Internal fixation device for total laminectomy

Abstract

The invention discloses an internal fixation device for total laminectomy, which belongs to the technical field of medical instruments for orthopedics department and comprises two bases, the two bases are an upper base and a lower base, the top end of the lower base is connected with the bottom end of the upper base through an elastic body, so that the upper base can deflect relative to the lower base, and the elastic body is arranged on the upper base; the axial distance between the upper base and the lower base can be changed; an upper spinous process connecting part is arranged at the top end of the upper base, a first fastening piece is arranged on the upper spinous process connecting part, and the first fastening piece extends in the left side direction and the right side direction of the upper base and is connected with the upper spinous process connecting part; by the adoption of the structure, vertebrae subjected to a total laminectomy and adjacent upper and lower vertebrae can be effectively connected, the stability of the spine is guaranteed while the activity degree of the spine is guaranteed, the vertebral plate connecting device adapts to the physiological structure of the vertebrae after the operation, and the vertebral plate connecting device has the advantages that the vertebral plate connecting device is simple in structure, convenient to use and high in practicability. And the damage to the surrounding physiological structure is small.

Description

Technical Field

[0001] This application relates to the field of orthopedic medical device technology, specifically to an internal fixation device for total laminectomy. Background Technology

[0002] Total laminectomy is a spinal surgery that removes the lamina to relieve nerve compression within the spinal canal. It is suitable for conditions such as severe spinal stenosis, herniated discs with calcification, spinal tumors, or traumatic spinal injuries. The surgery expands the spinal canal by removing the lamina, but it may affect spinal stability and requires the assistance of internal fixation or fusion.

[0003] Total laminectomy damages the posterior structures of the spine, including the lamina, spinous processes, and ligamentum flavum, which play a crucial role in maintaining spinal stability. After resection, the spine's biomechanical structure changes, leading to decreased stability. This decreased spinal stability may accelerate degeneration in adjacent segments, increasing the risk of conditions such as herniated discs and vertebral slippage in those segments, and impacting the patient's long-term quality of life.

[0004] If a rod-and-pin fixation system using flexible or rigid connecting rods in conjunction with pedicle screws is used, it is difficult to bend the rod according to the actual curvature of the spine, which affects the flexibility of the spine. Furthermore, the rod-and-pin system requires the placement of pedicle screws on multiple vertebrae, resulting in greater trauma and affecting the patient's postoperative recovery speed.

[0005] Interspinous spreading devices (such as Coflex, X) STOP (or similar devices) are elastic structures fixed to the interspinous space. Their main function is to open the interspinous space, enlarge the intervertebral foramen, increase the load on the posterior column, shift the lumbar spine's force line forward, and relieve pressure on the lumbar intervertebral discs. Their indications are relatively narrow, primarily suitable for patients with mild lumbar disc herniation, intervertebral foramen stenosis, no significant lumbar instability, and intact posterior lumbar columns. They are not suitable for patients with lumbar disc herniation with significant disc height reduction, severe lumbar spinal stenosis, or lumbar instability. Furthermore, for patients with lumbar instability, the interspinous spacer's restraining effect on posterior spinal stretching is weak when the spine flexes forward, and the spinous processes must withstand significant forces. Summary of the Invention

[0006] In order to ensure spinal stability while preserving the mobility of spinal segments, reduce stress concentration in the internal fixation system, and decrease the risk of adjacent segment degeneration and internal fixation fracture after the placement of an internal fixation device during total laminectomy, and to be applicable to patients requiring total laminectomy, this application provides an internal fixation device for total laminectomy that ensures spinal stability and reduces stress concentration in surrounding spinal segments when the spine bends forward, backward, left, or right, or undergoes axial torsion.

[0007] An internal fixation device for total laminectomy includes: two bases, an upper base and a lower base, the top end of the lower base being connected to the bottom end of the upper base via an elastic body, so that the upper base can be deflected relative to the lower base, and the axial distance between the upper base and the lower base can be changed; the top end of the upper base is provided with a superior spinous process connection portion, the superior spinous process connection portion is provided with a first fastener, the first fastener extends along the left and right sides of the upper base and is connected to the superior spinous process connection portion; pedicle screws are provided on the left and right sides of both bases.

[0008] This device is used to connect a vertebra that has undergone total laminectomy, and two adjacent vertebrae, referred to as the superior and inferior vertebrae. The vertebra that underwent total laminectomy is the middle vertebra. The inferior base is connected to the pedicle of the inferior vertebra via pedicle screws on its left and right sides. The superior base is connected to the pedicle of the middle vertebra via pedicle screws on its left and right sides. The superior spinous process connection at the top of the superior base is connected to the spinous process of the superior vertebra via a first fastener, thereby connecting the three vertebrae with minimal trauma. Furthermore, the superior and inferior bases are connected by an elastic body, allowing for deflection and changes in axial distance between the two bases. Thus, when the relative position of the middle and inferior vertebrae changes, the superior and inferior bases can change their relative position accordingly due to the presence of the elastic body. In addition, the fasteners connect the superior vertebra to the superior vertebra, thereby fixing the relative position of the superior and middle vertebrae and preventing degeneration of adjacent segments.

[0009] In one embodiment of this application, a ball joint limiting unit is further provided between the two bases. The ball joint limiting unit includes a ball head structure and a ball socket structure. The ball head structure includes a ball head and a ball rod connected to the ball head, the diameter of which is smaller than that of the ball head. The ball socket structure includes a first channel and a second channel arranged axially. The second channel communicates with the outside through the first channel. The ball head is located in the second channel, and the depth of the second channel is greater than the diameter of the ball head, so that the ball head can move along the second channel. The diameter of the first channel is greater than the diameter of the ball rod but smaller than the diameter of the ball head. The ball rod extends to the outside through the first channel and can swing around the center of the ball head within the first channel. One of the two bases is provided with a ball head structure and connected to the ball rod in the ball head structure, and the other is provided with a ball socket structure and connected to the second channel in the ball socket structure.

