Variable stiffness intramedullary fixation device

Abstract

The invention provides a variable-stiffness intramedullary fixing device, and relates to the technical field of medical instruments. The variable-stiffness intramedullary fixing device comprises a drill tail, a flexible shaft, a drill bit, a tensioning piece and a flexible piece. The drill tail, the flexible shaft and the drill bit are sequentially connected; the flexible parts are arranged around the axis of the flexible shaft at intervals and sequentially penetrate through the drill tail and the flexible shaft. The far ends of the flexible parts are connected with the drill bit, and the near ends of the flexible parts are connected with the tensioning part. The overall rigidity of the flexible shaft and the drill bit assembly can be continuously adjusted by adjusting the tensioning degree of the tensioning piece on the flexible piece, and the fixing strength is improved while the implanting flexibility is guaranteed. The device is compact in structure and flexible in steering, can reduce repeated adjustment and X-ray exposure in an operation, supports single-channel minimally invasive implantation, reduces the risk of combined use of multiple devices, effectively shortens the operation time, and improves the operation safety and clinical applicability.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a variable stiffness intramedullary fixation device. Background Technology

[0002] After successful reduction, pelvic fractures are primarily treated with internal or external fixation techniques. Minimally invasive intramedullary fixation is considered the most advantageous internal fixation method due to its minimal invasiveness. In contrast, traditional open reduction and plate fixation has significant drawbacks: it requires extensive soft tissue dissection, results in substantial intraoperative bleeding, and is prone to complications such as neurovascular injury due to anatomical variations. Over the past 20 years, percutaneous minimally invasive screw fixation has gradually replaced traditional surgical methods due to its advantages such as smaller incisions, less bleeding, lower infection rates, and reduced iatrogenic injury.

[0003] However, existing intramedullary fixation devices for pelvic fractures still face the following technical bottlenecks: 1. Excessive material rigidity: Currently, stainless steel is commonly used to fix steel nails. Although it has high strength, it lacks flexibility and is difficult to adjust the position in the medullary cavity environment; 2. Low operational efficiency: During the procedure, the device position needs to be repeatedly tapped and adjusted when the cortical bone is punctured, which not only prolongs the operation time and increases the physical exertion of doctors, but also causes medical staff to be exposed to X-ray radiation for a long time. 3. Risks of using multiple devices: In deep intramedullary fixation scenarios, it is often necessary to use multiple traditional fixation devices in combination, which can significantly increase the degree of trauma to the patient, intraoperative bleeding, and the probability of infection.

[0004] Based on the aforementioned clinical needs, there is an urgent need to develop a novel variable stiffness intramedullary fixation device. This device should possess the following characteristics: compact structure, flexible steering, adjustable stiffness, minimally invasive nature, and ease of operation. The development of such innovative devices will provide more reliable technical support for pelvic fracture reduction and internal fixation surgery. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a variable stiffness intramedullary fixation device for intramedullary fixation of pelvic fractures.

[0006] In a first aspect, the variable stiffness intramedullary fixation device provided by the present invention includes: a drill tail, a flexible shaft, a drill bit, a tensioning member, and a flexible member; The drill tail, the flexible shaft, and the drill bit are connected in sequence; Several of the flexible elements are spaced apart around the axis of the flexible shaft and pass through the drill bit and the flexible shaft in sequence; The distal ends of the plurality of flexible elements are connected to the drill bit, and the proximal ends of the plurality of flexible elements are connected to the tensioning element.

[0007] In conjunction with the first aspect, the present invention provides a first possible implementation of the first aspect, wherein the variable stiffness intramedullary fixation device is provided with a guide wire hole that passes through the drill tail, the flexible shaft and the drill bit in sequence, and the guide wire hole is coaxially arranged with the flexible shaft; Furthermore, the variable stiffness intramedullary fixation device is provided with several wire rope holes that pass through the flexible shaft, and the several wire rope holes are arranged at intervals around the guide wire hole.

