A bidirectional telescopic intramedullary nail and a driver therefor

Abstract

The utility model relates to a two -way telescopic intramedullary nail and driver thereof, and the intramedullary nail includes connecting sleeve, inner magnet and rotation axis, and the inner magnet drives both sides split wheel rotation through rotation axis, and split wheel drives flexible gear and outer thread rod rotation, makes both sides inner thread telescopic rod extension nail synchronous telescopic, realizes two -way adjustment function, can be applicable to long bone fracture repair and bone defect reconstruction etc. clinical demand, has expanded the application range of intramedullary nail significantly. The matched driver adopts brushless DC motor principle, and the current sequence of winding coil is regulated and controlled through electronic commutating controller, and the stator magnetic field is produced to drive the inner magnet rotation and further drive the intramedullary nail telescopic. Compared with the traditional magnetic coupling drive mode, the driver of the utility model provides greater torque output through electromagnetic field coupling, can effectively overcome various high load conditions, can dynamically adjust current parameter compensation magnetic field attenuation, ensures the driving stability, cancels the mechanical transmission part, eliminates the vibration error, improves the control precision.

Description

Technical Field

[0001] This utility model relates to the field of intramedullary nail technology, and in particular to a bidirectional telescopic intramedullary nail and its actuator. Background Technology

[0002] In orthopedic surgery, distraction osteogenesis (DO) is a medical technique that promotes new bone formation by gradually stretching bone tissue. It is mainly used to treat orthopedic diseases such as bone defects, limb length discrepancies, and complex fractures. This technique is based on the biological characteristics of bone tissue and activates the regenerative capacity of bone cells through mechanical stimulation to achieve bone lengthening. Distraction osteogenesis is usually divided into three stages: (1) Osteotomy stage: surgical osteotomy is performed on the target bone segment to form bone ends; (2) Distraction stage: the bone is lengthened by gradually stretching the bone ends. External or internal fixation instruments are required during the distraction process; (3) Consolidation stage: after distraction is stopped, the newly formed bone tissue gradually mineralizes and matures, reaching normal bone strength.

[0003] The external or internal fixation devices used during the distraction phase mainly include external fixators and internal fixation plates. While external fixators can effectively fix the fracture ends, they are prone to causing pain, and the traction on muscles and nerves can restrict joint movement, affecting patient comfort and postoperative recovery. Although internal fixation plates offer improved fixation, they may loosen or shift during bone lengthening, leading to fixation failure. Furthermore, internal fixation devices may damage surrounding soft tissues, increasing the risk of infection and secondary surgery.

[0004] Compared to traditional external fixators and internal fixation plates, intramedullary nails, as a novel type of internal fixation device, offer significant advantages such as low infection risk, high patient comfort, superior biomechanical properties, and wide applicability. Their application in fracture fixation and bone lengthening surgery effectively improves treatment outcomes, reduces complications, and promotes rapid patient recovery, making them an important instrument in modern distraction osteogenesis surgery. Chinese Patent CN105708537A, published on June 29, 2016, discloses a telescopic intramedullary nail and its actuation mechanism. An inner magnet is fixedly connected to a screw, which is rotatably mounted in the distal body. The proximal outer body is fixedly connected to a threaded sleeve fitted onto the screw. The rotation of the outer magnet drives the inner magnet and the screw to rotate, thereby causing the threaded sleeve and the proximal outer body to move axially relative to the distal body in a telescopic manner, thus achieving the telescopic extension and retraction of the intramedullary nail. When applied in distraction osteogenesis, after the target bone segment is cut into segments, the proximal lateral main body and the distal main body are fixed into the medullary cavity of the two segments respectively. The segments can then be lengthened (distraction) or shortened (contraction) as necessary by extending and retracting the telescopic intramedullary nail.

[0005] However, the telescopic intramedullary nails in the aforementioned prior art can only achieve unidirectional telescopic extension and retraction, resulting in limited functionality and applicability only to certain specific bone structures. They cannot meet complex clinical needs, such as long bone fractures or reconstruction of severe bone defects requiring bidirectional adjustment of bone length. Furthermore, the actuation mechanism in these prior art drives the telescopic intramedullary nail's extension and retraction through a rotating outer magnet driving an inner magnet. This relies on non-contact magnetic coupling between the outer and inner magnets to transmit torque. The magnetic field strength of the magnets is fixed, and limited by their volume and spacing, the torque output of the outer magnet is limited, making it difficult for the intramedullary nail to effectively overcome high loads, including soft tissue contracture resistance and bone end friction resistance. Moreover, as the thickness of human tissue increases, the magnetic field strength between the outer magnet and the implanted inner magnet significantly decreases, further affecting torque output and reducing driving efficiency. In addition, these prior art uses mechanical transmission methods such as gear sets, belt drives, and worm gear drives to rotate the outer magnet. Mechanical transmission is susceptible to vibration interference, which affects the rotational accuracy of both the outer and inner magnets, leading to a decrease in the control precision of the intramedullary nail's extension. Utility Model Content

[0006] The purpose of this invention is to provide a bidirectional telescopic intramedullary nail and its actuator, in order to solve the technical problems that existing telescopic intramedullary nails can only achieve unidirectional telescopic movement, and that the actuators used to drive telescopic intramedullary nails have limited torque output and insufficient driving accuracy.

