Spine internal fixing device with fusion function

Abstract

A spine internal fixing device with a fusion function comprises a pedicle screw, the pedicle screw comprises a screw body, a screw tail is arranged at the upper end of the screw body, a nut is connected to the screw tail through internal threads, the screw body and the screw tail are of a honeycomb structure simulating cancellous bone, and solid external threads are arranged on the outer surface of the screw body. According to the spinal internal fixation device with the fusion function, a full-assembly simulation cancellous bone honeycomb structure of a pedicle screw rod nut and a matched connecting piece is prepared by adopting a 3D printing technology, and meanwhile, solid structures of key stress parts such as an external thread tip threaded connection surface are reserved so as to guarantee early mechanical fixation strength; after the components are assembled, a continuous bone ingrowth channel is formed, so that the transformation of internal fixation of the spine from temporary mechanical support to permanent osseous fusion is realized, and various intervertebral, intervertebral, posterior lateral and transverse process bone grafting fusion steps in a traditional spine fusion operation can be omitted.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a spinal internal fixation device with fusion function. Background Technology

[0002] Spinal degenerative diseases, spinal trauma, spinal deformities, and spinal tumors are common spinal conditions in clinical practice. These diseases often lead to spinal instability, resulting in serious consequences such as nerve compression, pain, and even functional impairment. Spinal fusion surgery is the core surgical procedure for treating these diseases. It follows three basic principles: decompression, fusion, and fixation, achieving therapeutic goals by reconstructing spinal stability and relieving nerve compression. Among these, pedicle screw fixation systems, with their reliable anchoring effect and three-dimensional fixation capability, have become the most widely used internal fixation technique in spinal fusion surgery.

[0003] Traditional pedicle screw fixation systems mainly consist of three parts: pedicle screws, connecting rods, and locking nuts. For example, pedicle screws... Figure 1 As shown in the diagram. During the procedure, pedicle screws are inserted into the patient's pedicles as anchor points. Connecting rods longitudinally connect the pedicle screws of adjacent vertebrae to reconstruct the physiological sequence of the spine. Locking nuts secure the connecting rods to the pedicle screws, forming a rigid, integrated frame that provides immediate mechanical stability to the spine. However, with the increasing prevalence of clinical applications, the inherent defects of traditional pedicle screw internal fixation systems are becoming increasingly apparent, mainly in the following aspects: First, its function is limited, providing only temporary mechanical fixation. Traditional internal fixation systems are made of solid metal and their function is limited to providing temporary mechanical support before bone fusion is complete. Theoretically, after bone fusion, the internal fixation system should be removed via a second surgery. However, revision surgery is highly invasive and risky, and may cause complications such as nerve damage and bleeding. Therefore, in clinical practice, the vast majority of patients choose to leave the internal fixation system permanently in place. Permanently placed metal internal fixation systems produce a significant stress shielding effect, leading to reduced stress load on local bone tissue and potentially causing osteoporosis. Simultaneously, stress shielding accelerates degeneration of adjacent segments, increasing the risk of complications such as intervertebral disc herniation and vertebral fractures. Furthermore, long-term placement of metal internal fixation systems also presents problems such as metal corrosion and metal ion release, potentially causing local inflammatory reactions and systemic toxicity. It can also produce severe artifacts on imaging examinations such as CT and MRI, affecting postoperative assessment.

[0004] Secondly, the surgical procedure is complex, time-consuming, invasive, and involves high costs for consumables. A standard spinal fusion surgery requires three main steps: spinal canal decompression, interbody fusion (including placement of the interbody fusion cage and implantation of bone graft material), and posterior pedicle screw fixation. The entire procedure is cumbersome, typically time-consuming, and involves significant intraoperative blood loss, increasing the risks associated with anesthesia and postoperative infection. Furthermore, the use of additional consumables such as the interbody fusion cage and bone graft material significantly increases the overall cost of the surgery, placing a heavy financial burden on the patient.

[0005] Third, the success of bone fusion depends on bone grafting, which carries numerous associated complications. Traditional spinal fusion surgery primarily relies on intervertebral disc grafts or posterolateral bone grafts, typically taken from the patient's own iliac bone. While autologous bone grafts offer excellent osteoinductive and osteoconductive properties, they also present numerous donor site complications, such as pain, bleeding, infection, hematoma formation, and nerve damage. Furthermore, the amount of autologous bone available is limited, often resulting in insufficient graft volume for patients requiring multi-segment fusion. Artificial bone materials, on the other hand, have significantly lower osteoinductive and fusion rates than autologous bone, leading to a non-fusion rate of 5%-10% in clinical spinal fusion surgery. Non-fusion can cause loosening or breakage of the internal fixation system, resulting in surgical failure.

