A steel nail fixing assembly for pelvic fracture

Abstract

This invention relates to the field of medical device technology and discloses a steel nail fixation assembly for pelvic fractures, including a nail tube, an anchor head, a positioning core rod, and a sealing cap. The nail tube has at least one through-hole on its wall and a movable cavity inside. The anchor head is located at the front end of the nail tube and includes an expansion base and an elastic expansion flap extending posteriorly from the expansion base. The elastic expansion flap has locking teeth on its outer side. This invention uses a medical-grade elastic metal material to make the nail tube, allowing it to bend according to preoperative planning to adapt to the physiological curvature of the pelvis, effectively preventing straight bone nails from penetrating the cortical bone and damaging blood vessels and nerves. The invention also relies on the locking cooperation between the locking protrusion and the positioning ring groove, combined with the external thread locking of the sealing cap at the tail end and the double compression of its end face against the core rod and nail tube, to achieve a firm lock and prevent slippage of the fracture ends under pressure closure.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a steel nail fixation assembly for pelvic fractures. Background Technology

[0002] Pelvic fractures are a common and serious trauma in orthopedic clinics, and the quality of internal fixation surgery directly affects the patient's future functional recovery. Currently, the most widely used implants for internal fixation treatment of pelvic fractures are straight metal screws (such as hollow tension screws and fully threaded screws). During the surgical procedure, a straight bone tunnel is usually pre-drilled in the bone according to the fracture location. Then, the straight screw is directly screwed into or driven into the bone, relying on the threads at the end of the screw to lock with the bone tunnel, thereby achieving alignment and compression of the fracture ends.

[0003] However, the human pelvis has a complex anatomical structure. Its iliac wing, pubic ramus, ischium, and other parts have natural physiological curvatures, and the cross-section of the bone varies greatly in different locations. In practical applications, existing straight bone screws cannot conform to the natural curvature of the pelvis. If they are forcibly implanted along the curved bone channel, the screw body is very likely to deviate from the predetermined axis and pierce the contralateral cortical bone or the inner wall of the pelvis. This will not only lead to a significant decrease in the holding force of the bone screw, but may also cause collateral damage to important nerves, blood vessels and adjacent organs in the pelvic cavity, increasing the surgical risk. Furthermore, straight screws can only provide a single axial linear tensile force. For oblique, comminuted, or complex fractures involving pelvic ring instability, single linear compression often cannot achieve uniform and tight alignment of the fracture surface on various curved and oblique surfaces. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a steel nail fixation component for pelvic fractures. This component can match the anatomical curve of the pelvis, bend along the bone tunnel during implantation, and provide stable counter-tension to the fracture ends through internal traction while in a bent state, ultimately achieving a firmly locked tail end. This effectively solves the defects of the existing technologies.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A pelvic fracture fixation assembly using steel nails includes a nail tube, an anchor head, a positioning core rod, and a sealing cap. The nail tube has at least one through-hole on its wall and a movable cavity inside. The anchor head is located at the front end of the nail tube and includes an expansion base and an elastic expansion flap extending rearward from the expansion base. The elastic expansion flap has locking teeth on its outer side and is positioned corresponding to the through-hole, allowing it to expand radially outward from the through-hole. The positioning core rod is movably inserted into the nail tube, and its front end has a guide cone surface for radially expanding the elastic expansion flap. The sealing cap is detachably installed at the rear end of the nail tube to lock and fix the tail end of the positioning core rod to the tail end of the nail tube.

[0006] Preferably, the front end of the nail tube is provided with an arc-shaped inlet end, and a receiving groove is provided on the nail tube near the inlet end. The arc-shaped inlet end reduces damage to the bone tunnel and surrounding soft tissue during implantation, and the receiving groove provides contraction space for the expansion flap.