[0007] The technical problem solved by this utility model can be achieved by the following solutions:

[0008] This utility model provides a bidirectional telescopic intramedullary nail, including a connecting sleeve and an inner magnet rotatably installed inside the connecting sleeve and coaxially fixed with a rotating shaft. A dividing wheel, driven to rotate by the rotating shaft, is installed on each side of the rotating shaft. A flexible gear, driven to rotate by the dividing wheel, is fitted on each of the two dividing wheels. An externally threaded rod is fixed to each of the two flexible gears. An mounting sleeve, on each side of the connecting sleeve, has an internally threaded telescopic extension rod slidably mounted thereon. The two externally threaded rods are threadedly connected to an internally threaded telescopic extension rod. The rotation of the two externally threaded rods causes the internally threaded telescopic extension rod to slide along the mounting sleeve, thus performing a telescopic movement relative to the mounting sleeve.

[0009] Furthermore: a guide key is fixed on the mounting sleeve, and an extension pin keyway that is slidably connected to the guide key is provided on the internal thread telescopic rod extension pin. When the internal thread telescopic rod extension pin slides along the mounting sleeve, the extension pin keyway moves axially relative to the guide key.

[0010] Furthermore, a flexible retainer is sleeved between the dividing wheel and the flexible gear, and multiple rotating rollers that are in contact with the dividing wheel and the flexible gear are rotatably mounted on the flexible retainer. When the dividing wheel rotates, the rotating rollers drive the flexible gear to rotate.

[0011] Furthermore, both ends of the rotating shaft are rotatably mounted with ball bearings that are rotatably connected to the external threaded rod.

[0012] Furthermore, a key is detachably fixedly mounted on the rotating shaft, and the dividing wheel is keyed to the rotating shaft via the key.

[0013] Furthermore: the key is inserted and fixed in a through groove opened on the rotating shaft, and the two ends of the key pass through the through groove and are located on both sides of the rotating shaft. The dividing wheel is symmetrically provided with two dividing wheel keyways for accommodating the two ends of the key.

[0014] Furthermore, a rigid gear ring capable of meshing with the flexible gear is fixedly installed inside the mounting sleeve.

[0015] Furthermore: a first magnetostrictive displacement sensor is fixed at one end of the external threaded rod near the extension pin of the internal threaded telescopic rod, and a second magnetostrictive displacement sensor that cooperates with the first magnetostrictive displacement sensor is fixed in the hollow cavity of the external threaded rod.

[0016] Another aspect of this utility model provides an actuator for driving the aforementioned bidirectional telescopic intramedullary nail, comprising multiple drive units and an electronic commutation controller. Each drive unit includes a housing, an iron core fixedly installed in the housing, and a winding coil wound on the iron core. The electronic commutation controller controls the energizing sequence of the winding coils of each drive unit. The stator magnetic field generated after the winding coil is energized interacts with the rotor magnetic field of the inner magnet of the bidirectional telescopic intramedullary nail to generate torque, thereby driving the inner magnet to rotate.

[0017] Furthermore, each drive unit has a pin and a slot on both sides of its iron core, and each drive unit is detachably and fixedly connected in sequence, with the pin of each drive unit able to be inserted into the slot of the adjacent drive unit.

[0018] This invention relates to a bidirectional telescopic intramedullary nail, in which an installation sleeve is fixed to each side of a connecting sleeve. An internal magnet is rotatably mounted inside the connecting sleeve. A dividing wheel is mounted on each side of a rotating shaft coaxially fixed to the internal magnet. The rotation of the internal magnet drives the rotating shaft and the dividing wheels on both sides to rotate. The rotation of the dividing wheels drives the flexible gears mounted on them to rotate. The rotation of the two flexible gears drives the external threaded rods fixed to them to rotate. The rotation of the two external threaded rods drives an internal threaded telescopic extension nail to slide along the installation sleeve, thus performing telescopic movement relative to the installation sleeve and the connecting sleeve. Because the two internal threaded telescopic extension nails are located on both sides of the connecting sleeve, the rotation of the internal magnet inside the connecting sleeve can drive the internal threaded telescopic extension nails on both sides to extend and retract synchronously, thereby achieving bidirectional telescopic extension and retraction of the bidirectional telescopic intramedullary nail. This can address situations requiring bidirectional adjustment of bone length, such as long bone fractures and reconstruction of severe bone defects, expanding the clinical applicability of intramedullary nails.

