Motor-driven fixator that applies micro-motion to fracture sites to accelerate bone healing

Abstract

A device and method for treating bone fractures comprising a micro-motion unit, wherein the micro-motion unit (6) generates a reciprocating displacement between two bone fracture fragments (1) to apply controllable micro-motion to the fracture site.

Description

Technical Field

[0001] Devices, systems, and methods for facilitating bone healing are disclosed. Background Art

[0002] Fractures are a common bone disease that often require expensive surgical treatment. According to a 2013 audit report released by the International Osteoporosis Foundation (IOF), fracture rates in Asia are expected to increase significantly by 2050 due to an aging population, widespread vitamin D deficiency and low calcium intake.

[0003] Open reduction and implant fixation are considered the standard treatment for fractures that cannot be manually reduced. Many implants have been developed and widely used for fracture fixation, including dynamic compression plates (DCPs), locking compression plates (LCPs), intramedullary nails, and external fixators. Dynamic compression plates (DCPs) provide absolute stability by achieving compression across the fracture line, which can achieve primary fracture healing without callus formation. However, LCPs and intramedullary nails provide relative stability, which is conducive to secondary bone healing with extensive callus formation. Since primary fracture healing takes a long time and has a high refracture rate, secondary bone healing induced by relative stability is considered a better choice for fracture fixation.

[0004] Relatively stable implants can induce micromotion at the fracture site, promote callus formation, and thus accelerate fracture healing. This theory has been confirmed by clinical observations and animal experiments. In addition, a series of micromotion implants have been designed to take advantage of this theory, such as mobile plates and dynamic locking screws. Even with good clinical results, the number of clinical reports of fracture nonunion and delayed fracture union using relatively stable fixation methods remains high. The overall incidence of nonunion in the tibial shaft has been reported to be as high as 18.5%, while the rate of nonunion in the femoral shaft after medullary expansion and nailing is 1.7%. The effective stress range that can promote fracture healing remains unclear. This may be the reason why the relatively stable implants currently used show inconsistent clinical results. Summary of the invention

[0005] A brief description of the present invention is presented below to provide a basic understanding of some aspects of the present invention. This brief description is not a broad overview of the present invention. It is neither intended to specify the gist or key elements of the present invention, nor to describe the scope of the present invention. However, the sole purpose of this overview is to present some concepts of the present invention in a simplified form as a prelude to a more detailed description presented below.

[0006] The subject disclosure provides devices, systems and methods involving micromotions having an appropriate model (including displacement range and frequency) to improve callus formation along fractures. A series of micromotion fixators accelerate fracture healing. Traditional 'dynamic fixators' rely on the patient's weight bearing to produce micromotions across the fracture line, which makes the micromotions uncontrollable. In order to produce controllable and accurate micromotions at the fracture site, an electronic linear servo motor actuator and a micromotion unit are designed to convert electrical energy into reciprocating displacement between two fracture fragments. An electronic controller actuates the micromotion unit to produce micromotions with preset parameters and makes necessary compensations based on the measurements of the displacement sensor. The micromotion unit can be removed after use. Thus, this orthopedic fixator can be used to treat fractures in different parts of patients in need.

[0007] Essentially, the electromechanical machine converts electrical energy into reciprocating displacement between two components to impart controlled micromotion to the fracture site, which can be precisely adjusted by an electronic controller.

[0008] One aspect of the present invention relates to an external fixator for treating fractures, comprising a bracket attached to a bone at two locations, the two locations being on opposite sides of a fracture site; a micro-motion unit removably connected to the bracket, the micro-motion unit being configured to form a reciprocating displacement between two components to apply controllable micro-motion to the fracture site; and a controller connected to the micro-motion unit, the controller being used to control the micro-motion unit to produce the reciprocating displacement.

[0009] An external fixator for treating fractures includes: a bracket attached to the bone at two fracture fragments, the two fracture fragments are located on opposite sides of the fracture site; a micro-motion unit removably connected to the bracket, the micro-motion unit is configured to generate a reciprocating displacement between the two fracture fragments to apply a controllable micro-motion to the fracture site; and a controller connected to the micro-motion unit, the controller is configured to control the micro-motion unit to generate a reciprocating displacement between the two fracture fragments.

[0010] Another aspect of the present invention relates to a method for treating a fracture, comprising attaching a bracket at two positions, the two positions being located on opposite sides of the fracture site; generating a reciprocating displacement between the two components, the micro-motion unit being removably connected to the bracket to apply controllable micro-motion to the fracture site; and controlling the reciprocating displacement to facilitate fracture healing at the fracture site.

[0011] The method for treating a fracture comprises: attaching a bracket to a bone at two fracture fragments, the two fracture fragments being located on opposite sides of a fracture site; applying controllable micro-motion to the fracture site by generating a reciprocating displacement between the two fracture fragments through a micro-motion unit removably connected to the bracket; and controlling the reciprocating displacement between the two fracture fragments through a controller to facilitate fracture healing at the fracture site.

