A posterior spinal lamina transverse distraction fixation device

Abstract

This invention provides a posterior spinal lamina transverse expansion and fixation device, belonging to the field of medical device technology. The invention includes: an expansion body conforming to the physiological curvature of the posterior spine, divided into anterior and posterior wings, the front end of which can retract and automatically rebound after insertion, transversely expanding the lamina; and a snap-lock anti-displacement structure, formed by bending the wings, used to lock the expansion body after expansion, forming an irreversible fixation state and preventing retraction after expansion. This invention's expansion body with snap-lock anti-displacement structure, and overall adaptability to endoscopic channels smaller than 1cm, allows for transverse lamina expansion and fixation, implanted via a decompression groove using the spinous process as a positioning target. This device simultaneously addresses the mechanical requirements of high rigidity at the front end to maintain the expansion amplitude and high extensibility at the rear end for lamina fixation. It features a simple structure, low operational difficulty, no rebound after expansion, and is suitable for minimally invasive endoscopic procedures. It effectively reduces stress shielding, promotes bone healing, and reduces surgical trauma and complication risks.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a posterior spinal laminar transverse expansion and fixation device, referred to as the "Omega Ω" system, for posterior decompression laminoplasty for diseases such as cervical spondylotic myelopathy, cervical spinal stenosis, ossification of the posterior longitudinal ligament of the cervical spine, thoracic spinal stenosis and lumbar spinal stenosis, especially suitable for endoscopic-assisted minimally invasive surgery with a channel diameter of less than 1 cm. Background Technology

[0002] Posterior spinal decompression and fixation surgery is a primary surgical approach for treating degenerative spinal diseases (including cervical, thoracic, and lumbar spine) and cervical spinal cord injuries. With the development of minimally invasive techniques, endoscopic-assisted surgery has become the preferred clinical procedure due to its advantages of minimal trauma, rapid recovery, and minimal damage to surrounding tissues. Currently used posterior spinal fixation devices cannot flexibly and laterally expand the lamina, and most suffer from complex structures and cumbersome implantation procedures. This not only increases the difficulty of endoscopic operation but also increases the risk of internal fixation loosening or displacement, affecting the decompression effect and making it difficult to balance "rigidity in maintaining the expanded state" with "compliance with lamina fixation."

[0003] Current posterior spinal surgical devices lack the ability to provide transverse lateral expansion and fixation via the posterior midline lamina, do not consider the viscoelastic nature of bone, and are unsuitable for endoscopic-assisted minimally invasive surgery. They also struggle to achieve precise implantation targeting the spinous process, failing to meet clinical demands for "simple, efficient, and reliable" minimally invasive surgery. Therefore, there is an urgent need for a posterior spinal lamina transverse expansion and fixation device that is structurally simple, easy to operate, does not retract after transverse lamina expansion, and is suitable for endoscopic-assisted implantation. Summary of the Invention

[0004] In view of this, to address the technical problems of existing posterior spinal surgical devices lacking the function of transverse lateral expansion and fixation via the posterior midline lamina and being unsuitable for endoscopic-assisted minimally invasive surgery, this invention provides a posterior spinal lamina transverse expansion and fixation device. The device is made of a titanium alloy with a Ti-Mo-Zr-Fe-Sn-Cu composition, featuring a main body for expansion, a snap-lock anti-displacement structure, and is designed for transverse lamina expansion and fixation within an endoscopic channel of less than 1 cm. It can be implanted via a midline decompression groove with the spinous process as the positioning target point, providing elastic transverse expansion of the lamina. This device simultaneously meets the mechanical requirements of high rigidity at the anterior end to maintain the expansion range and high ductility at the posterior end to conform to the lamina for fixation. It has a simple structure, low operational difficulty, no rebound after expansion, elastic transverse lamina expansion without displacement, and is suitable for endoscopic minimally invasive surgery. It effectively reduces stress shielding, promotes bone-metal interface healing, and reduces surgical trauma and the risk of complications.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a posterior spinal lamina transverse expansion and fixation device, utilizing the viscoelastic material properties of the lamina, comprising: The main body is spread out, and the whole body is arc-shaped, conforming to the physiological curvature of the posterior spine. It is divided into two wings, the front and the back. The front end can retract and automatically rebound after insertion, and laterally spread the vertebral lamina. The snap-fit ​​anti-displacement structure is formed by bending the two wings and is used to lock the main body after it is opened, forming an irreversible fixed state and preventing it from retracting after being opened.

