Femoral intramedullary nail system

Abstract

The invention provides a femoral intramedullary nail system, which comprises a medullary cavity registration modeling unit used for performing three-dimensional reconstruction based on a patient preoperative CT or MRI image, automatically extracting femoral medullary cavity boundary, curvature radius and neck-shaft angle parameters, and generating an individualized medullary cavity geometric model; the intramedullary nail customization design unit is used for automatically matching the diameter, curvature and front rake angle of the intramedullary nail according to the medullary cavity model, ensuring that the gap between the outer diameter of the intramedullary nail and the inner diameter of the medullary cavity is less than or equal to 0.2 mm, and designing a radial limiting rib at the near end of the intramedullary nail to form multi-point contact support; according to the anti-swing matching structure, the head of the intramedullary nail adopts a double-spherical-surface-conical composite matching interface; according to the technical scheme, the intramedullary nail structure customization and surface hydroxyapatite gradient coating deposition are achieved through the metal 3D printing technology, continuous elastic modulus transition is formed at the near end and the far end of the intramedullary nail, and the fixing stability is remarkably improved, and the pendulum effect is restrained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of orthopedic implants, in particular to a femoral intramedullary nail. BACKGROUND

[0002] Proximal femoral fracture is a common clinical injury. Intramedullary nailing has become the mainstream treatment due to its biomechanical advantages. The currently widely used proximal femoral intramedullary nail (such as PFNA, Gamma Nail, etc.) adopts a standardized design, that is, a number of standardized nail diameters and fixation angles are provided for selection during operation. This mode has the advantages of simple production, universal surgical tools, and relatively stable learning curve, which embodies the "instrument-centered" mass treatment concept.

[0003] However, this standardized design objectively ignores the significant differences in the proximal femoral medullary cavity anatomical structure among individuals. Specifically, (1) the medullary cavity diameter varies significantly among individuals, and research shows that the matching degree of the same size intramedullary nail in different patients' medullary cavities can fluctuate by more than 25%; (2) the medullary cavity arc curvature radius varies significantly, with an average fluctuation range of 3-6 mm; (3) the femoral neck shaft angle (NSA), a key mechanical parameter, has a wide distribution in the population, with a common range of 120 degrees to 140 degrees. These inconsistencies in three-dimensional morphology result in the fact that the standardized intramedullary nail cannot achieve ideal "filling" and "fitting" in the medullary cavity of most patients.

[0004] The direct mechanical consequence is that the intramedullary nail does not fit tightly in the medullary cavity, and during the postoperative periodic weight-bearing process, it produces a slight swing, i.e., the "Pendulum Effect". This effect leads to a series of clinical complications: first, the repeated micro-motion of the intramedullary nail in the femoral head leads to the absorption of the surrounding bone, increasing the risk of screw or lag screw cut-out; second, the swing stress is concentrated in the distal locking hole area of the intramedullary nail, which is prone to metal fatigue, even cracks or fractures under long-term action; third, the abnormal micro-motion of the fracture fragments due to the insufficient stability of the internal fixation system interferes with the formation of callus, which can lead to delayed bone healing or nonunion. Clinical meta-analysis shows that after treatment with a standardized intramedullary nail, the rate of internal fixation displacement on imaging can reach 14.8%, and the rate of secondary fracture collapse is about 11.2%, of which a considerable part is related to poor mechanical matching.

[0005] Although existing technologies attempt to alleviate the above problems by increasing the size of the intramedullary nail, improving the internal fixation material, or optimizing the surgical technique, they have not fundamentally solved the inherent contradiction between individual anatomical differences and standardized implants. During the operation, excessive medullary expansion and other compromises are often forced, which not only increases the surgical trauma and bleeding, but also may further weaken the support strength of the bone itself. SUMMARY

[0006] The purpose of the present application is to provide a femoral intramedullary nail system, which should be able to realize the adaptive matching of the key parameters such as the shape, curvature and neck angle of the intramedullary nail according to the individualized medullary cavity geometry of the patient, so as to construct a stable nail interface at the level of biomechanics and fundamentally inhibit the "pendulum effect".