[0008] In conjunction with the first aspect, the present invention provides a second possible implementation of the first aspect, wherein the tensioning member comprises: a plurality of sliders and a plurality of threaded members; Multiple sliders are slidably fitted to the drill tail along the axial direction, and multiple threaded parts are installed on the drill tail, with each threaded part corresponding to and connected to one of the multiple sliders. Each of the sliders is connected to at least one of the flexible elements.

[0009] In conjunction with the first aspect, the present invention provides a third possible implementation of the first aspect, wherein the flexible shaft comprises: a plurality of double-sided convex bodies and a plurality of double-sided concave bodies; Multiple double-sided convex bodies and multiple double-sided concave bodies are alternately connected.

[0010] In conjunction with the third possible implementation of the first aspect, the present invention provides a fourth possible implementation of the first aspect, wherein the double-sided convex body comprises: a cylindrical base, a first convex piece, and a second convex piece; The first protrusion is connected to one axial end of the cylindrical base, and the second protrusion is connected to the other axial end of the cylindrical base.

[0011] In conjunction with the fourth possible implementation of the first aspect, the present invention provides a fifth possible implementation of the first aspect, wherein the first protrusion includes: a first connecting segment and a first bead portion; the first connecting segment connects the cylindrical base and the first bead portion, and the axis of the first bead portion is perpendicular to the axis of the cylindrical base; The second protrusion includes: a second connecting section and a second bead portion; the second connecting section connects the cylindrical base and the second bead portion, and the axis of the second bead portion is perpendicular to the axis of the cylindrical base; Furthermore, the axis of the first bead portion is perpendicular to the axis of the second bead portion.

[0012] In conjunction with the fifth possible implementation of the first aspect, the present invention provides a sixth possible implementation of the first aspect, wherein the drill bit is provided with a fourth superior arc groove adapted to the first protrusion or the second protrusion.

[0013] In conjunction with the third possible implementation of the first aspect, the present invention provides a seventh possible implementation of the first aspect, wherein a first superior arc groove is provided at one axial end of the double-sided concave bead, and a second superior arc groove is provided at the other axial end of the double-sided concave bead. The axis of the first superior arc groove is spatially perpendicular to the axis of the second superior arc groove, and both the axis of the first superior arc groove and the axis of the second superior arc groove are perpendicular to the axis of the double-sided concave bead. One of the first and second superior arc grooves is adapted to the first protrusion, and the other is adapted to the second protrusion; One of the first and second superior arc grooves engages with the first protrusion, and the other engages with the second protrusion, so as to realize the alternating connection of multiple double-sided protrusion bodies and multiple double-sided concave beads, and there is a gap between the cylindrical base and the opposite end face of the adjacent double-sided concave bead.

[0014] In conjunction with the seventh possible implementation of the first aspect, the present invention provides an eighth possible implementation of the first aspect, wherein the flexible shaft further includes a transition bead; One axial end of the transition bead is provided with a third protrusion that is adapted to the first or second superior arc groove, and the other axial end of the transition bead is provided with a third superior arc groove that is adapted to the drill bit.

[0015] In conjunction with the eighth possible implementation of the first aspect, the present invention provides a ninth possible implementation of the first aspect, wherein the drill breech is provided with a fourth protrusion that engages with the third superior arc groove.

[0016] The embodiments of this invention bring the following beneficial effects: The variable stiffness intramedullary fixation device achieves innovative structural design and multiple functional breakthroughs by integrating a drill tail, flexible shaft, drill bit, tensioning element, and multiple surrounding flexible elements. The device as a whole possesses excellent minimally invasiveness and operational flexibility. The flexible shaft, as the core force transmission and steering component, combined with the flexible elements arranged around its axis, allows the device to bend and deform in accordance with the natural direction of the bone tunnel during entry into the medullary cavity, thereby achieving flexible adjustment of position and posture, effectively avoiding neurovascular structures, and reducing iatrogenic injury. At the same time, by manipulating the tensioning element to adjust the tension of each flexible element, the overall stiffness of the device can be dynamically changed: maintaining lower stiffness during the delivery phase to improve compliance and facilitate navigation through complex anatomical paths; increasing tension after positioning to enhance the rigidity of the device, ensuring stable execution of cortical bone puncture and pin tract establishment by the drill bit, significantly improving surgical accuracy and reliability.