[0006] Preferably, the front end and rear wing of the supporting body are made of titanium alloy.

[0007] Preferably, the nominal composition of the titanium alloy is Ti-10Mo-5Zr-3Fe-2Sn-2Cu, and the allowable range by weight percentage is: Mo: 9.0%~10.5%, Zr: 4.5%~5.5%, Fe: 2.8%~3.2%, Sn: 1.5%~2.5%, Cu: 1.8%~2.2%, O: 0.15%~0.25%, with the balance being Ti and unavoidable impurities.

[0008] Preferably, it further includes: An external expansion handle adapter is located at the top of the expansion body and is used for detachable connection with the external handle.

[0009] Preferably, the external handle is an oval forceps.

[0010] Preferably, the external expansion handle adapter is connected to the external handle by bolts.

[0011] Preferably, the operating end of the external handle is provided with a scale.

[0012] Preferably, the buckle anti-displacement structure is in the shape of a "barb" to prevent the device from shifting into the spinal canal.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The new titanium alloy material possesses high strength, ensuring the front section remains open; high plasticity ensures the posterior wings adapt to the shape of the vertebral lamina; it can be bent for fixation, improving fixation reliability while reducing pressure on surrounding spinal tissues and lowering the incidence of complications; the material can be compressed and automatically rebounds, elastically expanding the vertebral lamina laterally; the material's mechanical properties are balanced. Low modulus: The alloy system containing 10wt%Mo, 5wt%Zr and 3wt%Fe described in this invention is a typical metastable β-type titanium alloy. Its elastic modulus can be stably controlled in the range of 75–85GPa, which is significantly lower than that of the traditional Ti-6Al-4V alloy. It can effectively alleviate the stress shielding effect, provide excellent mechanical compatibility for bone-metal interface tissue healing, and thus promote bone healing.

[0014] High strength: Through 3% Fe strengthening and subsequent aging treatment to induce the precipitation of nano-scale secondary α phase, the yield strength is expected to exceed 1000 MPa, fully meeting the requirements of the spinal spreader to resist axial load. The alloy is strengthened by solid solution of 3wt% Fe and then dispersed by induced precipitation of nano-scale secondary α phase through subsequent aging treatment. Its yield strength can exceed 1000 MPa, which can fully meet the requirements of the spinal spreader to bear axial load under service conditions.

[0015] With a simple structure, following the design logic of "solving complex problems with simple problems", it abandons complex adjustment and locking mechanisms. It achieves the functions of opening, locking and fixing only through the simple cooperation of the main body and the snap-lock anti-displacement structure (formed by bending the wings), which reduces the design and manufacturing costs, while reducing the difficulty of endoscopic operation and making it easier to promote and apply in clinical practice.

[0016] The external expansion and buckle anti-displacement design allows for precise control of the expansion range up to 1cm via an external handle. After expansion, the buckle automatically locks, completely solving the problem of easy rebound after expansion in existing devices. This effectively ensures the expansion range of the spinal canal, maintains a stable decompression range, and provides a feel that meets clinical needs.

