Degradable screw for complex bone environment

Abstract

The utility model relates to a degradable screw for a complex bone environment, which comprises a first degradable screw body with a hollow cavity, the first degradable screw body is conical, and a first end and a second end are arranged on two sides of the first degradable screw body in the length direction; the second degradable nail body is nailed into the hollow cavity of the first degradable nail body along the first end and is partially exposed out of the second end, and when the second degradable nail body extends into the hollow cavity of the first degradable nail body, the second degradable nail body abuts against the inner wall of the first degradable nail body to enable the first degradable nail body to expand. Compared with the prior art, the screw effectively solves the key clinical problems of screw slipping and fracture in an operation, uneven stress in a screw applying process and the like, and the holding force and the supporting force of the screw on bone tissues are enough.

Description

Technical Field

[0001] The utility model belongs to the technical field of orthopedic implants, in particular to a degradable screw used in a complex bone environment. Background Art

[0002] In the field of medical implants, especially in orthopedic surgery, the application of degradable metal screws has received widespread attention. These metals, including zinc-based metals, magnesium-based metals and iron-based metals, are favored for their excellent biosafety, biocompatibility and the advantage of avoiding secondary surgery for removal. These materials are not only essential trace elements for the human body, but are also crucial for protein synthesis, energy metabolism, cell development, gene expression, and the normal functioning of the immune and nervous systems. Another major advantage of degradable metals is their sufficient mechanical properties, which makes them excel in mechanical and degradation properties. In addition, their adaptive biological functions, such as promoting bone healing, inhibiting osteoclast activity or having anti-infection properties, further increase the clinical appeal of these materials. Therefore, they have been developed into a variety of orthopedic products, such as bone screws.

[0003] However, despite the obvious advantages of biodegradable metals, their acceptance in the market is limited. The reason is some inherent physical properties of these materials, such as softer material, poor toughness, and easy interface damage and pitting after nailing. These problems cause the screws to easily slip or break during surgery. At the same time, uneven degradation in the early and middle stages may also lead to problems such as local bone dissolution and loosening. In order to meet these challenges, scientists and medical research and development institutions have made a number of improvements to biodegradable metal materials and screw designs (including threads, nail head transition surfaces, and screw holes). However, even so, the existing screw products on the market still have the above-mentioned problems, which has become a major bottleneck in the clinical application of biodegradable metal products.

[0004] CN211049571U relates to the technical field of orthopedic surgical instruments, and specifically discloses an expansion screw for orthopedic implantation, including a top cap and a nail tip section, a first screw section is connected to the top cap, a second screw section is connected to the nail tip section, a connecting section is provided between the first screw section and the second screw section, and the diameter of the first screw section is greater than the diameter of the second screw section, the second screw section is composed of a left half screw and a right half screw, and the nail tip section is composed of a left half nail tip and a right half nail tip, and the expansion screw for orthopedic implantation also includes an expansion mechanism for controlling the expansion of the second screw section and the nail tip section. The expansion screw for orthopedic implantation rotates the first screw, thereby causing the first screw to move up and down, and the conical column also moves accordingly, and the conical column is used to squeeze the conical groove, so that the purpose of expanding the second screw section and the nail tip section can be achieved, so that the screw is more firmly fixed in the bone, avoiding the situation of looseness affecting the patient's bone recovery. However, the material is relatively hard, and it is inevitable to cause secondary damage when applied to patients with complex bone environment such as osteoporosis, and the retention force after nailing is not enough.

[0005] Patients with complex bone environments such as osteoporosis have abnormal bone reconstruction after fracture, slow fracture healing, and long recovery time. How to promote rapid recovery and improve the retention force of screws in the fracture site is an urgent problem that needs to be solved. Utility Model Content

[0006] The purpose of the utility model is to provide a degradable screw for complex bone environment in order to overcome the defects of the above-mentioned prior art. From the structural level of the screw, key clinical problems such as thread slippage, breakage and uneven force during nailing are effectively avoided, and the screw has sufficient retention and support force on bone tissue.

