A method for adjustable self-locking force of magnetically driven expandable intramedullary nails

Abstract

This invention discloses a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail. The method includes the following steps: Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with a three-dimensional structural model simulation of the intramedullary nail, establish a mathematical relationship curve A between the internal normal pressure of the intramedullary nail and the magnetic force experienced by the magnetic assembly; Step 2: Establish the input current of the rotating electromagnetic generator. I Simulation curve B of the magnetic force applied to the magnetic kit; Step 3: Establish the current of the rotating electromagnetic generator. I The curve relationship C with the intramedullary nail's internal normal pressure. The method of this invention utilizes simulation to change the magnetic force exerted by the electromagnetic field on the intramedullary nail by adjusting the current of the external electromagnetic field. When the intramedullary nail is subjected to different magnetic forces, the magnetically driven expansion portion tightens or loosens, thereby adjusting the self-locking torque of the intramedullary nail. This method does not require direct calculation of the required magnetic force, but it can determine the reasonable value of the required magnetic force, thus achieving reasonable and precise adjustment of the intramedullary nail's self-locking torque.

Description

Technical Field

[0001] This invention relates to a method for adjusting the self-locking force of an expandable intramedullary nail, specifically to a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail. Background Technology

[0002] Intramedullary nails, as an important internal fixation device in orthopedic surgery, are widely used in clinical treatment. Traditional intramedullary nails rely on mechanical locking mechanisms to maintain the stability of the fracture ends; however, this method has limitations such as greater surgical trauma, difficulty in postoperative adjustment, and potential complications. With the development of materials science and biomedical engineering, a new type of magnetically driven intramedullary nail has emerged. It utilizes the principle of magnetic force to achieve non-contact force transmission and adjustment, bringing revolutionary progress to orthopedic surgery.

[0003] The advantages of magnetically driven intramedullary nails are mainly reflected in the following aspects: First, it achieves precise control of the intramedullary nail through an external magnetic field, avoiding the inconvenience of secondary surgery for adjustment required by traditional methods, significantly reducing patient pain and medical costs; second, the magnetic adjustment process does not require incision of the skin or exposure of the fracture site, reducing the risk of infection and soft tissue damage, which is beneficial to postoperative recovery; in addition, magnetically driven intramedullary nails can achieve dynamic adjustment, flexibly adjusting the fixation force according to different stages of fracture healing, promoting fracture healing. At the same time, this technology is also characterized by its ease of operation and strong adaptability, and can meet the treatment needs of different types of fractures. Therefore, magnetically driven intramedullary nails have broad application prospects and important clinical value in the field of orthopedics.

[0004] Currently available magnetically driven intramedullary nails have a small internal diameter (5-9 mm is available) and a complex internal magnetic drive mechanical transmission structure, leaving no extra space to install pressure sensors to directly measure the self-locking pressure. However, the self-locking function of intramedullary nails requires accurate estimation and flexible adjustment of their self-locking pressure value. Therefore, it is necessary to find a method that can conveniently, safely, and non-invasively achieve precise adjustment of the internal magnetic force and positive pressure of the intramedullary nail.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail. By using simulation, the magnetic force of the electromagnetic field on the intramedullary nail is changed by adjusting the current of the external electromagnetic field. When the intramedullary nail is subjected to different magnetic forces, the expansion part driven by the magnetic force is tightened or loosened, thereby adjusting the self-locking torque of the intramedullary nail.

[0007] To achieve the above objectives, the present invention provides a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail, the method comprising the following steps:

[0008] Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with the simulation of the three-dimensional structural model of the intramedullary nail, establish the internal normal pressure of the intramedullary nail. Magnetic force on the magnetic kit Mathematical relationship curve A;

[0009] Step 2: A controllable magnetic field is generated by a rotating electromagnetic generator, which interacts with the permanent magnet inside the magnetically driven expandable intramedullary nail to achieve magnetic force adjustment and establish the input current of the rotating electromagnetic generator. I Applying magnetic force to the magnetic kit Simulation relationship curve B;

[0010] Step 3: Establish the current of the rotating electromagnetic generator I With intramedullary nail positive pressure Curve relationship C, by changing the current of the rotating electromagnetic generator I The electromagnetic field of the rotating electromagnetic generator exerts a magnetic force on the magnetic kit. The situation changes as the magnetic kit is subjected to different magnetic forces. During operation, the expansion groove block driven by the magnetic component tightens or loosens, thereby adjusting the positive pressure within the intramedullary nail. The size enables fastening.

