An intramedullary nail and aiming system for enhancing the stability of fixation of proximal femoral fractures

Abstract

The application relates to an intramedullary nail for enhancing the fixation stability of a proximal femoral fracture and a sighting system, belonging to the technical field of intramedullary nails, which comprises a main nail, a secondary nail, a retreat-preventing nail and a distal locking nail arranged along the femoral shaft and located in the bone marrow cavity; a longitudinal accommodating groove is arranged on the proximal lateral wall of the main nail, the accommodating groove is opposite to the lateral bone cortex of the greater trochanter of the femur, a shape memory alloy material expansion sheet is arranged in the accommodating groove, one end of the expansion sheet is fixed in the accommodating groove, and the other end is a free end; when the environment where the expansion sheet is located reaches the design temperature, the expansion sheet will be unfolded and extended out of the accommodating groove and embedded into the lateral bone cortex of the greater trochanter; the application changes the force line conduction which originally only depends on the distal locking nail into directly hooking the lateral bone cortex by the expansion sheet. The design directly transmits the bending stress to the most compact bone cortex layer instead of only being borne by the cancellous bone, and can significantly enhance the anti-varus stress.

Description

Technical Field

[0001] This invention belongs to the field of intramedullary nail technology, and specifically relates to an intramedullary nail and aiming system for enhancing the fixation stability of proximal femoral fractures. Background Technology

[0002] Hip fractures in the elderly have poor treatment outcomes and low overall recovery rates, and are often referred to as the last fracture of one's life. While intertrochanteric fractures of the femur have entered the era of minimally invasive intramedullary fixation, treatment failures still occur frequently. Currently, the goal of treatment is to restore the patient to their pre-injury lifestyle as quickly as possible.

[0003] Postoperative complications such as nonunion, malunion, loosening, internal fixation slippage, and breakage of the main or locking screw still occur frequently. The main reason for this is that, despite the good blood supply to the intertrochanteric fracture of the femur, the failure is still primarily due to the inability to achieve and maintain stability of the internal fixation and bone complex after surgery. The inability to control or reduce the strain at the fracture ends to a level that does not affect fracture healing and to maintain it until fracture healing is achieved can also lead to slower healing speed and poorer quality. This increases the stress on the internal fixation device and prolongs the time it bears high stress, thereby increasing the probability of complications such as nonunion, delayed healing, malunion, and loosening or breakage of the internal fixation device in intertrochanteric fractures of the femur. Therefore, insufficient postoperative stability remains the main cause of failure in proximal femoral fractures.

[0004] Intertrochanteric fractures of the femur in the elderly typically occur on a background of osteoporosis and are often comminuted, unstable fractures. Most existing proximal femoral intramedullary nail fixation systems rely on sliding compression of the head-neck screw. However, this sliding compression is a compromise that cannot achieve good and sustained static stability at the fracture ends. Furthermore, current proximal femoral fracture fixation systems do not effectively utilize the robust cortical bone of the femoral head-neck segment; the head-neck screw is merely embedded or screwed into the cancellous bone of the segment. Therefore, the main manifestation of internal fixation failure is the instability of the head-neck fracture fragment relative to the distal fracture, including sliding along the direction of the head-neck screw and displacement such as varus and posterior tilt relative to the screw. In severe cases, this can lead to extrusion of the internal fixation device, ultimately resulting in delayed union, nonunion, malunion, or even loosening and breakage of the internal fixation device, leading to treatment failure.

[0005] Current intramedullary nail fixation methods have not effectively solved the problem of retraction of head and neck nails and femoral head and neck bone blocks along the direction of the head and neck nails.

[0006] To address the aforementioned problems, this invention provides an intramedullary nail and aiming system for enhancing the fixation stability of proximal femoral fractures. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides an intramedullary nail and aiming system for enhancing the fixation stability of proximal femoral fractures, thereby improving resistance to varus stress.

[0008] To achieve the above objectives, the present invention provides the following solution: An intramedullary nail for enhancing the fixation stability of proximal femoral fractures includes a main nail positioned along the femoral axis and located within the medullary cavity; a secondary nail positioned proximal to the main nail and penetrating it, obliquely inserted upwards into the femoral head and neck; an anti-retraction nail with its front end penetrating the cortex and the main nail and positioned obliquely downwards; and a distal locking nail positioned distal to the main nail and penetrating the cortex and the main nail. A longitudinal receiving groove is provided on the proximal lateral wall of the main nail, directly opposite the lateral cortical bone of the greater trochanter of the femur. An expansion piece made of shape memory alloy is disposed within the receiving groove, with one end fixed within the receiving groove and the other end free. When the environment in which the expansion piece is located reaches a designed temperature, it expands and extends out of the receiving groove, embedding itself into the lateral cortical bone of the greater trochanter.

[0009] Preferably, the expansion plates are made of nickel-titanium alloy and are evenly spaced along the outer circumference of the main nail, with at least four plates provided.