[0012] Another aspect of the present invention relates to a micro-motion unit, comprising: an outer tube, an inner tube, a motor and a gear transmission mechanism. At least a portion of the inner tube is inserted into the outer tube; the motor and the gear transmission mechanism are configured to convert an electrical signal into a relative axial displacement between the outer tube and the inner tube along the axial direction of the inner tube and the outer tube; and the outer tube and the inner tube are respectively connected to two fracture fragments, so that the relative displacement between the outer tube and the inner tube generates a reciprocating displacement between the two fracture fragments.

[0013] To achieve the above and related ends, the present invention includes the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative aspects and embodiments of the present invention. However, these are only representative of a few of the various ways in which the principles of the present invention can be employed. When combined with the attached drawings, the present invention is described in detail. Figure 1 Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered together. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 An external fixator according to an embodiment is depicted, showing 1 - patient's fracture fragments; 2 - K-wire; 3 - slideway on the bracket body; 4 - slider; 5 - adapter ring between the micro-motion unit and the connecting rod; 6 - micro-motion unit; 7 - bracket body; 8 - connecting rod; and 9 - electronic controller.

[0015] Figure 2 The structure of the micro-motion unit according to the embodiment is depicted, showing 61-outer tube; 62-transmission screw; 63-elliptical gear; 64-wave generator; 65-sealing ring; 66-wire to electronic controller; 67-inner tube; 68-limit screw; 69-displacement sensor; 610-motor; 611-ring gear; and 612-guide rail.

[0016] Figure 3 A control logic diagram of an electronic controller according to an embodiment is shown.

[0017] Figure 4 FIG. 4 shows a displacement-time curve of a micro-motion unit measured according to an embodiment.

[0018] Figure 5 The measured displacement-time curve of a conventional micro-motion unit is shown.

[0019] Figure 6 The external fixator according to the embodiment is shown in FIG. Comparison of external fixators in terms of micromotion accuracy.

[0020] Figure 7 The application of a micro motion unit (MMU) at a fracture site according to an embodiment is shown.

[0021] Figure 8Depicted are X-ray images showing use and no use of a micro motion unit (MMU) at a fracture site according to an embodiment.

[0022] Fig. 9 An external fixator having a micro motion unit MMU according to an embodiment is shown.

[0023] Fig.10 The relationship between bone formation and interfragmentary strain (IFS) of fracture fragments is shown.

[0024] Fig.11 The structure of the micro-motion unit according to the embodiment is shown, showing 613 - coupler; 614 - screw rod; 615 - slider; 616 - screw.

[0025] Fig.12 Various applications of the micro motion unit MMU according to the embodiment are shown. DETAILED DESCRIPTION

[0026] With the continuous study of the mechanism of bone healing, applying a certain degree of micro-motion at the fracture site can accelerate fracture healing and reduce the incidence of bone non-union. Therefore, a series of "dynamic fixators" including external fixators and plates have been designed to form micro-motion at the fracture site. All the "dynamic fixators" currently used rely on the patient's weight-bearing to form micro-motion across the fracture line, which makes the micro-motion uncontrollable. The problem is that inappropriate micro-motion parameters have a negative impact on bone healing. For example, starting or ending micro-motion too early will delay fracture repair, while excessive displacement will lead to bone non-union. Therefore, a significant limitation of the "dynamic fixators" currently used is the lack of feasible methods to adjust the parameters of micro-motion, such as the range, frequency, duration and timing of micro-motion, to produce appropriate micro-motion to accelerate bone healing.

[0027] In order to produce controlled and appropriate micromotion to facilitate fracture healing, an external fixator is described herein. Figure 1 , Figure 2 and Fig.11 , the linear electronic servo motor actuator 610 is designed to convert electrical energy into a reciprocating displacement between two fracture fragments 1. For example, the core component is a micro-motion unit 6. For example, the micro-motion unit 6 has four components, an outer tube 61, an inner tube 67, a motor 610 and a gear transmission mechanism. In terms of the working principle, for example, the motor 610 and the gear transmission mechanism are configured to convert an electrical signal from an electronic controller 9 into a relative displacement between the outer tube 61 and the inner tube 67. For example, the outer tube 61 and the inner tube 67 are respectively fixed to the proximal and distal fracture fragments, so that the reciprocating motion of the motor device 610 produces micro-motion on the fracture site of the patient in a manner that is conducive to and / or promotes fracture healing, especially compared to a similar situation where the external fixator is not used.

[0028] As an orthopedic fixator to accelerate fracture healing, the advantages of the present invention can be summarized in at least four key words:

[0029] Autonomous - External fixators can autonomously apply micro-motion to the patient's fracture site rather than relying on manual action or weight bearing by the patient, making the micro-motion more effective than most conventional 'dynamic fixators'.

[0030] Programmable - The progression of micro-motion application, such as the duration and timing of application, is programmable. Depending on the patient's healing state, the micro-motion function can be turned on or off - i.e. tailored to each case.

[0031] Precision - The mechanical parameters of each micro-motion cycle, such as range and frequency, are precisely controlled and compensated by a closed-loop controller based on a displacement sensor in the micro-motion unit.

[0032] Removable - The micro-motion unit of the external fixator is designed to be removable at the end of each micro-motion application to relieve the burden on the patient.

