Method for aiming locking hole of intramedullary nail in navigation system and intramedullary nail navigation system

Abstract

The invention relates to a method for aiming a locking hole of an intramedullary nail in a navigation system for guiding a drill bit through a sleeve to align the locking hole, the locking hole having a locking hole distal end face and a locking hole proximal end face, the method comprising the following steps: a) acquiring the spatial position of the sleeve and the intramedullary nail by means of a tracking device of the navigation system; b) on the basis of the acquired spatial positions of the sleeve and the intramedullary nail, determining a spatial position relationship between the drill bit and the intramedullary nail by executing coordinate transformation and combining a preset spatial position relationship between the drill bit and the sleeve; c) an observation coordinate system is constructed in the navigation system, an observation view angle is in the axial direction of the sleeve, a navigation view is generated under the observation coordinate system, and the model of the drill bit in the navigation view is presented as point projection; and d) acquiring the position and the angle of the drill bit in real time, displaying the projection of the drill bit in the navigation view, and determining that the drill bit aims at the locking hole when the point-shaped projection of the drill bit is located in the overlapped area of the projections of the locking hole far end face and the locking hole near end face of the locking hole.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment, and in particular to a method for aiming a locking hole of an intramedullary nail in a navigation system, and an intramedullary nail navigation system. Background Art

[0002] Intramedullary nailing has become the standard clinical procedure for treating long bone fractures. However, due to the often asymmetric structure of the medullary cavity, intramedullary nails often deform during insertion, making distal locking screw positioning difficult. Currently, C-arm fluoroscopy is commonly used clinically to assist with nailing. While this can alleviate this problem, the procedure is cumbersome and results in significant radiation exposure for both the patient and the surgeon.

[0003] In recent years, computer-guided intramedullary nail navigation systems have demonstrated significant advantages, reducing radiation dose while improving operational efficiency. However, how to quickly and accurately guide the surgeon to aim the guide sleeve at the locking hole using a computer screen remains a challenge.

[0004] Ideally, the axis of the guide sleeve should completely align with the axis of the locking hole, allowing the drill to accurately pass through the sleeve and into the locking hole in one go. If the axes do not align, drill marks may be left on the main body of the intramedullary nail and the nail may even be misaligned or unable to penetrate the locking hole.

[0005] There are two commonly used distal locking holes: the larger one has a diameter of 5.3mm and the smaller one has a diameter of 4.6mm. The commonly used drill bit diameter is 4.1mm. Even with a 5.3mm locking hole, the maximum allowable positioning error is only (5.3-4.1) / 2 = 0.6mm. The core problem addressed by this invention is how to efficiently and intuitively guide the doctor to achieve accurate aiming within such a small error tolerance. Summary of the Invention

[0006] The object of the present invention is to solve at least one of the above problems and defects in the prior art as well as other technical problems.

[0007] According to one aspect of the present invention, a method for aiming a locking hole of an intramedullary nail in a navigation system is provided, wherein the navigation system is used to guide a drill bit through a sleeve to align with the locking hole, wherein the locking hole has a distal locking hole surface and a proximal locking hole surface, and the method comprises the following steps:

[0008] a) obtaining the spatial position of the sleeve and the intramedullary nail through the tracking device of the navigation system;

[0009] b) determining a spatial positional relationship between the drill bit and the intramedullary nail based on the acquired spatial positions of the sleeve and the intramedullary nail by performing a coordinate transformation and combining a preset spatial positional relationship between the drill bit and the sleeve;

[0010] c) constructing an observation coordinate system in a navigation system, wherein the observation angle is along the axial direction of the sleeve, and generating a navigation view in the observation coordinate system, so that the model of the drill bit in the navigation view appears as a point projection; and

[0011] d) acquiring the position and angle of the drill bit in real time and displaying the projection of the drill bit in the navigation view; and determining that the drill bit has been aimed at the locking hole when the point projection of the drill bit is located within the overlapping area of ​​the projections of the distal end surface of the locking hole and the proximal end surface of the locking hole.

[0012] The navigation view referred to in this article generally refers to an image displayed on the display device of the navigation system that can guide or assist the operator in aiming the locking hole, including but not limited to a three-dimensional model of the drill bit and a three-dimensional model of the intramedullary nail, preferably only including a three-dimensional model of the drill bit and a three-dimensional model of the intramedullary nail.

