. That is, applying a corresponding number of cyclic loads to the part can control its fatigue fracture, and the flexion, extension and torsion and scoliosis of the human spine can be used as a way to apply cyclic loads, so that obvious stress concentration occurs at the V-shaped groove. The groove 3 can be manufactured by turning technology, and the depth of the groove 3 can also be personalized according to the patient's own needs and doctor's evaluation to adjust the strength of the stress concentration area to meet the patient's personalized needs. It should be noted that the connecting rod 1 can be made of metal Ti-6A1-4V with good biocompatibility and low elastic modulus. Since the connecting rod 1 is made of a brittle metal material, substantially no debris will be generated when the groove 3 is broken, thereby ensuring safety.

[0039] As a third embodiment of the stress concentration area in the connecting rod 1 , the connecting rod 1 has a porous section, and the porous section is the stress concentration area.

[0040] In the above solution, the porous section of the connecting rod 1 is the porous structure 8. The material properties of the porous structure 8 are basically consistent with those of human trabeculae and have good mechanical properties. The porous structure 8 can be a porous titanium alloy structure. Figure 6As shown, its porosity ranges from 50% to 80%, and the yield strength basically reaches the level of human bone mechanics. The design parameters of the porous structure 8 include pore size and porosity, and the porous microstructure design has an important influence on the mechanical properties of the structure. Studies have shown that the elastic modulus and compressive strength of the porous structure 8 will decrease with the increase of porosity. In this device, the porous structure 8 is mainly subjected to axial pressure. The porous titanium will deform and collapse during the compression process. Due to the strain accumulation effect, the length of some microstructures gradually shortens until they break and fail. There are stress concentration points inside the porous structure 8. These parts will undergo fatigue fracture after being subjected to cyclic loads for a certain period of time. The fatigue cracks extend along the weakest part of the porous structure 8, eventually leading to the failure of the entire porous structure 8. According to needs, a larger load can be applied to the structure in a targeted manner, and an in vitro physical field intervention method can also be used to make the mechanical structure of the porous structure 8 fail.

[0041] See also Figure 5 As shown, a protective cover 4 is sleeved on the connecting rod 1, and the protective cover 4 covers the porous section. Both ends of the protective cover 4 are fixed on the connecting rod 1, and the rigidity of the protective cover 4 is higher than that of the porous section.

[0042] In the above scheme, the protective cover 4 can be a hollow cylindrical shape, which can also be called a mesh cage. The protective cover 4 can be made of the same titanium alloy as the connecting rod 1, such as Ti-6Al-4V. The two ends of the protective cover 4 are fixed to the connecting rod 1 by welding or other non-detachable connection methods, and the porous section is completely wrapped inside. Other forms of loads generated by vertebral movement are mainly borne by the external protective cover 4. The external protective cover 4 has a dense mesh structure, which can prevent the debris generated when the porous structure 8 breaks from falling into the intervertebral space and causing adverse effects on the patient. At the same time, the material stiffness of the protective cover 4 is higher than that of the porous structure 8, and its yield strength is higher than the vertebral load of the human body in daily activities. Since the porous structure 8 has a certain porosity, the overall fatigue resistance of the material is weaker than that of the dense protective cover 4. Therefore, the porous structure 8 fails before the protective cover 4. After the porous structure 8 fails, its overall stiffness is greatly reduced, achieving the effect of semi-rigid fixation. Further, the porous structure 8 occupies the entire interior of the protective cover 4, and can withstand the vertebral pressure to a certain extent without collapse. After the porous structure 8 is broken, the mesh structure of the external protective cover 4 can provide a certain connection function, and the entire connecting rod 1 will not completely lose its connection function, but the failure of the porous structure 8 greatly reduces the stiffness of the connecting rod 1, thereby reducing the stress shielding phenomenon. As a preferred embodiment, the porosity of the mesh structure of the protective cover 4 is greater than 80%, and the pore size is about 150μm, which is equivalent to the trabecular structure of the human body, so that X-rays can pass through, which is conducive to postoperative radiographic observation.

[0043] See also Figure 2 and 4As shown, the connecting rod 1 includes a rod body 11 and two sleeves 12. The two sleeves 12 are respectively detachably assembled on two nail seats 21. The stress concentration area is on the rod body 11. The two ends of the rod body 11 are respectively inserted into the two sleeves 12, and the two ends of the rod body 11 can move relative to the two sleeves 12.

