3D printing porous pedicle screw

Abstract

The utility model discloses a 3D printing porous pedicle screw which comprises a screw body part and a screw cap part, the screw body part comprises a cortical bone thread area close to one end of the screw cap part and a cancellous bone thread area far away from one end of the screw cap part, and a porous structure area is arranged at one end, not connected with the screw cap part, of the screw body part. The porous structure area comprises an inner core column extending in the axial direction of the nail body part, at least one reinforcing beam and a porous structure, the reinforcing beams extend outwards from the periphery of the inner core column, and the porous structure is annularly distributed on the outer periphery of the inner core column. The porous structure can efficiently induce bone tissue to grow in, the screw and a vertebral body are connected into a whole, stress is effectively dispersed, the stability of the screw is improved, the porous structure is arranged on the vertebral body at the front end of the screw, screw breakage caused by stress concentration of the screw in a vertebral pedicle area can be avoided, meanwhile, the stability of the screw can be better improved through the reinforcing beam, and the service life of the screw is prolonged. The possibility of fracture of a porous area of the screw is reduced, generalization performance is better, and the use experience feeling is improved.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and in particular to a 3D printed porous pedicle screw. Background Technology

[0002] Aseptic lumbar pedicle screw (LPS) loosening is one of the most common clinical phenomena after spinal internal fixation surgery, often causing postoperative complications such as low back pain and pseudoarthrosis, and even leading to internal fixation failure requiring revision surgery. Since 2000, the proportion of patients over 65 years of age undergoing spinal fusion surgery has increased exponentially, and this age group is expected to double by 2050. With the accelerating aging of my country's society, the proportion of osteopenia and osteoporotic spinal diseases in spinal surgery will increase year by year, making aseptic pedicle screw loosening even more noteworthy. The various complications caused by screw loosening not only cause great distress to both doctors and patients, but also place a heavy burden on the medical system. As the central axial skeleton of the human body, the lumbar spine has a large range of motion and high weight-bearing intensity, and LPS needs to face complex stresses of various degrees. Therefore, developing an LPS with high strength and osseointegration capacity to reduce or avoid the occurrence of pedicle screw loosening after lumbar internal fixation surgery has important scientific and clinical significance.

[0003] Currently, although bone cement reinforcement can increase both the immediate and long-term stability of LPS and significantly reduce the incidence of screw loosening, it is only suitable for use in cases of severe osteoporosis or partial revision surgery. Moreover, bone cement leakage can lead to serious consequences such as refracture of adjacent vertebrae, pulmonary embolism, and paraplegia, making it unsuitable as a routine surgical technique to reduce LPS loosening.

[0004] The rough surface and microporous structure formed by screw surface treatment technology have poor connectivity, limited porous space, and insufficient bone ingrowth capacity, making it impossible to form deep osseointegration. In addition, low modulus titanium alloy materials and the application of local drugs also have the same problem of insufficient osseointegration capacity.

[0005] In conclusion, existing aseptic lumbar pedicle screws may fail to fully meet clinical needs due to one or more of the above-mentioned design deficiencies, thereby affecting the overall quality of lumbar spine treatment.

[0006] Therefore, there is a need for a 3D-printed porous pedicle screw to solve the above problems. This application proposes a design for a Ti-6Al-4V (Ti64) alloy porous lumbar pedicle screw (PLPS), aiming to reduce the incidence of pedicle screw loosening after lumbar surgery and improve surgical outcomes by utilizing the osseointegration capacity of the porous structure. Utility Model Content

[0007] To address the aforementioned problems in the prior art, this application discloses a 3D-printed porous pedicle screw, comprising a screw body and a screw head. The screw body includes a cortical bone threaded area near one end of the screw head and a cancellous bone threaded area away from the screw head. The end of the screw body not connected to the screw head is provided with a porous structure area.

[0008] The porous structure area includes an inner core post extending axially along the nail body, a reinforcing beam, and a porous structure. At least one reinforcing beam is provided, and the reinforcing beam extends outward from the periphery of the inner core post. The porous structure is arranged around the outer periphery of the inner core post.

[0009] Furthermore, the porous structure area is located in the cancellous bone thread area near the tip of the nail body where the stress is low.

[0010] Furthermore, the unit shape of the porous structure is a diamond lattice structure, the pore size of the diamond lattice structure is 600 μm, the porosity is 70%, and the connectivity is 100%.

[0011] Furthermore, the reinforcing beams are three in number and are equidistantly arranged around the outer periphery of the inner core column. The reinforcing beams divide the porous structure area into three equal parts, so that the porous structure arranged around the outer periphery of the inner core column is divided into three equal parts and the outer peripheral surface of each part tends to be gentle.