[0013] Advantageously, the present invention employs a three-point-one-line aiming method for aiming the drill bit and the locking hole of the intramedullary nail. The sleeve has a distal bone end surface and a proximal bone end surface, and the intramedullary nail has two locking holes. In step c), when the viewing angle is set along the axial direction of the sleeve, the projections of the distal bone end surface and the proximal bone end surface of the sleeve in the navigation view are merged into a single point, so that the point is aligned with the center of the proximal end surface of the locking hole and the center of the distal end surface of the locking hole (i.e., the three-point-one-line aiming method). The distance from the point to the center of the proximal end surface of the locking hole defines the aiming end distance, and the distance from the center of the proximal end surface of the locking hole to the center of the distal end surface of the locking hole defines the target point distance.

[0014] In one embodiment of the present invention, in the step of constructing the observation coordinate system, the midpoint of the center line connecting the two locking holes is used as the origin, the axial direction of the intramedullary nail is determined as the X-axis, the axial direction of the sleeve is determined as the Z-axis, and the Y-axis is determined to be a direction perpendicular to the axial direction of the intramedullary nail (also known as the main nail direction of the intramedullary nail) and orthogonal to the Z-axis. In this way, when the navigation view is zoomed in, the information of the locking holes that is helpful for navigation is displayed on the screen of the display device. In such an observation coordinate system, when the sleeve is moved, the intramedullary nail can always be fixed in the center of the screen of the display device. The main nail direction of the intramedullary nail is fixed to the X-axis direction of the observation coordinate system, so that no matter how the sleeve rotates around the axis, the intramedullary nail will not swing up and down on the screen.

[0015] In one embodiment of the present invention, the observation coordinate system is a right-handed coordinate system, wherein the observation angle is set at the distal end face of the sleeve and points from the distal end face of the sleeve to the proximal end face of the sleeve along the axial direction of the sleeve. Here, the observation angle can also be referred to as a "virtual camera." "Virtual camera" refers to an observation tool created in software in a computer graphics or visualization system that simulates the position, direction, perspective, and projection of a real physical camera. With this embodiment, no matter how the sleeve moves relative to the intramedullary nail, the projection of the distal and proximal end faces of the sleeve on the screen is a circle, which can be viewed as an enlarged point.

[0016] In one embodiment of the present invention, the ratio of the aiming end distance to the target point distance is 1:24 to 1:30. Furthermore, when the drill bit's point projection lies within the overlapping region of the projections of the distal and proximal surfaces of the locking hole—that is, when the drill bit's projection coincides with the projection of the locking hole—the actual deviation between the drill bit and the locking hole is less than 0.6 mm. This selection maximizes the aiming end distance while minimizing the target point distance, improving aiming accuracy.

[0017] In a specific embodiment of the present invention, the aiming end distance is the sum of the distance from the proximal bone end surface of the sleeve to the intramedullary nail and the length of the sleeve, wherein the length of the sleeve is 100 mm to 150 mm, the distance from the proximal bone end surface of the sleeve to the intramedullary nail is 20 mm; the target point distance is 5 mm.

[0018] In a preferred embodiment of the present invention, the tracking device may be an electromagnetic tracking device, comprising a magnetic field generator, a first electromagnetic sensor fixed to the sleeve, and a second electromagnetic sensor fixed to the intramedullary nail. The magnetic field generator is configured to generate an alternating electromagnetic field in space, and the first and second electromagnetic sensors are configured to detect the alternating electromagnetic field and output spatial position information for determining the spatial positions of the sleeve and the intramedullary nail. It should be understood that the aforementioned aiming method described in the present invention is not dependent on a specific tracking method. In addition to implementing the tracking device as the aforementioned electromagnetic tracking device, optical tracking, etc., may also be employed.

[0019] In one embodiment of the present invention, the above step b) further comprises the following sub-steps:

[0020] i) performing coordinate transformation on spatial position information acquired in real time by the first electromagnetic sensor and the second electromagnetic sensor based on a pre-established fixed spatial position relationship between the sleeve and the first electromagnetic sensor, and a pre-established fixed spatial position relationship between the intramedullary nail and the second electromagnetic sensor, to determine the spatial position relationship between the sleeve and the intramedullary nail; and

[0021] ii) determining the spatial positional relationship between the three-dimensional model of the drill bit and the three-dimensional model of the intramedullary nail based on the fixed spatial positional relationship between the sleeve and the drill bit pre-established through machining.

[0022] In one embodiment of the present invention, creating an observation coordinate system in the navigation view further includes the following sub-steps: transforming the axial direction of the sleeve to the intramedullary nail coordinate system through coordinate transformation, and determining the transformed axial direction as the Z axis; determining the Y axis direction through the cross product between the Z axis and the axial direction of the intramedullary nail; and correcting the X axis direction through the cross product between the Y axis direction and the Z axis direction. Because the observation coordinate system is a right-handed coordinate system, the Z axis direction points from the proximal end surface of the sleeve to the distal end surface of the sleeve.

