Self-locking force adjustable method for magnetic drive type expansion intramedullary nail

Abstract

The invention discloses a self-locking force adjustable method for a magnetic drive type expansion intramedullary nail, which comprises the following steps of: 1, according to a self-locking principle of the magnetic drive type expansion intramedullary nail and by combining simulation of a three-dimensional structure model of the intramedullary nail, establishing a mathematical relation curve A of positive pressure # imgabs0 # in the intramedullary nail and magnetic force # imgabs1 # borne by a magnetic suite; 2, establishing a simulation relation curve B of the magnetic force # imgabs2 # applied to the magnetic suite by the input current I of the rotary electromagnetic generator; and 3, establishing a curvilinear relationship C between the current I of the rotary electromagnetic generator and the positive pressure # imgabs3 # in the intramedullary nail. According to the method, simulation is utilized, the magnetic force action of an external 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 force actions, the expansion part driven by the magnetic force is tightened, and then the self-locking torque of the intramedullary nail is adjusted. According to the method, the needed magnetic force does not need to be directly calculated, but the reasonable value of the needed magnetic force can be determined, and therefore reasonable and accurate adjustment of the self-locking torque of the intramedullary nail is achieved.

Description

Technical Field

[0001] The present invention relates to a method for adjusting the self-locking force of an expandable intramedullary nail, and more specifically to a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail. Background Art

[0002] As an important internal fixation device in the field of orthopedic surgery, intramedullary nails are widely used in clinical treatment. Traditional intramedullary nails rely on mechanical locking mechanisms to maintain the stability of the fracture site. However, this method has limitations such as relatively large surgical trauma, difficult postoperative adjustment, and possible complications. With the development of materials science and biomedical engineering, new types of magnetically driven intramedullary nails have emerged. They utilize the principle of magnetism 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 enables precise control of the intramedullary nail through an external magnetic field, avoiding the inconvenience of secondary surgery for adjustment in traditional methods, and significantly reducing the pain of patients and medical costs; Second, the magnetic adjustment process does not require incising the skin or exposing the fracture site, reducing the risk of infection and soft tissue damage, which is beneficial for postoperative recovery; In addition, magnetically driven intramedullary nails can achieve dynamic adjustment, flexibly adjusting the fixation force according to different stages of fracture healing to promote fracture healing. At the same time, this technology also has the characteristics of simple 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, commercially available magnetically driven intramedullary nails have a narrow internal diameter (usable inner diameter of 5 - 9 mm) and a complex magnetic drive mechanical transmission structure inside the diameter, leaving no extra space to install a pressure sensor to directly measure the self-locking pressure. However, the self-locking function of the intramedullary nail requires accurate estimation and flexible adjustment of its self-locking pressure value. Therefore, a method is needed to 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 above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The object of the present invention is to provide a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail. By using a simulation method, 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 under magnetic drive is tightened or loosened, thereby adjusting the self-locking torque of the intramedullary nail.

[0007] To achieve the above object, the present invention provides a method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail, which method comprises the following steps: Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with the simulation of the three-dimensional structure model of the intramedullary nail, establish the mathematical relationship curve A between the normal pressure inside the intramedullary nail and the magnetic force received by the magnetic force kit ; Step 2: Generate a controllable magnetic field by rotating the electromagnetic generator, interact with the built-in permanent magnet of the magnetically driven expandable intramedullary nail to achieve magnetic force adjustment, and establish the simulation relationship curve B between the input current of the rotating electromagnetic generator I and the magnetic force acting on the magnetic force kit ; Step 3: Establish the curve relationship C between the current of the rotating electromagnetic generator I and the normal pressure inside the intramedullary nail. By changing the current of the rotating electromagnetic generator , the electromagnetic field of the rotating electromagnetic generator acts on the magnetic force of the magnetic force kit I to change. When the magnetic force kit is affected by different magnetic forces , the expandable inclined groove block driven by the magnetic force kit is tightened or loosened, and the size of the normal pressure inside the intramedullary nail is adjusted to achieve fastening. Preferably, in Step 2, according to the structure and electromagnetic parameters of the rotating electromagnetic generator, including the number of turns of the internal coil of the rotating electromagnetic generator, the magnitude of the current, and the electromagnetic field intensity determined by the number of turns of the coil and the magnitude of the current, use the principle of electromagnetic induction to establish the electromagnetic field model of the rotating electromagnetic generator; establish the magnetic field model of the magnetic force kit according to the magnetic related parameters of the permanent magnet in the magnetic force kit (including the size of the permanent magnet, the magnetic induction coercive force, etc.), and then establish the finite element simulation model of the magnetic force generated by the action of the electromagnetic field of the rotating electromagnetic generator on the magnetic field of the magnetic force kit, and establish curve B from the relationship between the current 𝐼 of the rotating electromagnetic generator and the magnetic force acting on the magnetic force kit

[0008] ;

[0009] Preferably, the magnetic force adjustment device includes: an adjustable constant current source, a conductive slip ring, and a rotating electromagnetic generator, wherein a conductive slip ring is electrically connected between the adjustable constant current source and the rotating electromagnetic generator.