[0007] The purpose of the utility model can be achieved through the following technical solutions:

[0008] A degradable screw for complex bone environment, comprising:

[0009] The first degradable nail body has a hollow cavity extending downward from the top, and a plurality of slits are processed along the axial direction on the side wall surrounding the hollow cavity to form a plurality of sheet-like bodies that can be expanded outwards;

[0010] The outer diameter of the second degradable nail body is greater than the inner diameter of the hollow cavity, and when the second degradable nail body is inserted into the hollow cavity of the first degradable nail body and fixed, the sheet body is supported by the second degradable nail body and stretched outwards.

[0011] Furthermore, the hollow cavity is provided with an internal thread, and the outer side of the second degradable nail body is provided with a first external thread matching the internal thread.

[0012] Furthermore, the pitch of the first external thread is smaller than the pitch of the internal thread.

[0013] Furthermore, the outer diameter of the second degradable nail body is 0.1-2 mm larger than the inner diameter of the hollow cavity.

[0014] Furthermore, the slits are provided with at least two.

[0015] Furthermore, the outer surface of the first degradable nail body is also processed with a second external thread.

[0016] Furthermore, a plurality of barbs or protrusions are distributed on the outer surface of the first degradable nail body.

[0017] Furthermore, a slot is axially arranged in the middle portion of the second degradable nail body.

[0018] Furthermore, the slot is in the shape of an inner hexagon.

[0019] Furthermore, a plurality of micro-channels are distributed at the bottom end of the first degradable nail body and vertically penetrate the hollow cavity along the axial direction.

[0020] Furthermore, the first degradable nail body and the second degradable nail body are made of a zinc-based alloy, an iron-based alloy or a magnesium-based alloy.

[0021] Furthermore, the second degradable nail body and the hollow cavity are interference-fitted with each other through a mortise and tenon structure.

[0022] Compared with the prior art, the utility model has the following beneficial effects:

[0023] (1) The screw provided by the utility model effectively avoids key clinical problems such as thread slippage, breakage and uneven force during nailing, and the screw has sufficient holding and supporting force on bone tissue.

[0024] (2) The second degradable nail body and the first degradable nail body provided by the utility model, during the implantation process, the second degradable nail body continuously squeezes the inner wall of the first degradable nail body to make the first degradable nail body expand, so that there is a larger contact area between the first degradable nail body and the bone tissue. When used in patients with osteoporosis, the first degradable nail body has a greater holding force at the fracture site and is not easy to loosen or fall off.

[0025] (3) The first degradable nail body and the second degradable nail body provided by the utility model are made of degradable materials, and no additional surgery is required to remove the screws, thereby alleviating the patient's pain; at the same time, the metal ions released by the degradable metal during the degradation process will also promote or induce the formation of new bone.

[0026] (4) The slit provided by the utility model can allow bone marrow blood to infiltrate into the first degradable nail body and contact with the second degradable nail body, thereby forming bone tissue, thereby forming a structure of bone tissue-first degradable nail body-second degradable nail body, thereby improving the retention force of the overall structure. When the first degradable nail body is degraded, the corresponding bone tissue can provide sufficient supporting force to prevent the loosening of the overall structure, thereby achieving a very good therapeutic effect on patients with osteoporosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of a degradable screw;

[0028] Figure 2 is a schematic diagram of the second degradable nail body being screwed into the first degradable nail body;

[0029] Figure 3 for Figure 2 A cross-sectional schematic diagram of

[0030] Figure 4 is another structural schematic diagram of a degradable screw;

[0031] Numbers in the figure:

[0032] 1-first degradable nail body, 11-hollow cavity, 12-slit, 13-sheet body, 14-internal thread, 15-second external thread, 16-barb;

[0033] 2-second degradable nail body, 21-first external thread, 22-slot hole. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] Features such as component models, material names, connection structures, control methods, etc. that are not clearly stated in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0036] In the description of the present invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] In the description of the present invention, "multiple" means two or more than two, unless otherwise specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a bolt connection or a welding connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] Patients with complex bone environments, such as osteoporosis, experience abnormal bone reconstruction after fracture, slow fracture healing, long recovery time, and the risk of fixations or implants loosening and bone graft absorption. Existing screws cannot avoid the above situations during implantation.