[0017] Furthermore, this device integrates guidance, transmission, and stiffness adjustment functions, avoiding the need for alternating use of multiple instruments in traditional procedures. This significantly shortens surgical time, reduces the physical burden on surgeons from repeated tapping and adjustments, and minimizes X-ray radiation exposure for patients and medical staff during surgery. A single device can complete positioning, guidance, and initial fixation preparation, reducing the need for multiple instruments in deep medullary cavity operations, thereby effectively controlling the extent of trauma and reducing bleeding and postoperative infection risks. The overall solution not only addresses the issues of excessive rigidity and poor adaptability of existing stainless steel fixation nails but also improves surgical safety and operational efficiency from a clinical perspective, providing a technical approach for minimally invasive internal fixation treatment of pelvic fractures that combines intelligent adaptability and clinical practicality.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 2 A schematic diagram of the drill tail and tensioning member of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 3 A schematic diagram of the drill tail of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 4 A schematic diagram of the double-sided convex plate of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 5 This is a top view of the double-sided convex plate of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 6 A schematic diagram of the drill bit for the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 7 A schematic diagram of the double-sided concave bead of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 8 This is a top view of the double-sided concave bead of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention; Figure 9This is a schematic diagram of the transition bead of the variable stiffness intramedullary fixation device provided in an embodiment of the present invention.

[0021] Icons: 100 - Drill tail; 101 - Fourth convex tab; 200 - Flexible shaft; 210 - Double-sided convex tab body; 211 - Cylindrical base; 212 - First convex tab; 2121 - First connecting section; 2122 - First bead body; 213 - Second convex tab; 2131 - Second connecting section; 2132 - Second bead body; 220 - Double-sided concave bead; 221 - First superior arc groove; 222 - Second superior arc groove; 230 - Transition bead; 231 - Third convex tab; 232 - Third superior arc groove; 300 - Drill bit; 301 - Fourth superior arc groove; 400 - Tensioner; 410 - Slider; 420 - Threaded part; 500 - Guide wire hole; 600 - Wire rope hole. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used only to describe differences in name and should not be construed as indicating or implying relative importance. Physical quantities in formulas, unless otherwise specified, should be understood as basic quantities in the International System of Units (SI), or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] like Figure 1 and Figure 2As shown, the variable stiffness intramedullary fixation device provided in this embodiment of the invention includes: a drill shank 100, a flexible shaft 200, a drill bit 300, a tensioning member 400, and flexible components. The drill shank 100, flexible shaft 200, and drill bit 300 are sequentially connected along the same axis, forming the main transmission structure of the device. The flexible shaft 200, as the core flexible transmission component, has good axial bending capacity and circumferential torque transmission performance. Multiple flexible components are circumferentially spaced around the axis of the flexible shaft 200 and penetrate the drill shank 100 and the flexible shaft 200; one end of each flexible component is connected to the distal end of the drill bit 300, and the other end extends to the proximal end and connects to the tensioning member 400.

[0026] In the initial implantation state, the flexible components are in a relaxed state, and the entire device exhibits high compliance, allowing it to smoothly pass through the complex anatomical path within the pelvic medullary cavity along the pre-placed guidewire. Once the device is in place, the tensioning component 400 applies axial tension to each flexible component, causing the flexible components to tighten and thus transforming the entire flexible shaft 200 from a flexible state to a rigid state, achieving adjustable stiffness.