[0010] Preferably, the proximal end of the magnetically driven expandable intramedullary nail contains a magnetic force kit and a push head. The magnetic force kit contains a permanent magnet. The magnetic force kit is threadedly connected to the push head. The expandable inclined groove block is embedded in the side wall of the proximal end of the intramedullary nail. The end face of the expandable inclined groove block has a first inclined surface, and the push head has a second inclined surface adapted to the first inclined surface. When the push head moves axially inward, it will squeeze the expandable inclined groove block to move radially outward, thereby realizing self-locking.

[0011] The self-locking force adjustable method of the magnetic drive expandable intramedullary nail of the present invention has the following advantages: (1) In the method of the present invention, by using the simulation method, the magnetic force action of the electromagnetic field on the intramedullary nail is changed by adjusting the current of the external electromagnetic field. When the intramedullary nail is under different magnetic force actions, the expansion part driven by the magnetic force is tightened or loosened, and then the self-locking torque of the intramedullary nail is adjusted. 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 magnetic drive intramedullary nail products, the magnetic force input that can just achieve self-locking can always be found, so as to realize the reasonable and accurate adjustment of the self-locking torque of the intramedullary nail;

[0012] (2) By adjusting the electromagnetic intensity generated by the electromagnetic generator, the present invention dynamically changes the driving magnetic force intensity of the magnetic drive expandable intramedullary nail, so as to realize the flexible adjustment of the self-locking force of the intramedullary nail. This design significantly improves the adaptability and accuracy of the operation, and can be adjusted personalized according to the individual differences of the patient's bone structure; (3) The magnetic force adjustment device of the present invention has a simple structure, 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 economically feasible solution for wide clinical application; (4) The present invention fits the curve C of the current of the rotating electromagnetic generator and the internal positive pressure of the intramedullary nail through mathematical modeling. Based on this relationship, the self-locking force of the new magnetic drive expandable intramedullary nail can be accurately adjusted to ensure the scientificity and reliability of the adjustment process; (5) Compared with the traditional permanent magnet drive 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 the intramedullary nail. Description of the Drawings

[0013] Figure 1 is a schematic flow chart of the self-locking force adjustable method of the magnetic drive expandable intramedullary nail of the present invention.

[0014] Figure 2 is a schematic structural diagram of the magnetic drive expandable intramedullary nail of the present invention.

[0015] Figure 3 is a diagram of the magnetic force adjustment device of the present invention.

[0016] Figure 4 is a distribution diagram of the current magnetic field of the coil rotor of the present invention.

[0017] Figure 5 is a driving principle diagram of the magnetic drive expandable self-locking intramedullary nail of the present invention.

[0018] Figure 6 Curve A of the mathematical relationship between the internal normal pressure of the intramedullary nail and the magnetic force received by the magnetic force kit of the present invention.

[0019] Figure 7 Curve B of the simulation relationship between the input current of the rotating electromagnetic generator of the present invention and the magnetic force acting on the magnetic force kit.

[0020] Figure 8 For the current of the rotating electromagnetic generator of the present invention and the internal normal pressure of the intramedullary nail Curve C.

[0021] Among them, 1. Rubber patch; 2. Expanding inclined groove block; 3. Magnetic force kit; 4. Pusher; 5. Adjustable constant current source; 6. Conductive slip ring; 7. Coil rotor. Detailed implementation manners

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] The features mentioned in the present invention can be combined arbitrarily as long as there is no contradiction in the combination of these features. All possible combinations should be considered as the scope described in this specification. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent or similar purpose. Therefore, unless otherwise specifically stated, the disclosed features are only general examples of equivalent or similar features.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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, so it cannot be understood as a limitation of the present invention; the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Embodiment 1 A method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail, taking the magnetically driven expandable intramedullary nail shown in Figure 2 as an example. The end with a smaller diameter of the magnetically driven expandable intramedullary nail is the distal end of the intramedullary nail, and the end with a larger diameter is the proximal end of the intramedullary nail. The proximal end of the intramedullary nail contains a magnetic force kit 3 and a push head 4. The magnetic force kit 3 contains a permanent magnet. The magnetic force kit 3 is threadedly connected to the push head 4. The expansion inclined groove block 2 is embedded in the side wall of the proximal end of the intramedullary nail. The end face of the expansion inclined groove block 2 has a first inclined surface, and the push head 4 has a second inclined surface adapted to the first inclined surface. When the push head 4 moves axially inward, it will squeeze the expansion inclined groove block 2 to move radially outward, thereby realizing self-locking. See Figure 1 The flowchart of, the method specifically includes the following steps:

[0027] Step 1, based on the self-locking principle of the magnetically driven expandable intramedullary nail and combined with the simulation of the three-dimensional structure model of the intramedullary nail, establish the mathematical relationship curve A between the normal pressure inside the intramedullary nail and the magnetic force received by the magnetic force kit ; See Figure 5 , which is the self-locking principle of the magnetically driven expandable intramedullary nail. By driving the rotating electromagnetic generator, under the action of the magnetic field generated by the rotating electromagnetic generator and the magnetic field of the permanent magnet in the magnetic force kit 3, the push head 4 moves clockwise towards the distal end of the intramedullary nail. When the push head 4 is in matching contact with the inclined surface of the expansion inclined groove block 2, the expansion inclined groove block 2 slides relatively outward along the inclined surface of the push head 4. When the expansion inclined groove block 2 abuts against the inner cavity of the medulla, a normal pressure is generated on the inner wall of the intramedullary nail to lock, and the intramedullary nail completes the expansion self-locking state. The rubber patch 1 on the expansion inclined groove block 2 can increase the friction when the expansion inclined groove block 2 abuts against the inner cavity of the medulla, helping to further maintain the self-locking state.

[0028] According to the mechanical transmission characteristics between the internal parts of the intramedullary nail, including considering the shape and size of the parts, material density, etc., perform mechanical analysis on the magnetically driven expandable intramedullary nail, establish the relevant mechanical formulas for the normal pressure inside the intramedullary nail and the relevant mechanical formulas for the magnetic force received by the magnetic force kit , and solve the two related parameters simultaneously. In this embodiment, a magnetically driven intramedullary nail made of medical titanium alloy Ti6Al4V is selected, with a total length of 207 mm. Through mechanical mechanics analysis, the relationship between the normal pressure inside the intramedullary nail and the inclined surface angle of the expansion inclined groove block 2 and the supporting force and friction force received by the expansion inclined groove block 2 can be obtained. Through classical Newtonian mechanics calculation and derivation, the mechanical formula for the normal pressure inside the intramedullary nail and the force received by the expansion inclined groove block 2 can be established (abbreviated as formula 1); from the magnetic force received by the magnetic force kit The rotating screw generates a thread force on the push head 4. According to the thread principle, the magnetic force on the magnetic kit can be established. The mechanical formula of the force on the push head 4 (Formula 2 for short); the push head 4 exerts an interaction force on the expansion chute block 2, and the mechanical formula of the push head 4 and the expansion chute block 2 (Formula 3 for short) can be established by the inclined angle of the expansion chute block 2; the positive pressure inside the intramedullary nail can be obtained by solving Formula 1, Formula 2, and Formula 3 together The magnetic force of the magnetic kit Mathematical relationship curve A, such as Figure 6 shown.

[0029] Step 2: Generate a controllable magnetic field through a rotating electromagnetic generator, which interacts with the permanent magnet built into the magnetic drive expandable intramedullary nail to achieve magnetic force regulation, thereby establishing the input current of the rotating electromagnetic generator. I Apply magnetic force to the magnetic kit Simulation relationship curve B; See also Figure 3 , is a diagram of the magnetic force adjustment device of the present invention, the magnetic force adjustment method is to adjust the current of the adjustable constant current source 5, the conductive slip ring 6 is electrically connected between the adjustable constant current source 5 and the rotating electromagnetic generator to transmit current, the change of current causes the magnetic field strength generated by the rotating electromagnetic generator to change, and the magnetic field generated by the rotating electromagnetic generator and the magnetic field strength of the permanent magnet in the magnetic kit 3 can be adjusted and changed. By adjusting the adjustable constant current source, the electromagnetic field strength of the rotating electromagnetic generator can be changed.