[0007] In order to solve the above problems, the present application provides a femoral intramedullary nail system, which specifically comprises: a medullary cavity registration modeling unit for three-dimensional reconstruction based on preoperative CT or MRI images of the patient, automatic extraction of femoral medullary cavity boundary, curvature radius and neck angle parameters, and generation of an individualized medullary cavity geometric model; an intramedullary nail customized design unit for automatically matching the intramedullary nail diameter, curvature and anteversion angle according to the medullary cavity model, ensuring that the gap between the outer diameter of the intramedullary nail and the inner diameter of the medullary cavity is ≤0.2mm, and designing a radial limiting rib at the proximal end of the intramedullary nail for forming a multi-point contact support; a swing prevention matching structure, which is a spherical-tapered composite matching interface at the head of the intramedullary nail; for reducing the shear stress in the femoral neck area and inhibiting the swing of the intramedullary nail in the medullary cavity; an individualized manufacturing unit for realizing the customization of the intramedullary nail structure and the deposition of the hydroxyapatite gradient coating on the surface by metal 3D printing process, so as to form a continuous elastic modulus transition at the proximal and distal ends of the intramedullary nail.

[0008] Further, the medullary cavity registration modeling unit uses an improved 3D U-Net network for automatic segmentation of bone cortex, outputs the medullary cavity center line and cross section parameters, and realizes the adaptive fitting of the medullary cavity space curvature.

[0009] Further, the radial limiting rib is arranged in multiple groups along the longitudinal axis of the intramedullary nail, and the outer edge thereof forms an interference fit with the inner wall of the medullary cavity. For inhibiting the micro-motion of the intramedullary nail in the axial and radial directions; Further, the spherical-tapered composite matching interface at the head of the intramedullary nail comprises: a first spherical surface in contact with the inner wall of the femoral neck for uniformly distributing the contact stress; and a second tapered surface matched with the tapered section at the upper opening of the medullary cavity for forming axial limiting; so as to realize bidirectional constraint in the radial and axial directions.

[0010] Further, the individualized manufacturing unit realizes the printing of the intramedullary nail based on the Ti-6Al-4V powder selective laser sintering process, and forms a 50-80 micrometer thick hydroxyapatite functional coating by electrophoretic deposition. To enhance the bone integration ability.

[0011] Further, the femoral intramedullary nail system further comprises an intraoperative intelligent guiding module, which integrates an IMU inertial sensor with a sampling frequency ≥200Hz and an angle error ≤0.2°. For real-time monitoring of the deviation of the nail angle and the medullary cavity axis; Further, a multi-angle dynamic locking hole is arranged at the distal end of the intramedullary nail, the adjustable angle interval of the multi-angle dynamic locking hole is 0-10 degrees, and a locking screw provided with self-expanding fins is arranged. To realize the stable buffering fixation of the distal end; Further, a limiting block is arranged on the inner wall of the multi-angle dynamic locking hole, a thread is arranged on the limiting block, and the limiting block is engaged with the locking screw.

[0012] The technical scheme of the application is applied to a marrow cavity registration modeling unit, which is used for three-dimensional reconstruction based on preoperative CT or MRI images of a patient, automatic extraction of femoral marrow cavity boundary, curvature radius and neck-shaft angle parameters, and generation of an individualized marrow cavity geometric model; a intramedullary nail customization design unit, which automatically matches the intramedullary nail diameter, curvature and anteversion angle according to the marrow cavity model, ensures that the gap between the outer diameter of the intramedullary nail and the inner diameter of the marrow cavity is less than or equal to 0.2 mm, and designs a radial limiting rib at the proximal end of the intramedullary nail for forming multi-point contact support; a swing prevention matching structure, which is a spherical-tapered composite matching interface at the head of the intramedullary nail; an individualized manufacturing unit, which realizes intramedullary nail structure customization and surface hydroxyapatite gradient coating deposition through a metal 3D printing process, so that the proximal and distal ends of the intramedullary nail form a continuous elastic modulus transition. The individualized marrow cavity-intramedullary nail matching mechanism: for the first time, the intramedullary nail and the three-dimensional curvature of the patient's marrow cavity are adaptively registered; the swing prevention structure design: radial limiting rib + double spherical-tapered contact surface, forming a multi-point support anti-rotation combination; manufacturing-navigation integrated closed loop: from CT reconstruction, AI registration to 3D printing and intraoperative guidance, forming a complete customization chain; mechanical continuous gradient structure: through local material regulation, stress distribution homogenization is realized, and stress concentration is reduced. The matching error of the intramedullary nail and the marrow cavity is less than or equal to 0.2 mm, the swing amplitude of the intramedullary nail is less than 0.2 mm, and the postoperative femoral head collapse rate is less than 3%, which significantly improves the fixation stability and inhibits the "pendulum effect". BRIEF DESCRIPTION OF DRAWINGS