[0027] This design effectively solves the problem of excessive rigidity and inability to adapt to changes in the curvature of the medullary cavity caused by traditional stainless steel intramedullary nails. While ensuring stable fixation after surgery, it significantly improves intraoperative navigation compliance and minimal invasiveness.

[0028] like Figure 1 , Figure 2 , Figure 5 and Figure 8 As shown, the variable stiffness intramedullary fixation device is provided with a guide wire hole 500 that passes through the drill tail 100, the flexible shaft 200 and the drill bit 300. The guide wire hole 500 is coaxially arranged with the flexible shaft 200 and is used to accommodate a rigid guide wire with a diameter of about 2 mm, so as to realize the guiding function of the device entering the pelvic medullary cavity along a predetermined trajectory.

[0029] In addition, the flexible shaft 200 is provided with several wire rope holes 600 inside. The wire rope holes 600 penetrate the entire length of the flexible shaft 200 and are evenly distributed around the guide wire hole 500. Preferably, there are four wire rope holes 600 arranged in a circular array, and the diameter of the envelope circle formed is between 1 / 2 and 3 / 4 of the diameter of the end face of the flexible shaft, so as to balance structural strength and space utilization.

[0030] Each wire rope hole 600 is used to accommodate the flexible component (i.e., the wire rope) to ensure that it does not shift or jam during axial movement. The guide hole 500 and the wire rope hole 600 are independent of each other and do not interfere with each other, respectively undertaking the functions of guiding and variable stiffness control, realizing a multi-functional integrated design.

[0031] Furthermore, the tensioning member 400 includes a plurality of sliders 410 and a plurality of threaded members 420.

[0032] Multiple sliders 410 slide axially within a groove structure inside the drill shank 100, and each slider 410 is connected to at least one flexible element (steel wire rope) passing through the flexible shaft 200. Multiple threaded elements 420 are installed on the outside of the drill shank 100 and are threadedly connected to the multiple sliders 410 one by one.

[0033] When the threaded component 420 is rotated, it pushes the corresponding slider 410 to move axially towards the proximal end, thereby pulling the flexible component connected to it to generate tension. After all the flexible components are simultaneously subjected to force, the segmental structure in the flexible shaft 200 is compressed as a whole, eliminating the relative rotational degrees of freedom between the connection interfaces, and finally realizing the transformation of the device from flexible to rigid.

[0034] This tensioning mechanism has the advantages of high adjustment precision, simple operation, and reliable locking, and is suitable for the need to quickly switch stiffness in surgical environments.

[0035] like Figure 1 , Figure 4 and Figure 7 As shown, the flexible shaft 200 is composed of multiple double-sided convex plates 210 and multiple double-sided concave beads 220 connected alternately.

[0036] Each double-sided convex body 210 has outwardly protruding convex structures at both ends, while each double-sided concave bead 220 has matching groove structures at both ends. By embedding the convexities of the double-sided convex body 210 into the grooves of adjacent double-sided concave beads 220, a hinged series system is formed.

[0037] This structure allows for small-angle deflection between adjacent units in three-dimensional space, giving the flexible shaft excellent bending compliance and multi-directional steering capability. Simultaneously, when the flexible component is under tension, the contact surfaces are pressed together, increasing friction and preventing relative rotation, thus achieving rigid locking.

[0038] In a preferred embodiment, the flexible shaft 200 includes nine double-sided convex plates 210 and nine double-sided concave beads 220, which are arranged alternately to form a flexible chain structure of 18 sections, ensuring both sufficient flexible length and good torque transmission efficiency.

[0039] Furthermore, the double-sided convex body 210 includes a cylindrical base 211, a first convex piece 212, and a second convex piece 213. The first convex piece 212 is connected to one end of the cylindrical base 211 along its axial direction, and the second convex piece 213 is connected to the other end of the cylindrical base 211 along its axial direction. The two convex pieces are used to mechanically engage with adjacent double-sided concave beads 220. This symmetrical structural design facilitates assembly sequence independence, improves production assembly efficiency, and ensures stable torque transmission under both forward and reverse operating conditions.