[0033] The present invention relates to an external fixator to improve bone healing by applying micro-motion to a fracture site of a patient. The external fixator includes a micro-motion unit 6, an electronic controller 9 and a bracket. For example, two fracture fragments 1 of the patient are respectively fixed on a main body 7 and a slider 4 of the bracket. For example, the main body 7 and the slider 4 are connected to an inner tube 67 and an outer tube 61 of the micro-motion unit 6 through two connecting rods 8. For example, the micro-motion unit 6 is configured to convert an electrical signal from the electronic controller 9 into a periodic displacement between the inner tube 67 and the outer tube 61. For example, a sensor 69 in the micro-motion unit 6 is configured to measure an actual displacement, and the electronic controller 9 is configured to compensate based on the measured value. For example, the micro-motion unit 6 is detachable after use to relieve the burden on the patient. The present invention is used, for example, as an orthopedic fixator to treat fractures in various positions.

[0034] Reference Figure 1 , showing a diagram according to an embodiment. The present invention includes a micro-motion unit 6, an electronic controller 9 and a bracket. For example, the micro-motion unit 6 generates micro-motion under the control of the electronic controller 9. For example, the bracket is designed to provide stability to the fracture site FS of the patient. For example, the main body 7 of the bracket and the slider 4 of the bracket are fixed to the proximal fragment and the distal fracture fragment of the patient through three or so Kirschner wires 2, respectively. For example, the outer tube 61 and the inner tube 67 are inserted into the bracket main body 7 and the bracket slider 4, respectively, through two or more connecting rods 8. For example, the micro-motion unit is detachable and can be removed from the bracket after use.

[0035] Figure 2Figures showing a micro-motion unit are presented. For example, the micro-motion unit includes four components, an outer tube 61, an inner tube 67, a motor 610, and a gear transmission mechanism. For example, the motor 610 and the gear transmission mechanism in the micro-motion unit 6 are configured to convert an electrical signal from the electronic controller 9 into a relative displacement between the outer tube 61 and the inner tube 67. For example, a high-torque hollow cup motor 610 is rigidly fixed in a dedicated space of the inner tube 67. The reason for selecting the hollow cup motor 610 as the prime mover is that it has the advantages of high efficiency, fast response, and small size. For example, the hollow cup motor is a key technology for achieving the axial displacement of the micro-motion unit 6. For example, the output shaft of the motor 610 is connected to the wave generator 64. For example, the wave generator 64 presses the elliptical gear 63 from its inner side and forces the elliptical gear 63 to mesh with the ring gear 611 at one end of the inner tube 67. For example, the wave generator 64, the elliptical gear 63, and the ring gear 611 constitute a harmonic gear transmission mechanism to reduce the speed and increase the torque of the hollow cup motor 610. For example, the harmonic gear drive mechanism is an important component for completing the micro-motion of the micro-motion unit 6. For example, its 'backlash-free' characteristics help to achieve the reciprocating motion of the micro-motion unit 6. For example, such a drive can provide a high transmission ratio in a small volume (in the same space where the planetary gear usually only produces a ratio of 10:1, the transmission ratio may be from 30:1 to 300:1), which saves valuable space in the micro-motion unit. For example, the drive screw 62 is coaxially connected to the elliptical gear 63 through an output shaft, and the output shaft converts the rotation into an axial displacement. For example, a guide rail 612 (such as four guide rails 612) set between the inner tube 67 and the outer tube 61 limits lateral rotation or rotation. For example, a limit screw (such as four limit screws) imposes a limit on the maximum displacement, although two to 20 screws can be used. For example, a sealing ring 65, such as three sealing rings, is set between the inner tube 67 and the outer tube 61 to ensure the waterproofness and sealing of the micro-motion unit 6. For example, a displacement sensor 69 (such as a magnetic grid) is placed in a sealed space to output a displacement signal to the closed-loop controller 9 through a line 66 , and a micro-motion signal and a compensation signal from the controller 9 are transmitted to the motor 610 through the same line 66 .

[0036] For example, in order to facilitate the accuracy and controllability of micro-motion application, a closed-loop controller 9 is provided for regulating the operation of the micro-motion action unit 6. For example, the controller 9 is a commercial SCM (single chip microcomputer) with an I / O (input / output) model and a PMW output (pulse width modulation) model. Figure 3An exemplary control logic diagram of the electronic controller 9 is shown, although other control logic diagrams may be used. For example, at the beginning, the user sets the parameters of the micro-motion (such as range, frequency, duration and timing), and then the controller 9 generates a DC pulse signal (micro-motion signal) to make the motor 610 in the micro-motion unit 6 perform reciprocating motion. At the same time, the magnetic grid 69 detects the relative displacement of the micro-motion unit 6, and then converts the displacement into a 'displacement signal'. For example, the controller 9 compares the received signal with the parameters input by the user and adds an additional 'compensation signal' to the motor 610 to fix the displacement error.

[0037] For example, the micro-motion unit (MMU) 6 described herein includes components: a motor 610, such as a coreless motor; a gear transmission mechanism, such as a harmonic gear transmission mechanism, and a displacement sensor, such as a magnetic grid.

