Intramedullary fixation device for small-diameter bone fractures

Abstract

This invention discloses an intramedullary fixation device for small-diameter bone fractures, comprising Kirschner wires and locking screws. The Kirschner wires have recessed planes on their circumferential surfaces at both ends. The device also includes at least one pair of locking screws, each with an external thread on its shaft and a flat inner end face. The inner end face of each locking screw and the recessed plane on the side of the Kirschner wire can be pressed together in surface contact. This invention is suitable for fixing slender bone fractures with small intramedullary diameters. Compared to traditional intramedullary nailing with aiming and locking holes, this method is simpler and less invasive. Aiming and fixing only requires axial locking, allowing for moderate radial deviation without affecting the effectiveness, thus reducing the difficulty of operation.

Description

Technical Field

[0001] This invention belongs to the field of fracture fixation device technology, specifically relating to an intramedullary fixation device for small-diameter bone fractures. Background Technology

[0002] Internal fixation methods for fractures include plates and intramedullary nails. Plate fixation is simple to operate and has a short learning period, but it is more invasive, has a higher chance of accidental injury, and is prone to infection, nonunion, delayed healing, nail breakage, and plate breakage. Postoperative scars are large, affecting aesthetics and not in line with the principles of minimally invasive surgery. Intramedullary nails use closed and minimally invasive techniques. Locking intramedullary nails can prevent fracture rotational deformity, reduce the risk of internal device breakage, reduce surgical infection rates, promote high fracture healing rates, and central fixation avoids stress shielding, resulting in a low refracture rate. It conforms to the principles of minimally invasive surgery and is the current direction of development. However, it is difficult to operate and learn, and distal locking of intramedullary nails is difficult. Reduction is divided into closed and limited open reduction, but neither is anatomical reduction, and nonunion and delayed healing can occur, causing greater stress for patients.

[0003] For fractures of small bones such as the tibia or radius, and slender bones like the femur in children, conventional intramedullary nails are ineffective. This is because the intramedullary cavity diameter is small, and intramedullary nails typically require proximal and distal holes for fixation. When designing small intramedullary nails, it's impossible to further design proximal and distal holes. This not only reduces the nail's strength, making it unable to provide effective support, but also makes precise external aiming and drilling difficult with such small locking holes. Currently, plate fixation is still used for small bone fractures, which increases surgical trauma, increases the risk of infection, nonunion, and delayed healing, and is particularly unsuitable for pediatric surgery, increasing postoperative scarring and contradicting minimally invasive principles. Summary of the Invention

[0004] To address the issue that existing conventional intramedullary nails are only suitable for fractures with large bone cavity diameters and not for fractures with small bone cavities, this invention provides an intramedullary fixation device for small-diameter bone fractures, which can achieve intramedullary fixation for slender bone fractures with small inner diameters, thereby reducing the wound area and shortening the rehabilitation period.

[0005] The solution adopted by the present invention to solve its technical problem is: an intramedullary fixation device for small-diameter bone fractures, including Kirschner wires and locking pins. The Kirschner wires have concave planes on their two ends of the circumference. The device also includes at least one pair of locking pins. Each locking pin has an external thread on its shaft and a plane on its inner end. The plane on the inner end of the locking pin and the concave plane on the side of the Kirschner wire can be pressed together in a surface contact manner.

[0006] Each side of the recessed plane has a limiting stop, and the distance between the two limiting stops is adapted to the diameter of the locking pin. Thus, after the inner end plane of the locking pin contacts the recessed plane on the side of the Kirschner wire, the two limiting stops on both sides of the locking pin constrain the locking pin.

[0007] The locking pin is a locking pin with equal inner and outer diameters, and all segments of the pin are covered with blade-shaped threads, or the outer end of the locking pin has a cap.

[0008] It also includes an arc-shaped clamp plate, which is fitted onto the outer side of the bone wall. Threaded holes are provided on the side wall of the arc-shaped clamp plate, and the threads of the locking pin can be matched with the threaded holes for installation. The arc-shaped clamp plate is fixed to the bone wall, and the locking pin is fixed to the arc-shaped clamp plate by threads.