[0044] In the above scheme, by designing the connecting rod 1 as a combination of a rod body 11 and two sleeve bodies 12, and the two ends of the rod body 11 can move relative to the two sleeve bodies 12, the connecting rod 1 has a certain degree of mobility relative to the rigid fixation of the ordinary straight rod, which improves the patient's lumbar mobility to a certain extent, further reduces the stress shielding effect caused by the excessive rigidity of the fixing device, and is more conducive to bone integration. When the stress concentration area is a porous structure 8, preferably, the porous structure 8 and the rod body 11 are integrally manufactured using 3D printing technology.

[0045] See also Figure 2 and 4 As shown, both ends of the rod body 11 are provided with ball heads 5 , and the two ball heads 5 are respectively inserted into the two sleeve bodies 12 .

[0046] In the above scheme, the sleeve 12 completely wraps the ball head 5, and the diameter of the ball head 5 is slightly larger than the inner diameter of the sleeve 12, that is, the ball head 5 and the sleeve 12 are slightly interference fit, which allows the ball head 5 to have a certain small rolling or rotating range of motion in the sleeve 12, and also ensures that the rod 11 will not fall out of the sleeve 12. The way in which the ball head 5 is stuck in the sleeve 12 makes the movement direction of the rod 11 relative to the two sleeves 12 more variable, further improving the patient's lumbar spine mobility.

[0047] See also Figure 4 As shown, the nail seat 21 is constructed with a threaded hole 6 and a side opening 7 that are interconnected. The sleeve 12 extends from the side opening 7 into the threaded hole 6. A retaining nut 23 is threadedly connected to the threaded hole 6. The sleeve 12 is clamped between the retaining nut 23 and the bottom of the threaded hole 6.

[0048] In the above scheme, the retaining nut 23 is screwed into the threaded hole 6 of the nail seat 21 to tighten the sleeve 12, so that there is no relative sliding between the sleeve 12 and the nail seat 21, and the sleeve 12 can be detachably assembled in the nail seat 21 through the cooperation of the retaining nut 23 and the nail seat 21. It should be noted that the shape of the side opening 7 is a combination of a semicircle and a rectangle, and the sleeve 12 can be placed in the semicircle at the bottom of the side opening 7, and then the retaining nut 23 is tightened. Preferably, the outer diameter of the sleeve 12 is the same as the diameter of the semicircle, which can prevent the sleeve 12 from shaking left and right when assembled in the nail seat 21. At the same time, the side opening 7 can also be opened as two, which are respectively located on the left and right sides of the threaded hole 6, so that the sleeve 12 can be placed in the nail seat 21 from two directions, which is more convenient for the sleeve 12 to be assembled in the nail seat 21.

[0049] See also Figure 1 and Figure 4 As shown, both fasteners 2 have a nail rod 22 connected to their respective nail seats 21, and the lengths of the two nail rods 22 are different. For the fastener 2, the longer its nail rod 22 is, the greater the rigidity of the fastener 2 is, the deeper the pitch on the nail rod 22 is, and the more it can increase the bone integration ability. Existing studies have shown that after the implantation of the intervertebral fusion system, the stress on the lower vertebral body is greater. Therefore, the nail rods 22 of the two fasteners 2 are designed to have different lengths. The fastener 2 with a shorter nail rod 22 can be fixed in the upper vertebral body, and the fastener 2 with a longer nail rod 22 can be fixed in the lower vertebral body to better share the stress borne by the lower vertebral body. Preferably, according to clinical needs, the length difference of the two nail rods 22 can be designed to be 1 to 3 mm. Among them, the fastener 2 can also use the metal Ti-6Al-4V with good biocompatibility and low elastic modulus.

[0050] For personalized settings based on the patient's own needs and doctor's evaluation, in order to adjust the strength of the stress concentration area to meet the patient's personalized needs, the stress conditions of the fixation device and vertebral body implanted in the patient can be simulated and calculated by finite element software before surgery, and the stress conditions of the connecting rod 1 can be fatigue analyzed to calculate the theoretical fracture time of the stress concentration area. According to the stress conditions and fatigue time of the groove 3 obtained by finite element analysis, combined with the individual patient's bone mass and disease severity, the fastener 2 and connecting rod 1 that best match the patient's own situation can be designed. The adjustable parameters include the thread depth on the nail rod 22 of the fastener 2, the length of the fastener 2, and the strength of the stress concentration area on the rod body 11. After adjusting the design, the finite element analysis of the stress conditions and the damage life analysis are performed again, and the structural optimization is repeated until all parameters meet the use requirements to ensure its stability and reliability. The fatigue life of the stress concentration area can be carefully adjusted through parameter design. When the preliminary design does not meet the needs of the patient, the theoretical fatigue time of the material can be adjusted by changing the depth of the groove 3, the angle of the bottom sharp angle of the groove 3, or the porosity of the porous structure 8, etc., to ensure that the theoretical fatigue time is longer than the bone reconstruction period.