[0006] Fourth, the application of 3D printing technology in spinal internal fixation systems has significant limitations. In recent years, 3D printing technology has been widely used in orthopedic medical devices due to its personalized customization capabilities and ability to manufacture complex structures. Currently, 3D printing technology is mainly used to manufacture interbody fusion devices, artificial vertebrae, and surgical guides. These products utilize the porous structures of 3D printing to promote osseointegration, achieving good clinical results. However, for the core components of spinal internal fixation systems—pedicle screws, connecting rods, and locking nuts—existing technologies still predominantly employ solid metal structures. Only a few studies have attempted to design porous structures locally in the pedicle screws, failing to fully leverage the advantages of 3D printing technology in constructing biomimetic trabecular bone structures and promoting bone ingrowth, thus hindering the transformation of internal fixation systems from temporary mechanical fixation to permanent biological fixation. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a spinal internal fixation device with fusion function, so as to realize the fusion of bone and bone device, and transform the temporary mechanical fixation into permanent bone fusion.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a spinal internal fixation device with fusion function, including a pedicle screw, wherein the pedicle screw includes a screw body, a screw tail is provided at the upper end of the screw body, and a nut is connected to the screw tail by internal thread. The screw body and the screw tail are honeycomb structures that simulate cancellous bone, and a solid external thread is provided on the outer surface of the screw body.

[0009] Preferably, the lower end of the nail body has a solid tip. Preferably, the inner side of the nail tail is provided with a solid inner wall, the surface of the inner wall is provided with internal threads, and the solid nut is threadedly connected to the inner wall.

[0010] Preferably, it also includes a rod, which is a honeycomb structure that simulates cancellous bone; the rod is used to connect multiple pedicle screws, the rod passes through the screw tail, and the rod and screw tail are fixed together with a nut.

[0011] Preferably, the nail body, nail tail, nut, and nail rod are made using 3D printing technology, and the materials used are titanium alloy, pure titanium, tantalum metal, or magnesium alloy.

[0012] Preferably, the porosity of the honeycomb structure of the nail body, nail tail, nut, and nail rod is 60-80%.

[0013] Preferably, the pore size of the honeycomb structure of the nail body, nail tail, nut and nail rod is 300-800μm.

[0014] Preferably, the surface of the honeycomb structure of the nail body, nail tail, nut and nail rod has a hydroxyapatite coating, a bioactive glass coating, or contains bone morphogenetic proteins or antibiotics.

[0015] Preferably, it also includes a connecting rod for connecting multiple nail rods, the connecting rod being connected to the nail rods via a connector.

[0016] Preferably, the connecting rod and connector have a honeycomb structure that mimics cancellous bone.

[0017] This invention provides a spinal internal fixation device with fusion function, which has the following beneficial effects: 1. It achieves the integrated function of fixation and fusion. The internal fixation device itself serves as a bone fusion carrier, and bone tissue can grow into the honeycomb structure that simulates cancellous bone, transforming the traditional temporary mechanical fixation into permanent bone fusion. There is no need for a second surgery to remove the internal fixation, avoiding problems such as stress shielding, osteoporosis, adjacent segment degeneration, metal corrosion, ion release, and imaging artifacts caused by permanent internal fixation.

[0018] 2. Significantly simplifies the spinal fusion surgery procedure, omitting the separate intervertebral bone grafting and fusion step in traditional surgery, shortening the operation time, reducing intraoperative bleeding, and lowering the risk of anesthesia and the probability of postoperative infection.

[0019] 3. Significantly improves bone fusion rate. The honeycomb structure of cancellous bone provides an ideal space for bone cell growth and blood vessel ingrowth, promotes close integration of bone tissue and implant, reduces the incidence of bone nonfusion, and avoids internal fixation loosening and breakage and secondary surgical failure due to fusion failure.

[0020] 4. Completely avoids bone graft-related complications, without the need for additional autologous bone harvesting or the use of artificial bone materials. It solves the problems of pain, bleeding, infection, nerve damage, and insufficient bone graft volume in the autologous bone donor site, and also avoids the defects of insufficient bone induction capacity of artificial bone materials.

[0021] 5. Effectively reduces medical costs, reduces the use of additional consumables such as interbody fusion cage bone graft materials, and alleviates the economic burden on patients.