[0010] This application enables the ball head to move linearly relative to the second channel, allowing for changes in the axial distance between the upper and lower bases. Furthermore, the ball head can rotate relative to the second channel, and the rod can swing within the first channel, enabling deflection between the upper and lower bases. This design not only improves the device's adaptability to physiological movements but also prevents excessive displacement of the upper base relative to the lower base through structural constraints, enhancing safety and achieving a balance between motion controllability and safety.

[0011] In one embodiment of this application, connecting rods are pivotally connected to the left and right sides of the base, the axis of the connecting rods is perpendicular to the axis of the base, and the connecting rods can rotate in a direction perpendicular to the axis of the base; the base also includes a locking structure for locking the connecting rods to rotate relative to the base; pedicle screws are connected to the connecting rods, and the axis of the pedicle screws is perpendicular to the axis of the connecting rods.

[0012] By installing rotatable connecting rods on both sides of the base and connecting the pedicle screws to the connecting rods, flexible adjustment of the pedicle screw implantation angle is achieved. The connecting rods can rotate in a plane perpendicular to the base axis, adapting to differences in the anatomical structure of different patients and meeting the requirements for the optimal screw entry angle during surgery.

[0013] In one embodiment of this application, both the base and the connecting rod are provided with polygonal inner holes parallel to the axis of the base. The polygonal inner hole of the connecting rod is arranged radially along the connecting rod. The base is also provided with locking threaded holes coaxially arranged with the two polygonal inner holes. The locking threaded holes are coaxially arranged with the pivot axis of the base and the connecting rod. The internal fixation device for total laminectomy also includes a locking bolt. The locking structure is a polygonal sleeve, which is sleeved on the locking bolt and rotatably connected to the locking bolt. The locking bolt is threadedly connected to the locking threaded hole. When the locking bolt rotates, it drives the polygonal sleeve to simultaneously insert into the two polygonal inner holes to restrict the rotation of the connecting rod relative to the base.

[0014] Compared to methods where locking structures are placed in other locations on the base to lock the connecting rod's rotation relative to the base, this method, which uses a locking threaded hole coaxially with the pivot axis connecting the base and the connecting rod, and a polygonal inner hole and a polygonal sleeve coaxially with the locking threaded hole, eliminates the need for additional structures on the base and connecting rod to accommodate the locking mechanism. This reduces the complexity of the base and connecting rod, facilitating production. It simplifies the spatial layout of the locking mechanism, reduces manufacturing complexity, improves assembly convenience and structural reliability, and ensures uniform transmission of locking force.

[0015] In one embodiment of this application, a locking threaded hole is provided on one side of the connecting rod, and the head end of the locking bolt is provided on the other side of the connecting rod. When the locking bolt is threadedly connected to the locking threaded hole, the head end of the locking bolt applies a force close to the locking threaded hole to the connecting rod, and the locking bolt and the base clamp the connecting rod.

[0016] The locking bolts are installed with their heads on one side of the connecting rod and their threaded ends on the other side. When tightened, they create a clamping force that firmly presses the connecting rod against the base. This structure not only achieves angle locking but also provides anti-disengagement protection, effectively preventing the connecting rod from loosening or accidentally detaching under long-term stress or dynamic loads, thus improving the system's mechanical safety and durability.

[0017] In one embodiment of this application, the pedicle screw includes a collet assembly and a bone screw. The collet assembly includes a housing with a working through hole. The sidewall of the working through hole has a receiving groove around the axis of the working through hole. The bone screw passes through the working through hole. Along the axial direction of the bone screw, the bone screw includes a first mating part disposed in the receiving groove and two second mating parts respectively located at both ends of the first mating part. The axial length of the first mating part is less than the axial length of the receiving groove, the outer diameter is greater than the inner diameter of the working through hole, and the diameter of the first mating part is equal to the diameter of the receiving groove. The sidewall of the first mating part is an outwardly convex arc shape, or the diameter of the first mating part is less than the diameter of the receiving groove. The outer diameter of the second mating part is less than the outer diameter of the working through hole, so that the bone screw can deflect relative to the working through hole and move axially. The receiving groove is also provided with an elastic element to prevent the bone screw from deflecting relative to the working through hole and moving axially.

[0018] When relative movement occurs between the two bases, the bases exert force on the pedicle of the vertebra through the pedicle screws. However, because the screws can swing relative to the working holes and cause deformation of the elastic element, the elastic element can act as a buffer, protecting the pedicle and providing stress buffering and load distribution. This reduces stress concentration at the screw-bone interface, decreases the risk of complications such as bone cutting and screw loosening, and improves long-term fixation. It also reduces the likelihood of internal fixation device loosening in the body, requiring repeat surgery.

[0019] In one embodiment of this application, the pedicle screw includes a bone screw with a hollow structure communicating with its head end. The hollow structure includes an expansion section located at the tail end of the bone screw, and the sidewall of the expansion section can expand outward.

[0020] The bone screw can be anchored to the vertebrae through its outwardly expanding section, ensuring a stable fixation effect.

[0021] In one embodiment of this application, the bone nail has a hollow structure communicating with its head end, and the side wall of the bone nail has a release hole communicating with the hollow structure.

[0022] Growth factors can be released into the vertebrae through the hollow structure and release holes, accelerating bone healing.

[0023] In one embodiment of this application, the outer surface of the bone nail is provided with threads, and the hollow structure is a drive groove for inserting a torsion tool.

[0024] The torsion tool is inserted into the drive slot to rotate the bone screw, providing support and preventing deformation during rotation. When the torsion tool is inserted into the drive slot, the drive slot and the torsion tool fit tightly together, forming a stable force transmission channel. This fit ensures that the torque applied to the bone screw is evenly distributed across the entire structure, preventing localized stress concentration that could cause bending, twisting, or other deformations that would prevent the bone screw from reaching its designated position.

[0025] In one embodiment of this application, the bottom end of the lower base is provided with a lower ratchet connecting part, the lower ratchet connecting part is provided with a second fastener, the second fastener extends along the left and right sides of the upper base and is connected to the lower ratchet connecting part.