[0007] Preferably, the inner wall of the movable cavity is provided with limiting ribs and guiding ribs along the axial direction, and multiple through holes are provided and are equidistantly distributed along the receiving groove and communicate with the movable cavity. The end of the through hole away from the inlet end is provided with a fitting arc slope, and multiple locking protrusions are provided in a ring near the inlet end inside the movable cavity.

[0008] Preferably, the anchor head includes an expansion base and a plurality of elastic expansion petals extending rearward from the expansion base. The expansion base and the plurality of elastic expansion petals are integrally connected by a connecting transition arc. The integral connection between the expansion base and the elastic expansion petals avoids stress concentration and improves the fatigue life of the expansion petals under repeated deformation.

[0009] Preferably, the elastic expansion petal is provided with an axially extending deformation groove, and the end of the deformation groove near the expansion base is provided with a groove end hole. The multiple elastic expansion petals are respectively inserted into the corresponding multiple through holes. The deformation groove and the groove end hole enhance the elastic deformation capability of the expansion petal and effectively prevent stress cracks from forming.

[0010] Preferably, each of the elastic expansion petals has a plurality of push blocks on its inner side. The plurality of push blocks are arranged along the axial direction of the elastic expansion petal and form a wedge-shaped inclined surface that gradually converges from one end near the expansion base to the other end. The outer side of the elastic expansion petal has a plurality of locking teeth distributed along the axial direction. The inclined surface of the locking teeth faces the inlet end of the nail tube, and the tail end of the teeth faces the rear end of the nail tube. The wedge-shaped push blocks can convert the axial thrust into the radial expansion force. The inclined surface of the unidirectional locking teeth faces forward and the tail end of the teeth faces backward, providing extremely strong anti-pull-out locking capability.

[0011] Preferably, the expansion base is provided with a snap-fit ​​groove, the limiting rib abuts against the end of the expansion base, the guide rib is embedded in the snap-fit ​​groove, the connecting transition arc fits the fitting arc slope, the limiting rib and the snap-fit ​​groove cooperate to prevent the anchor head from rotating and moving, and the connecting transition arc fits the fitting arc slope to ensure smooth expansion.

[0012] Preferably, the positioning core rod includes a core shaft, the front end of the core shaft is provided with a push head, the front end of the push head forms an inclined guide cone surface, the push head is provided with a positioning ring groove for engaging with the locking protrusion, the guide cone surface smoothly pushes open the expansion flap, the positioning ring groove and the locking protrusion interfere and lock, preventing the positioning core rod from retracting and maintaining the expansion locking state.

[0013] Preferably, the end face of the sealing cap facing the nail tube is provided with a core rod receiving hole and an outer tube retaining groove. The core rod receiving hole abuts against the tail end of the mandrel, and the outer tube retaining groove abuts against the tail end of the nail tube. The outer periphery of the sealing cap is provided with an external thread for locking with the bone channel thread. The core rod receiving hole and the outer tube retaining groove on the end face of the sealing cap simultaneously press the mandrel and the tail end of the nail tube to achieve double locking. The locking of the external thread with the bone channel enhances the overall fixation stability.

[0014] Preferably, the nail tube is made of a medical metal material with elastic bending deformation capability, which can be bent by external instruments to fit the arc-shaped bone channel of the pelvis.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a nail tube made of medical-grade elastic metal material, allowing it to bend according to preoperative planning to adapt to the physiological curvature of the pelvis. This effectively prevents straight bone nails from penetrating the cortical bone and damaging blood vessels and nerves. By hammering in a pusher with a guide cone surface, the axial thrust is converted into radial expansion force through the engagement of the cone surface with the inclined surface of the wedge-shaped pusher on the inner side of the expansion flap. This allows the outer locking teeth to penetrate the bone wall, and the reverse-inclined unidirectional tooth tail provides strong anti-pulling capability. Relying on the locking interference engagement between the locking protrusion and the positioning ring groove, combined with the external thread locking of the tail cap and the double compression of its end face against the mandrel and nail tube, a firm locking and anti-pulling mechanism is achieved for the fracture ends under pressure closure. Because the nail tube has deformation capability and the expansion flap is an elastic structure, after the positioning mandrel is removed during removal, the expansion flap can automatically contract and detach from the bone wall due to its own elasticity. This significantly reduces the difficulty of removing internal fixation devices and improves the clinical safety and minimally invasiveness of the surgery. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is an overall sectional view of the present invention; Figure 3 This is a view of the anchoring position of the present invention; Figure 4 This is a structural view of the nail tube of the present invention; Figure 5 This is a structural view of the anchor head of the present invention; Figure 6 This is a cross-sectional view of the anchor head of the present invention; Figure 7 This is a view showing the position of the end cap of the present invention; Figure 8 This is a structural view of the end cap of the present invention.