[0039] To solve the above problems, the utility model provides a degradable screw for complex bone environment, see Figure 1 and Figure 4 As shown in the following, including:

[0040] The first degradable nail body 1 has a hollow cavity 11 extending downward from the top, and a plurality of slits 12 are processed along the axial direction on the side wall surrounding the hollow cavity 11 to form a plurality of sheet-like bodies 13 that can be expanded outwards;

[0041] The outer diameter of the second degradable nail body 2 is greater than the inner diameter of the hollow cavity 11 , and when the second degradable nail body 2 is inserted into the hollow cavity 11 of the first degradable nail body 1 and fixed, the sheet body 13 is supported by the second degradable nail body 2 and stretched outward.

[0042] When the degradable screw of the utility model is used, a hole is first drilled with a surgical electric drill, and then the first degradable nail body 1 is knocked or screwed into the drilled hole, and then the second degradable nail body 2 is implanted into the first degradable nail body 1 by means of internal and external thread matching, so that the second degradable nail body 2 can gradually open the sheet body 13 of the first degradable nail body 1 during the implantation process to achieve radial expansion, thereby applying pressure to the drilled hole, achieving strong fixation in a complex bone environment, and avoiding common problems of wire slippage, breakage, and early and mid-term nail withdrawal.

[0043] In some specific embodiments, the hollow cavity 11 is provided with an internal thread 14, and the outer side of the second degradable nail body 2 is provided with a first external thread 21 matching the internal thread 14. Furthermore, the pitch of the first external thread 21 is smaller than the pitch of the internal thread 14. By providing suitable internal threads 14 and first external threads 21, it is convenient to screw the second degradable nail body 2 into the first degradable nail body 1, and ensure good fixation between the two.

[0044] In some specific embodiments, the outer diameter of the second degradable nail body 2 is 0.1-2 mm larger than the inner diameter of the hollow cavity 11, so that the second degradable nail body 2 is gradually expanded during the nailing process, providing more contact surface with the adjacent bone tissue, better gripping, and preventing the nail from retreating. At the same time, the first degradable nail body 1 is evenly stressed during the nailing process, and is well matched with the second degradable nail body 2, without causing interface damage such as local threads.

[0045] In some specific embodiments, the slits 12 are provided with at least two. Generally, three, four or more slits can be provided, but the number should not be too large, so as not to affect the strength of the formed sheet 13. Through the provision of the slits 12, on the one hand, a sheet 13 that is gradually expanded during the nailing process can be formed, and at the same time, in the process of the sheet 13 being expanded outward, it can be appropriately expanded and deformed. In addition, in the subsequent growth and repair process, bone marrow blood can also penetrate into the degradable screw through the slits 12 to form a combined structure combined with the internal nail body, thereby improving the retention force of the overall structure.

[0046] In some specific embodiments, the outer surface of the first degradable nail body 1 is further processed with a second external thread 15, which can enable the first degradable nail body 1 to be better screwed into the fracture, and the design of the external thread makes the outer surface of the first degradable nail body 1 rough, so that when the bone tissue grows well, the connection surface between the first degradable nail body 1 and the first degradable nail body 1 is uneven, and the uneven connection surface increases the supporting force of the screw on the bone tissue, thereby improving the stability of the overall structure.