[0026] A lower spinous process connection and a second fastener are added to the bottom of the lower base to form a bidirectional connection structure to the spinous process of the lower vertebra, realizing the connection between the lower base and the pedicle and spinous process of the lower vertebra, ensuring the stability of the connection between the lower base and the vertebra. The internal fixation device can be fixed simultaneously with the spinous processes of the upper and lower vertebrae, further enhancing the overall restraint ability of the entire device on the posterior column of the spine, significantly improving the stability against shear and rotation, and more effectively preventing instability and degeneration of adjacent segments. Attached Figure Description

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic structural diagram of one embodiment of the present application; Figure 2 This is a schematic diagram of one possible embodiment of the present application when it is about to be installed in a designated location; Figure 3 This is a schematic diagram illustrating one possible implementation of this application when installed in a designated location; Figure 4 This is a schematic diagram illustrating one embodiment of the ball-head structure of this application; Figure 5 This is a schematic diagram of a possible embodiment of the ball head in the second channel in this application; Figure 6 This is a perspective view illustrating one embodiment of this application; Figure 7 This is a schematic diagram of a possible embodiment of the connecting rod in this application, which is pivotally connected to the base and can move in a swing space. Figure 8 This is a schematic structural diagram of one embodiment of the present application in which the connecting rod is connected to the upper base via a polygonal sleeve and a locking bolt; Figure 9 This is a schematic structural diagram of an embodiment in which the locking bolt, polygonal sleeve, and polygonal inner hole of the connecting rod are coaxial with the polygonal inner hole of the base. Figure 10 This is a schematic structural diagram of one embodiment of the upper and lower bases in this application, where the upper base and lower base are provided with locking bolts, polygonal sleeves, and polygonal inner holes; Figure 11 This is a schematic structural diagram of one embodiment of the housing in the chuck assembly of this application; Figure 12 This is a schematic diagram illustrating one embodiment of the bone nail in this application; Figure 13 This is a schematic structural diagram of one embodiment of the bone nail in this application when it is tilted relative to the outer shell of the clamp assembly; Figure 14 This is a schematic diagram of a structural embodiment in which the expansion head moves toward the tail end of the bone nail, causing the outer wall of the expansion segment to expand outward. Figure 15 This is a schematic diagram of a possible embodiment of the expansion head in this application retracting from the drive groove, causing the outer wall of the expansion section to expand outward.

[0028] Label Explanation: 101. Upper base; 102. Lower base; 103. Elastomer; 104. Upper spinous process connection; 105. First fastener; 106. Lower spinous process connection; 107. Second fastener; 108. Ball head; 109. Club; 110. First channel; 111. Second channel; 201. Connecting rod; 202. Polygonal sleeve; 203. Locking bolt; 204. Locking threaded hole; 205. Polygonal inner hole; 206. Swing space; 301. Pedicle screw; 302. Housing; 303. Tail plug; 304. Bone screw; 305. First mating part; 306. Second mating part; 307. Drive groove; 308. First drive groove section; 309. Expansion section; 310. Second drive groove section; 311. Release hole; 312. Working through hole; 313. Receiving groove; 314. Elastic element; 315. Expansion head; 401. Upper vertebra; 402. Upper spinous process; 403. Middle vertebra; 404. Middle pedicle; 405. Lower vertebra; 406. Lower spinous process. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of this application, specific embodiments of this application are now described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate components with the same or similar structures but the same function.

[0030] In this document, “illustrative” means “serving as an example, illustration or description”, and any illustration or implementation described herein as “illustrative” should not be construed as a more preferred or advantageous technical solution.

[0031] To keep the drawings concise, only the parts relevant to this application are shown schematically in each drawing, and they do not represent the actual structure of the product. In addition, to make the drawings concise and easy to understand, in some drawings, only one of the components with the same structure or function is shown schematically, or only one of them is labeled.

[0032] This device is used to connect the vertebra that has undergone total laminectomy to the two vertebrae adjacent to it above and below. The two vertebrae are named the superior vertebra 401 and the inferior vertebra 405, and the vertebra that has undergone total laminectomy is named the middle vertebra 403.

[0033] See Figure 1An internal fixation device for total laminectomy includes two bases: an upper base 101 and a lower base 102. The top end of the lower base 102 is connected to the bottom end of the upper base 101 via an elastic body 103. The elastic body 103 can be made of materials such as polyetheretherketone (PEEK), or it can be a titanium alloy spring structure that achieves macroscopic elastic behavior through microstructural design, ensuring good biocompatibility, moderate elastic modulus, and durability. Further details are omitted here. The elastic body 103 is fixedly connected to the two bases by bolts or other structures.

[0034] See Figures 1 to 3 Both bases have pedicle screws 301 on their left and right sides. The upper base 101 is connected to the mid pedicle 404 of the mid vertebra 403 via the pedicle screws 301 on its left and right sides, thus fixing the upper base 101 to the mid vertebra 403. The lower base 102 is connected to the pedicle of the lower vertebra 405 via the pedicle screws 301 on its left and right sides, thus fixing the lower base 102 to the lower vertebra 405.

[0035] See Figures 1 to 3 The upper base 101 has a superior spinous process connecting portion 104 at its top end. The superior spinous process connecting portion 104 has a first fastener 105. The first fastener 105 extends along the left and right sides of the upper base 101 and connects to the superior spinous process connecting portion 104. The first fastener 105 can be a bone nail 304 or similar structure. The superior spinous process connecting portion 104 has a hole for the bone nail 304 to pass through. (See [reference]) Figure 2 , Figure 3 The upper spinous process connecting part 104 is provided with a space for the upper spinous process 402 of the upper vertebra 401 to enter. Then, the first fastener 105 and the upper spinous process connecting part 104 are connected by means of threaded connection or riveting, and the first fastener 105 passes through the upper spinous process 402 laterally, so that the upper spinous process connecting part 104 and the upper spinous process 402 are fixedly connected.

[0036] The middle vertebra 403 and the upper vertebra 401 are fixedly connected by the upper base 101 and the upper spinous process connection 104, thereby fixing the relative position of the upper vertebra 401 and the middle vertebra 403 and preventing segmental degeneration of the upper vertebra 401 and the lower vertebra 405. This ensures the stability of the connection between the upper vertebra 401 and the middle vertebra 403 when the spine is flexed.