[0018] Drawing number descriptions: 1. Nail tube; 11. Inlet end; 12. Receiving groove; 13. Movable cavity hole; 14. Limiting rib; 15. Guide mating rib; 16. Through hole; 17. Fitting arc slope; 18. Locking protrusion; 2. Anchor head; 21. Expansion base; 211. Snap-fit ​​groove; 22. Expansion flap; 23. Connecting transition arc; 24. Deformation groove; 25. Groove end round hole; 26. Push block; 27. Locking tooth; 3. Positioning core rod; 31. Core shaft; 32. Push head; 33. Guide cone surface; 34. Positioning ring groove; 4. End cap; 41. Core rod receiving hole; 42. Outer tube retaining groove. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] The following description is intended to disclose the invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious modifications will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be used in other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0021] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or position based on the orientation or positional relationship shown in the accompanying drawings. They are merely simplified descriptions for the convenience of describing this invention and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this invention.

[0022] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0023] Example: Please see Figure 1-8 A steel nail fixation assembly for pelvic fractures includes a nail tube 1, an anchor head 2, a positioning core rod 3, and a sealing cap 4. The nail tube 1 is a long tubular structure, with its front end for implantation into the bone fragment at the fracture end and its rear end exposed outside the bone or at the tail of the bone tunnel. The anchor head 2 is pre-installed inside the front end of the nail tube 1, with part of its structure protruding from the tube wall of the nail tube 1. The positioning core rod 3 is movably inserted into the nail tube 1, with its front end having an expansion function and its rear end protruding a certain length from the tail end of the nail tube 1 during implantation. The sealing cap 4 is installed at the tail end of the nail tube 1 in the final stage of the operation to lock the nail tube 1 and the internal positioning core rod 3 simultaneously.

[0024] The front end of the nail tube 1 is an arc-shaped inlet end 11 with smooth and rounded edges, which can reduce the scraping of surrounding soft tissue and the cutting of the bone tunnel entrance when implanting the arc-shaped bone tunnel. The inside of the nail tube 1 is provided with a through movable cavity 13, which provides a channel for the movement of the positioning core rod 3. An annular storage groove 12 is provided near the inlet end 11 of the nail tube 1.

[0025] On the inner wall of the movable cavity 13, two annular ribs are provided along the axial direction, namely the limiting rib 14 and the guide fitting rib 15. At the corresponding position of the tube wall of the receiving groove 12, multiple through holes 16 are provided annularly at equal intervals on the nail tube 1. These through holes 16 connect the movable cavity 13 to the outside. The side wall of the through holes 16 away from the inlet end 11, that is, the side facing the tail end of the nail tube 1, is provided with an outwardly inclined arc-shaped slope, that is, the fitting arc slope 17. Multiple protruding locking protrusions 18 are provided annularly on the side of the movable cavity 13 near the inlet end 11.

[0026] The anchor head 2 includes an expansion base 21 in the shape of a smooth cylinder, and multiple elastic expansion petals 22 extending from the expansion base 21 to the rear end. In order to ensure that the elastic expansion petals 22 have good deformation and recovery ability when compressed, the expansion base 21 and the elastic expansion petals 22 are connected in one smooth manner by a transition arc 23 to avoid stress concentration and fracture caused by sharp corners.