[0012] Furthermore, the ratio of the inner diameter of the outer periphery of the inner core post to the inner diameter of the outer periphery formed by the porous structure is 60%, so that the porous structure can provide sufficient space for vertebral ingrowth and ensure the mechanical properties of the nail.

[0013] Furthermore, the porous structure region accounts for 20% of the total length of the nail body.

[0014] Furthermore, the porous structure region accounts for 30% of the total length of the nail body.

[0015] Furthermore, the porous structure region accounts for 40% of the total length of the nail body.

[0016] Furthermore, the nail head is U-shaped, and the inside of the U-shaped opening is provided with internal threads.

[0017] Furthermore, the pedicle screw can be manufactured by 3D printing in one piece.

[0018] The 3D-printed porous pedicle screw provided in this application has at least the following beneficial effects:

[0019] This application utilizes a porous structure to efficiently induce bone ingrowth, connecting the screw and vertebral body into a unified whole, effectively dispersing stress and increasing screw stability. The porous structure, located at the front end of the screw within the vertebral body, prevents screw breakage due to stress concentration in the pedicle region. The reinforcing beam further enhances screw stability, reduces the possibility of breakage in the porous area, and provides ample space for bone ingrowth while maintaining screw mechanical properties. This makes the application more widely applicable and improves the user experience. Attached Figure Description

[0020] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 : A three-dimensional schematic diagram of the pedicle screw involved in the embodiments of this application;

[0022] Figure 2 : Enlarged schematic diagram of the porous structure region involved in the embodiments of this application;

[0023] Figure 3 : A schematic cross-sectional view of the porous structure region involved in the embodiments of this application;

[0024] Figure 4 This application includes comparative schematic diagrams of porous structure regions with different proportions in its embodiments;

[0025] Figure 5 Microscopic images of the surface structure of the porous structure region involved in the embodiments of this application;

[0026] Figure 6 Microscopic images of the porous surface structure involved in the embodiments of this application;

[0027] In the diagram: 1-Pin body; 11-Cortical bone threaded area; 12-Cancellous bone threaded area; 13-Porous structure area; 131-Inner core post; 132-Reinforcing beam; 133-Porous structure;

[0028] 2-Nail head; 21-Internal thread; Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0030] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. In the description of the present invention, it should be understood that the terms "upper," "lower," "top," "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein.

[0031] Please refer to Figure 1-6 As shown, a 3D-printed porous pedicle screw includes a screw body 1 and a screw head 2. The screw body 1 includes a cortical bone threaded area 11 near the screw head 2 and a cancellous bone threaded area 12 away from the screw head 2. The cortical bone threaded area 11 has denser threads, while the cancellous bone threaded area 12 has a larger thread spacing. A porous structure area 13 is provided at the end of the screw body 1 that is not connected to the screw head 2. The porous structure area 13 includes an inner core post 131 extending axially along the screw body 1, a reinforcing beam 132, and a porous structure 133. At least one reinforcing beam 132 is provided, and the reinforcing beam 132 extends outward from the periphery of the inner core post 131. The reinforcing beam 132 can provide better support and fixation for the porous structure 133, which can better improve the screw stability and reduce the breakage of the screw in the porous area. Meanwhile, the porous structure 133 is arranged around the outer periphery of the inner core column 131. The osseointegration capability of the porous structure 133 can be used to efficiently induce bone tissue ingrowth, connecting the screw and the vertebral body into a whole, thereby effectively dispersing stress, reducing the incidence of pedicle screw loosening after lumbar spine surgery, and improving surgical outcomes.

[0032] Based on the above technical solution, the porous structure region 13 is located in the cancellous bone thread region 12, which has low stress near the tip of the screw body 1, thus preventing screw breakage due to stress concentration in the pedicle region. This is understandable. Figure 1 As shown, the porous structure region 13 preferably does not have threads, but instead the porous structure region 13 replaces the threads.

[0033] In a preferred embodiment, the pedicle screw of this application can be manufactured by 3D printing in one piece.

[0034] Based on this, considering factors such as bone ingrowth, microvascular formation, mechanical strength, and permeability, the preferred unit shape for porous structures is a diamond lattice structure. This diamond lattice structure has a pore size of 600 μm, a porosity of 70%, and a connectivity of 100%, which can effectively improve connectivity and increase the pore capacity.

[0035] Specifically, the reinforcing beams 132 are preferably three equidistant rings arranged around the outer periphery of the inner core column 131. This can be understood as a trilobal reinforcing beam structure extending outward from the inner core column 131. The reinforcing beams 132 divide the porous structure area 13 into three equal parts, so that the porous structure 133 arranged around the outer periphery of the inner core column 131 is divided into three equal parts and each part forms a gentler outer peripheral curved surface, that is, forming three minimal curved surface structures with the same period, which can improve the overall strength of the nail body and also has aesthetic appeal.