[0038] For example, in order to generate controllable and appropriate micro-motion for fracture healing, the inventors have developed a motor-driven fixator. In the present invention, for example, an electric actuator such as a motor 610 is designed to convert electrical energy into a reciprocating displacement between two fracture fragments 1. For example, the core component is a micro-motion unit (MMU) 6, which includes four components: an outer tube 61, an inner tube 67, a motor 610, and a gear transmission mechanism. In terms of the working principle, for example, the motor 610 and the gear transmission mechanism are configured to convert an electrical signal from an external controller 9 into a relative displacement between the outer tube 61 and the inner tube 67. For example, the outer tube 61 and the inner tube 67 are respectively fixed at the proximal fracture fragment and the distal fracture fragment, so that the reciprocating motion of the motor device 610 produces micro-motion on the fracture site FS of the patient.

[0039] For example, the high torque hollow cup motor 610 is rigidly fixed in the dedicated space of the inner tube 67. For example, the hollow cup motor 610 is selected as the prime mover because it has advantages such as high efficiency, fast response, and small size. For example, the hollow cup motor 610 is characterized in that it is conducive to achieving the axial displacement of the micro-motion unit MMU6. For example, the output shaft of the motor 610 is connected to the wave generator 64.

[0040] For example, the wave generator 64 presses the oval gear 63 from its inside and forces the oval gear 63 to mesh with the circular ring gear 611 at one end of the inner tube 67. For example, the wave generator 64, the oval gear 63 and the ring gear 611 constitute a harmonic gear transmission mechanism to reduce the rotation speed and increase the torque of the hollow cup motor 610. For example, the harmonic gear transmission mechanism is a key component to complete the micro-motion of the micro-motion unit MMU 6, and its 'backlash-free' characteristics help to achieve the reciprocating motion of the micro-motion unit MMU 6. For example, the driver provides a high drive ratio in a small volume (the transmission ratio can be from 30:1 to 300:1 in the same space). For example, the driver provides a high drive ratio in a small volume (the transmission ratio can be from 50:1 to 250:1 in the same space). For example, the drive screw 62 is coaxially connected to the oval gear 63 through an output shaft, and the output shaft converts the rotation into an axial displacement. For example, guide rails 612 (e.g., four guide rails 612) provided between the inner tube 67 and the outer tube 61 limit lateral rotation or rotation. For example, limit screws 68 (e.g., four limit screws 68) impose a limit on the maximum displacement. For example, sealing rings 65 (e.g., three sealing rings 65) are provided between the inner tube 67 and the outer tube 61 to maintain the waterproofness and sealing of the MMU 6.

[0041] For example, a displacement sensor 69 (eg, a magnetic grid) is placed in a sealed space to output a displacement signal to a closed-loop controller 9 through a line 66 , and transmits a micro-motion signal and a compensation signal from the controller 9 to a motor 610 through the same line 610 .

[0042] Figure 4 The measured displacement time curve of the micro-motion unit is shown; that is, the frequency (f) and range (R) are calculated using the micro-motion unit MMU according to the description herein. For example, the micro-motion unit 6 is set to produce micro-movements within a range of 2 millimeters (mm) at a frequency of 0.2 Hz. The displacement time curve proves that the electronic controller has achieved the compensation function.

[0043] Figure 5 shows the displacement time curve of the conventional device measured; that is, using External fixator to calculate frequency (f) and range (R).

[0044] Figure 6 The micro-motion unit MMU / external fixator according to the embodiment and the commercially available Comparison of micromotion accuracy of external fixators. Compared with the external fixator, the external fixator according to the present invention shows significant advantages in terms of the accuracy of the micro-motion range and micro-motion frequency. Figure 6As shown, the micro-motion unit MMU according to the embodiment can provide more uniform and stable micro-motion (smaller standard deviations of range (R) and frequency (f)) than the product of Orthofix.

[0045] Figure 7 The application of the micro-motion unit MMU on the FS of the fracture site after two weeks of recovery was shown. Figure 7 Particularly relevant, but an example range for this application is 0.246 ± 0.020 mm and an example frequency is 0.644 ± 0.032 Hz.

[0046] Figure 8 X-ray images of a control group not using a micro-motion unit MMU and a micro-motion group using a micro-motion unit MMU according to the present invention are depicted.

[0047] For example, according to the present invention, there are a large number of micro-motion units MMU 6 applications. The micro-motion unit MMU 6 is a core component that only generates reciprocating displacement in its axial direction. For example, the closed-loop controller 9 supplies power to the micro-motion unit MMU 6 and controls the MMU 6 through changes in electrical signals. Fig. 9 As shown, the micro-motion unit MMU is constructed as one of various forms of orthopedic fixators to meet different requirements of fracture classification in terms of fixation, such as fracture reduction, limb lengthening and scoliosis correction. Fig. 9 A micro-motion external fixator is shown.

[0048] Regular micro-motion frequency and range are important in clinical treatment. It has been noted that micro-motion within a certain range can promote bone healing, but below or above this optimal range can lead to delayed healing or bone non-union. Fig.10 The relationship between bone formation and interfragment strain (IFS) is shown. If the IFS of multiple fracture fragments is higher than point C or lower than point A, delayed union or nonunion will occur. According to current bone healing theories, the optimal range of micromotion is to keep the IFS of the fracture fragments at Fig.10 Between points A and C in the figure, theoretically, bone healing is enhanced as callus formation at the fracture site improves. And the rates of delayed healing and nonunion are reduced. Therefore, irregular micro-motion may lead to ineffective stimulation and even have a negative impact on fracture healing.