[0037] Figure 1Point a shows the overall axial direction of the device when the upper base 101 is in a neutral position relative to the lower base 102, at which point the axes of the upper base 101 and the lower base 102 coincide. Because the elastic body 103 can undergo elastic deformation, the upper base 101 can deflect relative to the lower base 102. During spinal bending, stretching, compression, or torsion, the elastic body 103 allows the angle between the axis of the upper base 101 and the axis of the lower base 102 to change, making the axes of the upper base 101 and the lower base 102 non-parallel, thus accommodating the forward, backward, left, and right bending of the spine. Simultaneously, the upper base 101 can also rotate relative to the lower base 102. Figure 1 The axis shown at point a rotates to accommodate the torsion of the spine, thus allowing the deflection movement between the upper base 101 and the lower base 102 to adapt to changes in the spine's angle. The relative position of the upper base 101 and the lower base 102 can change with the position of the middle vertebra 403 relative to the lower vertebra 405, altering the axial position of the upper base 101 and the lower base 102. Figure 1 The distance at point a (as shown in the diagram) preserves the flexibility between the mid-vertebra 403 and the lower-vertebra 405. Simultaneously, the elastomer 103 can undergo elastic deformation during this process, providing elastic force to ensure the stability of the posterior spinal column and acting as a buffer, thus protecting the spine and further reducing the possibility of segmental degeneration of the mid-vertebra 403. During forward flexion, the lower-vertebra 405 provides tension to the mid-vertebra 403 and the superior spinous process junction 104 via the elastomer 103. Both the mid-vertebra 403 and the superior spinous process junction 104 share this tension. Compared to situations where tension is only provided to the mid-vertebra 403 or the superior spinous process junction 104, this reduces the possibility of bone damage due to excessive local stress at the mid-vertebra 403 and the superior spinous process junction 104.

[0038] Since the lamina of the middle vertebra 403 is removed, this application utilizes the original lamina space at the middle vertebra 403 to accommodate two bases and an elastomer 103, achieving a mobile connection between the middle vertebra 403 and the lower vertebra 405 while preserving segmental flexibility. The upper vertebra 401 and the middle vertebra 403 are fixedly connected through the upper spinous process connection 104. This effectively utilizes the physiological characteristic of the upper spinous process 402 extending to the middle vertebra 403 in the human body's physiological structure. The upper vertebra 401 and the middle vertebra 403 can be connected with minimal trauma. Thus, this application fully utilizes surgical features to improve spinal stability while minimizing spinal trauma. Due to the physiological characteristics of the human body, the superior spinous process 402 extends to the middle vertebra 403. The superior spinous process connecting part 104 at the top of the upper base 101 does not need to be set at a high height to connect with the superior spinous process 402, thus achieving a fixed connection between the superior vertebra 401 and the middle vertebra 403. This prevents segmental degeneration between the two and minimizes damage to the surrounding physiological structures, effectively reducing surgical trauma. Because of the fixed connection between the superior vertebra 401 and the middle vertebra 403, the relative movement between the superior vertebra 401 and the middle vertebra 403 is minimal. Therefore, the relatively weak superior spinous process 402 does not need to withstand the complex forces generated by the relative movement between the superior vertebra 401 and the middle vertebra 403, effectively avoiding damage to the superior spinous process 402 by the internal fixation device.

[0039] See Figures 4 to 6In one embodiment of this application, a ball joint limiting unit is further provided between the two bases. The ball joint limiting unit includes a ball head structure provided on the upper base 101 and a ball socket structure provided on the lower base 102. The ball head structure includes a ball head 108 and a ball rod 109 connecting the ball head 108 and the upper base 101. The diameter of the ball rod 109 is smaller than that of the ball head 108, and the ball rod 109 is arranged axially. The ball socket structure includes a first channel 110 and a second channel 111 arranged axially. The second channel 111 is connected to the lower base 102 and communicates with the outside through the first channel 110. The ball head 108 is located in the second channel 111. The diameter of the first channel 110 is smaller than that of the ball head 108, so the ball head 108 cannot detach from the second channel 111 and enter the outside. Furthermore, the maximum distance between the center of the cue stick 109 and the center of the ball head 108 is greater than the maximum distance between the center of the ball head 108 and the first channel 110. The depth of the second channel 111 is greater than the diameter of the ball head 108. The ball head 108 can move up and down along the second channel 111, while the first channel 110 restricts the ball head 108 from exiting the second channel 111. The diameter of the first channel 110 is greater than the diameter of the cue stick 109. The cue stick 109 extends to the outside through the first channel 110 and can swing around the center of the ball head 108 within the first channel 110. Thus, the upper base 101 can move up and down relative to the lower base 102, and can also swing back and forth and left and right relative to the lower base 102. It can also rotate around the axis of the lower base 102. At the same time, the first channel 110 can limit the swing amplitude of the cue stick 109, limit the angle change of the upper base 101 relative to the lower base 102, and limit the deflection of the upper base 101 relative to the lower base 102. The depth of the second channel 111 is fixed, thereby limiting the change in the axial distance between the upper base 101 and the lower base 102.

[0040] Of course, those skilled in the art to which this application pertains will understand that the upper base 101 may also have a ball-and-socket structure and the lower base 102 may have a ball-and-head structure, which will not be elaborated further here.

[0041] This application enables the ball head 108 to move linearly relative to the second channel 111, allowing for changes in the axial distance between the upper base 101 and the lower base 102. Furthermore, the ball head 108 can rotate relative to the second channel 111, and the ball rod 109 can swing within the first channel 110, enabling deflection between the upper base 101 and the lower base 102. This design not only improves the internal fixation device's compliance with physiological movements but also prevents excessive displacement of the upper base 101 relative to the lower base 102 through structural limiting, thus enhancing safety and achieving a balance between controllable movement and safety.

[0042] Further, see Figure 6The cross-sections of the two bases and the elastomer 103 are convex arcs, which can better adapt to the shape of the spine and enhance the ability of the elastomer 103 to prevent the upper base 101 from twisting relative to the lower base 102 around the axis, thereby improving the stability of the internal fixation device.