[0011] Preferably, in step two, based on the structure and electromagnetic parameters of the rotating electromagnetic generator, including the number of coil turns and current magnitude inside the generator, the electromagnetic field strength is determined by the number of coil turns and current magnitude. An electromagnetic field model of the rotating electromagnetic generator is established using the principle of electromagnetism. A magnetic field model of the magnetic kit is established based on the magnetic parameters of the permanent magnets in the magnetic kit (including permanent magnet dimensions, magnetic coercivity, etc.). Furthermore, a finite element simulation model of the magnetic force generated by the interaction of the rotating electromagnetic generator's electromagnetic field with the magnetic kit's magnetic field is established. The magnetic force is then determined by the interaction between the current R of the rotating electromagnetic generator and the magnetic force of the magnetic kit. Relationship establishment curve B.

[0012] Preferably, the magnetic force adjustment device includes: an adjustable constant current source, a conductive slip ring, and a rotating electromagnetic generator, wherein the adjustable constant current source and the rotating electromagnetic generator are electrically connected to the conductive slip ring.

[0013] Preferably, the proximal end of the magnetically driven expandable intramedullary nail contains a magnetic assembly and a pusher. The magnetic assembly contains a permanent magnet and is threadedly connected to the pusher. The expandable groove block is embedded in the side wall of the proximal end of the intramedullary nail. The end face of the expandable groove block has a first inclined surface, and the pusher has a second inclined surface that matches the first inclined surface. When the pusher moves axially inward, it will squeeze the expandable groove block to move radially outward, thereby achieving self-locking.

[0014] The self-locking force adjustable method of the magnetically driven expandable intramedullary nail of the present invention has the following advantages:

[0015] (1) The method of the present invention utilizes simulation to change the magnetic force of the electromagnetic field on the intramedullary nail by adjusting the current of the external electromagnetic field. When the intramedullary nail is subjected to different magnetic forces, the expansion part driven by the magnetic force is tightened or loosened, thereby adjusting the self-locking torque of the intramedullary nail. The method of the present invention does not require direct calculation of the required magnetic force, but can cleverly and indirectly determine the reasonable value of the required magnetic force. For various magnetically driven intramedullary nail products, a corresponding magnetic force input that can just achieve self-locking can always be found, thereby achieving reasonable and precise adjustment of the self-locking torque of the intramedullary nail;

[0016] (2) This invention dynamically changes the driving magnetic force intensity of the magnetically driven expandable intramedullary nail by adjusting the electromagnetic intensity generated by the electromagnetic generator, thereby realizing flexible adjustment of the self-locking force of the intramedullary nail. This design significantly improves the adaptability and precision of the surgery and can be personalized according to the individual differences in the patient's bone structure.

[0017] (3) The magnetic force adjustment device of the present invention has a simple structure and is mainly composed of an adjustable constant current source, a conductive slip ring and a rotating electromagnetic generator. This design not only reduces the complexity of the device, but also reduces the manufacturing cost, providing an economical and feasible solution for widespread clinical application.

[0018] (4) The present invention fits the current of the rotating electromagnetic generator through mathematical modeling. With positive pressure inside the intramedullary nail Relationship curve C, based on which the self-locking force of the new magnetically driven expandable intramedullary nail can be precisely adjusted, ensuring the scientific nature and reliability of the adjustment process;

[0019] (5) Compared with the traditional permanent magnet driving method, the adjustment method of the present invention avoids complex and low-precision mathematical calculations, significantly simplifies the operation process, not only improves the adjustment efficiency, but also reduces the operation difficulty, enabling doctors to more intuitively and conveniently complete the self-locking force adjustment of intramedullary nails. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the self-locking force adjustable method of the magnetically driven expandable intramedullary nail of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the magnetically driven expandable intramedullary nail of the present invention.

[0022] Figure 3 This is a diagram of the magnetic force adjustment device of the present invention.

[0023] Figure 4 This is a diagram showing the magnetic field distribution of the coil rotor current in this invention.

[0024] Figure 5 This is a schematic diagram of the driving principle of the magnetically driven expansion self-locking intramedullary nail of the present invention.

[0025] Figure 6 Curve A shows the mathematical relationship between the internal positive pressure of the intramedullary nail and the magnetic force applied to the magnetic kit in this invention.

[0026] Figure 7 The simulation curve B shows the relationship between the input current of the rotating electromagnetic generator of the present invention and the magnetic force exerted by the magnetic kit.

[0027] Figure 8 The rotating electromagnetic generator current of the present invention With positive pressure inside the intramedullary nail Relationship curve C.