[0049] at the same time, Fixators can only limit the maximum displacement by means of stops. However, in some extreme cases, delayed union and nonunion may still occur due to low interfragmentary strain in multiple fracture fragments.

[0050] For example, the external fixator described in this article is designed to solve this problem by monitoring the actual range and frequency and making necessary compensations. And the micro-motion range can be precisely controlled within the optimal range, which is a major advancement in the field.

[0051] For example, the external fixator described herein operates within a frequency range that promotes fracture healing with a relatively low standard deviation. For example, the external fixator operates within a range of 0.01 mm to 5 mm. For example, the external fixator operates within a range of 0.1 mm to 3 mm. For example, the external fixator operates within a given range with a standard deviation of ±0.001 mm to 0.1 mm. For example, the external fixator operates within a given range with a standard deviation of ±0.01 mm to 0.075 mm. For example, the external fixator operates at a frequency from 0.05 Hz to 5 Hz. For example, the external fixator operates at a frequency from 0.1 Hz to 2.5 Hz. For example, the external fixator operates at a given frequency with a standard deviation from 0.001 Hz to 0.1 Hz. For example, the external fixator operates at a given frequency with a standard deviation from 0.01 Hz to 0.05 Hz.

[0052] For example, the external fixator described herein can provide surgeons with real-time feedback and help them adjust micro-motion parameters in a timely manner. This is an important treatment reference for surgeons, because both excessive micro-motion and insufficient micro-motion can adversely lead to delayed union or non-union of the bone.

[0053] For example, the electronic controller 9 described herein reduces the patient's workload. According to the protocol, the patient should shake the handle on one side of the fixator for 10 minutes every day and perform periodic micro-movements for 2-3 weeks, and then the patient should generate progressive loads by the same method for more than 2-3 weeks. Advantageously, these complex operations and repetitive work are performed by the electric controller 9 described herein, which greatly shortens the learning curve.

[0054] For example, the external fixator described in this article has significant advantages over current commercially available fixators in terms of integrated design, modular structure, and compatibility. For example, the integrated design is able to encapsulate all movable parts of the micro-motion unit into a tubular housing. This integrated design minimizes the risk of failure due to foreign matter (such as water, dust, and fibers) entering the mechanical parts and brings great benefits to the reliability of the micro-motion fixator.

[0055] For example, the modular structure makes the connection between the micro-motion unit 6, the electronic controller 9 and the support detachable. For example, the micro-motion unit 6 and the electronic controller 9 are removed from the support at the end of each micro-motion application to relieve the burden on the patient.

[0056] For example, the external fixator described herein is compatible with commercially available fixators in that the connector on the micro-motion unit 6 is designed to be compatible with commercially available fixators. Manual adapter on the product to give it the ability to work autonomously.

[0057] Based on our results in the rat model, a strain of 20% micro-range of motion showed the most significant improvement in fracture healing, but a strain of 2% to 40% may be used. For example, a strain of 15% to 25% may be used. For example, a strain of 10% to 20% may be used.

[0058] For example, the displacement sensor 69 and the electric controller 9 make the micro-motion unit MMU 6 controllable. In addition, the harmonic gear transmission mechanism facilitates the 'backlash-free' characteristic to achieve the reciprocating motion of the micro-motion unit MMU 6.

[0059] For example, the micro-motion unit MMU needs to reciprocate at high speed, and the mechanical parts need to respond quickly to the signals from the electronic controller 9. For example, the selection of the motor 610 and the gear transmission mechanism meets this requirement. For example, for the wireless motor 610, the rotating parts on this motor 610 are lighter than stepper motors and other common motors. For example, the motor achieves a 'rotate-stop-reverse' action at high speed. For example, a stepper motor is more likely to achieve high-precision action. The extremely high transmission ratio of the harmonic gear transmission mechanism weakens the precision advantage of the stepper motor.

[0060] For any graph or numerical range for a given property, a graph or parameter derived from one range can be combined with another graph or parameter for a different range for the same property to generate a numerical range.

[0061] For example, an external fixator for treating a fracture is provided. Figure 1 The external fixator includes: a bracket attached to the bone at two fracture fragments 1, and the two fracture fragments 1 are respectively located on opposite sides of the fracture site FS; a micro-motion unit 6 removably connected to the bracket, the micro-motion unit 6 is configured to generate a reciprocating displacement between the two fracture fragments 1 to apply a controllable micro-motion to the fracture site FS; and a controller 9 connected to the micro-motion unit 6, the controller 9 is configured to control the micro-motion unit 6 to form a reciprocating displacement between the two fracture fragments 1.