[0022] 6. The elastic modulus of the porous structure is closer to that of natural human bone tissue, which greatly reduces the stress shielding effect, facilitates the normal stress transmission of bone tissue, protects local bone mass, and slows down the degenerative process of the spine.

[0023] 7. The honeycomb structure surface can be loaded with bioactive factors or antibiotics, which can accelerate bone ingrowth and improve bone fusion quality, while also reducing the risk of infection in the postoperative incision and deep tissues.

[0024] 8. The matching connecting rods and connectors all adopt the same honeycomb structure, which can realize the overall bony connection of multi-segment spinal fusion and meet the clinical needs of spinal surgery with different degrees of complexity. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the existing technology; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a structural schematic diagram of the present invention from another angle. Detailed Implementation

[0026] Example 1, as Figure 2-3 As shown, a spinal internal fixation device with fusion function includes a pedicle screw. The pedicle screw includes a screw body 1 and a screw tail 2 at the upper end of the screw body 1. The screw tail 2 is internally threaded with a nut 3. The screw body 1 and screw tail 2 are honeycomb structures that simulate cancellous bone. A solid external thread 4 is provided on the outer surface of the screw body 1.

[0027] Preferably, the lower end of the nail body 1 is provided with a solid tip 5. Preferably, the inner side of the nail tail 2 is provided with a solid inner wall 5, the surface of the inner wall 5 is provided with internal threads, and the solid nut 3 is threadedly connected to the inner wall 5.

[0028] This embodiment is applicable to clinical scenarios that require only single vertebral body anchoring, such as minimally invasive fixation of single vertebral compression fractures and local osseointegration fixation after vertebral tumor resection.

[0029] The nail body 1 has a diameter of 6.0 mm and a length of 45 mm, with a honeycomb structure, a porosity of 70%, and a pore size of 400 μm. The solid external thread 4 has a tooth height of 1.0 mm and a pitch of 2.0 mm. The solid tip 5 is 5 mm long and tapered. The nail tail 2 has an outer diameter of 10 mm, a height of 8 mm, and a solid inner wall 9 with a thickness of 1.5 mm. The nut 3 has an outer diameter of 9 mm, a height of 6 mm, and is adapted to the internal thread of the nail tail 2.

[0030] This embodiment employs selective laser melting 3D printing for one-piece molding, using Ti-6Al-4V titanium alloy powder with a particle size of 15 to 45 μm as the raw material. After printing, stress-relief annealing is performed at 680°C for 2 hours followed by furnace cooling. Subsequently, alumina sandblasting is used to remove residual powder from the surface, followed by ultrasonic cleaning three times for 15 minutes each time. Finally, irradiation sterilization is carried out at a sterilization dose of 25 kGy.

[0031] Solid external threads 4 and solid tip 5 provide strong mechanical anchoring, maintaining vertebral stability. Postoperatively, bone tissue gradually grows into the honeycomb structure of screw body 1 and screw tail 2, forming preliminary biological fixation. Ultimately, bone tissue completely penetrates the honeycomb structure, and the screw fuses with the vertebral bone tissue, achieving permanent bony fixation without the risk of screw loosening or breakage.

[0032] Example 2: A spinal internal fixation device with fusion function, including a pedicle screw. The pedicle screw includes a screw body 1 and a screw tail 2 at the upper end of the screw body 1. The screw tail 2 is internally threaded with a nut 3. The screw body 1 and screw tail 2 are honeycomb structures that simulate cancellous bone. A solid external thread 4 is provided on the outer surface of the screw body 1.

[0033] Preferably, the lower end of the nail body 1 is provided with a solid tip 5. Preferably, the inner side of the nail tail 2 is provided with a solid inner wall 5, the surface of the inner wall 5 is provided with internal threads, and the solid nut 3 is threadedly connected to the inner wall 5.

[0034] Preferably, it also includes a rod 6, which has a honeycomb structure that mimics cancellous bone; the rod 6 is used to connect multiple pedicle screws, the rod 6 passes through the screw tail 2, and the rod 6 and screw tail 2 are fixedly connected together using a nut 3.

[0035] This embodiment is applicable to the most common spinal fusion surgery scenarios, such as single-segment lumbar disc herniation with instability and single-segment lumbar spinal stenosis.

[0036] The parameters of the pedicle screw are the same as in Example 1: the screw rod 6 has a diameter of 5.5 mm, a length of 50 mm, a honeycomb structure with a porosity of 65%, and a pore size of 350 μm. A 2 mm solid section is provided at both ends of the screw rod 6 for easy locking with the nut 3.