[0028] The components include: 1. Rubber patch; 2. Expansion groove block; 3. Magnetic kit; 4. Push head; 5. Adjustable constant current source; 6. Conductive slip ring; 7. Coil rotor. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0030] The features mentioned in this invention can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification, provided that there is no contradiction in the combination of these features. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0031] 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. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] A method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail, as follows: Figure 2 Taking the magnetically driven expandable intramedullary nail as an example, the smaller diameter end of the nail is the distal end, and the larger diameter end is the proximal end. The proximal end contains a magnetic assembly 3 and a pusher 4. The magnetic assembly 3 contains a permanent magnet and is threadedly connected to the pusher 4. An expansion groove block 2 is embedded in the side wall of the proximal end of the nail. The end face of the expansion groove block 2 has a first inclined surface, and the pusher 4 has a second inclined surface that matches this first inclined surface. When the pusher 4 moves axially inward, it compresses the expansion groove block 2, causing it to move radially outward, thus achieving self-locking. (See also...) Figure 1 The flowchart shows that the method specifically includes the following steps:

[0035] Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with the simulation of the three-dimensional structural model of the intramedullary nail, establish the internal positive pressure of the intramedullary nail. Magnetic force on the magnetic kit Mathematical relationship curve A;

[0036] See Figure 5The magnetically driven expandable intramedullary nail operates on a self-locking principle. Driven by a rotating electromagnetic generator, the pusher head 4 moves clockwise towards the distal end of the intramedullary nail under the influence of the magnetic field generated by the generator and the permanent magnet within the magnetic assembly 3. When the pusher head 4 contacts the inclined surface of the expansion groove block 2, the expansion groove block 2 slides outwards along the inclined surface of the pusher head 4. When the expansion groove block 2 abuts against the intramedullary cavity, positive pressure is generated on the inner wall of the intramedullary nail, locking it in place, thus completing the expansion and self-locking process. The rubber patch 1 on the expansion groove block 2 increases friction when it contacts the intramedullary cavity, further helping to maintain the self-locking state.

[0037] Based on the mechanical transmission characteristics between the internal components of the intramedullary nail, including considering the shape, size, and material density of the components, a mechanical analysis of the magnetically driven expandable intramedullary nail is conducted to establish the internal normal pressure of the intramedullary nail. The relevant mechanical formulas and the magnetic force on the magnetic kit The relevant mechanical formulas are used to solve the problem by simultaneously solving for the two related parameters.

[0038] In this embodiment, a medical-grade titanium alloy Ti6Al4V magnetically driven intramedullary nail was selected, with a total length of 207mm. Through mechanical analysis, the internal normal pressure of the intramedullary nail can be obtained. The relationship between the inclined plane angle of the expansion groove block 2 and the supporting force and friction force on the expansion groove block 2 can be derived through classical Newtonian mechanics calculations to establish the internal normal pressure of the intramedullary nail. The mechanical formula for the force on the expansion chute block 2 (referred to as Formula 1); the magnetic force on the magnetic component. The rotating screw generates a threaded force on the pusher 4. Based on the principle of threading, the magnetic force on the magnetic component can be established. The mechanical formula for the force on the pusher 4 (referred to as Formula 2); the pusher 4 and the expansion groove block 2 exert mutual interaction force, and the mechanical formula for the pusher 4 and the expansion groove block 2 can be established from the angle of the inclined surface of the expansion groove block 2 (referred to as Formula 3); by simultaneously solving Formula 1, Formula 2, and Formula 3, the internal normal pressure of the intramedullary nail can be obtained. Magnetic force on the magnetic kit Mathematical relationship curve A, such as Figure 6 As shown.

[0039] Step two involves generating a controllable magnetic field using a rotating electromagnetic generator, which interacts with the permanent magnet inside the magnetically driven expandable intramedullary nail to achieve magnetic force adjustment, thereby establishing the input current for the rotating electromagnetic generator. I Applying magnetic force to the magnetic kit Simulation relationship curve B;

[0040] See Figure 3The diagram shows the magnetic force adjustment device of the present invention. The magnetic force adjustment method involves adjusting the current of the adjustable constant current source 5. A conductive slip ring 6 electrically connects the adjustable constant current source 5 and the rotating electromagnetic generator to transmit current. Changes in the current cause changes in the magnetic field strength generated by the rotating electromagnetic generator. The magnetic field strength generated by the rotating electromagnetic generator and the magnetic field strength of the permanent magnet within the magnetic force kit 3 can be adjusted. By adjusting the adjustable constant current source, the electromagnetic field strength of the rotating electromagnetic generator can be changed.