[0017] It is suitable for endoscopic-assisted surgery, with an overall diameter of about 2-8mm. It is implanted through the midline approach and the central decompression groove, using the spinous process as the positioning target. It is convenient to operate, has little trauma, and conforms to the development trend of minimally invasive surgery. It can be widely used in various posterior spinal canal expansion and reconstruction surgeries. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention and a schematic diagram of its usage process; Figure 2 These are schematic diagrams illustrating the applications of different models of this invention; In the diagram, 1. the main body is opened; 2. the front section; 3. the wings; and 4. the external handle. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1-2 As shown, this invention provides a posterior spinal laminar fusion fixation device that fully utilizes the viscoelastic properties of the lamina, comprising: The main body 1, which is arc-shaped and conforms to the physiological curvature of the posterior spine, is divided into an anterior segment 2 and two posterior wings 3. As the core of the device, the main body 1 not only possesses high strength to ensure stable shape maintenance after expansion without deformation, guaranteeing a maximum expansion range of 8mm to meet clinical decompression and tactile requirements, but also exhibits good plasticity, allowing the posterior wings to have good extensibility. They can be flexibly bent according to the vertebral lamina shape, closely conforming to the lamina surface for secure fixation while reducing pressure on surrounding tissues. Furthermore, they can automatically rebound after compression, making the fixator more stable. The wings 3 are formed by bending the top of the main body 1 to prevent device displacement. Therefore, in a preferred embodiment of the invention, the front end of the main body 1 and the posterior wings 3 are made of titanium alloy. The good biocompatibility of titanium alloy is suitable for in-vivo implantation, while its adjustable mechanical properties simultaneously meet the dual requirements of the anterior segment 2's support stiffness and the posterior wings 3's plasticity and extensibility. It exhibits excellent biocompatibility with no risk of rejection, while simultaneously balancing support strength and shaping ability, meeting the general usage requirements for orthopedic implantable medical devices. In a further preferred embodiment, the nominal composition of the titanium alloy is Ti-10Mo-5Zr-3Fe-2Sn-2Cu, with the following permissible weight percentage ranges: Mo: 9.0%~10.5%, Zr: 4.5%~5.5%, Fe: 2.8%~3.2%, Sn: 1.5%~2.5%, Cu: 1.8%~2.2%, O: 0.15%~0.25%, with the balance being Ti and unavoidable impurities. This titanium alloy with a specific composition ratio achieves a β-type titanium alloy by controlling the Mo, Zr, and Fe elements to reduce the material's elastic modulus, optimizes the strength-plasticity balance by using Sn and Cu elements, and strictly controls the oxygen content to ensure the overall stability of the material's mechanical properties. With an elastic modulus of only 75-85 GPa, far lower than that of conventional medical titanium alloy Ti-6Al-4V, it can effectively reduce stress shielding effect and promote postoperative bone-metal interface healing. After aging treatment, its yield strength exceeds 1000 MPa, fully meeting the mechanical requirements of the spinal diffuser against lateral loads. This titanium alloy exhibits excellent strength-toughness matching, ensuring its anterior end can maintain its expanded state, elastically expanding the vertebral lamina to guarantee decompression, while its posterior wings can be bent and fixed to the vertebral lamina. When using this nominal composition ratio of titanium alloy, the proportion of each alloying element reaches optimal balance, and the matching degree of β-phase stability, strength, and plasticity reaches the highest level. The material's mechanical properties show good batch-to-batch consistency, resulting in high yield in industrial production. Simultaneously, the material's strength-toughness matching is optimal, fully adapting to the functional design requirements of the device.

[0021] The snap-fit ​​anti-displacement structure, formed by bending the two wings 3, is used to lock the main body 1 after it has been opened, forming an irreversible fixed state. This prevents retraction after opening and ensures the stability of the decompression effect. No additional locking components are required, simplifying the structural design. In a preferred embodiment of the invention, the snap-fit ​​anti-displacement structure is in the shape of a "barb." The barb deforms with the opening action, and locks when the opening reaches a preset value. It cannot retract without external force from a special tool, forming a stable and irreversible lock. The locking action requires no additional steps; locking is automatically completed once the opening is complete, simplifying the surgical procedure. The locking reliability is high, completely eliminating the risk of postoperative rebound after opening.