[0023] According to another aspect of the present invention, an intramedullary nail navigation system is also provided for guiding a drill bit through a sleeve to align with a locking hole of the intramedullary nail, wherein the intramedullary navigation system includes: a tracking device for obtaining the spatial position of the sleeve and the intramedullary nail; and a display device and a processor, wherein the processor is suitable for being connected to the tracking device, wherein the above method is executed when the processor is running, and the spatial position relationship between the drill bit and the intramedullary nail is displayed via a navigation view through the display device.

[0024] In one embodiment of the present invention, the tracking device is an electromagnetic tracking device, comprising a magnetic field generator for generating an alternating electromagnetic field in space, a first electromagnetic sensor secured to the sleeve, and a second electromagnetic sensor secured to the intramedullary nail. The electromagnetic sensors are used to track the three-dimensional position and orientation of the sleeve and intramedullary nail in space in real time. The magnetic field generator generates a known magnetic field, enabling precise positioning of the multiple sensors in space.

[0025] According to yet another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method are executed.

[0026] According to another aspect of the present invention, a control device is provided. The control device includes a memory, a processor, and a program stored in the memory and executable on the processor, wherein the method is executed when the processor executes the program.

[0027] According to yet another aspect of the present invention, a computer program product is provided, which includes a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0028] This invention proposes a convenient and fast locking hole aiming method for an intramedullary nail navigation system, used to accurately guide the surgeon in aligning the sleeve and locking hole. This method considers the alignment of the sleeve and locking hole as a four-point-one-line problem, which, through visualization technology, is simplified to a three-point-one-line approach. The proposed method significantly reduces the distal amplification of errors, resulting in greater accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is described in detail below by way of exemplary embodiments with reference to the accompanying drawings.

[0030] Figures 1a to 1c The schematic diagram of the three-point-one-line aiming method is shown, which respectively illustrates the basic principle of the aiming method and the error amplification effect;

[0031] Figure 2a and Figure 2b shows a comparison of the errors of the sureShot aiming method and the aiming method according to the present invention;

[0032] Figure 3 A schematic diagram showing an exemplary intramedullary nail navigation system according to the present invention;

[0033] Figure 4 is a flow chart of a method for aiming a locking hole of an intramedullary nail in a navigation system according to an exemplary embodiment of the present invention;

[0034] Figure 5 A three-dimensional model diagram of a drill bit according to the present invention, wherein the drill bit thread is not shown;

[0035] Figure 6 A three-dimensional model diagram of the intramedullary nail according to the present invention;

[0036] Figure 7 An embodiment of an observation coordinate system according to the present invention is shown;

[0037] Figure 8 shows the spatial position relationship transformation between the drill bit and the intramedullary nail; and

[0038] Figure 9 FIG1 is a navigation view of the intramedullary nail navigation system according to the present invention, in which only the intramedullary nail and the drill are shown.

[0039] It should be noted that the drawings are schematic only. They illustrate only those components or steps necessary to illustrate the present invention, and other components or steps may be omitted or only briefly mentioned. In addition to the components or steps shown in the drawings, the present invention may also include other components or steps. DETAILED DESCRIPTION

[0040] The following examples and accompanying drawings further illustrate the technical solution of the present invention. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall concept of the present invention and should not be construed as limiting the present invention.

[0041] The following describes, as a specific embodiment, the specific steps of a method for guiding a drill bit to aim at a locking hole of an intramedullary nail under a navigation system, as well as the intramedullary nail navigation system involved in the present invention. In the following detailed description, many specific details and steps are set forth in a concrete and detailed manner to provide a comprehensive understanding of the embodiments. However, it should be understood that one or more other embodiments may be practiced without these specific details and steps.

[0042] In this article, the "proximal bone end surface" of the sleeve refers to the end facing the locking hole of the intramedullary nail, and the "distal bone end surface" of the sleeve refers to the end facing away from the locking hole of the intramedullary nail; the "distal end surface of the locking hole" and the "proximal end surface of the locking hole" are arranged opposite to each other along the axial direction of the locking hole, wherein the end close to the sleeve is the proximal end surface of the locking hole, and the end away from the sleeve is the distal end surface of the locking hole.

[0043] In this article, "spatial position" generally includes three-dimensional position information (XYZ coordinates) + posture information (rotation around the XYZ axis), and the three-dimensional position information and posture information of the sleeve and intramedullary nail are obtained, including the displacement along the X, Y, and Z directions and the rotation angles around the X, Y, and Z axes.