[0027] Multiple elastic expansion petals 22 of the anchor head 2 are respectively inserted into multiple through holes 16 on the nail tube 1. The anchor head 2 is axially positioned on the expansion base 21 of the nail tube 1. A snap-fit ​​groove 211 is provided on the expansion base 21, and the limiting rib 14 just abuts against the end of the expansion base 21. The guide rib 15 is just embedded in the snap-fit ​​groove 211, thereby preventing the anchor head 2 from rotating or moving back and forth axially in the nail tube 1. The arc surface of the connecting transition arc 23 is just in contact with the fitting arc slope 17 on the nail tube 1. This arc surface design can greatly increase the contact area and provide good support and guidance when the elastic expansion petals 22 expand outward. In order to enhance the deformation performance of the elastic expansion petals 22, an axially extending deformation groove 24 is provided on the elastic expansion petals 22. A groove end round hole 25 is provided at one end of the deformation groove 24 near the expansion base 21. This round hole can effectively prevent the deformation groove 24 from generating stress cracks after multiple expansions.

[0028] Inside the elastic expansion flap 22, there are multiple protruding push blocks 26. These push blocks 26 are closely arranged along the axial direction to form a wedge-shaped inclined surface that gradually narrows from one end near the expansion base 21 to the other end. On the outside of the elastic expansion flap 22, there are multiple locking teeth 27 distributed along the axial direction. The locking teeth 27 have the characteristics of unidirectional ratchet teeth. The inclined surface of the teeth faces the direction of the inlet end 11 of the nail tube 1, while the tail end of the teeth faces the rear end of the nail tube 1.

[0029] The positioning core rod 3 includes a long straight core shaft 31. The front end of the core shaft 31 is coaxially provided with a cylindrical push head 32. The front end of the push head 32 is provided with an inclined guide cone surface 33, which is a cone-shaped end. At the rear position of the push head 32, an annular positioning groove 34 is opened on the outer periphery. The push head 32 of the positioning core rod 3 is inserted into the movable cavity hole 13 of the nail tube 1, and the tail end of the core shaft 31 extends backward.

[0030] The end cap 4 is a plug-like structure with external threads, used to close the tail of the component at the end of the operation. On the end face of the end cap 4 facing the inside of the nail tube 1, there are two concentric circular receiving holes, a core rod receiving hole 41 in the center and an outer tube retaining groove 42 around the periphery. The inner diameter of the core rod receiving hole 41 is adapted to the outer diameter of the core shaft 31, and the inner diameter of the outer tube retaining groove 42 is adapted to the outer diameter of the nail tube 1. The end cap 4 can be threaded and locked to the bone at the tail end of the patient's bone tunnel through its external threads.