[0009] Furthermore, at least two additional screw holes are added to the arc-shaped clamp plate, and corresponding locking pins are installed in each hole. The screw holes are distributed axially, circumferentially, or alternately. When two screw holes are adjacent, after the two locking pins are installed, the inner ends of both adjacent locking pins are supported in a pointer-like recessed plane. When two screw holes are opposite each other, after the two locking pins are installed, one locking pin is supported on the back of the Kirschner wire, and the other locking pin is supported in a recessed plane on the front of the Kirschner wire.

[0010] Further recessed surfaces can be added to the back or side of the Kirschner wire. Different distribution patterns correspond to different Kirschner wire models; the appropriate Kirschner wire should be selected based on the characteristics of the small-diameter bone.

[0011] Alternatively, a series of recessed planes can be arranged at equal intervals on one side of the Kirschner wire, thus providing more options for the location of the locking pins.

[0012] The beneficial effects of this invention are as follows: This invention is applicable to the fixation of slender bone fractures with small intramedullary diameters. Compared to traditional intramedullary nail aiming and locking techniques, this method is simpler and less invasive. Only axial locking is required during aiming and fixation, allowing for moderate radial deviation without affecting the effectiveness, thus reducing the difficulty of operation. It preserves the soft tissue attachment of the fracture fragments and maintains blood supply. The Kirschner wires are small in diameter and can be implanted from the fracture site, making the operation simple and easy to learn.

[0013] The locking pins have threads with a cutting edge that penetrates the inner wall of the drilled hole in the bone, allowing the flat surface of the inner end of the locking pin to press firmly against the corresponding concave surface. After each locking pin presses the Kirschner wire into the inner wall of the bone cavity, a stable support relationship is formed between the locking pin and the Kirschner wire, preventing axial sliding, rotation, and oscillation in any direction. This ensures the stability of the fractured bone segments after joining.

[0014] Multiple locking screws are used to press the Kirschner wire against the inner wall of the bone cavity. The supporting force of the bone cavity wall on the Kirschner wire, as well as the supporting force between the locking screws and the inner wall of the drilled hole in the bone, ensures that the inner end plane of the locking screws is tightly pressed against the concave plane of the Kirschner wire, thus preventing axial slippage and rotation of the Kirschner wire. With the Kirschner wire unable to slide or rotate axially, the two fractured segments and the Kirschner wire become one, preventing slippage, rotation, and wobbling.

[0015] An arc-shaped clamp plate was fitted onto the outer side of the bone wall. The arc-shaped clamp plate itself has a certain degree of rigidity, and after selecting an appropriate size and fitting it onto the outer side of the bone wall, it can be firmly clamped to the bone wall. After the arc-shaped clamp plate is fixed to the bone wall, it is further secured with locking screws. This overcomes the problem of weak connection between the locking screws and the bone wall in weak areas, and also allows for the fixation of bone fragments in comminuted fractures. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the fixing device of the present invention in use.

[0017] Figure 2 This is an external structural diagram of a Kirschner wire in the fixing device of the present invention.

[0018] Figure 3 This is one of the schematic diagrams showing the concave plane connection relationship between the locking pin and the Kirschner wire.

[0019] Figure 4 This is the second schematic diagram showing the relationship between the recessed plane of the locking pin and the Kirschner wire.

[0020] Figure 5 This is a structural diagram illustrating one method of using an arc-shaped clamp plate.

[0021] Figure 6 This is a structural diagram illustrating another application of the curved clamp plate.

[0022] Figure 7 This is a structural diagram of an arc-shaped clamp plate.

[0023] Figure 8 This is another structural diagram of the curved clamp plate.

[0024] Figure 9 This is a cross-sectional view of a Kirschner wire.

[0025] Figure 10 This is another cross-sectional view of a Kirschner wire.