[0043] See Figure 6 In one embodiment of this application, the top end of the upper base 101 is provided with a groove that abuts against the upper spinous process 402, and the bottom end of the lower base 102 is provided with a groove that abuts against the lower spinous process 406 of the lower vertebra 405, so as to prevent relative rotation between the two bases and the spinous process, which is beneficial to improving the stability of the spine.

[0044] See Figures 2 to 4 , Figure 6 , Figure 7 In one embodiment of this application, the lower base 102 has a lower spinous process connecting portion 106 at its bottom end. The lower spinous process connecting portion 106 has a space for the lower spinous process 406 of the lower vertebra 405 to enter. The lower spinous process connecting portion 106 has a second fastener 107, which extends along the left and right sides of the lower base 102 and connects to the lower spinous process connecting portion 106. The second fastener 107 can be a bone nail 304 or the like. The lower spinous process connecting portion 106 has a hole for the second fastener 107 to pass through. In use, the second fastener 107 passes laterally through the lower spinous process connecting portion 106 and the lower spinous process 406, and is fixedly connected to the lower spinous process connecting portion 106 by threading, riveting, or other means, so that the lower spinous process connecting portion 106 and the lower spinous process 406 are fixedly connected.

[0045] A lower spinous process connecting part 106 and a second fastener 107 are added to the bottom end of the lower base 102 to form a bidirectional connection structure for the spinous process of the lower vertebra 405. This connects the lower base 102 with the pedicles and spinous process of the lower vertebra 405, thus connecting the lower base 102 with the pedicles on both sides of the lower vertebra 405 and the lower spinous process 406 for three-point fixation. This ensures the connection strength between the lower base 102 and the lower vertebra 405 and the stability of the connection between the lower base 102 and the vertebra. This allows the lower base 102 to maintain its connection with the lower vertebra 405 even when subjected to significant pressure from above, enabling the internal fixation device to withstand complex forces. The internal fixation device can simultaneously fix the spinous processes of the upper vertebra 401 and the lower vertebra 405, further enhancing the overall restraint capacity of the entire internal fixation device on the posterior column of the spine, significantly improving shear and rotational stability, and more effectively preventing instability and degeneration of adjacent segments.

[0046] See Figure 1 , Figure 6 , Figure 7In one embodiment of this application, connecting rods 201 are pivotally connected to the left and right sides of the base, respectively. The axis of the connecting rods 201 is perpendicular to the axis of the base, and the connecting rods 201 can rotate in a direction perpendicular to the axis of the base. The base also includes a locking structure to lock the connecting rods 201 relative to the base. The pedicle screw 301 is connected to the connecting rods 201, and the axis of the pedicle screw 301 is perpendicular to the axis of the connecting rods 201. By providing rotatable connecting rods 201 on both sides of the base and connecting the pedicle screw 301 to the connecting rods 201, flexible adjustment of the pedicle screw 301 implantation angle is achieved. The connecting rods 201 can rotate in a plane perpendicular to the axis of the base, adapting to the differences in the anatomical structure of different patients and meeting the requirements of the optimal screw insertion angle during surgery. There are multiple ways to achieve the pivotal connection and locking between the connecting rod 201 and the base. For example, the connecting rod 201 can be pivotally connected to the base via a pivot shaft. The locking structure includes a positioning pin and a first pin hole on the connecting rod 201. The base has multiple second pin holes around the axis of the pivot shaft. When the angle between the connecting rod 201 and the base is appropriate, the positioning pin is inserted into the first and second pin holes simultaneously to prevent the connecting rod 201 from continuing to rotate relative to the base. Of course, there are other implementation methods, which will be detailed below.

[0047] See Figure 8 , Figure 9When the connecting rod 201 is pivotally connected to the upper base 101, the direction is described in the figure. In one embodiment of this application, the locking structure is a polygonal sleeve 202. The internal fixation device for total laminectomy also includes a locking bolt 203. The polygonal sleeve 202 is fitted onto the locking bolt 203 through a circular hole provided inside it. The polygonal sleeve 202 and the locking bolt 203 are coaxially arranged and rotatably connected. The polygonal sleeve 202 can rotate around the axis of the locking bolt 203. The upper base 101 is provided with a swing space 206 for the working rod to swing and communicate with the outside. The upper base 101 is provided with a polygonal inner hole 205 above the swing space 206 and a locking threaded hole 204 parallel to the axial direction of the internal fixation device below. The locking threaded hole 204 is coaxially arranged with the pivot axis of the base and the connecting rod 201, which are pivotally connected. The polygonal inner hole 205 provided in the connecting rod 201 is arranged radially along the connecting rod 201. The connecting rod 201 rotates around the axis of the locking threaded hole 204 and rotates to a suitable angle relative to the upper base 101. Since the maximum outer diameter of the locking bolt 203 is greater than the minimum inner diameter of the polygonal sleeve 202, when the locking bolt 203 rotates and is threadedly connected to the locking threaded hole 204, the locking bolt 203 can pull the polygonal sleeve 202 closer to the locking threaded hole 204. The polygonal sleeve 202 is simultaneously inserted into two polygonal inner holes 205. The polygonal inner holes 205 are non-circular cross-section holes, preferably hexagonal holes. The polygonal sleeve 202 cooperates with the two polygonal inner holes 205 to restrict the rotation of the connecting rod 201 relative to the base.

[0048] The cross-sectional shape of the polygonal inner hole 205 and the cross-sectional shape of the polygonal sleeve 202 can be hexagonal, staggered, or other shapes. That is, the polygonal inner hole 205 can be an internal hexagonal hole, a staggered hole, or other shapes. The shape of the polygonal sleeve 202 matches the shape of the polygonal inner hole 205 so that it can be inserted into the polygonal inner hole 205. Those skilled in the art will understand that when the polygonal sleeve 202, polygonal inner hole 205, and locking screw hole are located on the lower base 102, the relative positions of the polygonal sleeve 202, polygonal inner hole 205, and locking screw hole can be adaptively designed. See [reference needed]. Figure 10 The polygonal inner hole 205 provided in the upper base 101 is connected to the top end of the upper base 101, and the polygonal inner hole 205 provided in the lower base 102 is connected to the bottom end of the lower base 102, so that the twisting tool can be better inserted into the locking bolt 203, which is convenient for medical staff to operate.