[0031] In clinical use, since the nail tube 1 is made of medical metal material with elastic bending deformation capability (its material properties and bending process can be compared with the bending operation of elastic intramedullary nails in clinical practice), the doctor can use an external bending tool to bend the nail tube 1 according to the preoperative planned pelvic curvature. During bending, the anchor head 2 will not be deformed or damaged. An arc-shaped bone channel matching the bending curvature of the nail tube 1 is pre-drilled on the patient's pelvis. The bent component is slowly inserted from the bone channel entrance. Since the inlet end 11 is arc-shaped, it can smoothly pass through the turning point of the curved bone channel and be continuously pushed so that the inlet end 11 of the nail tube 1 reaches the inside of the fracture fragment that needs to be pressure fixed. At this time, the locking tooth 27 of the anchor head 2 is located in the bone channel and is close to the bone wall, but has not penetrated. The doctor holds an external percussion tool and taps the tail end of the mandrel 31 exposed outside the bone channel. With the tapping, the mandrel 31 pushes the push head 32 to move towards the front end of the nail tube 1, which is the direction of the inlet end 11. As the guide cone 33 continues to move inward, the inclined surface of the guide cone 33 begins to engage at an angle with the wedge-shaped pusher 26 on the inner side of the elastic expansion flap 22. Under the action of the wedge-shaped push, the forward thrust is converted into a radially outward expansion force, forcing multiple elastic expansion flaps 22 to expand outward along the perforation hole 16. The elastic expansion flap 22 undergoes elastic deformation. As the expansion continues, the inclined surface of the locking tooth 27 continuously compresses the bone of the inner wall of the bone tunnel, eventually causing the locking tooth 27 to penetrate into the bone. Since the tooth tail faces the rear end of the nail tube 1, this structure provides extremely strong anti-pulling force, which firmly holds the fracture fragment. As the doctor continues to push the mandrel 31, the guide cone 33 continues to move forward, eventually passing the locking protrusion 18. Due to the elasticity of the medical metal material, the locking protrusion 18, after being deformed by force, passes the guide cone 33 and instantly locks into the positioning ring groove 34. At this time, an interference-fitting locking state is formed. The positioning ring groove 34 is limited by the locking protrusion 18, thereby temporarily preventing the positioning mandrel 3 from retracting backward. With the locking teeth 27 firmly gripping the distal bone fragment, the doctor can pull the nail tube 1 with external tools and use the tube body of the nail tube 1 to pull the distal fracture fragment towards the proximal end, so that the fracture ends are tightly closed. After confirming that the closure and reduction are good, the excess metal at the tail needs to be cut off. When cutting, it is important to note that the tail end of the mandrel 31 must protrude a certain distance from the tail end of the nail tube 1. External measuring tools can be used to assist in the measurement. Cut off the excess material at the tail end of the mandrel 31 and the nail tube 1 to ensure that the above length is reserved correctly. After the cutting is completed, the end cap 4 is installed at the end of the component. Tighten the end cap 4 so that its external thread fits tightly with the bone wall thread of the bone tunnel. After it is tightened in place, the core rod receiving hole 41 on the front end face of the end cap 4 directly abuts against the cut end of the core shaft 31, while the outer tube retaining groove 42 abuts against the cut end of the nail tube 1. This can firmly press the core shaft 31 towards the inlet end 11, further ensuring that the guide cone surface 33 will not disengage from the locking protrusion 18, thus completing the complete insertion and fixation of the bone nail.

[0032] When the patient's fracture has healed and internal fixation needs to be removed, first loosen and remove the end cap 4 counterclockwise. Then, use medical forceps (such as heavy-duty forceps) to clamp the end of the mandrel 31 that is exposed outside the end of the nail tube 1, and pull the mandrel 31 outward with force. The pulling force must be greater than the interference holding force between the positioning ring groove 34 and the locking protrusion 18. When the force reaches a certain level, the two will disengage. As the positioning mandrel 3 is pulled out as a whole, the guide cone surface 33 leaves the push block 26. Due to the elasticity of the elastic expansion flap 22 itself, after losing the radial spreading force of the guide cone surface 33, the elastic expansion flap 22 will rebound and deform on its own, shrinking and retracting into the receiving groove 12. At this time, the locking teeth 27 disengage from the bone wall. Finally, use forceps to clamp the end of the nail tube 1 and pull it out easily, sliding the entire nail tube 1 assembly out of the arc-shaped bone tunnel, completing the removal.

[0033] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments, and any modifications or variations of the embodiments of the present invention may be made without departing from the stated principles.