[0026] Figure 11 This is a diagram showing the external structure of another type of Kirschner wire.

[0027] Figure 12 This is a schematic diagram showing the correspondence between the locking pin and the recessed plane of the Kirschner wire. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Example 1: An intramedullary fixation device for small-diameter bone fractures, its application status is as follows. Figure 1 As shown, this fixation device is installed in the cavity of a small bone and is designed to address the problem that existing conventional intramedullary nails are only suitable for fractures with large bone cavity diameters and not for fractures with small bone cavities. With this device, intramedullary fixation of slender bone fractures with small inner diameters can be achieved. The wound only needs to expose the fracture ends to achieve reduction, thus achieving the goal of minimally invasive surgery.

[0030] One implementation of this device has the following specific structure: Figure 2 As shown, a recessed plane 2 is provided on the circumferential surface of the Kirschner wire 1. In this embodiment, there are two recessed planes at each end of the Kirschner wire. The number of recessed planes is not limited, but at least one recessed plane is provided at each end. The Kirschner wire penetrates the internal cavity of both fracture segments, as shown... Figure 1 As shown, the two segments correspond to two concave planes and two locking pins, respectively.

[0031] like Figure 3 As shown, a locking pin 4 is installed corresponding to each recessed plane 2, and the inner end face of each locking pin is flat. Moreover, the circumferential surface of each locking pin has threads, and the threads have a cutting edge that can penetrate into the inner wall of the bone drill hole.

[0032] from Figure 1 As can be seen, after drilling a hole in the bone arm, the diameter of the hole is smaller than the diameter of the locking pin 4. The locking pin 4 is screwed into the inner wall of the corresponding hole, and the threaded cutting edge of the locking pin is pressed and embedded in the inside of the hole, so that the plane 5 of the inner end of the locking pin can be pressed tightly against the corresponding concave plane.

[0033] Figure 2 It can also be seen that there are limiting stops 3 on both sides of the concave plane. The distance between the limiting stops 3 on both sides is adapted to the diameter of the locking pin 4, so that when the locking pin presses against the corresponding concave plane, the two sides of the locking pin are constrained by the limiting stops 3.

[0034] Based on the above structure, after each locking screw 4 presses the Kirschner wire 1 into the inner wall of the bone cavity, a stable support relationship is formed between each locking screw and the Kirschner wire, so that each component cannot slide axially, rotate, or swing in any direction. This ensures the stability of the two fractured segments after docking.

[0035] The type of locking pin structure used is not limited, but it must ensure that its shank is threaded and its inner end is flat. The outer end of the locking pin is not strictly required to have a cap; in this embodiment, the outer end of the locking pin is designed not to have a cap. Figure 3However, other embodiments may design the outer end of the locking pin to have a cap, such as... Figure 4 As shown. The locking pin, excluding the cap, has its inner end plane pressed against the recessed plane of the Kirschner wire, with the locking pin partially exposed or completely screwed into the drilled hole.

[0036] In this embodiment, the Kirschner wire is inserted into the bone cavity along the fixed end. Then, holes are drilled in the bone wall at the corresponding positions of the Kirschner wire's grooves. Due to the small diameter of the Kirschner wire, medullary reaming is unnecessary or only a very short reaming is required, reducing the occurrence of fat embolism and internal bleeding. It can be seen that this embodiment uses multiple locking pins to press the Kirschner wire against the inner wall of the bone cavity. The supporting force of the bone cavity wall on the Kirschner wire, as well as the supporting force between the locking pins and the inner wall of the drilled holes in the bone, ensures that the inner end plane of the locking pins is tightly pressed against the recessed plane of the Kirschner wire, thereby preventing axial slippage and rotation of the Kirschner wire. With the Kirschner wire not sliding or rotating axially, the two fractured segments and the Kirschner wire become one, preventing slippage, rotation, and wobbling.