[0044] Figures 1a to 1c The figure shows the principle diagram of the three-point-one-line aiming method, which respectively shows the basic principle of the aiming method and the error amplification effect. The figure shows the factors that affect the aiming accuracy in the three-point-one-line aiming method. Figure 1a In the figure, there are three points: point 1, point 2, and target point 3. Point 1 is the aiming end. The vertical distance between points 1 and 2 is the aiming end distance d1, and the vertical distance between points 2 and target point 3 is the target point distance d2. The dashed line passing through points 2 and 3 is the theoretical aiming direction, which is typically used to indicate the direction of the target's true position. The solid line extending through points 1 and 2 is the actual aiming direction. Due to the aiming end error Δ1, the actual extension direction is at an angle to the theoretical direction, resulting in a target point error Δ2 at the target distance. Figure 1b It shows that the reduction of the aiming end distance causes the target point error Δ2 to produce the error magnification part Δx, Figure 1c It shows that the increase in the target point distance also causes the target point error Δ2 to produce an error amplification part Δy. From the figure, it can be seen that Δx is obviously greater than Δy. Therefore, in order to improve the aiming accuracy, we need to increase the aiming end distance as much as possible while reducing the target point distance as much as possible.

[0045] Figure 2aA schematic diagram of the prior art Smith & Nephew targeting method is shown, where the sleeve distal end is simplified as point 1, the sleeve proximal end is simplified as point 2, and the distal end of the locking hole is simplified as target point 3. As can be seen from the diagram, the Smith & Nephew targeting system does not fully consider the impact of the aiming end distance d1 and the target point distance d2 on targeting accuracy. The Smith & Nephew targeting method uses the distance between the sleeve's front and rear ends as the aiming end distance, and the distance between the sleeve's proximal end and the proximal end of the locking hole as the target point distance, failing to optimize the aiming end and target point distances.

[0046] Figure 2b A schematic diagram of the aiming method according to the present invention illustrates a simplified four-point-in-a-line aiming scheme, simplifying it to a three-point-in-a-line approach. Specifically, the viewing angle is along the axial direction of the sleeve, with the distal end of the sleeve simplified as point 1, the proximal end of the locking hole simplified as point 2, and the distal end of the locking hole simplified as target point 3. The aiming method according to the present invention utilizes the sleeve's length and its distance from the proximal end of the locking hole in the intramedullary nail to maximize the aiming distance. Simultaneously, the distance between the distal and proximal ends of the locking hole serves as the target distance to minimize the target distance. In a specific embodiment, the sleeve length is typically between 100 mm and 150 mm, while the distance between the proximal end of the sleeve and the intramedullary nail is approximately 20 mm. Therefore, the aiming distance in the present invention is at least 120 mm. The distance between the distal and proximal ends of the locking hole in the intramedullary nail is approximately 5 mm, allowing the target distance to be as short as approximately 5 mm. As can be seen from the diagram, the aiming method according to the present invention significantly reduces target point error compared to the existing Smith & Nephew aiming method.

[0047] See also Figure 3, shows a schematic diagram of the principles of an exemplary embodiment of an intramedullary nail navigation system according to the present invention. As can be seen from the figure, the intramedullary nail navigation system 100 is used to guide a drill bit 10 through a sleeve 11 to align with the locking hole of an intramedullary nail 14. It includes a tracking device for obtaining the spatial position of the sleeve and intramedullary nail, a display device 12, and a processor 13. In this embodiment, the sleeve 11 has a distal bone end surface 112 and a proximal bone end surface 111, and the intramedullary nail 14 has two locking holes 15 located at one end. Each locking hole 15 of the intramedullary nail 14 has a distal locking hole surface 15a and a proximal locking hole surface 15b. Aligning the sleeve 11 with the locking holes 15 involves aligning the central axis of the sleeve and the central axis of the locking holes. The central axis of the sleeve can be represented by a line connecting the center points of the sleeve's distal bone end surface 112 and the proximal bone end surface 111. Similarly, the central axis of the locking holes can be represented by a line connecting the center points of the distal locking hole surface 15a and the proximal locking hole surface 15b. In this way, the alignment of the sleeve and the intramedullary nail locking hole is a matter of four points and one line. With the help of visualization technology, the distal end face and the proximal end face of the sleeve in the four points can be combined into one point to achieve the improved three-point one-line aiming (see Figure 2b ).

[0048] The intramedullary nail navigation system also includes a control device, which includes the above-mentioned display device 12, a processor 13, a memory, and a program stored in the memory and capable of running on the processor. As a specific example, the control device can be a general-purpose computer, a special-purpose computer, an embedded processor, or any other appropriate programmable data processing device such as a single-chip microcomputer or a chip. The display device 12 displays the spatial position relationship between the drill bit 10 and the intramedullary nail 14 via a navigation view. The processor 13 can be attached with a memory storing a program. The data interface of the processor 13 can also be connected to a tracking device of the navigation system, so that the position and direction of the tracked target, such as the sleeve 11 and the intramedullary nail 14, can be obtained from the tracking device in real time.