Claims

1. A steel nail fixation assembly for pelvic fractures, characterized in that, include: The nail tube (1) has at least one through-hole (16) on its wall and a movable cavity (13) inside the tube. An anchor head (2) is provided at the front end of the nail tube (1), including an expansion base (21) and an elastic expansion flap (22) extending backward from the expansion base (21). The outer side of the elastic expansion flap (22) is provided with locking teeth (27), and the elastic expansion flap (22) is provided with a through-hole (16) and can expand radially outward from the through-hole (16). The positioning core rod (3) is movably inserted into the nail tube (1), and its front end is provided with a guide cone surface (33) for radially expanding the elastic expansion flap (22). The end cap (4) is detachably installed at the rear end of the nail tube (1) to lock and fix the tail end of the positioning core rod (3) to the tail end of the nail tube (1).

2. The steel nail fixation assembly for pelvic fractures according to claim 1, characterized in that, The front end of the nail tube (1) is provided with an arc-shaped inlet end (11), and a storage groove (12) is provided on the nail tube (1) near the inlet end (11).

3. A steel nail fixation assembly for pelvic fractures according to claim 2, characterized in that, The inner wall of the movable cavity (13) is provided with limiting ribs (14) and guide ribs (15) along the axial direction. Multiple through holes (16) are provided and are distributed equidistantly along the receiving groove (12) and communicate with the movable cavity (13). The end of the through hole (16) away from the inlet end (11) is provided with a fitting arc slope (17). Multiple locking protrusions (18) are provided circumferentially in the movable cavity (13) near the inlet end (11).

4. A steel nail fixation assembly for pelvic fractures according to claim 3, characterized in that, The anchor head (2) includes an expansion base (21) and a plurality of elastic expansion lobes (22) extending rearward from the expansion base (21), wherein the expansion base (21) and the plurality of elastic expansion lobes (22) are integrally connected by a connecting transition arc (23).

5. A steel nail fixation assembly for pelvic fractures according to claim 4, characterized in that, The elastic expansion petal (22) is provided with an axially extending deformation groove (24), and the deformation groove (24) is provided with a groove end hole (25) at one end near the expansion base (21). The multiple elastic expansion petals (22) are respectively inserted into the corresponding multiple through holes (16).

6. A steel nail fixation assembly for pelvic fractures according to claim 5, characterized in that, Each of the elastic expansion petals (22) has a plurality of push blocks (26) on its inner side. The plurality of push blocks (26) are arranged along the axial direction of the elastic expansion petal (22) and form a wedge-shaped inclined surface that gradually converges from one end near the expansion base (21) to the other end. The outer side of the elastic expansion petal (22) has a plurality of locking teeth (27) distributed along the axial direction. The inclined surface of the locking teeth (27) faces the inlet end (11) of the nail tube (1) and the tail end faces the rear end of the nail tube (1).

7. A steel nail fixation assembly for pelvic fractures according to claim 4, characterized in that, The expansion base (21) is provided with a snap-fit ​​groove (211), the limiting rib (14) abuts against the end of the expansion base (21), the guide mating rib (15) is embedded in the snap-fit ​​groove (211), and the connecting transition arc (23) fits against the fitting arc slope (17).

8. A steel nail fixation assembly for pelvic fractures according to claim 1, characterized in that, The positioning core rod (3) includes a core shaft (31), and the front end of the core shaft (31) is provided with a push head (32). The front end of the push head (32) forms an inclined guide cone surface (33), and the push head (32) is provided with a positioning ring groove (34) for engaging with the locking protrusion (18).

9. A steel nail fixation assembly for pelvic fractures according to claim 8, characterized in that, The end cap (4) has a core rod receiving hole (41) and an outer tube retaining groove (42) on one end face facing the nail tube (1). The core rod receiving hole (41) abuts against the tail end of the mandrel (31), and the outer tube retaining groove (42) abuts against the tail end of the nail tube (1). The outer periphery of the end cap (4) is provided with an external thread for locking with the bone channel thread.

10. A steel nail fixation assembly for pelvic fractures according to claim 1, characterized in that, The nail tube (1) is made of medical metal material with elastic bending deformation capability and can be bent by external instruments to fit the arc-shaped bone channel of the pelvis.

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