[0013] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in Figure 1 A schematic diagram of an intramedullary nail system is shown; Figure 2 A flowchart of the execution process of the intramedullary nail system is shown; Figure 3 A sectional view of an intramedullary nail is shown; Figure 4 A structure diagram of a locking hole is shown; Figure 5 A structure diagram of a locking screw is shown In the above figure, the following reference signs are included: 10, medullary cavity registration modeling unit; 20, main nail customized design unit; 30, adaptive locking and guiding unit; 40, personalized manufacturing unit; 50, limiting rib; 60, anti-swing matching structure; 601, first spherical surface; 602, second conical surface; 70, locking hole; 701, limiting block; 80, locking screw; 801, wing. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0015] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component and / or combinations thereof.

[0016] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the various examples herein are not limiting of the scope of the application. Also, it is to be understood that the specific devices illustrated in the attached figures, and herein described, are merely exemplary embodiments and are not intended to limit the scope of the application. All such examples and exemplary language recited herein are indicative of the various possible alternatives of elements, and / or methods that can be employed in accordance with the principles of the present application. Selection of these are a matter of design choice and, dependent upon the specific application, can result in differing examples and / or implementations. It is intended that each of these alternatives be considered within the scope of the present application. Thus, the examples are non-limiting.

[0017] As Figures 1-2 shown: the present application provides a femoral intramedullary nail system, which specifically includes the following four core functional units, each unit is coordinated with each other in structure design and function implementation, forming a complete personalized treatment solution: The medullary cavity registration modeling unit 10 is used to complete the accurate digital reconstruction of the anatomical structure of the femoral medullary cavity based on the preoperative CT or MRI image data of the patient, and to provide data support for the subsequent personalized design of the intramedullary nail. The specific technical implementation is as follows: S1: Image Data Processing: High-resolution CT or MRI images of the proximal femur of the patient were acquired (CT slice thickness ≤1mm, MRI sequences using T1-weighted enhancement sequences to clearly display the bone cortex boundary). The image data was preprocessed using medical image processing software, including denoising, grayscale correction, and image alignment, to ensure clear differentiation between bone tissue and surrounding soft tissue. Automatic Cortical Bone Segmentation: An improved 3D U-Net deep learning network was used for automatic segmentation of the femoral medullary cavity cortex. This network, based on the traditional 3D U-Net architecture, added residual connection modules and an attention mechanism, which can effectively identify the grayscale differences between the bone cortex and the medullary cavity. Based on the segmentation results, the inner and outer boundary contours of the femoral medullary cavity were automatically extracted, generating a three-dimensional mesh model of the medullary cavity. Key Parameter Extraction and Model Generation: Based on the segmented 3D mesh model of the medullary cavity, key anatomical parameters of the medullary cavity are automatically calculated and output, including: medullary cavity diameter: Samples are taken every 2 mm along the centerline of the medullary cavity, recording the maximum and minimum inner diameters of each section to form a diameter variation curve; radius of curvature: The radius of curvature of the medullary cavity arc is calculated by fitting the centerline of the medullary cavity to an arc using the least squares method; neck-shaft angle: Calculated based on the angle between the femoral neck axis and the femoral shaft axis; anteversion angle: Calculated by the projection angles of the femoral neck axis in the coronal and sagittal planes. Finally, the above parameters are integrated to generate a geometric model of the medullary cavity that conforms to the individual anatomical characteristics of the patient and stored in the system database for subsequent use by the intramedullary nail design unit.