[0019] This invention relates to an actuator for driving the aforementioned bidirectional telescopic intramedullary nail. It utilizes the basic working principle of an existing brushless DC motor (this principle will be explained in detail in the specific implementation section). Each drive unit has a winding coil wound around its iron core. An electronic commutation controller controls the energizing sequence of the winding coils in each drive unit. The stator magnetic field generated after the winding coils are energized interacts with the rotor magnetic field of the inner magnet of the bidirectional telescopic intramedullary nail to generate torque, thereby rotating the inner magnet and driving the intramedullary nail to extend and retract. This invention drives the inner magnet to rotate through electromagnetic field coupling. The torque output of the electromagnetic field is significantly superior to that of a rotating magnet drive system. Therefore, compared to the traditional magnetic coupling drive method using rotating magnets, this invention directly drives the inner magnet through a high-intensity stator magnetic field (electromagnetic field) generated after the winding coils are energized, significantly improving the torque output capability of the actuator. This allows the intramedullary nail to effectively overcome high load conditions, including soft tissue contracture resistance and bone end friction resistance. Furthermore, by adjusting the current parameters of the winding coils, the strength of the stator magnetic field can be controlled, thereby compensating for magnetic field attenuation caused by changes in tissue thickness and ensuring the stability of torque output and driving efficiency. Furthermore, by completely eliminating the mechanical transmission components required for rotating magnets and directly driving the inner magnet to rotate through electromagnetic field coupling, the transmission error caused by mechanical vibration is fundamentally eliminated, significantly improving the control accuracy of intramedullary nail extension and greatly enhancing the driving accuracy of the actuator for intramedullary nails. Attached Figure Description

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

[0021] Figure 1 This is a schematic diagram of the structure of a bidirectional telescopic intramedullary nail according to this utility model;

[0022] Figure 2 This is a cross-sectional view of a bidirectional telescopic intramedullary nail according to this utility model;

[0023] Figure 3 yes Figure 2 A magnified view of part A;

[0024] Figure 4 This is a schematic diagram of the structure of a bidirectional telescopic intramedullary nail according to the present invention. The connecting sleeve, the mounting sleeve on one side, and the internal thread telescopic extension nail have been removed from the diagram.

[0025] Figure 5 yes Figure 4 A magnified view of section B;

[0026] Figure 6 This is a structural schematic diagram of a flexible gear, external threaded rod, internal threaded telescopic rod extension nail, and guide key on one side of a bidirectional telescopic intramedullary nail according to this utility model.

[0027] Figure 7 This is a structural schematic diagram of the cross-section of the dividing wheel, flexible retainer, rotating roller, and flexible gear of a bidirectional telescopic intramedullary nail according to this utility model.

[0028] Figure 8 This is a schematic diagram of the structure of the dividing wheel, flexible retainer, rotating roller, flexible gear and external threaded rod on one side of a bidirectional telescopic intramedullary nail according to this utility model.

[0029] Figure 9 This is a schematic diagram of the structure of the dividing wheel, flexible retainer, and rotating roller of a bidirectional telescopic intramedullary nail according to this utility model;

[0030] Figure 10 This is a schematic diagram of the dividing wheel, flexible retainer, and rotating roller of a bidirectional telescopic intramedullary nail according to this utility model. One of the rotating rollers has been removed from the diagram.

[0031] Figure 11 This is a schematic diagram of the structure of a bidirectional telescopic intramedullary nail according to this utility model. The connecting sleeve, the mounting sleeve on one side, the flexible gear, the external threaded rod, and the internal threaded telescopic rod extension nail have been removed from the diagram.

[0032] Figure 12 This is a schematic diagram of the connecting sleeve, inner magnet, and rotating shaft of a bidirectional telescopic intramedullary nail according to this utility model.

[0033] Figure 13This is a schematic diagram of the connecting sleeve, inner magnet, and rotating shaft of a bidirectional telescopic intramedullary nail according to this utility model. The key inserted into the rotating shaft has been removed from the diagram.

[0034] Figure 14 This is a schematic diagram of the connecting sleeve, inner magnet, rotating shaft, and dividing wheel of a bidirectional telescopic intramedullary nail according to this utility model.

[0035] Figure 15 This is a schematic diagram of the installation sleeve for a bidirectional telescopic intramedullary nail according to this utility model;

[0036] Figure 16 This is a schematic diagram of the structure of a driver for driving a bidirectional telescopic intramedullary nail according to the present invention;

[0037] Figure 17 This is a schematic diagram of the drive unit of a driver for driving a bidirectional telescopic intramedullary nail according to the present invention.