[0010] Preferably, the expansion plate is claw-shaped or wing-shaped.

[0011] Preferably, the proximal end of the main nail has an upwardly inclined proximal locking hole and an downwardly inclined anti-recoil locking hole, and the distal end of the main nail has a distal locking hole. The front part of the secondary nail is a smooth cylinder with a hemispherical front end and a rhomboid rear cross-section, and the tail end has a circular retaining shank. The secondary nail passes through the proximal locking hole and enters the femoral head and neck obliquely upward. The circular retaining shank is engaged on one side of the proximal locking hole, and the circular retaining shank has two symmetrical arc-shaped notches. The rear section of the anti-recoil nail is a smooth body that mates with the anti-recoil locking hole. The front section has external threads, and the front end penetrates the cortical layer. The rear end is engaged at the arc-shaped notch of the circular retaining shank and abuts against the circular retaining shank of the secondary nail.

[0012] Preferably, the end face of the circular shank has a threaded groove for engaging with the secondary nail aiming bracket.

[0013] Preferably, both the proximal locking hole and the anti-reverse locking hole are light holes, and the axes of the two holes form an angle of 90°-100°, so that the angle between the anti-reverse pin and the secondary pin is 90°-100°.

[0014] Preferably, the secondary nail has two staggered locking holes with smooth inner walls, namely a first locking hole and a second locking hole. Both the first and second locking holes are connected by fully threaded locking nails that can penetrate the femoral head and neck fracture fragment. These two locking nails pass through the two locking holes on the secondary nail and cross through the secondary nail, penetrating the strong cortical bone of the femoral head and neck fracture fragment. The locking nails on the secondary nail cross lock with the secondary nail, and the first and second locking holes do not interfere with the notch and the expansion flap.

[0015] Preferably, the diameter of the diamond-shaped main body of the secondary nail matches the diameter of the proximal locking hole, and the diameter of the circular shank at the rear end of the secondary nail is larger than the diameter of the proximal locking hole.

[0016] An aiming system includes a main aiming frame, a first auxiliary aiming frame, a second auxiliary aiming frame, and an auxiliary pin locking hole aiming frame; The main aiming frame includes a vertically arranged first arm, a horizontally arranged second arm, an inclined third arm, and a vertically arranged fourth arm, all of which are integrally formed. The first arm has a locking hole along its axial direction, through which a screw passes to connect with a threaded hole and a slot at the upper end of the main pin. The third arm has the same inclination angle as the auxiliary pin and is provided with an anti-retardant aiming hole. The outer side of the fourth arm is a vertical plane, on which adjustment holes and positioning slots are provided. The first auxiliary aiming frame includes an integrally formed first connecting arm and a first aiming arm. The first connecting arm is provided with a first connecting hole and an elastic plunger. A locking screw passes through the first connecting hole and connects to an adjustment hole. The elastic plunger cooperates with a positioning groove on the fourth arm. The aiming arm is provided with an inclined auxiliary pin aiming hole. The included angle between the axis of the auxiliary pin aiming hole and the anti-recoil pin aiming hole on the main aiming frame is the same as the included angle between the auxiliary pin and the anti-recoil pin. A first limiting platform is provided between the inner side of the first connecting arm and the first aiming arm. When the first connecting arm cooperates with the fourth arm, it can limit the fourth arm. The second auxiliary aiming frame includes an integrally formed second connecting arm and a second aiming arm. The second connecting arm is provided with a second connecting hole. When the second connecting arm is engaged with the fourth support arm, the locking screw passes through the second connecting hole and connects with the adjustment hole. The second aiming arm is provided with a locking pin aiming hole for aiming and locking the remote locking pin. A second limiting platform is provided between the inner side of the second connecting arm and the second aiming arm. The secondary nail locking hole aiming bracket includes a secondary nail connecting arm, a support arm, a first side arm, and a second side arm. The secondary nail connecting arm is threadedly connected to the end of the secondary nail by a screw, and the locking protrusions on both sides of the front section of the secondary nail connecting arm are precisely engaged with the arc-shaped notch of the circular locking handle at the end of the secondary nail. The support arm is connected to the secondary nail connecting arm and bends above the secondary nail, parallel to the secondary nail. The first side arm and the second side arm are connected to both sides of the support arm. Aiming holes corresponding to the first locking hole and the second locking hole are respectively opened on the first side arm and the second side arm. Two parallel aiming holes are also opened along the length direction of the support arm.

[0017] Preferably, the adjustment hole is a countersunk waist-shaped hole, and the first connecting hole and the second connecting hole are both through waist-shaped holes. In use, the nut of the locking screw is locked in the countersunk waist-shaped hole, and the locking screw passes through the connecting hole and connects with the nut. Limiting plates are provided on both sides of the first connecting arm. When the first connecting arm is engaged with the fourth support arm, the limiting plates slide and lock on both sides of the fourth support arm.