[0037] The solid structure of the pedicle screw and the overall strength of the rod provide reliable three-dimensional mechanical fixation, allowing patients to get out of bed early. Bone tissue grows into the honeycomb structure of the screw body, screw tail, and rod, forming a biological connection between the screw and the vertebral body, the rod, and the screw tail.

[0038] Example 3: A spinal internal fixation device with fusion function, including a pedicle screw. The pedicle screw includes a screw body 1 and a screw tail 2 at the upper end of the screw body 1. The screw tail 2 is internally threaded with a nut 3. The screw body 1 and screw tail 2 are honeycomb structures that simulate cancellous bone. A solid external thread 4 is provided on the outer surface of the screw body 1.

[0039] Preferably, the lower end of the nail body 1 is provided with a solid tip 5. Preferably, the inner side of the nail tail 2 is provided with a solid inner wall 5, the surface of the inner wall 5 is provided with internal threads, and the solid nut 3 is threadedly connected to the inner wall 5.

[0040] Preferably, it also includes a rod 6, which has a honeycomb structure that mimics cancellous bone; the rod 6 is used to connect multiple pedicle screws, the rod 6 passes through the screw tail 2, and the rod 6 and screw tail 2 are fixedly connected together using a nut 3.

[0041] Preferably, it also includes a connecting rod 7 for connecting the plurality of nail rods 6, the connecting rod 7 being connected to the nail rods 6 via a connector 8.

[0042] Preferably, the connecting rod 7 and the connector 8 are honeycomb structures that simulate cancellous bone.

[0043] This embodiment is applicable to clinical scenarios requiring multi-segmental fixation and high spinal torsion resistance, such as multi-segmental spinal fractures, scoliosis, and multi-segmental lumbar degenerative diseases. The parameters of the pedicle screw and rod 6 are consistent with those in Embodiment 2. The connecting rod 7 has a diameter of 5.0 mm, a length of 40 mm, a honeycomb structure with a porosity of 60%, and a pore size of 300 μm. The connector 8 has a U-shaped structure, adapted to the rod 6 and connecting rod 7, and its honeycomb structure has a porosity of 60% and a pore size of 300 μm.

[0044] The three-dimensional framework composed of longitudinal rods and transverse connecting rods provides excellent early mechanical stability, effectively resisting flexion, extension, rotation, and lateral stresses of the spine. Bone tissue grows into the honeycomb structure of all components, forming an integrated structure between the entire internal fixation system and the spinal bone tissue.

[0045] Example 4: A spinal internal fixation device with fusion function, including a pedicle screw, wherein the pedicle screw includes a screw body 1, a screw tail 2 is provided at the upper end of the screw body 1, and a nut 3 is internally threaded to the screw tail 2. The screw body 1 and the screw tail 2 are honeycomb structures that simulate cancellous bone, and a solid external thread 4 is provided on the outer surface of the screw body 1.

[0046] Preferably, the lower end of the nail body 1 is provided with a solid tip 5. Preferably, the inner side of the nail tail 2 is provided with a solid inner wall 5, the surface of the inner wall 5 is provided with internal threads, and the solid nut 3 is threadedly connected to the inner wall 5.

[0047] Preferably, it also includes a rod 6, which has a honeycomb structure that mimics cancellous bone; the rod 6 is used to connect multiple pedicle screws, the rod 6 passes through the screw tail 2, and the rod 6 and screw tail 2 are fixedly connected together using a nut 3.

[0048] Preferably, the nail body 1, nail tail 2, nut 3, and nail rod 6 are made using 3D printing technology, and the materials used are titanium alloy, pure titanium, tantalum metal, or magnesium alloy.

[0049] Preferably, the porosity of the honeycomb structure of the nail body 1, nail tail 2, nut 3, and nail rod 6 is 60-80%.

[0050] Preferably, the honeycomb structure of the nail body 1, nail tail 2, nut 3, and nail rod 6 has a pore size of 300-800 μm.

[0051] Preferably, the honeycomb structure of the nail body 1, nail tail 2, nut 3 and nail rod 6 has a hydroxyapatite coating, a bioactive glass coating, or carries bone morphogenetic proteins, antibiotics or other bioactive substances.

[0052] Preferably, it also includes a connecting rod 7 for connecting the plurality of nail rods 6, the connecting rod 7 being connected to the nail rods 6 via a connector 8.

[0053] Preferably, the connecting rod 7 and the connector 8 are honeycomb structures that simulate cancellous bone.