[0038] Figure 18 This is a schematic diagram of the drive unit of a driver for driving a bidirectional telescopic intramedullary nail according to the present invention. The housing of the drive unit has been removed from the figure.

[0039] Main components and designations:

[0040] Bidirectional telescopic intramedullary nail: 100;

[0041] Connecting sleeve: 111; Mounting sleeve: 112; Guide key: 1121; Rigid gear ring: 1122;

[0042] Rotating shaft: 12; Ball bearing: 121; Key: 122; Through slot: 123;

[0043] Internal magnet: 13;

[0044] Dividing wheel: 14; Dividing wheel keyway: 141;

[0045] Flexible gears: 15;

[0046] External threaded rod: 16; First magnetostrictive displacement sensor: 161;

[0047] Internal threaded telescopic rod extension pin: 17; extension pin keyway: 171; second magnetostrictive displacement sensor: 172;

[0048] Flexible retainer: 181; Mounting slot: 1811; Rotating roller: 182;

[0049] Drive: 200;

[0050] Drive unit: 210; Housing: 211; Iron core: 212; Pin: 2121; Slot: 2122; Winding coil: 213; Electrode: 214. Detailed Implementation

[0051] To make the objectives, technical solutions and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0052] Example 1: Figure 1-3 This is a structural diagram of a bidirectional telescopic intramedullary nail 100 according to this embodiment, as shown below. Figure 1-3 As shown, the bidirectional telescopic intramedullary nail 100 includes a connecting sleeve 111, within which an inner magnet 13 is rotatably mounted. In this embodiment, the inner magnet 13 is made of a high-permeability material (such as neodymium iron boron) to ensure that even with a small size, it can still generate a strong and uniform magnetic field. The inner magnet 13 is coaxially and fixedly connected to the rotating shaft 12. In this embodiment, an interference fit is used to install the inner magnet 13 onto the rotating shaft 12. When the inner magnet 13 rotates, it drives the rotating shaft 12 to rotate. A dividing wheel 14 is mounted on each side of the rotating shaft 12. The rotation of the rotating shaft 12 drives the two dividing wheels 14 to rotate. Each of the two dividing wheels 14 is fitted with a flexible gear 15. The rotation of the dividing wheels 14 drives the flexible gear 15 to rotate. Each of the two flexible gears 15 has an externally threaded rod 16 fixed to it, with the externally threaded rod 16 located at the end of the flexible gear 15 furthest from the inner magnet 13. The connection and fit between the inner magnet 13, the rotating shaft 12, the dividing wheels 14, the flexible gears 15, and the externally threaded rods 16 are also shown in… Figure 4 , Figure 5 middle( Figure 4 (The external thread of the threaded rod 16 is not shown). A mounting sleeve 112 is fixed to each side of the connecting sleeve 111. The dividing wheel 14, flexible gear 15, and threaded rod 16 are all rotatably mounted inside the mounting sleeve 112. An internally threaded telescopic rod extension pin 17 is slidably mounted on the mounting sleeve 112. Each of the two externally threaded rods 16 is threadedly connected to one internally threaded telescopic rod extension pin 17. The rotation of the two externally threaded rods 16 respectively drives one of the internally threaded telescopic rod extension pins 17 threadedly connected to it to slide along the mounting sleeve 112. During the sliding process, the internally threaded telescopic rod extension pin 17 performs telescopic movement relative to the mounting sleeve 112 and the connecting sleeve 111.

[0053] In this embodiment, the bidirectional telescopic intramedullary nail 100 is driven by the rotation of the inner magnet 13, which in turn drives the rotation shaft 12 and the dividing wheels 14 on both sides of the rotation shaft 12. The rotation of the dividing wheels 14 drives the rotation of the flexible gears 15 sleeved on them. The rotation of the two flexible gears 15 drives the rotation of the external threaded rods 16 fixed to them. The rotation of the two external threaded rods 16 drives one internal threaded telescopic extension nail 17 to slide along the mounting sleeve 112 and thus perform telescopic movement relative to the mounting sleeve 112 and the connecting sleeve 111. Since the two internal threaded telescopic extension nails 17 are located on both sides of the connecting sleeve 111, when the inner magnet 13 inside the connecting sleeve 111 rotates, it can drive the internal threaded telescopic extension nails 17 on both sides to telescopically extend and retract synchronously, thereby realizing the bidirectional telescopic extension and retraction of the telescopic intramedullary nail 100. When applied in distraction osteogenesis surgery, after the target bone segment is cut into segments, the connecting sleeve 111 and the internally threaded telescopic extension nails 17 located on both sides of the connecting sleeve 111 are fixed to the medullary cavity of different segments. The segments can then be bidirectionally lengthened (distracted) or shortened (contracted) by the bidirectional extension and retraction of the telescopic intramedullary nail 100.