[0018] The present invention achieves the following technical effects compared to the prior art: 1. This invention transforms the force transmission method, which originally relied solely on distal locking pins, into one that uses an expansion plate to directly hook onto the lateral cortical bone. This design directly transfers bending stress to the densest cortical bone layer, rather than relying solely on cancellous bone, significantly enhancing resistance to varus stress.

[0019] 2. This invention directly uses an anti-removal screw to press against the end of the secondary nail, effectively preventing the secondary nail from coming out, loosening, or becoming unstable within the proximal locking hole. The front half of the secondary nail has a smooth cylindrical structure, while the rear half has a rhomboid structure that matches the locking hole of the main nail. This allows it to fit into the proximal locking hole of the main nail, eliminating gaps, providing strong stability, and preventing wobbling. It also determines the rotation angle of the secondary nail when inserted into the main nail, ensuring that the long axis of the rhomboid cross-section is parallel to the long axis of the main nail. This provides a reference for subsequent secondary nail locking operations, establishes a locking channel for the anti-removal locking screw, and facilitates nail removal after fracture healing, preventing nail breakage. Furthermore, the use of two proximal cortical locking screws enhances the stability between the secondary nail and the femoral head and neck bone fragment. The technical solution of this application increases the stability of internal fixation and the bone complex, enhances the postoperative limb's ability to withstand movement, reduces fracture end strain, improves healing rate and speed, helps prevent complications, and facilitates a rapid return to pre-injury life. Attached Figure Description

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

[0021] Figure 1 This is a schematic diagram of the expansion device of the present invention; Figure 2 This is a diagram showing the usage state of the present invention; Figure 3 This is a front view structural diagram of the present invention; Figure 4 This is a left-side structural diagram of the present invention; Figure 5 This is a three-dimensional structural diagram of the present invention; Figure 6 This is a schematic diagram of the anti-removal screw and main screw separation structure of the present invention; Figure 7 yes Figure 6 Enlarged structural diagram; Figure 8 This is a structural diagram of the secondary nail of the present invention; Figure 9 This is a front view structural diagram of the intramedullary nail of the present invention combined with an aiming system using a first-stage aiming frame; Figure 10 This is a right-side structural diagram of the intramedullary nail of the present invention combined with an aiming system using a first-stage aiming frame; Figure 11 This is a three-dimensional structural diagram of the intramedullary nail of the present invention combined with the aiming system using the first aiming frame; Figure 12 This is a three-dimensional structural view of the intramedullary nail of the present invention combined with the aiming system using the first auxiliary aiming frame from another direction; Figure 13 This is a three-dimensional structural diagram of the intramedullary nail of the present invention combined with an aiming system using a second aiming frame; Figure 14 This is a right view of the main aiming frame of the present invention; Figure 15 yes Figure 14 Axonometric drawing; Figure 16 This is a front view of the first aiming frame of the present invention; Figure 17 yes Figure 16 Axonometric drawing; Figure 18 This is a structural diagram of the aiming bracket for the secondary nail locking hole of the present invention.

[0022] Among them, 1. Main pin; 1a. Proximal locking hole; 1b. Anti-recoil locking hole; 1c. Distal locking hole; 2. Anti-recoil pin; 2a. Smooth body; 2b. External thread; 3. Secondary pin; 3a. Hemispherical structure; 3b. First locking hole; 3c. Second locking hole; 3d. Circular shank; 3e. Arc-shaped notch; 3f. Threaded groove; 4. Distal locking pin; 5. Leather layer; 6. Main aiming frame; 6a. First arm; 6b. Second arm; 6c. Third arm; 6d. Fourth arm; 6e. Locking hole; 6f. Anti-recoil pin aiming hole; 6g. Positioning groove; 6h, Adjustment hole; 7, First auxiliary aiming frame; 7a, First connecting arm; 7b, First aiming arm; 7c, First connecting hole; 7d, Secondary pin aiming hole; 7e, Limiting plate; 8, Second auxiliary aiming frame; 8a, Second connecting arm; 8b, Second connecting hole; 8c, Second aiming arm; 8d, Locking pin aiming hole; 9, Elastic plunger; 10, Locking screw; 11, Secondary pin locking hole aiming frame; 11a, Secondary pin connecting arm; 11b, Support arm; 11c, First side support arm; 11d, Second side support arm; 12, Receiving groove; 13, Expansion plate. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides an intramedullary nail and aiming system to enhance the fixation stability of proximal femoral fractures, thereby improving resistance to varus stress.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] refer to Figure 1An intramedullary nail for enhancing the fixation stability of proximal femoral fractures includes a main nail 1 positioned along the femoral axis and located within the medullary cavity; a secondary nail 3 positioned proximal to the main nail 1 and inserted obliquely upwards into the femoral head and neck; an anti-retraction nail 2 positioned with its front end penetrating the cortex and the main nail 1 and positioned obliquely downwards; and a distal locking nail 4 positioned distal to the main nail 1 and penetrating the cortex and the main nail. A longitudinal receiving groove is provided on the proximal lateral wall of the main nail 1, directly opposite the lateral cortical bone of the greater trochanter of the femur. An expansion piece 13 made of shape memory alloy is placed within the receiving groove. One end of the expansion piece 13 is fixed within the receiving groove, while the other end is free. When the environment surrounding the expansion piece 13 reaches the designed temperature, it expands and extends out of the receiving groove, embedding itself into the lateral cortical bone of the greater trochanter. Upon reaching the designed temperature, the expansion piece 13 springs outwards along the receiving groove, its tip or cutting edge design providing sufficient mechanical force to directly cut into or embed into the relatively dense cortical bone of the lateral greater trochanter. This step cleverly utilizes the hardness of the metal material and the preset deformation force to achieve mechanical interlocking with the bone cortex. This invention transforms the force transmission, which originally relied solely on the distal locking pin, into directly hooking the lateral bone cortex with the expansion plate 13. This design directly transmits bending stress to the densest bone cortex layer, rather than relying solely on cancellous bone, significantly enhancing resistance to inversion stress.