[0049] In this embodiment, the tracking device is an electromagnetic tracking device, which includes a magnetic field generator (not shown), a first electromagnetic sensor 11a fixed to the sleeve 11, and a second electromagnetic sensor 14a fixed to the intramedullary nail 14. The electromagnetic tracking device can achieve high-precision real-time tracking of the electromagnetic sensors by sensing changes in the magnetic field. Specifically, the first electromagnetic sensor 11a is used to provide real-time feedback on the spatial position and orientation of the sleeve 11, and the second electromagnetic sensor is used to provide real-time feedback on the spatial position and orientation of the intramedullary nail 14. The electromagnetic sensors are small in size and can be embedded in the sleeve and intramedullary nail, highly integrated with the structure, and do not affect the normal use of the medical device.

[0050] By installing electromagnetic sensors on the sleeve 11 and the intramedullary nail 14 respectively, the positional relationship between the drill bit and the intramedullary nail can be obtained. Specifically, the spatial positional relationship between the sleeve 11 and the first electromagnetic sensor 11a and the spatial positional relationship between the intramedullary nail 14 and the second electromagnetic sensor 14a are completed by calibration before leaving the factory (i.e., a pre-established spatial positional relationship). In this way, with the help of the external magnetic field generated by the magnetic field generator, the spatial positional relationship between the sleeve 11 and the intramedullary nail 14 can be obtained. The spatial relationship between the sleeve and the drill bit is determined by mechanical processing, so the spatial positional relationship between the drill bit 10 and the intramedullary nail 14 can be obtained. In the above embodiment, since installing the first electromagnetic sensor 11a on the drill bit 10 will hinder the drilling operation, it is preferred to fix the first electromagnetic sensor 11a on the sleeve 11, and track the drill bit 10 by the first electromagnetic sensor 11a on the sleeve.

[0051] In this article, "determined by machining" means that during the manufacturing stage, the spatial position relationship between the sleeve and the drill bit is established and locked in one go through the same clamping reference, high-precision coaxial / parallel machining, strict tolerance matching and rigid assembly structure. This spatial position relationship does not require additional measurement or correction in subsequent use and can be directly used as a reliable basis for electromagnetic sensor calibration.

[0052] Those skilled in the art should understand that, although an electromagnetic tracking device is preferably used in the above embodiments, other suitable tracking methods, such as optical tracking, may also be used, which are also covered within the scope of this application.

[0053] The following will be combined with the Figure 4 The steps of a specific embodiment of the method for aiming the locking hole of an intramedullary nail in a navigation system of the present invention are described in detail. The process of aiming the drill bit 10 with the locking hole 15 of the intramedullary nail 14 includes the following steps: a) obtaining the spatial position of the sleeve and the intramedullary nail by the tracking device of the navigation system;

[0054] b) determining a spatial positional relationship between the drill bit and the intramedullary nail based on the acquired spatial positions of the sleeve and the intramedullary nail by performing a coordinate transformation and combining a preset spatial positional relationship between the drill bit and the sleeve;

[0055] c) constructing an observation coordinate system in a navigation system, wherein the observation angle is along the axial direction of the sleeve, and generating a navigation view in the observation coordinate system, so that the model of the drill bit in the navigation view appears as a point projection; and

[0056] d) acquiring the position and angle of the drill bit in real time and displaying the projection of the drill bit in the navigation view; when the point projection of the drill bit is located in the overlapping area of ​​the projection of the distal end surface of the locking hole and the projection of the proximal end surface of the locking hole, it is determined that the drill bit has been aimed at the locking hole.

[0057] In the above step a), since the tracking device is an electromagnetic tracking device, the magnetic field generator is used to generate an alternating electromagnetic field in space, and the first electromagnetic sensor and the second electromagnetic sensor are used to detect the alternating electromagnetic field and determine the spatial positions of the sleeve and the intramedullary nail.

[0058] In one example, the navigation view includes a three-dimensional model of the drill bit and a three-dimensional model of the intramedullary nail. In step b), the following sub-steps are also included: based on a pre-established fixed spatial position relationship between the sleeve 11 and the first electromagnetic sensor 11a, and a pre-established fixed spatial position relationship between the intramedullary nail 14 and the second electromagnetic sensor 14a, coordinate transformation is performed on spatial position information acquired in real time by the first electromagnetic sensor 11a and the second electromagnetic sensor 14a to obtain the spatial position relationship between the sleeve and the intramedullary nail; and based on a pre-established fixed spatial position relationship between the sleeve 11 and the drill bit 10 through machining, the spatial position relationship between the three-dimensional model of the drill bit and the three-dimensional model of the intramedullary nail is determined.