[0054] In order to guide the sliding of the internal thread telescopic rod extension pin 17 and to limit the rotation of the internal thread telescopic rod extension pin 17, such as Figure 1 , 6 As shown, a guide key 1121 is detachably fixed on the mounting sleeve 112. Figure 1 The guide key 1121 on the right side of the mounting sleeve 112 is located below the mounting sleeve 112 and is obscured by the mounting sleeve 112 (not shown in the accompanying drawings). The outer surface of the internally threaded telescopic rod extension pin 17 has an extension pin keyway 171 that slides with the guide key 1121 (shown in the accompanying drawings). Figure 6 In the middle section, when the internal threaded telescopic rod extension pin 17 slides along the mounting sleeve 112, the extension pin keyway 171 moves axially relative to the guide key 1121. The cooperation between the guide key 1121 and the extension pin keyway 171 guides the internal threaded telescopic rod extension pin 17 and restricts its rotation, so that the internal threaded telescopic rod extension pin 17 does not rotate with the external threaded rod 16 when the external threaded rod 16 rotates. Furthermore, through the inclined plane effect of the thread, when the internal threaded telescopic rod extension pin 17 is subjected to the axial force transmitted by the threaded section of the external threaded rod 16, the internal threaded telescopic rod extension pin 17 slides along the mounting sleeve 112 and thus performs telescopic movement relative to the mounting sleeve 112.

[0055] like Figure 7 , Figure 8As shown, in order to enable the flexible gear 15 to rotate when the dividing wheel 14 rotates, a flexible retainer 181 is sleeved between the dividing wheel 14 and the flexible gear 15. Multiple rotating rollers 182 are rotatably mounted on the flexible retainer 181. The connection and cooperation relationship between the flexible retainer 181 and the rotating rollers 182 is also shown in... Figure 9 , Figure 10 In this configuration, one side of the rotating roller 182 contacts the outer surface of the dividing wheel 14, and the other side contacts the inner surface of the flexible gear 15. Through the frictional forces between the rotating roller 182 and the dividing wheel 14, and between the rotating roller 182 and the flexible gear 15, the dividing wheel 14 rotates, causing the flexible gear 15 to rotate via the rotating roller 182. Figure 9 , 10 As shown, a plurality of mounting slots 1811 are provided on the flexible retainer 181, and rotating rollers 182 are rotatably mounted in the mounting slots 1811. The plurality of rotating rollers 182 are arranged in a circular array around the central axis of the flexible retainer 181. The arrangement of the flexible retainer 181 and the rotating rollers 182 enables the flexible gear 15 to deform uniformly and transmit the rotational motion of the flexible gear 15 to the external threaded rod 16.

[0056] like Figure 2 , 3 As shown in Figure 11, both ends of the rotating shaft 12 are rotatably mounted with ball bearings 121, which are rotatably connected to the end of the external threaded rod 16 near the flexible gear 15. In this embodiment, the ball bearings 121 function as ball bearings, capable of withstanding certain axial and radial loads to ensure the overall strength of the bidirectional telescopic intramedullary nail 100.

[0057] In order to enable the rotating shaft 12 to drive the dividing wheel 14 to rotate, such as Figure 3 , 12 As shown in Figures 1 and 13, a key 122 is detachably and fixedly mounted on the rotating shaft 12, as follows: Figure 3 , 14 As shown, the dividing wheel 14 is connected to the rotating shaft 12 via the key 122.

[0058] like Figure 12 , 13 As shown, the key 122 is inserted and fixed in the through groove 123 opened on the rotating shaft 12, and the two ends of the key 122 respectively protrude from the through groove 123 and are located on both sides of the rotating shaft 12, as shown. Figure 14 As shown, two symmetrically arranged dividing wheel keyways 141 are provided inside the dividing wheel 14 (the dividing wheel keyways 141 are also shown in...). Figure 8 , Figure 9The two keyways 141 of the dividing wheel are respectively used to accommodate the two ends of the key 122. The design of the bidirectional key connection between the dividing wheel 14 and the rotating shaft 12 ensures that the relative position between the dividing wheel 14 and the rotating shaft 12 is accurate and will not be offset axially or radially due to load changes or vibrations. It allows torque to be transmitted in both directions (clockwise or counterclockwise), so that the dividing wheel 14 can operate reliably regardless of whether the rotating shaft 12 rotates clockwise or counterclockwise, meeting the usage requirements of the bidirectional telescopic intramedullary nail 100.