[0018] The intramedullary nail customization design unit 20, based on the individualized medullary canal geometry model generated by the medullary canal registration and modeling unit, completes the structural design and parameter optimization of the intramedullary nail, ensuring a high degree of fit between the intramedullary nail and the medullary canal and postoperative mechanical stability. Its specific technical implementation is as follows: S2: Basic parameter adaptive matching: based on the diameter change curve of the medullary cavity geometric model, the main body diameter of the intramedullary nail is automatically matched to ensure that the gap between the outer diameter of the intramedullary nail and the inner diameter of the medullary cavity is ≤0.2mm. At the same time, according to the curvature radius and anteversion angle parameters of the medullary cavity, the curvature of the intramedullary nail body and the anteversion angle of the proximal end are adjusted to make the overall shape of the intramedullary nail completely match the natural trend of the medullary cavity, avoiding local gaps or excessive compression. Radial limiting rib 50 design: multiple groups of radial limiting ribs 50 are arranged along the longitudinal axis at the proximal end of the intramedullary nail (starting 10-15mm from the intramedullary nail head), the height of the limiting rib is determined according to the local inner diameter of the medullary cavity, and the outer edge of the limiting rib forms an interference fit (interference amount is 0.05-0.1mm) with the inner wall of the medullary cavity. Through the multi-point contact support structure, the radial micro-motion and axial displacement of the intramedullary nail in the medullary cavity are effectively limited, further enhancing the stability of the bone-nail interface. Structural strength optimization: use finite element analysis software (such as ANSYS, ABAQUS) to simulate the mechanical properties of the designed intramedullary nail model under the stress distribution of the postoperative patient's weight-bearing state. Structural optimization is carried out for the stress concentration area (such as the area around the distal locking hole, the root of the limiting rib), for example, increasing the local wall thickness, using circular arc transition design, to ensure that the yield strength of the intramedullary nail is ≥860MPa and the fatigue strength is ≥600MPa, meeting the long-term weight-bearing requirements after surgery.

[0019] The adaptive locking and guiding unit 30 integrates IMU inertial sensors and real-time data transmission functions to provide precise implant angle feedback for the surgeon. The specific technical parameters and function implementation are as follows: S3: Hardware composition: this module includes a guide body, IMU inertial sensors, a wireless data transmission module, and a display screen. Among them, the IMU inertial sensor adopts a six-axis (three-axis accelerometer + three-axis gyroscope) sensor, with a sampling frequency ≥200Hz, an angle measurement range of 0-360°, and an angle error ≤0.2°, which can collect spatial attitude data of the guide in real time; the wireless data transmission module uses Bluetooth 5.0 protocol, with a transmission distance ≥10m and a delay ≤10ms, ensuring the real-time and stability of the data; the display screen is a 5.5-inch high-definition touch screen that can display the implant angle, deviation from the medullary cavity axis, and implant depth of the guide in real time. Function implementation: before surgery, import the medullary cavity geometric model generated by the medullary cavity registration modeling unit into the control software of the control module of the guide module, and the software automatically generates the ideal implant path and angle parameters; during surgery, the surgeon connects the guide with the intramedullary nail, the IMU inertial sensor collects spatial attitude data of the guide in real time, and compares it with the ideal implant path, and feedbacks the angle deviation (including coronal plane deviation and sagittal plane deviation) to the surgeon through the display screen; when the angle deviation exceeds 0.5°, the system issues an audible and visual alarm to prompt the surgeon to adjust the guide attitude, ensuring that the intramedullary nail is implanted accurately according to the pre-set path, with an implantation accuracy of ±0.3°.