[0022] The technical solution of this invention fully utilizes the viscoelastic properties of bone. The arc-shaped main body 1 conforms to the physiological curvature of the posterior spine. The front section 2 is used to expand the lamina and increase the volume of the spinal canal, while the two rear wings 3 are used to adhere to the lamina for anchoring and fixation. After the main body 1 is fully expanded, the snap-locking anti-displacement structure directly engages and locks, forming an irreversible fixed state, elastically expanding the lamina laterally. The structural design is extremely simple, adaptable to the limited operating space under minimally invasive endoscopy, and completely solves the pain points of existing devices from a mechanistic perspective, ensuring the long-term stability of the expanded area of ​​the spinal canal.

[0023] In a preferred embodiment of the present invention, it further includes: An external retractor handle adapter is located at the top of the retractor body 1 and is detachably connected to the external handle 4. During the operation, the retraction range of the retractor body 1 can be precisely controlled by the external handle 4, with a maximum retraction distance of 8mm. The operation is convenient and does not require a complex intraoperative adjustment mechanism, reducing the difficulty of endoscopic operation. After the retraction is in place, the external handle 4 can be removed without affecting the fixation effect of the fixator or postoperative recovery.

[0024] In a preferred embodiment of the present invention, the external handle 4 is an oval forceps. Using a clinically common oval forceps as the external operating handle allows for direct clamping of the adapter, completing the entire process of opening, contracting, implanting, and opening the main body 1. No additional customized operating instruments are required, reducing clinical usage costs; operators do not need to learn new instrument operation methods, resulting in a very low learning threshold and facilitating rapid clinical adoption.

[0025] In a preferred embodiment of the present invention, the external expansion handle adapter and the external handle 4 are connected by bolts. The bolt structure ensures a stable connection between the adapter and the external handle 4, preventing slippage or displacement during operation. The handle can be quickly removed by rotating it after expansion is complete. This design offers high connection stability, safe and controllable operation, convenient disassembly, and avoids disturbance to the already expanded and locked device, thus preventing the risk of intraoperative displacement.

[0026] In a preferred embodiment of the present invention, the operating end of the external handle 4 is provided with a scale, which can intuitively provide feedback on the current expansion range. The operator can precisely adjust the expansion distance to the target value according to the patient's spinal stenosis. The lamina is elastically expanded laterally, and the expansion range control accuracy can reach 0.1mm. The spinal canal expansion area (decompression range) can be adjusted individually according to different patients' conditions, avoiding over-expansion or under-expansion, resulting in high operational precision.

[0027] In a preferred embodiment of the present invention, the anti-displacement buckle structure is in the shape of a "barb". The barb-shaped elastic buckle deforms with the expansion action, and automatically pops out and engages when the expansion reaches a preset value. It cannot retract without the external force of a special tool to unlock, forming a stable and irreversible locking elastic lateral expansion of the vertebral lamina. The locking action requires no additional operation steps; locking is automatically completed when the expansion is in place, simplifying the surgical procedure. The locking reliability is high, completely eliminating the risk of postoperative expansion rebound.

[0028] like Figure 1 As shown, during the procedure, a decompression groove was drilled at the spinous process of the cervical vertebrae along the posterior midline of the patient, and the compressed expansion body 1 was implanted into the decompression groove. After the ovum forceps were released, the expansion body 1 automatically expanded to the preset range, and its main body automatically conformed to the decompression groove, generating a lateral expansion force to achieve stable fixation; at the same time, the two wings of the fixator automatically conformed to the two vertebral lamina, further achieving a self-anchoring effect.

[0029] The technical solution of the present invention will be clearly and thoroughly described below with reference to specific embodiments.

[0030] Example 1 This embodiment provides a novel posterior spinal distraction and fixation device that fully utilizes the viscoelastic properties of bone. It has an overall diameter of 2-8mm and is made of titanium alloy. Specifically, it includes: The main body 1 is arc-shaped, conforming to the physiological curvature of the posterior spine. It is made of titanium alloy. The front section 2 is 0.5cm long and has a yield strength of over 800MPa, ensuring that it will not deform after being opened. The two rear wings are each 0.3cm long, with good ductility and a bending angle range of 0-45°, which facilitates fitting and fixing the vertebral lamina. At the same time, it elastically and laterally opens the vertebral lamina.