[0059] To constrain the deformation path of the flexible gear 15 and ensure transmission stability, such as Figure 15 As shown, a rigid gear ring 1122 capable of meshing with the flexible gear 15 is fixedly installed inside the mounting sleeve 112. During rotation, the flexible gear 15 forms a dynamic meshing relationship with the rigid gear ring 1122 through its elastic deformation. Specifically, the flexible gear 15 undergoes elastic deformation during rotation, causing its tooth profile to alternately mesh and disengage with the tooth groove of the rigid gear ring 1122. The dynamic meshing between the rigid gear ring 1122 and the flexible gear 15 constrains the deformation path of the flexible gear 15. During the rotation and deformation of the flexible gear 15, the rigid gear ring 1122 provides radial force to increase the friction between the flexible gear 15 and the rotating roller 182, allowing the dividing wheel 14 to better provide torque to the flexible gear 15 through the rotating roller 182 when rotating, thus ensuring the stability of the transmission.

[0060] To detect the displacement of the internally threaded telescopic extension pin 17 in order to obtain the extension amount of the bidirectional telescopic intramedullary nail 100, such as... Figure 2 , Figure 4As shown, a first magnetostrictive displacement sensor 161 is fixed at one end of the externally threaded rod 16 near the internally threaded telescopic rod extension pin 17. The internally threaded telescopic rod extension pin 17 is inserted into the hollow cavity of the externally threaded rod 16 and a second magnetostrictive displacement sensor 172, which cooperates with the first magnetostrictive displacement sensor 161, is fixed therein. When the internally threaded telescopic rod extension pin 17 extends or retracts, causing a change in the distance between the first magnetostrictive displacement sensor 161 and the second magnetostrictive displacement sensor 172, the magnetic field strength between them changes. When the magnetic field changes, an external magnetostrictive displacement detector can measure the relative displacement between the first magnetostrictive displacement sensor 161 and the second magnetostrictive displacement sensor 172 based on the change in the magnetic field, thereby obtaining the displacement of the internally threaded telescopic rod extension pin 17 and the extension of the bidirectional telescopic intramedullary nail 100. The first magnetostrictive displacement sensor 161, the second magnetostrictive displacement sensor 172, and the external magnetostrictive displacement detector all use existing models of magnetostrictive displacement sensors and detectors. Furthermore, the use of a magnetostrictive displacement detector to measure the relative displacement between two magnetostrictive displacement sensors based on the change in the magnetic field between them is an existing displacement detection technology.

[0061] In this embodiment, the bidirectional telescopic intramedullary nail 100 is driven by the rotation of the inner magnet 13, which in turn drives the rotation shaft 12 and the dividing wheels 14 on both sides of the rotation shaft 12. When the dividing wheels 14 rotate, they drive the flexible gear 15 to rotate through the rotating roller 182 mounted on the flexible retainer 181. Under the combined action of the rotating roller 182 and the rigid gear ring 1122, the flexible gear 15 deforms uniformly and transmits the rotational motion to the external threaded rods 16. The rotation of the two external threaded rods 16 drives one internal threaded telescopic rod extension nail 17 to slide along the mounting sleeve 112 and thus perform telescopic motion relative to the mounting sleeve 112 and the connecting sleeve 111. Since the two internal threaded telescopic rod extension nails 17 are located on both sides of the connecting sleeve 111, when the inner magnet 13 inside the connecting sleeve 111 rotates, it can drive the internal threaded telescopic rod extension nails 17 on both sides to telescopically extend and retract synchronously, thereby realizing the bidirectional telescopic extension and retraction of the telescopic intramedullary nail 100. When applied in distraction osteogenesis surgery, after the target bone segment is cut into segments, the connecting sleeve 111 and the internally threaded telescopic extension nails 17 located on both sides of the connecting sleeve 111 are fixed to the medullary cavity of different segments. The segments can then be bidirectionally lengthened (distracted) or shortened (contracted) by the bidirectional extension and retraction of the telescopic intramedullary nail 100.

[0062] Example 2: Figure 16 As shown, this embodiment provides a driver 200 for driving the bidirectional telescopic intramedullary nail 100 of Embodiment 1. The driver 200 can drive the inner magnet 13 of the bidirectional telescopic intramedullary nail 100 to rotate, thereby realizing the telescopic movement of the internal thread telescopic rod extension nail 17.

[0063] The driver 200 in this embodiment is based on the basic working principle of existing brushless DC motors. The following is a detailed description of brushless DC motors and their working principle.

[0064] A brushless DC motor (BLDC) is an electromagnetic device that converts electrical energy into mechanical energy. It is a type of motor that uses electronic commutation instead of mechanical brushes. The motor mainly consists of three parts: a stator, a rotor, and an electronic commutation controller. The stator employs a multi-phase (usually three-phase) winding structure, which includes an iron core and winding coils wound around it. The windings are arranged in a specific phase (such as star or delta configuration), and when energized, they generate a stator magnetic field (also known as a rotating magnetic field). The rotor is composed of permanent magnets made of high-performance rare-earth materials such as neodymium iron boron, which generate a rotor magnetic field that interacts with the stator magnetic field. The electronic commutation controller controls the current direction and timing based on the rotor position signal to achieve electronic commutation, thus enabling continuous rotor rotation. The torque of a brushless DC motor is output through an electromagnetic field, and its torque output capability is significantly superior to that of traditional rotating magnet drive systems. The electronic commutation controller can regulate the strength of the stator magnetic field by adjusting the current parameters of the winding coils.