[0036] Furthermore, in a preferred embodiment, the ratio of the inner diameter of the outer periphery of the inner core post 131 to the inner diameter of the outer periphery formed by the porous structure 133 surrounding the inner core post 131 is 60%, which enables the porous structure 133 to provide sufficient space for vertebral ingrowth and ensures the mechanical properties of the nail.

[0037] In optional embodiments, such as Figure 4 The porous structure zone 13 accounts for 20% of the total length of the nail body.

[0038] In optional embodiments, such as Figure 4 The porous structure zone 13 accounts for 30% of the total length of the nail body.

[0039] In optional embodiments, such as Figure 4 The porous structure zone 13 accounts for 40% of the total length of the nail body.

[0040] To increase structural stability and nail connection, the nail head 2 is U-shaped, and the inside of the U-shaped opening is provided with internal thread 21.

[0041] The 3D-printed porous pedicle screw provided in this application has at least the following beneficial effects:

[0042] 1. The porous structure can efficiently induce bone tissue ingrowth, connecting the screw and the vertebral body into a whole, effectively dispersing stress and increasing screw stability;

[0043] 2. The porous structure is located at the front end of the screw in contact with the vertebral body, which can prevent the screw from breaking due to stress concentration in the pedicle area. The porous structure is distributed in the cancellous bone thread area near the screw tip where the stress is less, i.e., the tapered design near the insertion end, which facilitates the screw implantation into the bone.

[0044] 3. By reinforcing the beams, the stability of the screw can be improved, the possibility of screw fracture in the porous area can be reduced, and sufficient porous structural space can be provided for bone ingrowth while taking into account the mechanical properties of the screw. Postoperative patients do not have a foreign body sensation. Furthermore, the three-reinforcing beam scheme can form three periodic minimal curved surface structures on the outer periphery of the porous structure, and the unit shape of the porous structure is a diamond lattice structure, which is more conducive to providing more gap space and ensuring the overall strength of the screw body. It is more widely applicable and can better improve the user experience.

[0045] 4. Pedicle screws can be manufactured using 3D printing in one piece, and the process parameters can be adjusted according to different patient requests, making them more applicable.

[0046] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. A 3D-printed porous pedicle screw, characterized in that: It includes a nail body and a nail head. The nail body includes a cortical bone threaded area near one end of the nail head and a cancellous bone threaded area away from the nail head. The end of the nail body that is not connected to the nail head has a porous structure area. The porous structure area includes an inner core post extending axially along the nail body, a reinforcing beam, and a porous structure. At least one reinforcing beam is provided, and the reinforcing beam extends outward from the periphery of the inner core post. The porous structure is arranged around the outer periphery of the inner core post.

2. The 3D-printed porous pedicle screw according to claim 1, characterized in that, The porous structure area is located in the cancellous bone thread area near the tip of the nail body where the stress is low.

3. The 3D-printed porous pedicle screw according to claim 1, characterized in that, The porous structure has a unit shape of diamond lattice, with a pore size of 600 μm, a porosity of 70%, and a connectivity of 100%.

4. The 3D-printed porous pedicle screw according to claim 1, characterized in that, The reinforcing beams are three in number and are equidistantly arranged around the outer periphery of the inner core column. The reinforcing beams divide the porous structure area into three equal parts, so that the porous structure arranged around the outer periphery of the inner core column is divided into three equal parts and the outer peripheral surface of each part tends to be flat.

5. A 3D-printed porous pedicle screw according to claim 1, characterized in that, The ratio of the inner diameter of the outer periphery of the inner core post to the inner diameter of the outer periphery formed by the porous structure is 60%, so that the porous structure can provide sufficient space for vertebral ingrowth and ensure the mechanical properties of the nail.

6. The 3D-printed porous pedicle screw according to claim 1, characterized in that, The porous structure area accounts for 20% of the total length of the nail body.

7. A 3D-printed porous pedicle screw according to claim 1, characterized in that, The porous structure area accounts for 30% of the total length of the nail body.

8. A 3D-printed porous pedicle screw according to claim 1, characterized in that, The porous structure area accounts for 40% of the total length of the nail body.

9. A 3D-printed porous pedicle screw according to claim 1, characterized in that, The nail head is U-shaped, and the inside of the U-shaped opening is provided with internal threads.

10. A 3D-printed porous pedicle screw according to any one of claims 1-9, characterized in that, The pedicle screw can be manufactured by 3D printing in one piece.

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