[0059] Figure 8 The above-mentioned spatial transformation is shown. The black arrow shown in the figure shows that the coordinate system of the drill bit three-dimensional model is transformed to the coordinate system of the intramedullary nail three-dimensional model through the first electromagnetic sensor 11a and the second electromagnetic sensor 14a. As shown in the figure, in order to achieve precise aiming between the drill bit and the intramedullary nail locking hole, the present invention uses an electromagnetic navigation system to achieve spatial transformation of the drill bit coordinate system to the intramedullary nail coordinate system. The first electromagnetic sensor 11a shown in the figure is fixed on the sleeve and can obtain the spatial position information of the sleeve (and its internal drill bit) in the navigation coordinate system in real time. The second electromagnetic sensor 14a is fixed on the intramedullary nail or its connecting structure, and is used to determine the spatial position of the intramedullary nail three-dimensional model in the navigation coordinate system. Since the drill bit is inserted into the sleeve during use, and the spatial relationship between the two is fixed (for example, achieved by structural limiting, calibration device, etc.), the spatial transformation relationship of the drill bit relative to the sleeve can be measured and stored in advance, which is recorded as the rigid body transformation matrix T ST .

[0060] In one embodiment, the navigation system may deduce the spatial position of the drill bit relative to the intramedullary nail according to the following coordinate transformation formula:

[0061] P IMN =T IM ·T ST ·P drill

[0062] in:

[0063] P drill Indicates the spatial position of the drill bit in its own coordinate system;

[0064] T ST Represents the spatial transformation matrix of the drill bit relative to the sleeve, which is determined by machining;

[0065] T IM The spatial transformation matrix of the sleeve relative to the intramedullary nail is obtained in real time by the navigation system;

[0066] P IMN This indicates the spatial position of the drill bit within the intramedullary nail coordinate system, which is used for subsequent navigation image generation and alignment determination. This transformation can be performed in real time within the navigation system. By visually displaying the drill bit's position within the intramedullary nail coordinate system (e.g., projecting it onto a display), the operator can accurately determine whether the drill bit is aligned with the locking hole in the intramedullary nail, thereby improving the accuracy and safety of the procedure or positioning.

[0067] Since the concern is whether the drill bit 10 passing through the sleeve 11 can pass through the locking hole 15 smoothly, the drill bit 3D model is visualized in the specific implementation. The actual drill bit has threads, and since the threads are not helpful for the aiming process, a simplified drill bit 3D model without the threads is used in this example (see Figure 5 ).

[0068] Figure 6 1 shows a three-dimensional model of an intramedullary nail 14. As can be seen from the figure, the intramedullary nail 14 includes an intramedullary nail body 140, two locking holes 15 located at one end of the intramedullary nail, and an elliptical hole located between the two locking holes.

[0069] In the above step c), when the viewing angle is along the axial direction of the sleeve 11, the projection of the distal bone end surface 112 of the sleeve 11 and the projection of the proximal bone end surface 111 of the sleeve are merged into one point in the navigation view (corresponding to Figure 2b Point 1 in the middle), so that the point 1 is aligned with the center 15b of the proximal end surface of the locking hole (corresponding to Figure 2b Point 2 in the middle) and the locking hole distal end surface 15a (corresponding to Figure 2bThe center of the target point 3) is aligned, wherein the distance from this point to the center of the proximal end surface 15b of the locking hole is the aiming end distance, and the distance from the center of the proximal end surface 15a of the locking hole to the center of the distal end surface of the locking hole is the target point distance. In one example, the ratio of the aiming end distance to the target point distance is 1:24 to 1:30, and when the dot-shaped projection of the drill bit is located within the overlapping area of ​​the projection of the distal end surface of the locking hole and the projection of the proximal end surface of the locking hole in the guide view, the actual deviation between the drill bit and the locking hole is less than 0.6mm. The above data are merely exemplary, mainly for maximizing the aiming end distance and minimizing the target point distance. However, adopting other suitable data is also within the scope of this application. For example, the aiming end distance can be the sum of the distance from the proximal end surface of the sleeve to the intramedullary nail and the length of the sleeve, wherein the length of the sleeve can be 100mm to 150mm, and the distance from the proximal end surface of the sleeve to the intramedullary nail is 20mm; the target point distance is 5mm.