[0062] For example, refer to Figure 2The micro-motion unit 6 includes an outer tube 61, an inner tube 67, a motor 610 and a gear transmission mechanism, and at least a portion of the inner tube 67 is inserted into the outer tube 61; the motor 610 and the gear transmission mechanism are configured to convert an electrical signal from the controller 9 into a relative axial displacement between the outer tube 61 and the inner tube 67 along the axial direction of the inner tube 67 and the outer tube 61; and the outer tube 61 and the inner tube 67 are respectively connected to the two fracture fragments 1, so that the relative axial displacement between the outer tube 61 and the inner tube 67 produces a reciprocating displacement between the two fracture fragments 1.

[0063] For example, refer to Figure 2 The gear transmission mechanism is a harmonic gear transmission mechanism, and the harmonic gear transmission mechanism includes a wave generator 64, an elliptical gear 63 and a ring gear 611; and the wave generator 64 is connected to the output shaft of the motor 610, and the ring gear 611 is arranged on the inner tube 67, and the motor 610 drives the wave generator 64 to press the elliptical gear 63 from the inner side of the elliptical gear to force the elliptical gear 63 to mesh with the ring gear 611.

[0064] For example, refer to Figure 2 The micro-motion unit 6 also includes a transmission screw 62, which is coaxially connected to the elliptical gear 63 and meshes with the outer tube 61, and while the motor 610 drives the wave generator 64 to press the elliptical gear 63 from the inner side of the elliptical gear 63, the motor 610 drives the transmission screw 62 to rotate, thereby generating a relative axial displacement between the outer tube 61 and the inner tube 67.

[0065] For example, the motor 610 rotates in a first direction, and the outer tube 61 and the inner tube 67 move toward each other along the axial direction of the inner tube 67 and the outer tube 61; and the motor 610 rotates in a second direction opposite to the first direction, and the outer tube 61 and the inner tube 67 move away from each other along the axial direction of the inner tube 67 and the outer tube 61.

[0066] For example, Fig.11 The structure of the micro-motion unit according to the embodiment is shown, wherein for simplicity, the motor 610, the wave generator 64, the elliptical gear 63 and the ring gear 611 are integrated together as a whole, and the details and the connections between them can be referred to Figure 2 In order to show the internal structure, the parts of the outer tube 61 and the inner tube 67 have been Fig.11 For example, refer to Fig.11The micro-motion unit 6 also includes a threaded rod 614 connected to the motor 610 and a slider 615 connected to the threaded rod 613; while the motor 610 drives the wave generator 64 to press the elliptical gear 63 from the inner side of the elliptical gear 63, the motor 610 drives the slider 615 to move, and the outer tube 61 is connected to the slider 615 and moves with the slider 615 to generate a relative axial displacement between the outer tube 61 and the inner tube 67. For example, the threaded rod 614 is connected to the motor 610 through a connector 613. For example, the outer tube 61 is connected to the slider 615 through a screw 616. It should be noted that the micro-motion unit 6 also includes a displacement sensor 69, the details of which can be seen in Figure 2 For example, the slider 615 is connected to the displacement sensor 69 .

[0067] For example, refer to Figure 2 , the micro-motion unit 6 also includes a displacement sensor 69, which detects the relative axial displacement between the inner tube 67 and the outer tube 61, converts the relative axial displacement into a displacement signal, and outputs the displacement signal to the controller 9. Then, based on the displacement signal, the controller 9 determines whether there is a compensation signal for compensating the electrical signal from the controller. In this way, the external fixator described in this article is designed to monitor the actual micro-motion applied to the fracture site and make necessary compensation. And the micro-motion applied to the fracture site can be accurately controlled within an optimal range, which is an important advancement in the field. For example, the compensation signal includes: whether the electrical signal from the controller needs to be compensated; if so, how much compensation is. For example, the displacement sensor 69 is a magnetic grid.

[0068] For example, the motor 610 is a coreless motor. For example, the coreless motor 610 is rigidly fixed in a dedicated space of the inner tube 67.

[0069] For example, refer to Figure 2 The micro-motion unit 6 further includes a guide rail 612 disposed between the inner tube 67 and the outer tube 61 and extending along the axial direction of the inner tube 67 and the outer tube 61 to limit lateral rotation or rotation between the outer tube 61 and the inner tube 67 .

[0070] For example, refer to Figure 2 The micro-motion unit 6 also includes a limit screw 68 to limit the maximum relative displacement between the outer tube 61 and the inner tube 67 .

[0071] For example, refer to Figure 2 The micro-motion unit 6 further includes a sealing ring 65 disposed between the inner tube 67 and the outer tube 61 .

[0072] For example, refer to Figure 1The stent includes a main body 7 and a movable block 4, the movable block 4 is movable relative to the main body 7, and the main body 7 and the movable block 4 are respectively attached to the two fracture fragments 1; the outer tube 61 and the inner tube 67 are respectively connected to the main body 7 and the movable block 4 of the stent; the relative axial displacement between the outer tube 61 and the inner tube 67 generates a reciprocating displacement between the main body 7 and the movable block 4 of the stent, thereby generating a reciprocating displacement between the two fracture fragments 1. For example, during the period of applying micro-motion to the fracture site FS, the movable block 4 is movable relative to the main body 7; during the period of not applying micro-motion to the fracture site FS, the movable block 4 is locked and cannot be moved relative to the main body 7.