[0040] Furthermore, the first protrusion 212 includes a first connecting segment 2121 and a first bead portion 2122. The first connecting segment 2121 is connected between the cylindrical base 211 and the first bead portion 2122, and the axis of the first bead portion 2122 is perpendicular to the axis of the cylindrical base 211.

[0041] Similarly, the second protrusion 213 includes a second connecting section 2131 and a second bead portion 2132, and the axis of the second bead portion 2132 is also perpendicular to the axis of the cylindrical base 211.

[0042] Specifically, the axis of the first bead portion 2122 is spatially perpendicular to the axis of the second bead portion 2132. This orthogonal arrangement allows the flexible shaft 200 to bend and deform in any plane, greatly enhancing the spatial adaptability of the device, and making it particularly suitable for traversing the pelvic medullary cavity, which has multidimensional bending characteristics.

[0043] The bead body adopts a circular cross-section design, which, together with the groove, forms a ball-and-socket type local hinge. It can withstand a torque of ≥3 N·m without plastic deformation, meeting the strength requirements for clinical use.

[0044] See Figure 4 and Figure 6 The drill bit 300 is provided with a fourth superior arc groove 301, the geometry of which is adapted to the first protrusion 212 or the second protrusion 213.

[0045] Specifically, the fourth superior arc groove 301 is opened on the end face of the drill bit 300 facing the flexible shaft 200. Its notch structure includes a notch neck of uniform width and a circular cross-section notch mouth connected thereto, which can fully engage with the protrusion at the end of the double-sided protrusion body 210.

[0046] Through this mechanical connection, the drill bit 300 can receive rotational power from the flexible shaft 200 for penetrating cortical bone or completing channel enlargement operations. Even under high load conditions, it ensures efficient torque transmission, preventing slippage or disengagement.

[0047] See Figure 4 and Figure 7 The double-sided concave bead 220 has a first superior arc groove 221 at one axial end and a second superior arc groove 222 at the other end. The spatial axes of the first superior arc groove 221 and the second superior arc groove 222 are perpendicular to each other, and both are perpendicular to the overall axis of the double-sided concave bead 220. One superior arc groove is used to accommodate the first protrusion 212 of the preceding double-sided convex sheet body 210, and the other is used to accommodate the second protrusion 213 of the following double-sided convex sheet body 210.

[0048] Since the axes of the two protrusions of the adjacent double-sided protrusion body 210 are orthogonal, they form a matching connection with the two orthogonal grooves on the double-sided concave bead body 220, thus forming a spatial universal joint structure.

[0049] It is worth noting that a small gap is maintained between the cylindrical base 211 and the opposite end faces of the adjacent double-sided concave beads 220. This gap allows the adjacent units to deflect freely in an unlocked state, which is one of the key structural parameters for achieving compliant bending.

[0050] The superior arc groove design adopts a superior arc shape (i.e., the arc length is greater than that of a semicircle), which helps to increase the contact area, improve torsional resistance and connection stability.

[0051] like Figure 1 and Figure 9 As shown, the flexible shaft 200 also includes a transition ball 230 for structural connection between the flexible shaft 200 and the drill shank 100. One end of the transition ball 230 is provided with a third protrusion 231, the structure of which is adapted to the first superior arc groove 221 or the second superior arc groove 222 for connecting the last double-sided concave ball 220; the other end is provided with a third superior arc groove 232 for meshing with the fourth protrusion 101 on the drill shank 100.

[0052] The transition bead 230 serves as a structural bridge and stress relief mechanism, ensuring that power is smoothly transmitted from the drill tail 100 to the flexible shaft 200 segment system, and avoiding stress concentration caused by sudden changes in stiffness.