[0037] It should be noted that, in this scheme, the direction and position of the internal concave plane on the corresponding side and position of the intramedullary nail can be determined based on the external dimensions of the corresponding position. The concave plane locking of the Kirschner wire uses a direct-view locking technique, requiring little or no fluoroscopy. Figure 12 The correspondence between the locking pin and the concave plane of the Kirschner wire shows that, despite the small diameter of the Kirschner wire, even a slight deviation in the corresponding position of the locking pin and the concave plane does not affect the stability of the fixation or the effectiveness of the product. This reduces the difficulty of operation and makes it easy to lock the concave plane corresponding to the Kirschner wire. However, existing intramedullary nails need to be inserted from the bone end and require strict and precise locking of the distal hole. Due to the large amount of deformation at the end, locking the locking hole at the end is difficult.

[0038] Example 2: Based on the structural features described in Example 1, this example further adds an arc-shaped clamping plate 6, as shown in Example 1. Figure 5 As shown. Example 1 uses locking screws screwed into the bone for fixation, but from... Figure 5 As can be seen, in the thin bone wall area 7 of small-diameter bone, when locking screws 4 are used, the engagement between the screw threads and the bone is small, resulting in weakened stability. To address this issue, an arc-shaped clamping plate 6 is used. Figure 5 As can be seen, the arc-shaped clamp plate 6 is fitted onto the outer side of the bone wall. The arc-shaped clamp plate 6 itself has a certain rigidity. After selecting the appropriate model and fitting it onto the outer side of the bone wall, it can be firmly clamped onto the bone wall.

[0039] A threaded hole 7 is provided on the side wall of the arc-shaped clamp plate 6. The thread of the locking nail 4 can be matched with the threaded hole 7 for installation. Thus, after the arc-shaped clamp plate 6 is fixed to the bone wall, it is also fixed to the arc-shaped clamp plate 6 by the locking nail. This is used to overcome the problem that the connection between the locking nail and the weak area 8 of the bone wall is not strong.

[0040] This embodiment uses an arc-shaped clamp plate 6, which is particularly suitable for circumferential fixation of comminuted fractures. The bone fragments are placed inside the arc-shaped clamp plate 6. Figure 6 9 represents the suture of bone fragments in a comminuted fracture.

[0041] In this embodiment, the arc-shaped clamp plate 6 has a moderate pressure function. The appropriate length of Kirschner wire is selected according to the length of the bone shaft involved in the fracture. For example, for comminuted fractures, the arc-shaped clamp plate can clamp the bone fragments in the bone gap and keep them naturally locked.

[0042] Example 3: Based on Example 2, two screw holes are added to the arc-shaped clamp plate 6 and corresponding locking screws are installed respectively.

[0043] One implementation method is as follows Figure 7 As shown, the two screw holes are distributed adjacently, so that after the two locking pins are installed, the inner ends of the two adjacent locking pins can be supported in the indented plane.

[0044] Another implementation method is as follows Figure 8 As shown, the two screw holes are distributed opposite each other. After the two locking pins are installed, one locking pin is supported on the back of the Kirschner wire, and the other locking pin is supported in the concave plane on the front of the Kirschner wire, which can still form a stable structure.

[0045] The above-mentioned method of setting two or more screw holes on the arc-shaped clamp plate 6 and installing corresponding locking nails can improve the connection strength between the arc-shaped clamp plate 6 and the bone wall, and also maintain the stability of each locking nail.

[0046] Example 4: Based on the above examples, a recessed plane can be added to the back or side of the Kirschner wire, as shown in the examples below. Figure 9 and Figure 10 As shown. Considering the strength of Kirschner wires, it is generally not recommended to add recessed surfaces on the back or sides of Kirschner wires and to install locking pins, but this is suitable for some special cases, such as... Figure 6 The diagram shows a situation where the arc-shaped clamp plate 6 can be fixed simultaneously from two directions, or on the back or side where the bone wall is relatively thick.