[0073] For example, refer to Figure 1 The bracket also includes a slideway 3 connected to the main body 7, and the movable block 4 is a slider that can slide on the slideway 3 relative to the main body 7.

[0074] For example, the stent includes a main body 7 and two movable blocks 4, each of which can move relative to the main body 7, and the two movable blocks 4 are respectively attached to the two fracture fragments 1; the outer tube 61 and the inner tube 67 are respectively connected to the two movable blocks 4 of the stent; and the relative axial displacement between the outer tube 61 and the inner tube 67 generates a reciprocating displacement between the two movable blocks 4 of the stent, thereby generating a reciprocating displacement between the two fracture fragments 1. For example, during the application of micro-motion to the fracture site FS, the two movable blocks 4 are movable relative to the main body 7; during the application of micro-motion to the fracture site FS, the two movable blocks 4 are locked and cannot move relative to the main body 7.

[0075] For example, the bracket further includes a slideway 3 connected to the main body 7 , and each of the two movable blocks 4 is a slider that can slide on the slideway 3 relative to the main body 7 .

[0076] For example, a method for treating fractures is provided, comprising: attaching a bracket to a bone at two fracture fragments 1, the two fracture fragments 1 being on opposite sides of a fracture site FS; generating a reciprocating displacement between the two fracture fragments 1 by a micro-motion unit 6 removably connected to the bracket, thereby applying controllable micro-motion to the fracture site FS; and controlling the reciprocating displacement between the two fracture fragments 1 by a controller 9 to facilitate fracture healing at the fracture site.

[0077] For example, the method further includes: when the controllable micro-motion is applied to the fracture site FS, removing the micro-motion action unit 6 from the support to relieve the burden on the patient.

[0078] For example, the micro-motion unit includes an outer tube 61, an inner tube 67, a motor 610 and a gear transmission mechanism, and at least a portion of the inner tube 67 is inserted into the outer tube 61; the motor 610 and the gear transmission mechanism are configured to convert an electrical signal from the controller 9 into a relative axial displacement between the outer tube 61 and the inner tube 67 along the axial direction of the inner tube 67 and the outer tube 61; the relative axial displacement between the outer tube 67 and the inner tube 61 generates a reciprocating displacement between the two fracture fragments 1; the method further includes: detecting the relative axial displacement between the inner tube 67 and the outer tube 61, converting the relative axial displacement into a displacement signal, and outputting the displacement signal to the controller 9; and determining a compensation signal for compensating the electrical signal from the controller 9 based on the displacement signal. In this way, the external fixator described herein is designed to monitor the actual micro-motion applied to the fracture site and make necessary compensation. The micro-motion applied to the fracture site can also be accurately controlled within an optimal range, which is a significant advancement in the art. For example, the compensation signal includes: whether the electrical signal from the controller needs to be compensated; if so, how much the compensation is. For example, the displacement sensor 69 is a magnetic grid.

[0079] For example, two fracture fragments 1 are spaced a certain distance apart from each other at the fracture site FS; the method further comprises: the displacement between the two fracture fragments 1 is 10%-20% of the distance, preferably 20% of the distance, that is, a strain of 10% to 20%, preferably 20%.

[0080] For example, a strain of 2% to 40% may be used. For example, a strain of 15% to 25% may be used.

[0081] For example, the method further includes: forming a reciprocating displacement within a frequency range, wherein the frequency has a relatively low standard deviation, which is beneficial to fracture healing at the fracture site.

[0082] For example, a micro-motion unit 6 is provided, including: an outer tube 61, an inner tube 67, a motor 610 and a gear transmission mechanism; at least a portion of the inner tube 67 is inserted into the outer tube 61; the motor 610 and the gear transmission mechanism are constructed to convert electrical signals into relative axial displacements between the outer tube 61 and the inner tube 67 along the axial directions of the inner tube 61 and the outer tube 67; and the outer tube 61 and the inner tube 67 are respectively connected to two fracture fragments 1, so that the relative axial displacement between the outer tube 61 and the inner tube 67 produces a reciprocating displacement between the two fracture fragments 1.

[0083] For example, the micro-motion unit produces reciprocating displacement within a frequency range with a relatively low standard deviation, which is beneficial for fracture healing at the fracture site.

[0084] For example, the micro-motion unit 6 has a large number of potential applications. For example, referring to Fig.12The micro-motion unit 6 is applied to: (a) micro-motion external fixator; (b) micro-motion plate; (c) micro-motion intramedullary nail. It should be noted that the application of the micro-motion unit 6 is not limited to Fig.12 The situation shown in .

[0085] Where possible, except in the operating examples or where otherwise indicated, all numbers, values ​​and / or expressions relating to parameters, measurements, conditions and the like used in the specification and claims are to be understood as referring to the term "about" in all instances.

[0086] Although certain embodiments have been described, it should be understood that various modifications will be apparent to those skilled in the art after reading the specification. Therefore, it should be understood that the disclosure herein is intended to cover modifications falling within the scope of the appended claims.

[0087] Further description is included in Appendix 1.