[0053] like Figure 1 , Figure 2 , Figure 3 and Figure 9 As shown, the drill shank 100 is provided with a fourth protrusion 101, the structure of which is perfectly adapted to the third superior arc groove 232. The fourth protrusion 101 is disposed on the end face of the drill shank 100 near the flexible shaft 200, and includes a protrusion neck and a protrusion head (approximately the structure of the first protrusion 212 or the second protrusion 213). The protrusion head has a circular cross-section and can be embedded in the third superior arc groove 232 of the transition bead 230 to form a reliable mechanical connection. This connection method can not only transmit rotational torque, but also withstand a certain axial thrust, ensuring the structural integrity of the device during the propulsion process.

[0054] In addition, the bottom of the drill shank 100 is provided with a clamping groove for easy clamping by external clamps; a guide wire hole is provided at the center of the bottom, which communicates with the guide wire hole 500; two symmetrically distributed bolt holes are provided on the side for installing tension bolts and connecting them with the slider 410 to form a complete tensioning system.

[0055] In use, the variable stiffness intramedullary fixation device of the present invention first involves percutaneous insertion of a rigid guidewire with a diameter of approximately 2 mm, which is then guided to the pelvic fracture area. Subsequently, the device is fitted over the guidewire, and the drill tail 100 is held in place by a clamp, and slowly pushed along the guidewire to the target position.

[0056] During this process, the flexible components are in a relaxed state, and each segment of the flexible shaft 200 can deflect freely. The device as a whole exhibits high flexibility and can smoothly pass through the curved medullary cavity.

[0057] Once the device is fully in place, the doctor operates the tightening bolt, driving the slider 410 to move axially, gradually tensioning the flexible components (steel wire ropes). As the tension increases, the gaps between the double-sided convex bodies 210 and the double-sided concave bodies 220 in the flexible shaft 200 are compressed, and the friction between the contact surfaces increases sharply, ultimately achieving rigid locking of the entire device.

[0058] At this point, a rotational torque can be applied through the drill tail 100 to drive the drill bit 300 for tapping the bone tunnel or implanting auxiliary instruments. Postoperatively, the device can remain in the body as a permanent or temporary internal fixation device, and its removal depends on clinical needs.

[0059] Compared with the prior art, the variable stiffness intramedullary fixation device provided by the present invention has the following outstanding advantages: 1. Adjustable stiffness: Enables a dynamic transition from "flexible introduction" to "rigid operation" during surgery, balancing compliance and stability; 2. Highly efficient operation: No need for repeated tapping and adjustment, significantly shortening operation time and reducing the risk of X-ray exposure for physicians; 3. Compact structure: It adopts a modular bead series design with small outer diameter and few burrs, reducing iatrogenic damage to the medullary cavity tissue; 4. Flexible steering: The orthogonal convex-groove structure gives the device multi-planar bending capability, adapting to complex anatomical environments; 5. Highly minimally invasive: A single device replaces multiple traditional fixation screws, reducing the probability of trauma, bleeding, and infection; 6. High reliability: Key connection parts can withstand ≥3 N·m torque, meeting the mechanical requirements of orthopedic surgery.

[0060] In summary, this invention provides a safe, efficient, and intelligent next-generation intramedullary fixation solution for minimally invasive treatment of pelvic fractures, with broad clinical application prospects and industrialization value.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A variable stiffness intramedullary fixation device, characterized in that, include: Drill tail (100), flexible shaft (200), drill bit (300), tensioning element (400) and flexible element; The shank (100), the flexible shaft (200), and the drill bit (300) are connected in sequence; Several of the flexible elements are spaced apart around the axis of the flexible shaft (200) and pass through the drill tail (100) and the flexible shaft (200) in sequence. The distal ends of a plurality of the flexible elements are connected to the drill bit (300), and the proximal ends of a plurality of the flexible elements are connected to the tensioning element (400).