[0027] Furthermore, the design temperature mentioned here is generally normal human body temperature; the expansion plate 13 can be positioned in the following way: Utilizing the shape memory effect of nickel-titanium shape memory alloy, the material is in a martensitic state (soft and malleable) at low temperatures, and transforms into an austenitic state (restoring the preset shape) after reaching a specific temperature. The restoration of the preset shape mentioned here refers to the state after the expansion sheet 13 unfolds and is embedded in the bone cortex.

[0028] Specifically: Pre-implantation preparation: The intramedullary nail is placed in low-temperature sterile saline or special preservation solution, and the expansion sheet 13 is kept in a folded storage state; Implantation process: The implant is quickly placed into the medullary cavity, at which point the expansion flap 13 is still in an unexpanded state; Body temperature triggering: About 1-3 minutes after placement, body temperature causes the shape memory alloy temperature to gradually rise; Automatic unfolding: After reaching the phase change temperature, the expansion plate 13 automatically pops open along the preset direction and embeds into the bone cortex; Fixation complete: X-ray confirmed that the expansion sheet 13 has been fully unfolded; When removing it, the expansion plate 13 can be retracted by utilizing the reverse phase transition characteristic: Infuse the intramedullary nail cavity with sterile saline at 0-4℃ for local cooling; After the temperature drops below the phase transition temperature, the shape memory alloy returns to the martensitic state, and the expansion plate 13 automatically retracts into the slot. At this time, the outer wall of the main nail becomes smooth again and can be pulled out normally.

[0029] Furthermore, the expansion piece 13 is made of nickel-titanium alloy and is evenly spaced along the outer wall of the main nail, with at least four pieces. The purpose is to ensure that the expansion piece 13 can be evenly and stably fixed on the outer cortex after expansion, further strengthening the fixation strength of the main nail 1 in the medulla.

[0030] Furthermore, the expansion piece 13 is claw-shaped or wing-shaped.

[0031] Furthermore, to ensure the stability of the main nail 1 within the medullary cavity, the position of the expansion piece 13 on the main nail 1 is selected and set as follows: The femoral neck is a dense vertical bone plate located on the posteromedial side of the femoral neck, at the junction of the femoral neck and shaft. It is the core hub for bearing compressive stress. Placing the expansion plate 13 here allows it to "hook" the core area of ​​proximal femoral mechanical transmission from the outside, directly transferring inversion stress to the densest cortical bone layer. This maximizes the load-bearing capacity of the bone structure itself, achieving a "mechanical interlocking" effect. The axial position of the expansion plate 13 should match the aforementioned mechanical region, i.e., located proximal to the main nail (approximately the first 1 / 3 of the main nail's total length). To accurately determine the optimal position, a biomechanical comparative experiment is recommended: setting up models at different axial positions (e.g., 10mm, 20mm, and 30mm from the proximal end face of the main nail), and using finite element analysis to find the position with the minimum stress and displacement at the bone-expansion plate 13 interface under simulated physiological loads (e.g., above 700N).

[0032] See Figures 2 to 8 As shown, the present invention provides an intramedullary nail for enhancing the fixation stability of proximal femoral fractures, comprising a main nail 1, a secondary nail 3, an anti-retraction nail 2, and a distal locking nail 4.

[0033] The main nail 1 is positioned within the medullary cavity along the femoral axis. The proximal end of the main nail 1 has an upwardly angled proximal locking hole 1a and a downwardly angled anti-recoil locking hole 1b, while the distal end of the main nail 1 has a distal locking hole 1c. The proximal locking hole 1a mates with the secondary nail 3, the anti-recoil locking hole 1b mates with the anti-recoil nail 2, and the distal locking hole 1c mates with the distal locking nail 4.