[0020] The individual manufacturing unit 40 adopts metal 3D printing and surface coating technology to realize the personalized structure manufacturing and biocompatibility optimization of the intramedullary nail, and to ensure the formation of continuous elastic modulus transition of the proximal and distal ends of the intramedullary nail, and to improve the postoperative bone integration effect and mechanical compatibility. The specific technical implementation manner is as follows: S4: 3D printing of intramedullary nail body: Ti-6Al-4V titanium alloy powder is used to realize 3D printing of the intramedullary nail body by selective laser sintering process. Hydroxyapatite gradient coating deposition: hydroxyapatite (HA) gradient coating is prepared on the surface of the intramedullary nail by electrophoretic deposition process. The deposition process is divided into two stages: the first stage (proximal coating): a 70-80 μm thick HA coating is deposited on the proximal end of the intramedullary nail (50-60 mm in length, corresponding to the femoral neck and fracture end region), the HA particle content in the coating is ≥95%, and the porosity is 20%-30%, to promote the direct integration of bone tissue and the intramedullary nail; the second stage (distal coating): the HA coating thickness is gradually reduced from the proximal end to the distal end, and when the distal end of the intramedullary nail (10-15 mm away from the distal locking hole) is reached, the coating thickness is reduced to 50-60 μm, and by adjusting the electrophoretic parameters, the HA particle content is gradually reduced to 85%-90% and the porosity is reduced to 10%-20%. After the coating deposition is completed, sintering treatment is carried out in a vacuum sintering furnace (temperature 900-950℃, holding for 1h), so that the HA coating and the intramedullary nail substrate form a firm combination. Elastic modulus transition control: through the mechanical properties of the Ti-6Al-4V substrate and the porosity gradient design of the HA coating, the continuous transition of the elastic modulus of the proximal and distal ends of the intramedullary nail is realized. Among them, the elastic modulus of the proximal end of the intramedullary nail (containing the HA coating) is 8.0-8.5 GPa, which is close to the elastic modulus of 7-10 GPa of the femoral neck bone tissue; from the proximal end to the distal end, with the reduction of the HA coating thickness and the reduction of the porosity, the elastic modulus of the intramedullary nail gradually increases, and reaches 3.0-3.5 GPa at the distal end. The elastic modulus of the Ti-6Al-4V substrate is about 110 GPa, and the overall elastic modulus is lowered and transitioned through the gradient design of the coating. This continuous transition of the elastic modulus can effectively reduce the stress shielding effect of the bone-nail interface and avoid bone loss caused by mechanical property mismatch.

[0021] As Figures 3-5The system is shown: to realize the stable fixation of the distal end of the intramedullary nail and the femoral shaft, and to adapt to the anatomical differences of the medullary cavity of different patients. The system also includes a swing prevention matching structure 60, which has a composite matching interface: the head of the intramedullary nail adopts a spherical-taper composite matching interface, which is composed of a first spherical surface 601 and a second conical surface 602, which are integrally formed and made of the same Ti-6Al-4V material as the main body of the intramedullary nail: the first spherical surface is located at the distal end of the head of the intramedullary nail (close to the head of the femoral neck), and its spherical radius is determined according to the anatomical radius of the femoral head of the patient. The spherical surface closely fits the arc-shaped area of the inner wall of the femoral neck, which can evenly distribute the concentrated stress generated by postoperative weight-bearing to the femoral neck bone tissue, avoiding local stress-induced bone damage, and can reduce the shear stress in the femoral neck area by more than 30% through finite element analysis verification. The second conical surface 602 is located at the proximal end of the head of the intramedullary nail. The conical surface forms a close fit with the conical section at the upper opening of the medullary cavity (determined by preoperative CT imaging), with a matching gap of ≤0.1 mm, which can effectively limit the axial displacement of the intramedullary nail, while providing radial support for the head of the intramedullary nail, further suppressing the "pendulum effect".