[0065] The working principle of a brushless DC motor is as follows: The electronic commutation controller energizes the stator windings sequentially based on the rotor position signal (e.g., the energizing sequence for three-phase windings is U→V→W). The energized windings generate a stator magnetic field, which attracts or repels the rotor magnetic field, generating torque to drive the rotor to rotate. After the rotor rotates, the electronic commutation controller switches the energizing sequence of the next set of windings according to the updated rotor position signal, repeating the cycle. Traditional brushless DC motors mostly use square wave drive, switching the winding energizing sequence every 60°, resulting in a rectangular (square wave) current waveform. Square wave drive is simple to control and low in cost, but it has large torque ripple and noticeable noise and vibration. A few brushless DC motors use sinusoidal wave drive, where the current changes continuously according to a sine wave, resulting in smooth magnetic field rotation. Sine wave drive offers stable torque, low noise, and high efficiency. Using sinusoidal wave drive allows for a more precise phase relationship between the current and the rotor magnetic field, thereby improving the motor's stability and efficiency. It can effectively manage the current flow direction, ensuring that the rotor maintains good rotation even when the stator magnetic field is uneven. Square wave drive or sine wave drive can be achieved by adjusting the phase angle and timing of the electronic commutation controller.

[0066] The driver 200 of this embodiment is described in detail based on the basic working principle of existing brushless DC motors.

[0067] like Figure 16As shown, the driver 200 in this embodiment includes multiple drive units 210 and an electronic commutation controller (not shown in the figures), such as Figure 17 , 18 As shown, each drive unit 210 includes a housing 211, within which an iron core 212 and a winding coil 213 wound around the iron core 212 are fixedly disposed. An electronic commutation controller can be fixedly disposed inside the housing 211 of a certain drive unit 210. The magnetostrictive detector in Embodiment 1 can be disposed outside or inside the housing 211 of a certain drive unit 210 (the magnetostrictive detector is not shown in the accompanying drawings). Similar to the working principle of a brushless DC motor, the electronic commutation controller controls the energizing sequence of the winding coils 213 of each drive unit 210. The stator magnetic field generated after the winding coils 213 are energized interacts with the bidirectional telescopic intramedullary nail 100 (…). Figure 16 The bidirectional telescopic intramedullary nail 100 is shown only in schematic form. For the specific structure of the bidirectional telescopic intramedullary nail 100, please refer to Embodiment 1. The rotor magnetic field of the inner magnet 13 interacts to generate torque, thereby driving the inner magnet 13 to rotate. The inner magnet 13 is equivalent to the rotor of a brushless DC motor.

[0068] To improve the compatibility of driver 200, such as Figure 16-18 As shown, in this embodiment, each drive unit 210 is detachably fixedly connected. Each drive unit 210 has a pin 2121 and a slot 2122 on both sides of its iron core 212. The cross-sections of the pin 2121 and slot 2122 are T-shaped. Each drive unit 210 is sequentially and detachably fixedly connected, and the pin 2121 of each drive unit 210 can be inserted into the slot 2122 of the adjacent drive unit 210. The driver 200 in this embodiment can be disassembled into multiple drive units 210. Each drive unit 210 can be quickly assembled using pins 2121 and slots 2122. By using different numbers of drive units 210, it can adapt to different patients or different body parts, enhancing patient comfort and avoiding discomfort caused by a single size.

[0069] Each drive unit 210 of the actuator 200 is shaped to accommodate a patient's limb in which the bidirectional telescopic intramedullary nail 100 is inserted. Preferably, in this embodiment, each drive unit 210 of the actuator 200 is distributed circumferentially around the axis of the bidirectional telescopic intramedullary nail 100. Of course, the drive units 210 can also be arranged in other ways according to actual usage requirements.

[0070] Furthermore, such as Figure 17 , 18As shown, electrodes 214 for connecting the winding coils 213 of each drive unit 210 are provided at the pins 2121 and slots 2122 of the core 212 of each drive unit 210, so that the control circuit of the driver 200 can be integrated inside the housing 211, providing high-fidelity signal transmission in the control stage.

[0071] Furthermore, in this embodiment, the electronic commutation controller uses a sine wave drive instead of a square wave drive. Based on the aforementioned advantages of using a sine wave drive for the brushless DC motor, this embodiment uses a sine wave drive, which enables the driver 200 to operate with lower noise and vibration, improving the smoothness and efficiency of the driver 200. Even when the stator magnetic field is non-uniform, the inner magnet 13 of the bidirectional telescopic intramedullary nail 100 can still maintain good rotation.