[0034] refer to Figure 8The secondary nail 3 has a hollow structure, allowing a 2.5mm diameter guide pin to pass through. Its front part is a smooth cylinder with a hemispherical tip and a rhomboid cross-section at the rear. A circular retaining shank 3d is located at the tail end. The length ratio between the rhomboid and cylindrical parts is 1:4. The rhomboid portion of the secondary nail engages with the proximal locking hole 1a to prevent rotation and also determines the rotation angle of the secondary nail during insertion into the main nail, ensuring that the long axis of the rhomboid cross-section is parallel to the long axis of the main nail. This provides a reference for subsequent secondary nail locking operations and establishes a locking channel for the anti-retrograde locking nail. The secondary nail 3 passes through the proximal locking hole 1a obliquely upwards into the femoral head and neck, with the circular retaining shank 3d locking onto one side of the proximal locking hole 1a. The circular retaining shank 3d prevents complete insertion into the secondary nail hole on the main nail. Both the near-end locking hole 1a and the anti-recoil locking hole 1b are smooth holes, and the axes of the two holes form an angle of 90°-100°, so that the angle between the anti-recoil pin 2 and the auxiliary pin 3 is 90°-100°. After the auxiliary pin 3, the anti-recoil pin 2, and the main pin 1 are assembled, the anti-recoil pin 2 and the auxiliary pin 3 abut against each other, with the anti-recoil pin 2 pressing against the end of the auxiliary pin 3 to prevent the auxiliary pin 3 from moving backward and maintain stability; the end of the auxiliary pin 3 presses against the smooth part of the anti-recoil pin 2, which also prevents the anti-recoil pin 2 from loosening. Furthermore, after passing through the anti-recoil locking hole 1b, the front end of the anti-recoil pin 2 penetrates the leather layer 5, and the rear end presses against the circular catch 3d of the auxiliary pin 3; the leather layer 5 is used to increase the stability of the anti-recoil pin 2.

[0035] The distal locking pin 4 passes through the distal locking hole 1c and penetrates the cortical layer 5 to fix the distal end of the main pin 1. One or two distal locking holes 1c can be provided, employing either a static locking method inclined to the main pin 1 or a dynamic locking method perpendicular to the main pin 1. The distal locking hole 1c is a smooth, horizontal hole. This structure ensures the stability of the distal end of the main pin 1.

[0036] Using the above technical solution, an anti-retraction locking hole 1b is added to the main nail 1 to cooperate with the anti-retraction nail 2. The anti-retraction nail 2 can abut against the end of the secondary nail 3, directly preventing the secondary nail 3 from withdrawing within the proximal locking hole 1a of the main nail 1. Furthermore, the anti-retraction nail 2 penetrates the cortical layer 5 through the anti-retraction locking hole 1b, utilizing the cortical layer 5 to maintain the stability of the anti-retraction nail 2. Moreover, the secondary nail 3 is tilted upwards, while the anti-retraction nail 2 is tilted downwards, with an angle of 90°-100° between them. They abut against each other, making it difficult for the nail to withdraw or loosen. At the same time, the two proximal cortical locking nails enhance the stability between the secondary nail 3 and the femoral head and neck bone block. In addition, the anterior half of the secondary nail 3 that enters the femoral head and neck has a smooth cylindrical structure, while the posterior half has a rhomboid structure that matches the locking hole of the main nail, which can cooperate with the proximal locking hole 1a of the main nail 1, eliminating gaps, providing strong stability, and preventing shaking.

[0037] When removing the nail after the patient's fracture has healed, first remove the anti-retraction nail 2 with a screwdriver. Then, install the secondary nail aiming bracket and sliding hammer connecting rod through the thread at the tail end of the secondary nail, remove the locking nail on the secondary nail, and finally hammer the sliding hammer connecting rod to drive the secondary nail 3. Since the front half of the secondary nail 3 is a smooth cylindrical structure, it can be easily removed and it is difficult for the nail to break.

[0038] As a preferred embodiment in this case, refer to Figure 6 and Figure 7 The rear section of the anti-reverse pin 2 is a smooth body 2a that fits with the anti-reverse locking hole 1b. The front section is provided with an external thread 2b, and the front end penetrates the leather layer 5. The leather layer 5 can make the anti-reverse pin 2 more stable.