[0049] When the locking bolt 203 is threadedly connected to the locking threaded hole 204, there are several ways to drive the polygonal sleeve 202 to move, as shown in [reference needed]. Figure 7The head of the locking bolt 203 is larger than the minimum inner diameter of the polygonal sleeve 202, so that the locking bolt 203 can drive the polygonal sleeve 202 to be inserted into the two polygonal inner holes 205 at the same time. Alternatively, when the locking threaded hole 204 is located above the swing space 206 and the polygonal inner hole 205 of the upper base 101 is located below the swing space 206, the head of the locking bolt 203 is threadedly connected to the locking threaded hole 204, and the tail of the locking bolt 203 is rotatably connected to the polygonal sleeve 202. Thus, when the locking bolt 203 is threadedly connected to the locking threaded hole 204, it drives the polygonal sleeve 202 to move. The locking bolt 203 pushes the polygonal sleeve 202 away from the locking threaded hole 204 and pushes the polygonal sleeve 202 into the two polygonal inner holes 205. Of course, there are other implementation methods, which will not be described in detail here.

[0050] Compared to methods where locking structures are installed in other locations on the base, allowing the connecting rod 201 to rotate relative to the base, this method, where the connecting rod 201 rotates around the axis of the locking threaded hole 204, with the locking bolt 203, polygonal inner hole 205, and polygonal sleeve 202 coaxially aligned with the locking threaded hole 204, eliminates the need for additional structures on the base and connecting rod 201 to accommodate the locking mechanism. This reduces the complexity of the connection between the base and connecting rod 201, facilitating production. It simplifies the spatial layout of the locking mechanism, reduces manufacturing complexity, improves assembly convenience and structural reliability, and ensures uniform transmission of locking force.

[0051] In one embodiment of this application, a locking threaded hole 204 is provided on one side of the connecting rod 201, and the head end of the locking bolt 203 is provided on the other side of the connecting rod 201. When the locking bolt 203 is threadedly connected to the locking threaded hole 204, the head end of the locking bolt 203 applies a force close to the locking threaded hole 204 to the connecting rod 201, and the locking bolt 203 and the base clamp the connecting rod 201. See also Figure 8 , Figure 9 When the connecting rod 201 is pivotally connected to the upper base 101, as described in the figure, the polygonal inner hole 205 of the connecting rod 201 is a stepped hole that passes through the connecting rod 201. The stepped hole has two sections with varying inner diameters, a large hole and a small hole. The polygonal sleeve 202 can abut against the shoulder of the polygonal inner hole 205 of the connecting rod 201. When the locking bolt 203 is threadedly connected to the locking threaded hole 204, the head end of the locking bolt 203 applies a force close to the locking threaded hole to the connecting rod 201 through the polygonal sleeve 202, thereby clamping the connecting rod 201 between the locking bolt 203 and the upper base 101.

[0052] Alternatively, the polygonal inner hole 205 of the connecting rod 201 can be a through hole with no change in inner diameter, but the diameter of the head end of the locking bolt 203 is larger than the inner diameter of the polygonal inner hole 205 of the connecting rod 201. The locking threaded hole 204 and the polygonal inner hole 205 of the base are both located below the swing space 206. Thus, when the locking bolt 203 is threadedly connected to the locking threaded hole 204, the head end of the locking bolt 203 drives the polygonal sleeve 202 to insert into the two polygonal inner holes 205. The head end of the locking bolt 203 directly presses the connecting rod 201 onto the base. The locking bolt 203 and the base can clamp the connecting rod 201, thereby restricting the movement of the connecting rod 201.

[0053] Those skilled in the art to which this application pertains will understand that when the polygonal sleeve 202, the polygonal inner hole 205, and the locking screw hole are located on the lower base 102, the relative positions of the polygonal sleeve 202, the polygonal inner hole 205, and the locking screw hole can be adaptively designed. See [reference needed]. Figure 6 , Figure 10 Further details will not be elaborated here; the goal is simply to make it easy for medical staff to operate.

[0054] By optimizing the installation method of the locking bolt 203, with its head end located on one side of the connecting rod 201 and its threaded end located on the other side, the connecting rod 201 is firmly pressed onto the base. This structure not only achieves the angle locking function but also provides anti-disengagement protection, effectively preventing the connecting rod 201 from loosening or accidentally disengaging under long-term stress or dynamic loads, thus improving the mechanical safety and durability of the system.

[0055] When an internal fixation device is placed in the body, its axis is parallel to the direction of spinal extension. Therefore, the internal fixation device is susceptible to relatively complex axial forces within the body. To ensure the stability of the internal fixation device within the body, see [reference needed]. Figure 6 , Figure 7 In one embodiment of this application, swing spaces 206 are provided on both the left and right sides of the base. The connecting rod 201 enters the outside through the swing spaces 206. The swing spaces 206 extend along the rotation direction of the connecting rod 201 and are perpendicular to the axial direction of the inner fixing device. The upper inner wall and lower inner wall of the swing spaces 206 can restrict the linear movement of the connecting rod 201 along the axial direction of the base, ensuring the stability of the connection between the connecting rod 201 and the base when the connecting rod 201 is subjected to a force parallel to the axial direction.

[0056] Of course, the connecting rod 201 can also be fixedly connected to the base by means of integration with the base, and the connecting rod 201 is not pivotally connected to the base.

[0057] See Figure 1 , Figures 11 to 13In one embodiment of this application, the pedicle screw 301 includes a clamp assembly and a bone screw 304. The clamp assembly includes a housing, and a connecting rod 201 can be placed in a U-shaped groove provided in the housing. The angle of the pedicle screw 301 relative to the connecting rod 201 can be adjusted to select the optimal insertion angle for the patient's pedicle position. Subsequently, a tail plug 303 that can be threaded to the housing is used to clamp the connecting rod 201 with the housing, so that the pedicle screw 301 can be fixed to the connecting rod 201.