[0072] When the actuator 200 of this embodiment drives the bidirectional telescopic intramedullary nail 100 to extend and retract, after the bidirectional telescopic intramedullary nail 100 is placed into the medullary cavity of the patient's target bone segment, the limb at the target bone segment is accommodated within the actuator 200, and each drive unit 210 of the actuator 200 is arranged around the bidirectional telescopic intramedullary nail 100. Then, the energizing sequence of the winding coils 213 of each drive unit 210 is controlled by an electronic commutation controller. The stator magnetic field generated after the winding coils 213 are energized interacts with the rotor magnetic field of the inner magnet 13 of the bidirectional telescopic intramedullary nail 100 to generate torque, thereby driving the inner magnet 13 to rotate, thus realizing the bidirectional telescopic movement of the bidirectional telescopic intramedullary nail 100.

[0073] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A bidirectional telescopic intramedullary nail, characterized in that: The device includes a connecting sleeve (111) and an inner magnet (13) rotatably mounted inside the connecting sleeve (111) and coaxially fixed to a rotating shaft (12). On both sides of the rotating shaft (12), there is a dividing wheel (14) that is driven to rotate by the rotating shaft (12). On each of the two dividing wheels (14), there is a flexible gear (15) that is driven to rotate by the dividing wheel (14). On each of the two flexible gears (15), there is an external thread rod (16). On both sides of the connecting sleeve (111), there is an mounting sleeve (112) on which an internal thread telescopic rod extension pin (17) is slidably mounted. The two external thread rods (16) are threadedly connected to an internal thread telescopic rod extension pin (17). The rotation of the two external thread rods (16) drives an internal thread telescopic rod extension pin (17) to slide along the mounting sleeve (112) and thus perform telescopic movement relative to the mounting sleeve (112) and the connecting sleeve (111).

2. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: A guide key (1121) is fixed on the mounting sleeve (112), and an extension pin keyway (171) is provided on the internal thread telescopic rod extension pin (17) that is slidably connected to the guide key (1121). When the internal thread telescopic rod extension pin (17) slides along the mounting sleeve (112), the extension pin keyway (171) moves axially relative to the guide key (1121).

3. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: A flexible retainer (181) is sleeved between the dividing wheel (14) and the flexible gear (15). Multiple rotating rollers (182) that are in contact with the dividing wheel (14) and the flexible gear (15) are rotatably mounted on the flexible retainer (181). When the dividing wheel (14) rotates, it drives the flexible gear (15) to rotate through the rotating rollers (182).

4. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: Both ends of the rotating shaft (12) are rotatably mounted with ball bearings (121) that are rotatably connected to the external threaded rod (16).

5. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: A key (122) is detachably fixedly mounted on the rotating shaft (12), and the dividing wheel (14) is connected to the rotating shaft (12) via the key (122).

6. The bidirectional telescopic intramedullary nail according to claim 5, characterized in that: The key (122) is inserted and fixed in the through groove (123) opened on the rotating shaft (12), and the two ends of the key (122) respectively pass through the through groove (123) and are located on both sides of the rotating shaft (12). The dividing wheel (14) is symmetrically provided with two dividing wheel keyways (141) for accommodating the two ends of the key (122).

7. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: The mounting sleeve (112) is internally fixed with a rigid gear ring (1122) that can mesh with the flexible gear (15).

8. The bidirectional telescopic intramedullary nail according to claim 1, characterized in that: A first magnetostrictive displacement sensor (161) is fixed at one end of the external threaded rod (16) near the internal threaded telescopic rod extension pin (17). The internal threaded telescopic rod extension pin (17) is used to insert into the hollow cavity of the external threaded rod (16) and fix a second magnetostrictive displacement sensor (172) that cooperates with the first magnetostrictive displacement sensor (161).

9. A actuator for driving the bidirectional telescopic intramedullary nail of any one of claims 1-8, characterized in that: The device includes multiple drive units (210) and an electronic commutation controller. Each drive unit (210) includes a housing (211), an iron core (212) fixedly installed in the housing (211), and a winding coil (213) wound on the iron core (212). The electronic commutation controller controls the energizing sequence of the winding coils (213) of each drive unit (210). The stator magnetic field generated after the winding coil (213) is energized interacts with the rotor magnetic field of the inner magnet (13) of the bidirectional telescopic intramedullary nail (100) to generate torque, thereby driving the inner magnet (13) to rotate.

10. The driver according to claim 9, characterized in that: Each drive unit (210) has a pin (2121) and a slot (2122) on both sides of the iron core (212). Each drive unit (210) is detachably and fixedly connected in sequence, and the pin (2121) of each drive unit (210) can be inserted into the slot (2122) of the adjacent drive unit (210).

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