[0039] The circular clasp 3d has a threaded groove 3f on its end face for engaging with the secondary nail aiming frame. After the patient's fracture recovery, if the nail needs to be removed, the secondary nail aiming frame is connected via the threaded engagement with the circular clasp 3d of the secondary nail 3. A screwdriver is used to remove the secondary nail locking screw, and a hammer is used to strike the sliding hammer handle connected to the end of the aiming frame to pull out the secondary nail 3. Currently, the front end of the secondary nail 3 generally uses a threaded or spiral blade, requiring spiral removal, which is prone to breakage or difficult to remove, potentially causing secondary damage to the patient's fracture site. The smooth part's engagement with the proximal locking hole 1a is also very unstable. The secondary nail 3 of this application facilitates nail removal, and during use, the proximal cortical bone locking screw enhances the stability between the head and neck nail and the femoral head and neck bone fragments, preventing rotation. The locking screw can further improve stability by crossing through the cortical bone and locking with the secondary nail to form a three-dimensional spatial structure, which is beneficial to the healing of proximal femoral fractures. The circular retainer 3d has two symmetrical arc-shaped notches 3e. The anti-retraction pin 2 passes through the anti-retraction hole, and the smooth body 2a is engaged at the corresponding arc-shaped notch 3e of the circular retainer 3d. During assembly, the secondary pin 3 is first driven into the femoral head and neck. Because its posterior half has a matching rhomboid structure with the main pin locking hole, it can mate with the proximal locking hole of the main pin. At the same time, it can ensure that the long axis of the rhomboid section is parallel to the long axis of the main pin, providing a reference for the subsequent secondary pin locking pin operation and establishing a locking channel for the anti-retraction locking pin. Then, at this time, the arc-shaped notch 3e at the tail of the secondary pin is parallel to the axial direction of the anti-retraction pin 2 hole, and then enters the bone cortex 5 from the arc-shaped notch 3e along the anti-retraction pin 2 hole. This structure can also press the end of the secondary pin 3 tightly with the end of the anti-retraction pin 2, providing strong stability.

[0040] In clinical practice, the current auxiliary nail 3 works in conjunction with the main nail 1. The end of the auxiliary nail 3 needs to remain outside the bone for easy removal, but this results in poor stability and easy nail retraction. Using the auxiliary nail 3 of this application, the circular shank 3d at the end of the auxiliary nail 3 can be locked at the proximal locking hole 1a of the main nail 1, making it less prone to retraction. Furthermore, it can increase the length of the auxiliary nail 3 inserted into the femoral head and neck, improving stability.

[0041] Furthermore, the secondary nail 3 has two staggered locking holes with smooth inner walls, namely a first locking hole 3b and a second locking hole 3c. Both the first locking hole 3b and the second locking hole 3c penetrate the secondary nail and the bone cortex, respectively, and a locking screw is present. The locking screw can further improve stability by crossing through the bone cortex and locking with the secondary nail to form a three-dimensional spatial structure, which facilitates the recovery of patients with proximal femoral fractures.

[0042] The rhomboid body of the secondary nail 3 matches the shape of the proximal keyhole 1a, and the diameter of the circular retaining shank 3d at the rear end of the secondary nail 3 is larger than the diameter of the proximal keyhole 1a. This structure avoids a large gap between the secondary nail 3 and the inner wall of the proximal keyhole 1a, reducing wobbling, and also prevents the tail of the secondary nail 3 from penetrating into the proximal keyhole of the main nail. Preferably, the rear end of the anti-reverse nail 2 has a Torx groove, which is used with a Torx screwdriver to prevent it from falling off and stripping.

[0043] This application directly uses an anti-removal screw 2 to press against the end of the secondary screw 3, effectively preventing the secondary screw 3 from coming out, loosening, or becoming unstable within the proximal locking hole 1a. The secondary screw 3 has a smooth micro-rhomboid structure, which can stably fit with the proximal micro-rhomboid locking hole 1a, reducing shaking, facilitating screw removal, and preventing screw breakage. Simultaneously, two proximal cortical locking screws enhance the stability between the secondary screw 3 and the femoral head and neck bone fragment. The technical solution of this application increases the stability of internal fixation and the bone complex, enhances the postoperative limb's ability to withstand movement, reduces fracture end strain, improves healing rate and speed, helps prevent complications, and facilitates a faster return to pre-injury life.

[0044] refer to Figures 9 to 17 This application also discloses an intramedullary nail aiming system for enhancing the fixation stability of proximal femoral fractures, including a main aiming frame 6, a first auxiliary aiming frame 7, a second auxiliary aiming frame 8, and an auxiliary nail locking hole aiming frame 11.

[0045] The main aiming frame 6 includes a vertically arranged first arm 6a, a horizontally arranged second arm 6b, an inclined third arm 6c, and a vertically arranged fourth arm 6d, all of which are integrally formed. The first arm 6a has a locking hole 6e along its axial direction, through which a screw passes to connect with the threaded hole and slot at the upper end of the main pin 1. The third arm 6c has the same inclination angle as the auxiliary pin 3 and is provided with an anti-recoil aiming hole 6f, through which the anti-recoil pin 2 can be aimed and locked. The outer side of the fourth arm 6d is a vertical plane, on which an adjustment hole 6h and a positioning groove 6g are provided. The vertical plane is used to cooperate with the first auxiliary aiming frame 7 and the second auxiliary aiming frame 8, and is fixedly connected through the adjustment hole 6h.