[0051] The installation process of the fixing device of the present application on the lumbar spine is as follows: after removing the intervertebral disc of the patient with lumbar degenerative disease in the posterior lumbar fusion surgery, a fusion device is inserted between the upper and lower vertebral bodies, and the fixing device is used for fixation in the posterior route. The preferred embodiment is to insert four fasteners 2 in the direction parallel to the upper and lower surfaces of the vertebral body at the pedicle, and respectively place the sleeves 12 of the two sets of assembled connecting rods 1 into the four screw seats 21, and respectively screw in their respective retaining nuts 23 to fix the connecting rods 1.

[0052] During the postoperative rehabilitation process, regular imaging examinations are performed to observe bone integration and rod fatigue, and rehabilitation guidance is given to patients. After the patient is considered to have completed the bone reconstruction process through medical imaging assessment, a greater load can be applied to the rod 11 through enhanced exercise to accelerate the fatigue process of the stress concentration area of ​​the rod 11. In order to achieve the best effect during the postoperative period, patients should strictly follow the doctor's instructions for daily rehabilitation activities.

[0053] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details in detail, nor do they limit the present application to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can understand and use the present application well. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A lumbar intervertebral fixation device, characterized in that: include: A connecting rod and two fasteners, the two fasteners are arranged at intervals, the two fasteners each have a nail seat, the connecting rod connects the two nail seats respectively, the connecting rod has a stress concentration area, and the stress concentration area is located between the two nail seats.

2. The lumbar intervertebral fixation device according to claim 1, characterized in that: The connecting rod is provided with a groove which goes around the connecting rod, and the portion of the connecting rod corresponding to the bottom of the groove is the stress concentration area.

3. The lumbar intervertebral fixation device according to claim 2, characterized in that: The groove has a first groove wall and a second groove wall intersecting each other, the intersection of the first groove wall and the second groove wall forms the groove bottom of the groove, and the side of the first groove wall and the second groove wall away from the intersection forms the notch of the groove.

4. The lumbar intervertebral fixation device according to claim 1, characterized in that: The connecting rod gradually becomes thinner from both ends of the connecting rod to the middle area of ​​the connecting rod, and the thinnest part of the connecting rod is the stress concentration area.

5. The lumbar intervertebral fixation device according to claim 1, characterized in that: The connecting rod has a porous section, and the porous section is the stress concentration area.

6. The lumbar intervertebral fixation device according to claim 5, characterized in that: A protective cover is sleeved on the connecting rod, the protective cover covers the porous section, two ends of the protective cover are fixed on the connecting rod, and the rigidity of the protective cover is higher than the rigidity of the porous section.

7. The lumbar intervertebral fixation device according to any one of claims 1 to 6, characterized in that: The connecting rod includes a rod body and two sleeves, the two sleeves are respectively detachably assembled on the two nail seats, the stress concentration area is located on the rod body, the two ends of the rod body are respectively inserted into the two sleeves, and the two ends of the rod body can move relative to the two sleeves.

8. The lumbar intervertebral fixation device according to claim 7, characterized in that: Both ends of the rod body have ball heads, and the two ball heads are respectively inserted into the two sleeves; and / or, the nail seat is constructed with a threaded hole and a side opening that are interconnected, the sleeve body extends from the side opening into the threaded hole, and a retaining nut is threadedly connected to the threaded hole, and the sleeve body is clamped between the retaining nut and the bottom of the threaded hole.

9. The lumbar intervertebral fixation device according to any one of claims 1 to 6, characterized in that: The two fasteners each have a nail rod connected to the respective nail seats, and the lengths of the two nail rods are different.

10. The lumbar intervertebral fixation device according to claim 9, characterized in that: The length difference between the two nail rods is 1 to 3 mm.

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