[0047] In some specific embodiments, a plurality of barbs 16 or protrusions are also distributed on the outer surface of the first degradable nail body 1. For structures such as the barbs 16, after the first degradable nail body 1 is implanted, the barbs 16 extend into the bone tissue, forming a structure in which the bone tissue includes the barbs 16, thereby increasing the holding force and effectively preventing the first degradable nail body 1 from slipping out of the fracture of the patient.

[0048] In some specific embodiments, a slot 22 is axially provided in the middle portion of the second degradable nail body 2. Furthermore, the slot 22 is hexagonal. Specifically, the slot 22 can be provided in the head region of the second degradable nail body 2, or can be provided to penetrate the entire nail body. Preferably, the slot 22 is provided in a manner of penetrating the entire second degradable nail body 2. In this way, such a structural design allows the screw tool to be inserted to the bottom of the nail body when tightening the second degradable nail body 2, ensuring that the entire nail body can be evenly stressed when applying force, thereby avoiding breakage or damage caused by concentrated force.

[0049] In some specific embodiments, the bottom end of the first degradable nail body 1 is also provided with a plurality of micro-channels that vertically penetrate the axial direction and connect to the hollow cavity 11. After the screw is implanted, bone marrow blood infiltrates into the micro-channels to form bone tissue in the micro-channels, forming a structure of bone tissue-first degradable nail body 1-second degradable nail body 2-bone tissue, thereby improving the support force of the screw on the bone tissue when being nailed in, and improving the stability of the overall screw structure.

[0050] In some specific embodiments, the first degradable nail body 1 and the second degradable nail body 2 are made of zinc-based alloy, iron-based alloy or magnesium-based alloy. Specifically, the metal material can be Zn-Sr, Zn-Mg, Zn-Fe, Zn-Ca, Zn-Mn, Zn-Cu, Zn-Li, Zn-Ag, Zn-Li-Ag, Zn-Li-Sr, Zn-Li-Ca, Zn-Li-Mg, Zn-Mg-Sr or Zn-Mg-Ca, etc. The selection of the specific material type of the degradable metal in this part is a conventional technology in the field and is not an innovative protection point of the present utility model.

[0051] In some specific embodiments, the second degradable nail body 2 is interference-fitted with the hollow cavity 11 through a mortise and tenon structure. The use of the mortise and tenon structure can not only provide a stable fixing method that does not rely on threads, but also simplify the manufacturing process and may reduce the stress on bone tissue during implantation.

[0052] The above embodiments may be implemented individually or in any combination of two or more.

[0053] The above implementation is described in more detail below in conjunction with specific examples.

[0054] Embodiment 1:

[0055] like Figures 1 to 3As shown, this embodiment provides a degradable screw for complex bone environment, including a first degradable nail body 1 and a second degradable nail body 2, the first degradable nail body 1 has a hollow cavity 11, the second degradable nail body 2 cooperates with the hollow cavity 11 and is nailed into the hollow cavity 11, and the first degradable nail body 1 and the second degradable nail body 2 are roughly cylindrical. Three slits 12 are opened axially on the side wall of the hollow cavity 11 to form a three-petal sheet 13 structure. Roughly matching internal threads 14 and first external threads 21 are respectively arranged between the hollow cavity 11 and the second degradable nail body 2, and the pitch of the internal threads 14 is slightly larger than the first external threads 21, and at the same time, the outer diameter of the second degradable nail body 2 is slightly larger than the inner diameter of the hollow cavity 11. The outer surface of the first degradable nail body 1 is also provided with a second external thread 15. The middle area of ​​the second degradable nail body 2 is processed with a slot 22 that penetrates along the axial direction. The degradable metal material of this embodiment can be Zn-0.8Li-0.5Ag alloy prepared by CN114748686B.

[0056] In this embodiment, the length of the second degradable nail body 2 is 4 cm and the diameter is about 6 mm. The length of the first degradable nail body 1 is about 3 cm and the diameter is about 8 mm. The width of the slit 12 is about 1.5 mm and the length is about 2 cm. The inner diameter of the cavity in the slit area is about 5 mm (i.e., about 1 mm smaller than the diameter of the second degradable nail body 2).