[0070] See also Figure 7 In the step of constructing the observation coordinate system, the observation coordinate system uses the midpoint of the line connecting the centers of the two locking holes as the origin O, the axial direction of the intramedullary nail is determined as the X-axis, the axial direction of the sleeve is determined as the Z-axis, and the Y-axis is determined as a direction perpendicular to the axial direction of the intramedullary nail and orthogonal to the Z-axis. The observation coordinate system shown in the figure is a right-handed coordinate system, in which the observation angle is set at the distal bone end surface of the sleeve and points from the distal bone end surface of the sleeve to the proximal bone end surface of the sleeve. In such an observation coordinate system, when the view is zoomed in, the screen of the display device displays information about the locking holes that is helpful for navigation. At the same time, when the sleeve is moved, the intramedullary nail can always be fixed in the center of the screen. The main nail direction of the intramedullary nail is fixed to the X-direction of the observation coordinate system, so that no matter how the sleeve rotates around the axis, the intramedullary nail will not swing up and down on the screen.

[0071] In the above-mentioned observation coordinate system construction step, it also includes transforming the axial direction of the sleeve to the intramedullary nail coordinate system through coordinate transformation, and determining the transformed axial direction as the Z axis; determining the Y axis direction through the cross product between the Z axis and the axial direction of the intramedullary nail; and correcting the X axis direction through the cross product between the Y axis direction and the Z axis direction.

[0072] Figure 9The figure shows a navigation view realized based on the aiming method proposed in the present invention. The navigation view only includes the three-dimensional model of the intramedullary nail and the projection of the drill bit 10 (the green circle in the figure). When the drill bit 10 moves, the intramedullary nail is fixed, and the green projection moves on the screen of the display device. When the drill bit rotates around the axis, the intramedullary nail does not move, and the green projection also remains stationary. When the drill bit swings left and right, the green projection does not move, and the intramedullary nail rotates around the Y axis of the screen. When the drill bit swings up and down, the green projection does not move, and the intramedullary nail rotates around the axis. By controlling the position and direction of the sleeve 11, the distal end face and the proximal end face of the locking hole of the intramedullary nail locking hole are basically coincident, and the green projection is moved to the overlapping area of ​​the projection of the distal end face and the projection of the proximal end face of the locking hole of the locking hole 15, navigation and aiming can be completed.

[0073] The present invention models the spatial transformation relationship between the real-time position of the sleeve / drill bit and the three-dimensional model of the intramedullary nail, constructs a unified navigation coordinate system, realizes the visual tracking of the drill bit trajectory in the intramedullary nail locking hole space, and provides doctors with accurate three-dimensional alignment guidance.

[0074] Furthermore, the present invention provides a real-time spatial coordinate transformation method based on electromagnetic sensors, designed to accurately guide surgeons in the positioning of the distal locking hole of an intramedullary nail. This method allows the alignment of the drill bit trajectory with the locking hole axis to be displayed in real time on a display device, thereby improving the accuracy and efficiency of surgical procedures.

[0075] The aiming method according to this invention significantly reduces the error accumulation problem in traditional operations, especially the error amplification effect when locating the locking hole. Through real-time feedback and precise guidance, surgeons can quickly and accurately align the drill bit with the locking hole without fluoroscopy, thereby improving surgical efficiency, reducing X-ray usage, and effectively reducing operational difficulty and failure rates.

[0076] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, is capable of performing the steps of the above-mentioned method of the present invention. Furthermore, the present invention also provides a control device, which may include a memory, a processor, and a program stored on the memory and executable by the processor, wherein the steps of the above-mentioned method of the present invention are performed when the program is executed by the processor. The present invention also provides a computer program product, including the computer program, wherein the computer program, when executed by the processor, implements the steps of the above-mentioned method of the present invention.

[0077] Those skilled in the art will appreciate that the steps of the methods or algorithms described herein can be implemented directly using hardware, software modules executed by a processor, or a combination of the two. The software module can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. Those skilled in the art will appreciate that the memory of the control device of the present invention can include random access memory (RAM) and can also include non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory can also be at least one storage device separate from the processor.

[0078] The processor of the control device can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0079] Although certain embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A method for aiming a locking hole of an intramedullary nail in a navigation system, the navigation system being configured to guide a drill bit through a sleeve to align the locking hole, the locking hole having a distal locking hole surface and a proximal locking hole surface, the method comprising the following steps: a) obtaining the spatial position of the sleeve and the intramedullary nail through the tracking device of the navigation system; b) determining a spatial positional relationship between the drill bit and the intramedullary nail based on the acquired spatial positions of the sleeve and the intramedullary nail by performing a coordinate transformation and combining a preset spatial positional relationship between the drill bit and the sleeve; c) constructing an observation coordinate system in a navigation system, wherein the observation angle is along the axial direction of the sleeve, and generating a navigation view in the observation coordinate system, so that the model of the drill bit in the navigation view appears as a point projection; and d) acquiring the position and angle of the drill bit in real time and displaying the projection of the drill bit in the navigation view; and determining that the drill bit has been aimed at the locking hole when the point projection of the drill bit is located within the overlapping area of ​​the projections of the distal end surface of the locking hole and the proximal end surface of the locking hole.