[0030] According to the structure of the rotating electromagnetic generator and its electromagnetic parameters, including the number of turns of the internal coil of the rotating electromagnetic generator, the current size, etc., the electromagnetic field model of the rotating electromagnetic generator is established by using the principle of electromagnetism. Specifically, the structural model of the rotating electromagnetic generator is created by using simulation software, and the parameters such as the coil and current in the electromagnetic generator are defined. The electromagnetic field model is simulated by the simulation software. According to the magnetic parameters of the permanent magnet in the magnetic kit, the magnetic field model of the magnetic kit is established (using commercial simulation software for modeling and magnetic field simulation calculation, creating a permanent magnet geometric model, and defining the performance parameters of the permanent magnet, and simulating its magnetic field model by simulation software to obtain the magnetic interaction relationship). According to the magnetic field effects of the two, a magnetic finite element simulation model of the electromagnetic field of the rotating electromagnetic generator on the magnetic kit is established, thereby obtaining the current of the rotating electromagnetic generator. I Apply magnetic force to the magnetic kit The simulation relationship curve B is as follows: Figure 7 shown.

[0031] Magnetic force acting on the magnetic kit The 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.

[0032] Step 3: Establish the current of the rotating electromagnetic generator I and the positive pressure inside the intramedullary nail Curve relationship C. By changing the current of the rotating electromagnetic generator I , the electromagnetic field of the rotating electromagnetic generator acts on the magnetic force kit with a magnetic force which changes. When the magnetic force kit is subjected to different magnetic forces , the expansion chute block driven by the magnetic force kit is tightened or loosened, realizing the adjustment of the positive pressure inside the intramedullary nail and achieving fastening by adjusting the magnitude of the positive pressure inside the intramedullary nail.

[0033] From the mathematical relationship curve A between the positive pressure inside the intramedullary nail and the magnetic force received by the magnetic force kit , and the simulation relationship curve B between the input current of the rotating electromagnetic generator I and the magnetic force acting on the magnetic force kit , the positive pressure inside the intramedullary nail can be fitted according to the input current of the rotating electromagnetic generator I . Furthermore, the curve relationship C between the current of the rotating electromagnetic generator and the positive pressure inside the intramedullary nail I is established, as shown in Figure 8 .

[0034] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.​

Claims

1. A method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail, characterized in that: The method comprises the following steps: Step 1: Based on the self-locking principle of the magnetically driven expandable intramedullary nail and the simulation of the three-dimensional structure model of the intramedullary nail, establish the positive pressure inside the intramedullary nail The magnetic force of the magnetic kit Mathematical relationship curve A; Step 2: Generate a controllable magnetic field through a rotating electromagnetic generator, interact with the built-in permanent magnet of the magnetic-driven expandable intramedullary nail, realize magnetic force regulation, and establish the input current of the rotating electromagnetic generator I Apply magnetic force to the magnetic kit Simulation relationship curve B; Step 3: Establish the current of the rotating electromagnetic generator I Positive pressure inside the intramedullary nail Curve relationship C, by changing the current of the rotating electromagnetic generator I The electromagnetic field of the rotating electromagnetic generator exerts magnetic force on the magnetic kit. Changes occur when the magnetic kit is subjected to different magnetic forces When the magnetic kit is in effect, the expansion chute block driven by the magnetic kit is tightened and loosened to adjust the positive pressure inside the intramedullary nail. The size is tightened.

2. The method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail according to claim 1, characterized in that: In step 2, according to the structure of the rotating electromagnetic generator and its electromagnetic parameters, including the number of turns of the internal coil of the rotating electromagnetic generator and the current size, the electromagnetic field model of the rotating electromagnetic generator is established by using the principle of electromagnetism; according to the magnetic parameters of the permanent magnets in the magnetic kit, the magnetic field model of the magnetic kit is established, and then a finite element simulation model of the magnetic force generated by the electromagnetic field of the rotating electromagnetic generator on the magnetic field of the magnetic kit is established. Relationship establishes curve B.

3. The method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail according to claim 1, characterized in that: The magnetic force regulating device comprises: an adjustable constant current source, a conductive slip ring and a rotating electromagnetic generator, wherein the conductive slip ring is electrically connected between the adjustable constant current source and the rotating electromagnetic generator.

4. The method for adjusting the self-locking force of a magnetically driven expandable intramedullary nail according to claim 1, characterized in that: The proximal end of the magnetically driven expandable intramedullary nail contains a magnetic kit (3) and a push head (4), the magnetic kit (3) contains a permanent magnet, the magnetic kit (3) is threadedly connected to the push head (4), the expansion chute block (2) is embedded in the side wall of the proximal end of the intramedullary nail, the end face of the expansion chute block (2) has a first bevel, and the push head (4) has a second bevel matched with the first bevel. When the push head (4) moves axially inward, it squeezes the expansion chute block (2) to move radially outward, thereby achieving self-locking.

Images