Claims

1. An external fixator for treating fractures, comprising: A bracket that is attached to the bone at two fracture fragments that are located on opposite sides of the fracture site; a micro-motion unit removably coupled to the support, the micro-motion unit being configured to generate a reciprocating displacement between the two fracture fragments to impart a controllable micro-motion to the fracture site; as well as a controller coupled to the micro-motion unit, the controller being configured to control the micro-motion unit to produce a reciprocating displacement between two bone fracture fragments; Wherein, the micro-motion unit includes an outer tube, an inner tube, a motor and a gear transmission mechanism, and at least a portion of the inner tube is inserted into the inner side of the outer tube, the motor and the gear transmission mechanism are constructed to convert the electrical signal from the controller into a relative axial displacement between the outer tube and the inner tube along the axial direction of the inner tube and the outer tube, the outer tube and the inner tube are respectively connected to the two fracture fragments, so that the relative axial displacement between the outer tube and the inner tube produces a reciprocating displacement between the two fracture fragments, wherein the gear transmission mechanism is a harmonic gear transmission mechanism, and the harmonic gear transmission mechanism includes a wave generator, an elliptical gear and a ring gear, the wave generator is connected to the output shaft of the motor, the ring gear is arranged on the inner tube, and the motor drives the wave generator to press the elliptical gear from the inner side of the elliptical gear to force the elliptical gear to mesh with the ring gear.

2. The external fixator according to claim 1, wherein the micro-motion unit further comprises a drive screw coaxially connected to the elliptical gear and meshed with the outer tube, and while the motor drives the wave generator to press the elliptical gear from the inner side of the elliptical gear, the motor drives the drive screw to rotate, thereby generating a relative axial displacement between the outer tube and the inner tube.

3. The external fixator according to claim 1, wherein the micro-motion unit further comprises a threaded rod connected to the motor and a slider connected to the threaded rod; and While the motor drives the wave generator to press the elliptical gear from the inner side of the elliptical gear, the motor drives the slider to move, and the outer tube is connected to the slider and moves with the slider, thereby generating a relative axial displacement between the outer tube and the inner tube.

4. The external fixator according to any one of claims 1 to 3, wherein the micro-motion unit further comprises a displacement sensor, which detects the relative axial displacement between the inner tube and the outer tube, converts the relative axial displacement into a displacement signal, and outputs the displacement signal to the controller.

5. The external fixator according to claim 4, wherein the displacement sensor is a magnetic grid.

6. The external fixator according to any one of claims 1 to 3, wherein the motor is a coreless motor.

7. The external fixator according to any one of claims 1 to 3, wherein the micro-motion unit further comprises a guide rail provided between the inner tube and the outer tube and extending in an axial direction of the inner tube and the outer tube, thereby limiting lateral rotation and rotation between the outer tube and the inner tube.

8. The external fixator according to any one of claims 1 to 3, wherein the micro-motion unit further comprises a limit screw for applying a maximum relative displacement limit between the outer tube and the inner tube.

9. The external fixator according to any one of claims 1 to 3, wherein the micro-motion unit further comprises a sealing ring disposed between the inner tube and the outer tube.

10. The external fixator according to any one of claims 1 to 3, wherein the bracket comprises a main body and a movable block, the movable block is movable relative to the main body, and the main body and the movable block are respectively attached to the two fracture fragments; The outer tube and the inner tube are connected to the body and the movable block of the bracket, respectively; and The relative axial displacement between the outer tube and the inner tube generates a reciprocating displacement between the main body of the stent and the movable block, thereby generating a reciprocating displacement between the two fracture fragments. 11 . The external fixator according to claim 10 , wherein the bracket further comprises a slideway connected to the main body, and the movable block is a slider that can slide on the slideway relative to the main body.

12. The external fixator according to any one of claims 1 to 3, wherein The bracket includes a main body and two movable blocks, each of the two movable blocks is movable relative to the main body, and the two movable blocks are respectively attached to the two fracture fragments; The outer tube and the inner tube are respectively connected to the two movable blocks of the bracket, and The relative axial displacement between the outer tube and the inner tube generates a reciprocating displacement between the two movable blocks of the stent, thereby generating a reciprocating displacement between the two bone fracture fragments. 13 . The external fixator according to claim 12 , wherein the bracket further comprises a slideway connected to the main body, and each of the two movable blocks is a sliding block capable of sliding on the slideway relative to the main body.

14. A micro-motion unit, comprising: An outer tube, an inner tube, a motor and a gear transmission mechanism, wherein: At least a portion of the inner tube is inserted into the inner side of the outer tube; The motor and the gear transmission mechanism are configured to convert an electrical signal into a relative axial displacement between the outer tube and the inner tube in an axial direction of the outer tube and the inner tube; and The outer tube and the inner tube are connected to two fracture fragments respectively, so that the relative axial displacement between the outer tube and the inner tube produces a reciprocal displacement between the two fracture fragments; wherein the gear transmission mechanism is a harmonic gear transmission mechanism, and the harmonic gear transmission mechanism includes a wave generator, an elliptical gear and a ring gear; and The wave generator is connected to the output shaft of the motor, the ring gear is disposed on the inner tube, and the motor drives the wave generator to press the elliptical gear from the inner side of the elliptical gear to force the elliptical gear to mesh with the ring gear.

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