[0046] The first auxiliary aiming frame 7 includes an integrally formed first connecting arm 7a and a first aiming arm 7b. The first connecting arm 7a has a first connecting hole 7c and an elastic plunger 9. A locking screw 10 passes through the first connecting hole 7c and connects to the adjustment hole 6h. The elastic plunger 9 engages with the positioning groove 6g on the fourth arm 6d. The position where the elastic plunger 9 engages with the positioning groove 6g is such that the auxiliary nail aiming hole 7d is exactly aligned with the position of the auxiliary nail 3. This structure facilitates quick positioning. If there is a slight deviation in position, the position can be adjusted using the locking screw 10 on the adjustment hole 6h. This structure also facilitates the use of this aiming frame for aiming and locking other intramedullary nails. The first aiming arm 7b has an inclined auxiliary nail aiming hole 7d. The angle between the axis of the auxiliary nail aiming hole 7d and the anti-recoil nail aiming hole 6f on the main aiming frame 6 is the same as the angle between the auxiliary nail 3 and the anti-recoil nail 2, which is 90°-100°. First, aim at the auxiliary nail 3 and lock, and then aim at the anti-recoil nail 2 through the anti-recoil nail aiming hole 6f and lock. This is convenient to use. A first limiting platform is provided between the inner side of the first connecting arm 7a and the first aiming arm 7b. When the first connecting arm 7a cooperates with the fourth support arm 6d, it can limit the fourth support arm 6d, thereby limiting the extreme position between the first connecting arm 7a and the fourth support arm 6d.

[0047] The second aiming frame 8 includes an integrally formed second connecting arm 8a and a second aiming arm 8c. The second connecting arm 8a has a second connecting hole 8b. When the second connecting arm 8a is engaged with the fourth support arm 6d, the locking screw 10 passes through the second connecting hole 8b and connects to the adjustment hole 6h. The second aiming arm 8c has a locking pin aiming hole 8d for aiming and locking the distal locking pin 4. A second limiting platform is provided between the inner side of the second connecting arm 8a and the second aiming arm 8c. The second aiming frame 8 can be used to aim and lock the distal locking pin 4 of the main pin 1.

[0048] refer to Figure 17 The auxiliary nail locking hole aiming bracket 11 includes an auxiliary nail connecting arm 11a, a support arm 11b, a first side support arm 11c, and a second side support arm 11d. The auxiliary nail connecting arm 11a is threadedly connected to the end of the auxiliary nail 3 by screws, and the locking protrusions on both sides of the front section of the auxiliary nail connecting arm 11a are precisely engaged at the arc-shaped notch 3e of the circular locking handle 3d at the end of the auxiliary nail 3. The support arm 11b is connected to the auxiliary nail connecting arm 11a and bent above the auxiliary nail 3, parallel to the auxiliary nail 3. The first side support arm 11c and the second side support arm 11d are connected to both sides of the support arm 11b. Aiming holes corresponding to the first locking hole 3b and the second locking hole 3c are respectively opened on the first side support arm 11c and the second side support arm 11d. Two parallel aiming holes are also opened along the length direction of the support arm 11b. For ease of use, the locking hole positions are set according to different patients, and the two parallel aiming holes can be used to nail and lock the two parallel locking holes on the auxiliary nail. The aiming bracket can lock the secondary nail by driving it into the locking hole of the secondary nail, and Preferably, the adjustment hole 6h is a countersunk oblong hole, and the first connecting hole 7c and the second connecting hole 8b are both through oblong holes. In use, the nut of the locking screw 10 is engaged in the countersunk oblong hole, and the locking screw 10 passes through the connecting hole and connects with the nut, facilitating locking. Furthermore, the two oblong holes provide ample adjustment space, making the aiming mount more versatile. Limiting plates 7e are provided on both sides of the first connecting arm 7a. When the first connecting arm 7a engages with the fourth support arm 6d, the limiting plates 7e slide and engage on both sides of the fourth support arm 6d. During aiming, the anti-reverse pin 2 and the auxiliary pin 3 are prone to angular deviation. The structure of the limiting plates 7e prevents slight rotation of the first connecting arm 7a, resulting in more accurate aiming.

[0049] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0050] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An intramedullary nail for enhancing the fixation stability of proximal femoral fractures, characterized in that, The device includes a main nail positioned along the femoral axis and located within the medullary cavity; a secondary nail positioned proximal to the main nail and inserted obliquely upwards into the femoral head and neck; an anti-retraction nail with its front end penetrating the cortex and the main nail and positioned obliquely downwards; and a distal locking nail positioned distal to the main nail and penetrating the cortex and the main nail. A longitudinal receiving groove is provided on the proximal lateral wall of the main nail, the receiving groove being directly opposite the lateral cortical bone of the greater trochanter of the femur. An expansion piece made of shape memory alloy is provided in the receiving groove, one end of which is fixed in the receiving groove, and the other end is a free end. When the environment in which the expansion piece is located reaches the design temperature, it will expand and extend out of the receiving groove and embed into the cortical bone of the lateral side of the greater trochanter.

2. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 1, characterized in that, The expansion plates are made of nickel-titanium alloy and are evenly spaced along the outer circumference of the main nail, with at least four plates.

3. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 2, characterized in that, The expansion plate is claw-shaped or wing-shaped.

4. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 3, characterized in that, The main nail has an upwardly inclined proximal locking hole and a downwardly inclined anti-recoil locking hole at its proximal end, and a distal locking hole at its distal end. The secondary nail has a smooth cylindrical front end with a hemispherical front end and a rhomboid rear cross-section, and a circular retaining shank at its tail end. The secondary nail passes through the proximal locking hole and enters the femoral head and neck obliquely upwards. The circular retaining shank is engaged on one side of the proximal locking hole and has two symmetrical arc-shaped notches. The anti-recoil nail has a smooth rear section that mates with the anti-recoil locking hole. Its front section has external threads, and its front end penetrates the cortical layer. Its rear end is engaged at the arc-shaped notch of the circular retaining shank and abuts against the circular retaining shank of the secondary nail.

5. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 4, characterized in that, The circular clasp has a threaded groove on its end face for engaging with the secondary nail aiming frame.

6. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 4, characterized in that, Both the near-end locking hole and the anti-reverse locking hole are light holes, and the axes of the two holes form an angle of 90°-100°, so that the angle between the anti-reverse pin and the secondary pin is 90°-100°.

7. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 4, characterized in that, The secondary nail has two staggered locking holes with smooth inner walls, namely the first locking hole and the second locking hole. Both the first locking hole and the second locking hole are connected to a fully threaded locking nail that can penetrate the femoral head and neck fracture fragment. The two locking nails pass through the two locking holes on the secondary nail and cross the secondary nail, and penetrate the strong cortical bone of the femoral head and neck fracture fragment. The locking pin on the secondary pin is cross-locked with the secondary pin, and the first locking hole and the second locking hole do not interfere with the notch and the expansion flap.

8. The intramedullary nail for enhancing the fixation stability of proximal femoral fractures according to claim 4, characterized in that, The diameter of the diamond-shaped main body of the secondary nail matches the diameter of the proximal keyhole, and the diameter of the circular shank at the rear end of the secondary nail is larger than the diameter of the proximal keyhole.

9. An aiming system, characterized in that, An intramedullary nail for enhancing the fixation stability of proximal femoral fractures as described in any one of claims 1 to 8 includes a main aiming frame, a first auxiliary aiming frame, a second auxiliary aiming frame, and an auxiliary nail locking hole aiming frame; The main aiming frame includes a vertically arranged first arm, a horizontally arranged second arm, an inclined third arm, and a vertically arranged fourth arm, all of which are integrally formed. The first arm has a locking hole along its axial direction, through which a screw passes to connect with a threaded hole and a slot at the upper end of the main pin. The third arm has the same inclination angle as the auxiliary pin and is provided with an anti-retardant aiming hole. The outer side of the fourth arm is a vertical plane, on which adjustment holes and positioning slots are provided. The first auxiliary aiming frame includes an integrally formed first connecting arm and a first aiming arm. The first connecting arm is provided with a first connecting hole and an elastic plunger. A locking screw passes through the first connecting hole and connects to an adjustment hole. The elastic plunger cooperates with a positioning groove on the fourth arm. The aiming arm is provided with an inclined auxiliary pin aiming hole. The included angle between the axis of the auxiliary pin aiming hole and the anti-recoil pin aiming hole on the main aiming frame is the same as the included angle between the auxiliary pin and the anti-recoil pin. A first limiting platform is provided between the inner side of the first connecting arm and the first aiming arm. When the first connecting arm cooperates with the fourth arm, it can limit the fourth arm. The second auxiliary aiming frame includes an integrally formed second connecting arm and a second aiming arm. The second connecting arm is provided with a second connecting hole. When the second connecting arm is engaged with the fourth support arm, the locking screw passes through the second connecting hole and connects with the adjustment hole. The second aiming arm is provided with a locking pin aiming hole for aiming and locking the remote locking pin. A second limiting platform is provided between the inner side of the second connecting arm and the second aiming arm. The secondary nail locking hole aiming bracket includes a secondary nail connecting arm, a support arm, a first side arm, and a second side arm. The secondary nail connecting arm is threadedly connected to the end of the secondary nail by a screw, and the locking protrusions on both sides of the front section of the secondary nail connecting arm are precisely engaged with the arc-shaped notch of the circular locking handle at the end of the secondary nail. The support arm is connected to the secondary nail connecting arm and bends above the secondary nail, parallel to the secondary nail. The first side arm and the second side arm are connected to both sides of the support arm. Aiming holes corresponding to the first locking hole and the second locking hole are respectively opened on the first side arm and the second side arm. Two parallel aiming holes are also opened along the length direction of the support arm.

10. The aiming system according to claim 9, characterized in that, The adjustment hole is a countersunk waist-shaped hole, and the first connecting hole and the second connecting hole are both through waist-shaped holes. In use, the nut of the locking screw is locked in the countersunk waist-shaped hole, and the locking screw passes through the connecting hole and connects with the nut. Limiting plates are provided on both sides of the first connecting arm. When the first connecting arm is engaged with the fourth support arm, the limiting plates slide and lock on both sides of the fourth support arm.

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