[0054] This embodiment is applicable to clinical scenarios with poor bone healing capacity or high postoperative infection risk, such as elderly patients with osteoporotic vertebral fractures, diabetic patients undergoing spinal surgery, and revision surgery. After 3D printing and routine post-processing, a surface functionalization step is added: a hydroxyapatite coating with a thickness of 50 to 100 μm is prepared on the honeycomb structure surface of all components using plasma spraying technology. For high-risk patients, the components are immersed in a saline solution containing vancomycin, and vacuum suction is used to ensure the solution fully penetrates the honeycomb structure. Subsequently, freeze-drying is performed to load the antibiotic onto the porous surface. For patients with poor bone healing capacity, bone morphogenetic protein 2 can be further loaded onto the hydroxyapatite coating surface.

[0055] The hydroxyapatite coating significantly improves the integration of bone tissue with the implant, accelerating bone ingrowth by approximately two weeks compared to ordinary titanium alloy surfaces. Loaded bone morphogenetic protein 2 further promotes osteoblast proliferation and differentiation, increasing bone fusion rates in osteoporosis patients. Loaded antibiotics are slowly released over 4 to 6 weeks post-surgery, effectively reducing the incidence of postoperative incision and deep tissue infections.

[0056] This invention provides a spinal internal fixation device with fusion function. It uses 3D printing technology to prepare the entire assembly of pedicle screws, rods, nuts, and matching connectors to simulate the honeycomb structure of cancellous bone. At the same time, it retains the solid structure of key stress-bearing parts such as the external thread tip and threaded connection surface to ensure the strength of early mechanical fixation. After the components are assembled, they form a continuous bone ingrowth channel, realizing the transformation of spinal internal fixation from temporary mechanical support to permanent bony fusion. It can eliminate the need for various separate intervertebral, interlaminar, posterolateral, and intertransverse process bone grafting fusion steps in traditional spinal fusion surgery. Furthermore, it can further improve the bone fusion effect and reduce the risk of postoperative infection by loading bioactive factors or antibiotics on the porous structure surface, greatly simplifying the surgical procedure and reducing surgical trauma and complications.

[0057] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A spinal internal fixation device with fusion function, comprising a pedicle screw, wherein the pedicle screw comprises a screw body (1), a screw tail (2) is provided at the upper end of the screw body (1), and a nut (3) is internally threaded onto the screw tail (2), characterized in that: The nail body (1) and nail tail (2) are designed to mimic the honeycomb structure of cancellous bone, and solid external threads (4) are provided on the outer surface of the nail body (1).

2. According to claim 1, a spinal internal fixation device with fusion function is characterized in that, The lower end of the nail body (1) is provided with a solid tip (5).

3. The spinal internal fixation device with fusion function according to claim 1, characterized in that, The inner side of the nail tail (2) is provided with a solid inner wall (5), and the surface of the inner wall (5) is provided with an internal thread. The solid nut (3) is threadedly connected to the inner wall (5).

4. The spinal internal fixation device with fusion function according to claim 3, characterized in that, It also includes a rod (6), which is a honeycomb structure that simulates cancellous bone; the rod (6) is used to connect multiple pedicle screws, the rod (6) passes through the screw tail (2), and the rod (6) and the screw tail (2) are fixed together using a nut (3).

5. The spinal internal fixation device with fusion function according to claim 4, characterized in that, The nail body (1), nail tail (2), nut (3) and nail rod (6) are made by 3D printing process, and the materials are titanium alloy, pure titanium, tantalum metal or magnesium alloy.

6. The spinal internal fixation device with fusion function according to claim 4, characterized in that, The honeycomb structure of the nail body (1), nail tail (2), nut (3) and nail rod (6) has a porosity of 60-80%.

7. The spinal internal fixation device with fusion function according to claim 4, characterized in that, The honeycomb structure of the nail body (1), nail tail (2), nut (3) and nail rod (6) has a pore size of 300-800μm.

8. The spinal internal fixation device with fusion function according to claim 4, characterized in that, The honeycomb structure of the nail body (1), nail tail (2), nut (3) and nail rod (6) has a hydroxyapatite coating, a bioactive glass coating, or contains bone morphogenetic protein or antibiotics.

9. The spinal internal fixation device with fusion function according to claim 4, characterized in that, It also includes a connecting rod (7) for connecting multiple nail bars (6), the connecting rod (7) being connected to the nail bars (6) via a connector (8).

10. The spinal internal fixation device with fusion function according to claim 9, characterized in that, The connecting rod (7) and the connector (8) are designed to mimic the honeycomb structure of cancellous bone.

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