[0041] Based on the structure and electromagnetic parameters of the rotating electromagnetic generator, including the number of coil turns and current magnitude inside the generator, an electromagnetic field model of the rotating electromagnetic generator is established using the principle of electromagnetism. Specifically, a structural model of the rotating electromagnetic generator is created using simulation software, and parameters such as the coils and current within the generator are defined. The electromagnetic field model is then simulated using the software. A magnetic field model of the magnetic kit is established based on the magnetic parameters of the permanent magnet in the magnetic kit (using commercial simulation software for modeling and magnetic field simulation calculations, a geometric model of the permanent magnet is created, and its performance parameters are defined. The magnetic field model is then simulated using the software to obtain the magnetic interaction relationship). Based on the magnetic field effects of both, a finite element simulation model of the electromagnetic field of the rotating electromagnetic generator acting on the magnetic kit is established, thereby obtaining the current of the rotating electromagnetic generator. I Applying magnetic force to the magnetic kit The simulation relationship curve B, such as Figure 7 As shown.

[0042] Magnetic force acting on the magnetic kit Current from the rotating electromagnetic generator I The magnetic field effect simulation model is fitted to avoid directly calculating the magnetic force exerted by the electromagnetic field of the rotating electromagnetic generator on the magnetic kit.

[0043] Step 3: Establish the current of the rotating electromagnetic generator I With intramedullary nail positive pressure Curve relationship C. By changing the current of the rotating electromagnetic generator. I The electromagnetic field of the rotating electromagnetic generator exerts a magnetic force on the magnetic kit. The situation changes as the magnetic kit is subjected to different magnetic forces. During operation, the expansion groove block driven by the magnetic component tightens or loosens, thereby adjusting the positive pressure within the intramedullary nail. The size enables fastening.

[0044] Positive pressure from the inside of the intramedullary nail Magnetic force on the magnetic kit Mathematical relationship curve A, and the input current of the rotating electromagnetic generator. I Applying magnetic force to the magnetic kit The simulation relationship curve B shows that the input current of the rotating electromagnetic generator can be used to determine the relationship. I To fit the internal positive pressure of the intramedullary nail This leads to the establishment of a rotating electromagnetic generator current. I With intramedullary nail positive pressure Curve relationship C, such as Figure 8 As shown.

[0045] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A magnetically driven expandable intramedullary nail, characterized in that, The magnetically driven expandable intramedullary nail contains a magnetic assembly (3) and a pusher (4) in its proximal end. The magnetic assembly (3) contains a permanent magnet and is threadedly connected to the pusher (4). The expansion groove block (2) is embedded in the side wall of the proximal end of the intramedullary nail. The end face of the expansion groove block (2) has a first inclined surface, and the pusher (4) has a second inclined surface that matches the first inclined surface. When the pusher (4) moves axially inward, it will squeeze the expansion groove block (2) to move radially outward, thereby achieving self-locking. The magnetically driven expandable intramedullary nail uses the following method to adjust its self-locking force: Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with the simulation of the three-dimensional structural model of the intramedullary nail, establish the internal normal pressure of the intramedullary nail. Magnetic force on the magnetic kit Mathematical relationship curve A; Step 2: A controllable magnetic field is generated by a rotating electromagnetic generator, which interacts with the permanent magnet inside the magnetically driven expandable intramedullary nail to achieve magnetic force adjustment and establish the input current of the rotating electromagnetic generator. I Applying magnetic force to the magnetic kit Simulation relationship curve B; Step 3: Establish the current of the rotating electromagnetic generator I With intramedullary nail positive pressure Curve relationship C, by changing the current of the rotating electromagnetic generator I The electromagnetic field of the rotating electromagnetic generator exerts a magnetic force on the magnetic kit. The situation changes as the magnetic kit is subjected to different magnetic forces. During operation, the expansion groove block driven by the magnetic component tightens or loosens, thereby adjusting the positive pressure within the intramedullary nail. The size enables fastening; In step two, based on the structure and electromagnetic parameters of the rotating electromagnetic generator, including the number of coil turns and current magnitude inside the generator, an electromagnetic field model of the rotating electromagnetic generator is established using the principle of electromagnetism. A magnetic field model of the magnetic kit is established based on the magnetic parameters of the permanent magnets in the magnetic kit. Furthermore, a finite element simulation model of the magnetic force generated by the electromagnetic field of the rotating electromagnetic generator acting on the magnetic field of the magnetic kit is established, based on the current of the rotating electromagnetic generator. Magnetic force interacting with magnetic kit Relationship establishment curve B.

2. The magnetically driven expandable intramedullary nail according to claim 1, characterized in that, The magnetic force adjustment device includes: an adjustable constant current source, a conductive slip ring, and a rotating electromagnetic generator, wherein the adjustable constant current source and the rotating electromagnetic generator are electrically connected to the conductive slip ring.

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