2. The method according to claim 1, wherein The sleeve has a distal bone end surface and a proximal bone end surface, and the intramedullary nail has two locking holes; In step c), when the viewing angle is set along the axial direction of the sleeve, the projections of the distal bone end surface of the sleeve and the proximal bone end surface of the sleeve in the navigation view are a point, so that the point is in a straight line with the center of the proximal end surface of the locking hole and the center of the distal end surface of the locking hole, wherein the distance from the point to the center of the proximal end surface of the locking hole is defined as the aiming end distance, and the distance from the center of the proximal end surface of the locking hole to the center of the distal end surface of the locking hole is defined as the target point distance.

3. The method according to claim 2, wherein: The ratio of the aiming end distance to the target point distance is 1:24 to 1:30; and When the drill bit has been aligned with the locking hole, the actual deviation between the drill bit and the locking hole can be less than 0.6 mm.

4. The method according to claim 2, wherein: In the step of constructing the observation coordinate system, the midpoint of the center line connecting the two locking holes is taken as the origin, the axial direction of the intramedullary nail is determined as the X-axis, the axial direction of the sleeve is determined as the Z-axis, and the Y-axis is determined as a direction perpendicular to the axial direction of the intramedullary nail and orthogonal to the Z-axis.

5. The method according to claim 4, wherein The observation coordinate system is a right-handed coordinate system, wherein the observation angle is set at the distal bone end surface of the sleeve and is from the distal bone end surface of the sleeve toward the proximal bone end surface of the sleeve along the axial direction of the sleeve.

6. The method according to claim 5, wherein: The aiming end distance is the sum of the length of the sleeve and the distance from the proximal bone end surface of the sleeve to the intramedullary nail, wherein the length of the sleeve is 100mm to 150mm, and the distance from the proximal bone end surface of the sleeve to the intramedullary nail is 20mm; the target point distance is 5mm.

7. The method according to any one of claims 1 to 6, wherein The tracking device is an electromagnetic tracking device, which includes a magnetic field generator, a first electromagnetic sensor fixed to the sleeve, and a second electromagnetic sensor fixed to the intramedullary nail; The magnetic field generator is used to generate an alternating electromagnetic field in space, and the first electromagnetic sensor and the second electromagnetic sensor are used to detect the alternating electromagnetic field and output spatial position information for determining the spatial positions of the sleeve and the intramedullary nail.

8. The method according to claim 7, wherein: The navigation view includes a three-dimensional model of the drill bit and a three-dimensional model of the intramedullary nail. In step b), the following steps are also included: Based on a pre-established fixed spatial position relationship between the sleeve and the first electromagnetic sensor, and a pre-established fixed spatial position relationship between the intramedullary nail and the second electromagnetic sensor, coordinate transformation is performed on spatial position information acquired in real time by the first electromagnetic sensor and the second electromagnetic sensor to determine the spatial position relationship between the sleeve and the intramedullary nail; and The spatial position relationship between the three-dimensional model of the drill bit and the three-dimensional model of the intramedullary nail is determined according to the fixed spatial position relationship pre-established between the sleeve and the drill bit through mechanical processing.

9. The method according to any one of claims 3 to 6, wherein: The method further comprises: Converting the axial direction of the sleeve to the intramedullary nail coordinate system through coordinate transformation, and determining the converted axial direction as the Z-axis direction; determining a Y-axis direction based on a cross product between the Z-axis direction and the axial direction of the intramedullary nail; and The X-axis direction is corrected based on a cross product between the Y-axis direction and the Z-axis direction.

10. An intramedullary nail navigation system for guiding a drill bit through a sleeve to align with a locking hole of an intramedullary nail, wherein: The intramedullary navigation system comprises: a tracking device for obtaining the spatial positions of the sleeve and the intramedullary nail; and A display device and a processor, the processor being adapted to be connected to the tracking device, wherein when the processor is running, the method according to any one of claims 1 to 9 is executed, and the spatial positional relationship between the drill bit and the intramedullary nail is displayed via a navigation view on the display device.

11. The intramedullary nail navigation system according to claim 10, wherein: The tracking device is an electromagnetic tracking device, which includes a magnetic field generator for generating an alternating electromagnetic field in space, a first electromagnetic sensor fixed to the sleeve, and a second electromagnetic sensor fixed to the intramedullary nail.

12. A computer-readable storage medium having a computer program stored thereon, wherein: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are executed.

13. A control device comprising a memory, a processor, and a program stored in the memory and capable of running on the processor, wherein: When the processor runs the program, the steps of the method according to any one of claims 1 to 9 are performed.

14. A computer program product comprising a computer program, wherein When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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