2. The variable stiffness intramedullary fixation device according to claim 1, characterized in that, The variable stiffness intramedullary fixation device is provided with a guide wire hole (500) that passes through the drill tail (100), the flexible shaft (200) and the drill bit (300) in sequence, and the guide wire hole (500) is coaxially arranged with the flexible shaft (200); Furthermore, the variable stiffness intramedullary fixation device is provided with a plurality of wire rope holes (600) penetrating the flexible shaft (200), and the plurality of wire rope holes (600) are arranged at intervals around the guide wire hole (500).

3. The variable stiffness intramedullary fixation device according to claim 1, characterized in that, The tensioning member (400) includes: a plurality of sliders (410) and a plurality of threaded members (420); Multiple sliders (410) are axially slidably fitted onto the drill tail (100), and multiple threaded parts (420) are installed on the drill tail (100), with each threaded part (420) corresponding to and connected to the multiple sliders (410). Each of the sliders (410) is connected to at least one of the flexible elements.

4. The variable stiffness intramedullary fixation device according to claim 1, characterized in that, The flexible shaft (200) includes: a plurality of double-sided convex bodies (210) and a plurality of double-sided concave bodies (220). Multiple double-sided convex bodies (210) and multiple double-sided concave bodies (220) are alternately connected.

5. The variable stiffness intramedullary fixation device according to claim 4, characterized in that, The double-sided convex body (210) includes: a cylindrical base (211), a first convex piece (212), and a second convex piece (213); The first protrusion (212) is connected to one axial end of the cylindrical base (211), and the second protrusion (213) is connected to the other axial end of the cylindrical base (211).

6. The variable stiffness intramedullary fixation device according to claim 5, characterized in that, The first protrusion (212) includes: a first connecting segment (2121) and a first bead portion (2122); the first connecting segment (2121) is connected between the cylindrical base (211) and the first bead portion (2122), and the axis of the first bead portion (2122) is perpendicular to the axis of the cylindrical base (211); The second protrusion (213) includes: a second connecting section (2131) and a second bead portion (2132); the second connecting section (2131) is connected between the cylindrical base (211) and the second bead portion (2132), and the axis of the second bead portion (2132) is perpendicular to the axis of the cylindrical base (211); Furthermore, the axis of the first bead portion (2122) is perpendicular to the axis of the second bead portion (2132).

7. The variable stiffness intramedullary fixation device according to claim 6, characterized in that, The drill bit (300) is provided with a fourth superior arc groove (301) that is adapted to the first protrusion (212) or the second protrusion (213).

8. The variable stiffness intramedullary fixation device according to claim 5, characterized in that, The double-sided concave bead (220) has a first superior arc groove (221) at one axial end and a second superior arc groove (222) at the other axial end. The axis of the first superior arc groove (221) is spatially perpendicular to the axis of the second superior arc groove (222), and the axes of the first superior arc groove (221) and the second superior arc groove (222) are both perpendicular to the axis of the double-sided concave bead (220). One of the first superior arc groove (221) and the second superior arc groove (222) is adapted to the first protrusion (212), and the other is adapted to the second protrusion (213); One of the first superior arc groove (221) and the second superior arc groove (222) is engaged with the first protrusion (212), and the other is engaged with the second protrusion (213) to realize the alternating connection of multiple double-sided protrusion bodies (210) and multiple double-sided concave beads (220), and there is a gap between the cylindrical base (211) and the opposite end face of the adjacent double-sided concave beads (220).

9. The variable stiffness intramedullary fixation device according to claim 8, characterized in that, The flexible shaft (200) also includes a transition bead (230); The transition bead (230) has a third protrusion (231) at one axial end that is adapted to the first superior arc groove (221) or the second superior arc groove (222), and the transition bead (230) has a third superior arc groove (232) at the other axial end that is adapted to the drill nut (100).

10. The variable stiffness intramedullary fixation device according to claim 9, characterized in that, The drill tail (100) is provided with a fourth protrusion (101) that matches the third superior arc groove (232).

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