[0058] See Figures 11 to 13 The housing has a working through hole 312 through which the bone nail 304 passes. The twisting tool can pass through the working through hole 312 and be twisted to connect with the bone nail 304, so that the bone nail 304 is screwed into the pedicle through the external thread on its outer side wall.

[0059] See Figure 12 , Figure 13 In one embodiment of this application, the bone nail 304 has a hollow structure communicating with its head end, and the side wall of the bone nail 304 has a release hole 311 communicating with the hollow structure. After the bone nail 304 enters the vertebra, growth factors can be injected into the hollow structure, and the growth factors can be released into the vertebra through the release hole 311 to accelerate bone healing.

[0060] In one embodiment of this application, the outer surface of the bone nail 304 is threaded, and the hollow structure is a drive groove 307 for inserting a torsion tool. The drive groove 307 has a hexagonal or polygonal inner cavity, adapted to a correspondingly shaped Allen wrench or electric screwdriver, ensuring effective torque transmission. See also Figures 12 to 13 The drive groove 307 is arranged along the axial direction of the bone screw 304. A torsion tool can be inserted into the drive groove 307 to rotate the bone screw 304, providing support and preventing deformation during rotation. When the torsion tool is inserted into the drive groove 307, the drive groove 307 and the torsion tool fit tightly together, forming a stable force transmission channel. This fit ensures that the torque applied to the bone screw 304 is evenly distributed across its entire structure, preventing localized stress concentration that could lead to bending, twisting, or other deformations, thus preventing the bone screw 304 from reaching its designated position.

[0061] The sidewall of the working through hole 312 is provided with a receiving groove 313 around the axis of the working through hole 312; the bone screw 304 passes through the working through hole 312. Along the axial direction of the bone screw 304, the bone screw 304 includes a first mating part 305 and two second mating parts 306 located at both ends of the first mating part 305. The first mating part 305 is disposed in the receiving groove 313, and the outer diameter of the first mating part 305 is larger than the inner diameter of the working through hole 312 to prevent the first mating part 305 from coming out of the working through hole 312. In this application, the bone screw 304 can deflect relative to the axis of the working through hole 312. The axial distance of the first mating part 305 is less than the axial distance of the receiving groove 313. The diameter of the first mating part 305 can be equal to the diameter of the receiving groove 313. The sidewall of the first mating part 305 is an outwardly convex arc shape, and the arc cross-section is parallel to the axis of the bone screw 304. The first mating part 305 can deflect better within the receiving groove 313. Alternatively, the diameter of the first mating part 305 is less than the diameter of the receiving groove 313. Furthermore, the outer diameter of the second mating part 306 is less than the outer diameter of the working through hole 312, thereby enabling the bone screw 304 to deflect relative to the axis of the working through hole 312 and to undergo relative axial movement.

[0062] The receiving groove 313 is also provided with an elastic element 314 to prevent the bone nail 304 from deflecting and moving axially relative to the working through hole 312. An elastic element 314 is also provided between the shoulder at the connection of the first mating part 305 and the groove wall of the receiving groove 313 perpendicular to the axis of the working through hole 312. The elastic element 314 can be an elastic pad made of materials such as polyetheretherketone, or it can be a titanium alloy spring structure that achieves macroscopic elastic behavior through microstructure design, and it is located at both ends of the first mating part 305 in the axial direction.

[0063] The groove wall of the receiving groove 313, perpendicular to the axis of the working through hole 312, can limit the deflection of the bone screw 304. Alternatively, the deflection of the bone screw 304 can be limited by the abutment of the second mating part 306 against the inner wall of the working through hole 312. The inner wall of the receiving groove 313, perpendicular to the axis of the working through hole 312, can limit the axial movement of the first mating part 305, thereby limiting the axial movement of the bone screw 304 relative to the receiving groove 313.

[0064] Furthermore, the outer diameter of the first mating part 305 is equal to the inner diameter of the receiving groove 313. When the bone nail 304 is coaxial with the working through hole 312, the side wall of the first mating part 305 abuts against the inner wall of the receiving groove 313 to prevent loosening between the bone nail 304 and the receiving groove 313.

[0065] When relative movement occurs between the two bases, the bases exert force on the pedicle of the vertebra through the pedicle screws 301. However, because the bone nail 304 can deflect and move axially relative to the working through-hole 312, and cause deformation of the elastic element 314, the elastic element 314 can act as a buffer, protecting the pedicle and playing a role in stress buffering and load distribution. This reduces stress concentration at the bone-screw interface, reduces the risk of complications such as bone cutting and loosening of the bone nail 304, and improves long-term fixation. It also reduces the possibility of loosening of the internal fixation device in the body, requiring reoperation.

[0066] In one embodiment of this application, the pedicle screw 301 includes a bone screw 304. The bone screw 304 has a hollow structure communicating with its head end. The hollow structure includes an expansion section 309 located at the tail end of the bone screw 304. The sidewall of the expansion section 309 can expand outward. The expansion section 309, made of materials such as titanium, has plasticity. There are various ways to achieve the outward expansion of the expansion section 309; see [link to relevant documentation]. Figure 14 The hollow structure is a driving groove 307, extending from the head end to the tail end of the bone screw 304. The driving groove 307 sequentially includes a first driving groove segment 308, an expansion segment 309, and a second driving groove segment 310. The inner diameter of the expansion segment 309 is smaller than that of the first driving groove segment 308. The expansion head 315 can reach the expansion segment 309 through the first driving groove segment 308. The expansion head 315 compresses the inwardly convex expansion segment 309, causing the expansion segment 309 to bulge outward under the compression of the expansion head 315, thereby anchoring it within the bone. Subsequently, the expansion head 315 is removed. To allow the torsion tool to connect with the second drive groove segment 310, the inner diameter of the second drive groove segment 310 can be smaller than the minimum inner diameter of the expansion segment 309. This allows the torsion tool to be inserted into the second drive groove segment 310 through the first drive groove segment 308 and the expansion segment 309, driving the tail end of the bone screw 304 to rotate, thus preventing deformation of the expansion segment 309 during the rotation of the bone screw 304. Of course, to prevent deformation of the expansion segment 309, a reinforcing rib with a circumferential thickness greater than its radial thickness can be provided to prevent circumferential deformation of the expansion segment 309.