[0022] The system also sets up multi-angle dynamic locking holes 70 at the distal end of the intramedullary nail, and designs self-expanding fin 801 locking screws 80 to match, the specific structure and function are as follows: multi-angle dynamic locking hole: a plurality of multi-angle dynamic locking holes are arranged along the longitudinal axis at the distal end of the intramedullary nail. Limiting blocks are arranged on the inner wall of the locking hole, the limiting blocks 701 are integrally formed with the inner wall of the locking hole, and threads are processed on the limiting blocks for engaging with the locking screw to fix the angle of the locking screw. The limiting blocks are evenly distributed on the inner wall of the locking hole to ensure that the locking screw can obtain stable thread engagement at different angles. Locking screw 80: the locking screw is made of Ti-6Al-4V material, the length of the screw is determined according to the diameter of the patient's femoral shaft, the screw rod is processed with fine threads matching the limiting blocks of the locking hole, and the screw head is provided with three self-expanding fins 801. The self-expanding fin is made of nickel-titanium shape memory alloy material, and in the initial state (room temperature), the fin is retracted in the groove of the screw head. When the screw is implanted into the femoral bone, the fin automatically expands and unfolds under the action of body temperature, forming a mechanical bite with the bone cortex, significantly improving the pull-out force of the screw.

[0023] In the description of the application, it needs to be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship is generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application; the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component.

[0024] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0025] In addition, it should be noted that the use of "first", "second" and the like words to define parts, only for the convenience of corresponding parts, such as no further declaration, the above words have no special meaning, therefore, it cannot be understood as a limitation on the scope of protection of the application.

[0026] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A femoral intramedullary nail system, characterized in that, The system includes: The medullary cavity registration and modeling unit is used to perform three-dimensional reconstruction based on the patient's preoperative CT or MRI images, automatically extract the femoral medullary cavity boundary, radius of curvature, and neck-shaft angle parameters, and generate an individualized medullary cavity geometric model. The intramedullary nail customization design unit automatically matches the diameter, curvature, and forward tilt angle of the intramedullary nail according to the medullary cavity model, ensuring that the gap between the outer diameter of the intramedullary nail and the inner diameter of the medullary cavity is ≤0.2mm, and designs radial limiting ribs at the proximal end of the intramedullary nail to form multi-point contact support; Anti-swaying mating structure, wherein the anti-swaying mating structure is an intramedullary nail head with a spherical-conical composite mating interface; The individualized manufacturing unit achieves customized intramedullary nail structure and deposition of surface hydroxyapatite gradient coating through metal 3D printing process, so that the intramedullary nail forms a continuous elastic modulus transition at the proximal and distal ends.

2. The femoral intramedullary nail system according to claim 1, characterized in that, The medullary cavity registration and modeling unit uses an improved 3D U-Net network to automatically segment the bone cortex, outputs the medullary cavity centerline and cross-sectional parameters, and achieves adaptive fitting of the medullary cavity spatial curvature.

3. The femoral intramedullary nail system according to claim 1, characterized in that, The radial limiting ribs are arranged in multiple sets at intervals along the longitudinal axis of the intramedullary nail, and their outer edges form an interference fit with the inner wall of the medullary cavity.

4. The femoral intramedullary nail system according to claim 1, characterized in that, The spherical-conical composite mating interface of the intramedullary nail head includes: The first spherical surface fits against the inner wall of the femoral neck to evenly distribute contact stress. The second conical surface mates with the conical segment at the upper opening of the medullary cavity to form axial restraint.

5. The femoral intramedullary nail system according to claim 1, characterized in that, The individualized manufacturing unit achieves intramedullary nail printing based on Ti-6Al-4V powder selective laser sintering process, and uses electrophoretic deposition to form a 50-80 micrometer thick hydroxyapatite functional coating.

6. The femoral intramedullary nail system according to claim 1, characterized in that, The femoral intramedullary nailing system also includes an intraoperative intelligent guidance module, which integrates an IMU inertial sensor with a sampling frequency ≥200Hz and an angle error ≤0.2°.

7. The femoral intramedullary nail system according to claim 1, characterized in that, The distal end of the intramedullary nail is provided with a multi-angle dynamic locking hole, the multi-angle dynamic locking hole has an adjustable angle range of 0-10 degrees, and is equipped with a locking screw with a self-expanding wing.

8. The femoral intramedullary nail system according to claim 7, characterized in that, The inner wall of the multi-angle dynamic locking hole is provided with a limiting block, and the limiting block is provided with a thread to engage with the aforementioned locking screw. The self-expanding wing is a shape memory alloy.

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