[0057] When the degradable screw of this embodiment is used, a hole is first drilled with a surgical electric drill, and then the first degradable nail body 1 is knocked or screwed into the drilled hole. Subsequently, the second degradable nail body 2 is implanted into the first degradable nail body 1 by means of internal and external thread matching through the tool matching slot 22, so that the second degradable nail body 2 can gradually open the sheet body 13 of the first degradable nail body 1 during the implantation process to achieve radial expansion, thereby applying pressure to the drilled hole, achieving strong fixation in a complex bone environment, and avoiding common problems such as wire slippage, breakage, and early and mid-term nail withdrawal.

[0058] Embodiment 2:

[0059] Different from the first embodiment, in the degradable screw for complex bone environment provided in the present embodiment, the second external thread 15 is abandoned on the outer surface of the first degradable nail body 1, and a barb 16 is provided instead. Figure 4 shown.

[0060] Embodiment 3:

[0061] Different from the first embodiment, in this embodiment, a plurality of micro-channels are distributed at the bottom end of the first degradable nail body 1 and are vertically penetrated in the axial direction and connected to the hollow cavity 11 .

[0062] Embodiment 4:

[0063] Different from the first embodiment, in the degradable screw for complex bone environment provided in the present embodiment, the first degradable nail body 1 and the second degradable nail body 2 are replaced by an interference fit through a mortise and tenon structure.

[0064] The above description of the embodiments is to facilitate the understanding and use of the utility model by those skilled in the art. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the utility model is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the utility model without departing from the scope of the utility model should be within the scope of protection of the utility model.

Claims

1. A degradable screw for complex bone environment, characterized in that: include: The first degradable nail body has a hollow cavity extending downward from the top, and a plurality of slits are processed along the axial direction on the side wall surrounding the hollow cavity to form a plurality of sheet-like bodies that can be expanded outwards; The outer diameter of the second degradable nail body is greater than the inner diameter of the hollow cavity, and when the second degradable nail body is inserted into the hollow cavity of the first degradable nail body and fixed, the sheet body is supported by the second degradable nail body and stretched outwards.

2. The degradable screw for complex bone environment according to claim 1, characterized in that: An internal thread is arranged in the hollow cavity, and a first external thread matching the internal thread is arranged on the outer side of the second degradable nail body.

3. The degradable screw for complex bone environment according to claim 2, characterized in that: The pitch of the first external thread is smaller than the pitch of the internal thread.

4. The degradable screw for complex bone environment according to claim 1, characterized in that: The outer diameter of the second degradable nail body is 0.1-2 mm larger than the inner diameter of the hollow cavity.

5. The degradable screw for complex bone environment according to claim 1, characterized in that: The slits are provided with at least two.

6. The degradable screw for complex bone environment according to claim 1, characterized in that: The outer surface of the first degradable nail body is further processed with a second external thread; Or the outer surface of the first degradable nail body is also distributed with a plurality of barbs or protrusions.

7. The degradable screw for complex bone environment according to claim 1, characterized in that: A slot is axially arranged at the middle portion of the second degradable nail body.

8. The degradable screw for complex bone environment according to claim 7, characterized in that: The slot is in the shape of an inner hexagon.

9. The degradable screw for complex bone environment according to claim 1, characterized in that: A plurality of micro-channels are also distributed at the bottom end of the first degradable nail body and vertically penetrate through the axial direction and communicate with the hollow cavity.

10. The degradable screw for complex bone environment according to claim 1, characterized in that: The first degradable nail body and the second degradable nail body are made of a zinc-based alloy, an iron-based alloy or a magnesium-based alloy; The second degradable nail body and the hollow cavity are interference-fitted with each other through a mortise and tenon structure.

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