[0067] Of course, other methods can also be used to achieve the outward expansion of the expansion segment 309. Referring to 15, the expansion head 315 is pre-positioned on the side of the expansion segment 309 near the tail end of the bone screw 304. When the expansion head 315, located in the second drive groove segment 310, moves outward from the drive groove 307 via the first drive groove segment 308, the expansion segment 309 bulges outward under the compression of the expansion head 315. Through the outwardly expandable expansion segment 309, the bone screw 304 can be anchored to the vertebra, ensuring a fixation effect. Alternatively, the expansion segment 309 can be made of a nickel-titanium shape memory alloy, which can be compressed and inserted into the body at low temperatures and automatically recovers its preset expansion shape at body temperature.

[0068] It should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0069] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of this application and are not intended to limit the scope of protection of this application. All equivalent implementations or modifications made without departing from the spirit of the art of this application, such as combinations, divisions or repetitions of features, should be included within the scope of protection of this application.

Claims

1. An internal fixation device for total laminectomy, characterized in that, include: Two bases, an upper base and a lower base, are provided. The top end of the lower base is connected to the bottom end of the upper base via an elastic body, so that the upper base can be deflected relative to the lower base, and the axial distance between the upper base and the lower base can be changed. The upper base is provided with an upper ratchet connecting part at its top end. The upper ratchet connecting part is provided with a first fastener. The first fastener extends along the left and right sides of the upper base and is connected to the upper ratchet connecting part. Both of the aforementioned bases have pedicle screws on their left and right sides.

2. The internal fixation device for total laminectomy according to claim 1, characterized in that, A ball joint limiting unit is also provided between the two bases, the ball joint limiting unit including a ball head structure and a ball socket structure; The ball head structure includes a ball head and a club connected to the ball head, wherein the diameter of the club is smaller than that of the ball head; The ball-and-socket structure includes a first channel and a second channel arranged along the axial direction. The second channel communicates with the outside through the first channel. The ball head is located in the second channel, and the depth of the second channel is greater than the diameter of the ball head so that the ball head can move along the second channel. The diameter of the first channel is greater than the diameter of the club and smaller than the diameter of the ball head. The club extends to the outside through the first channel and can swing around the center of the ball head within the first channel. One of the two bases is provided with the ball head structure and connected to the ball rod in the ball head structure, and the other is provided with the ball socket structure and connected to the second channel in the ball socket structure.

3. The internal fixation device for total laminectomy according to claim 1, characterized in that, Connecting rods are pivotally connected to the left and right sides of the base, respectively. The axis of the connecting rods is perpendicular to the axis of the base, and the connecting rods can rotate in a direction perpendicular to the axis of the base. The base also includes a locking structure that locks the connecting rod from rotating relative to the base; The pedicle screw is connected to the connecting rod, and the axis of the pedicle screw is perpendicular to the axis of the connecting rod.

4. The internal fixation device for total laminectomy according to claim 3, characterized in that, Both the base and the connecting rod are provided with polygonal inner holes parallel to the axis of the base. The polygonal inner hole of the connecting rod is arranged radially along the connecting rod. The base is also provided with locking threaded holes coaxially arranged with the two polygonal inner holes. The locking threaded holes are coaxially arranged with the pivot axis of the base and the connecting rod. The internal fixation device for total laminectomy also includes a locking bolt, the locking structure being a polygonal sleeve, the polygonal sleeve being fitted onto the locking bolt, and the polygonal sleeve being rotatably connected to the locking bolt; The locking bolt is threadedly connected to the locking threaded hole. When the locking bolt rotates, it drives the polygonal sleeve to be inserted into the two polygonal inner holes at the same time, so as to restrict the rotation of the connecting rod relative to the base.

5. The internal fixation device for total laminectomy according to claim 4, characterized in that, The locking threaded hole is located on one side of the connecting rod, and the head of the locking bolt is located on the other side of the connecting rod. When the locking bolt is threadedly connected to the locking threaded hole, the head of the locking bolt applies a force close to the locking threaded hole to the connecting rod, and the locking bolt and the base clamp the connecting rod.

6. The internal fixation device for total laminectomy according to claim 1, characterized in that, The pedicle screw includes a clamp assembly and a bone screw. The clamp assembly includes a housing with a working through hole, and the sidewall of the working through hole is provided with a receiving groove around the axis of the working through hole. The bone screw passes through the working through hole. Along the axial direction of the bone screw, the bone screw includes a first mating part disposed in the receiving groove and two second mating parts respectively located at both ends of the first mating part. The axial length of the first mating part is less than the axial length of the receiving groove, the outer diameter is greater than the inner diameter of the working through hole, and the diameter of the first mating part is equal to the diameter of the receiving groove. The sidewall of the first mating part is an outwardly convex arc shape, or the diameter of the first mating part is less than the diameter of the receiving groove. The outer diameter of the second mating part is smaller than the outer diameter of the working through hole, so that the bone screw can deflect relative to the working through hole and move axially; The receiving groove is also provided with an elastic element to prevent the bone nail from deflecting and moving axially relative to the working through hole.

7. The internal fixation device for total laminectomy according to claim 1, characterized in that, The pedicle screw includes a bone screw with a hollow structure communicating with its head end. The hollow structure includes an expansion section located at the tail end of the bone screw, and the sidewall of the expansion section can expand outward.

8. The internal fixation device for total laminectomy according to claim 1, characterized in that, The bone nail has a hollow structure communicating with its head end, and the side wall of the bone nail has a release hole communicating with the hollow structure.

9. An internal fixation device for total laminectomy according to claim 7 or claim 8, characterized in that, The outer surface of the bone nail is threaded, and the hollow structure is a drive groove for inserting a torsion tool.

10. The internal fixation device for total laminectomy according to claim 1, characterized in that, The lower base is provided with a lower ratchet connecting part at its bottom end. The lower ratchet connecting part is provided with a second fastener. The second fastener extends along the left and right sides of the upper base and is connected to the lower ratchet connecting part.

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