[0031] External expansion handle adapter: Located at the top of the expansion body 1, it is connected to the external expansion handle by a threaded connection. The operating end of the handle is marked with a scale, which can accurately control the expansion range. The minimum adjustment accuracy is 1mm and the maximum expansion range is 8mm.

[0032] The snap-lock anti-displacement structure is formed by bending two wings into a "barbed" shape. When the main body 1 is opened to 2-8mm, it locks with the vertebral lamina. Unlocking requires a special tool to avoid misoperation during surgery.

[0033] Implantation procedure as follows Figure 1 As shown: 1. The patient is placed in a prone position, and routine disinfection and draping are performed. Using endoscopic access surgical equipment, a surgical channel with a diameter of about 1 cm is established through the posterior midline approach of the spine. 2. Using the spinous process as the target point for positioning and landing, the paravertebral soft tissue is dissected along both sides of the spinous process using endoscopic instruments to expose the spinous process and lamina; 3. Use a drill to remove part of the spinous process tissue, drill a groove in the middle of the spinous process, and grind out a decompression groove. The width of the groove should match the diameter of the fixator (about 1cm) to complete the spinal canal decompression. 4. The expansion body 1 is retracted to its minimum state (expansion range 0cm) through the external handle 4 and implanted from the middle decompression groove. The position is adjusted so that the front part 2 of the expansion body 1 fits the edge of the spinal canal decompression and the wings 3 on both sides of the back are aligned with the lamina. 5. Slowly operate the external handle 4 to expand the main body 1 to the preset range (adjustable within the range of 2-8mm according to the patient's condition and the relationship between the expansion distance and the diameters and areas of the spinal canal, as shown in Table 1).

[0034] 6. Rotate to remove the external handle 4. When the target amplitude is reached, the anti-displacement structure on both sides automatically locks the vertebral plate and locks the open state to ensure a firm fixation. 7. Examine the position, spread, and fixation of the fixator under a microscope. After confirming that there are no abnormalities, suture the incision to complete the surgery.

[0035] Table 1: Relationship between the spreading distance and the diameters and areas of the spinal canal

[0036] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A posterior spinal laminectomy fixation device, characterized by: The main body is spread out, and the whole body is arc-shaped, conforming to the physiological curvature of the posterior spine. It is divided into two wings, the front and the back. The front end can retract and automatically rebound after insertion, and laterally spread the vertebral lamina. The snap-fit ​​anti-displacement structure is formed by bending the two wings and is used to lock the main body after it is opened, forming an irreversible fixed state and preventing it from retracting after being opened.

2. The posterior spinal laminar transverse bracing and fixation device according to claim 1, characterized in that, The front and rear wings of the main body are made of titanium alloy.

3. The posterior spinal laminar lamina distraction and fixation device according to claim 2, characterized in that, The nominal composition of the titanium alloy is Ti-10Mo-5Zr-3Fe-2Sn-2Cu, and the permissible range by weight percentage is: Mo: 9.0%~10.5%, Zr: 4.5%~5.5%, Fe: 2.8%~3.2%, Sn: 1.5%~2.5%, Cu: 1.8%~2.2%, O: 0.15%~0.25%, with the balance being Ti and unavoidable impurities.

4. A posterior spinal laminar transverse bracing and fixation device according to any one of claims 1-3, characterized in that, Also includes: An external expansion handle adapter is located at the top of the expansion body and is used for detachable connection with the external handle.

5. The posterior spinal laminar transverse bracing and fixation device according to claim 4, characterized in that, The external handle is an oval forceps.

6. The posterior spinal laminar lamina distraction and fixation device according to claim 4, characterized in that, The external expansion handle adapter is connected to the external handle by bolts.

7. The posterior spinal laminar transverse bracing and fixation device according to claim 4, characterized in that, The operating end of the external handle is equipped with a scale.

8. A posterior spinal laminar transverse bracing and fixation device according to any one of claims 1-7, characterized in that, The buckle anti-displacement structure is in the shape of a "barb" to prevent the device from shifting into the spinal canal.

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