[0047] Example 5: Based on the above examples, one possible method for using Kirschner wires is as follows: Figure 11The structure shown features a series of equally spaced recessed planes on one side of the Kirschner wire. Although the excessive number of recessed planes reduces the overall support strength, it improves versatility when strength requirements are not high or when the needs are met by increasing the strength of the steel. During use, holes can be drilled in thicker areas of different bone segments, and corresponding locking screws can be screwed in. The Kirschner wire's implantation position can be flexibly adjusted according to the fracture type. For example, in comminuted fractures, rotating the Kirschner wire keeps the recessed planes aligned with areas with more bone fragments, facilitating the addition of screws to fix the fracture.

[0048] It should be understood that the specific embodiments described above are merely illustrative of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, or improvements made without departing from the spirit and scope of the invention should be included within the scope of protection of the invention. It is not excluded that, based on Embodiment 2, a connecting member may be added to the end of the arc-shaped clamp plate to facilitate the formation of a closed ring structure. For example, holes or posts may be provided on the two arc-shaped edges of the arc-shaped clamp plate, and the two holes or posts may be fixed together by a connecting strap or rope. It is not excluded that a U-shaped rod may be connected to the outer end of the Kirschner wire, with the exposed portion of the U-shaped rod parallel to the Kirschner wire in the bone cavity. The exposed portion is located directly in front of or to the side of the Kirschner wire's recessed plane, and has a mark corresponding to the position of the Kirschner wire's recessed plane on the exposed portion. It is not excluded that a reinforcing rib parallel to the axial direction (generatrix) may be added to the side of the Kirschner wire.

Claims

1. one An intramedullary fixation device for small-diameter bone fractures, comprising Kirschner wires (1), locking screws (4), and an arc-shaped clamp plate (6), characterized in that: The Kirschner wire (1) is a slender rod suitable for implantation into a narrow bone marrow cavity. The front of the Kirschner wire (1) has a recessed plane (2) that does not penetrate the cross-section of the rod at least at both ends. Each recessed plane (2) has a limiting stop (3) on both sides. The arc-shaped clamp plate (6) is fitted onto the outer side of the bone wall, and two threaded holes (7) are provided on the side wall of the arc-shaped clamp plate (6) in a relatively distributed manner. The lock pins (4) are at least two in number, each lock pin (4) has an external thread on its shaft, and the inner end face of each lock pin (4) is a plane; each lock pin (4) corresponds one-to-one with each recessed plane (2); The two locking pins (4) are screwed into the two oppositely distributed threaded holes (7), the inner end plane (5) of one locking pin (4) is used to press against the back of the Kirschner wire (1) or the recessed plane provided on the back, and the inner end plane (5) of the other locking pin (4) is used to directly press against the recessed plane (2) on the front of the Kirschner wire (1) in a face contact manner, and the two side limiting stops (3) provide lateral restraint to the locking pin (4); Thus, the two locking pins (4) press against the Kirschner wire (1) from opposite directions, forming opposing repulsive forces to lock the Kirschner wire (1). At the same time, each locking pin (4) is fixedly connected to the threaded hole (7) of the arc-shaped clamp plate (6) through its external thread, thereby locking and fixing the Kirschner wire (1) located in the medullary cavity, the locking pin (4) penetrating the bone wall, and the arc-shaped clamp plate (6) located on the outside of the bone wall into one unit. The broken bone is clamped and fixed in the interlayer between the Kirschner wire (1) and the arc-shaped clamp plate (6).

2. The intramedullary fixation device for small-diameter bone fractures according to claim 1, characterized in that, The locking pins are equal in diameter inside and out, and all sections of the rod are covered with blade-shaped threads.

3. The intramedullary fixation device for small-diameter bone fractures according to claim 1, characterized in that, The outer end of the locking pin has a cap.

4. The intramedullary fixation device for small-diameter bone fractures according to claim 1, characterized in that, A recessed plane is added to the back or side of the Kirschner wire (1).

5. The intramedullary fixation device for small-diameter bone fractures according to claim 1, characterized in that, A series of recessed planes are arranged at equal intervals on one side of the Kirschner wire (1).

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