A combined patella fracture fixation device

Abstract

This invention relates to a combined patellar fracture fixation device, comprising a Kirschner wire with threads at both ends, a tail cap, and a two-hole steel plate. The threaded Kirschner wire has a sharp end and a flat end, with an unthreaded middle section. The tail cap has a central channel connecting both ends of the Kirschner wire, with the thinner end embedded in the patellar bone. The two-hole steel plate has different widths at both ends; the wider end has a hole that connects to the tail cap, while the narrower end has a hole through which a tension band cable can pass. The Kirschner wire, tail cap, and steel plate are combined to form a patellar fracture fixation device, used in pairs. Connecting the cable creates a tension band for fixation. This invention offers better stability than traditional Kirschner wire tension band technology, effectively reducing the likelihood of loosening and displacement of the traditional Kirschner wire, the risk of cable slippage leading to tension band failure, and reducing the risk of irritation to surrounding tissues and skin puncture by the tail of the traditional Kirschner wire. This facilitates early postoperative functional exercises for patients, promotes patellar fracture healing, and provides a new and more effective fixation device for patellar fractures.

Description

Technical Field

[0001] This invention relates to the field of medical device design, specifically to a combined patellar fracture fixation device. Background Technology

[0002] The patella is an important component of the knee extensor mechanism, located at the front of the knee joint. It slides within the femoral trochlea to complete knee flexion and extension movements. Due to its superficial location, the patella is easily fractured by direct or indirect trauma. Patellar fractures are relatively common clinically, accounting for approximately 1% of all fractures. Patellar fractures can be broadly classified based on their morphology into transverse fractures, vertical fractures, and comminuted fractures, with transverse patellar fractures being the most frequent. Poorly managed patellar fractures can lead to patellofemoral joint degeneration, eventually developing into traumatic osteoarthritis. For patellar fractures with minimal displacement and articular surface misalignment, and where the extensor mechanisms remain largely intact, conservative treatment with plaster casts or braces is possible. However, for patellar fractures with significant displacement and articular surface misalignment, and where the extensor mechanism is damaged, aggressive surgical treatment is necessary.

[0003] Wire cerclage, Kirschner wire tension banding, patellar claws, plate fixation, cannulated lag screws, and anchors can all be used for patellar fracture fixation. Among these, the Kirschner wire tension banding technique is considered the gold standard for treating transverse patellar fractures. First proposed by the AO (Aggregate Osteoarthritis) organization, the basic principle of the Kirschner wire tension banding technique is as follows: two parallel Kirschner wires are initially fixed perpendicular to the fracture line. Then, a wire is sequentially wrapped around the ends of the two Kirschner wires in a figure-eight pattern and finally tied at the anterior side of the patella for fixation. When the knee joint completes flexion and extension, the tension of the quadriceps muscle causes the patella to separate. The Kirschner wire tension banding technique converts this separation tension into pressure between the fracture fragments, stabilizing the fracture and promoting healing. The Kirschner wire tension banding technique is particularly suitable for transverse patellar fractures, as well as fractures of the inferior pole of the patella with large bone fragments and comminuted fractures. Although the Kirschner wire tension band technique is widely used in patellar fractures, some serious complications exist during its application, such as wire slippage and failure, Kirschner wire displacement, and infection caused by the Kirschner wire tip puncturing the skin. These complications require removal of internal fixation devices, revision surgery, or anti-infection treatment, causing significant pain to patients and troubling clinicians. It is these shortcomings that have forced us to modify and upgrade this technique.

[0004] The reason for Kirschner wire tension band failure is analyzed as follows: During the procedure, the tail end of the Kirschner wire needs to be bent, shortened, and embedded within the quadriceps tendon and patellar ligament. During knee joint movement, the bent tail end of the Kirschner wire moves with the tendon, causing displacement and loosening. The displaced tail end is palpable subcutaneously, irritating surrounding tissues and causing inflammation. In severe cases, it can puncture the skin, causing infection, and even lead to wire slippage and tension band failure. Some researchers have replaced the Kirschner wire with a hollow tension screw, achieving better results. As long as the screw length is appropriate, it significantly reduces tension band loosening and failure, as well as irritation to surrounding soft tissues. Other researchers have modified the Kirschner wire by designing a special hole at the tail end, preventing wire slippage and failure after passing through. Drawing on the advantages of the two technologies mentioned above and avoiding their patents, we plan to design a modular fixation device that retains the core of tension band technology while avoiding its drawbacks. This modular patellar fracture fixation device features a split design for assembly and use. The split design avoids the shortcomings of traditional Kirschner wire tension band devices, while the combined use retains the core of traditional tension band technology. To address Kirschner wire loosening, a new type of Kirschner wire is designed with threads at both ends for stronger holding force with surrounding bone, and a smooth middle section located near the fracture line for easy sliding. To address the drawback of Kirschner wires irritating surrounding soft tissues, this design completely embeds the Kirschner wire within the patella, connecting both ends with a cap. The body of the cap is also embedded within the patellar bone, leaving only a small portion exposed, minimizing irritation to surrounding soft tissues. For tension band cable fixation, a novel steel plate is designed as an intermediate connecting device. One end connects to the cap behind the Kirschner wire, while the other end has a small hole for the tension band cable to pass through. The cable achieves a figure-eight fixation through the holes in the special steel plate, with almost no irritation to the quadriceps tendon and patellar ligament. This combined patellar fixation device retains the core technology of Kirschner wire tension band fixation while reducing the chance of loosening and wire slippage, causing almost no irritation to surrounding tissues, meeting the requirements of early knee joint mobilization, stabilizing and promoting fracture healing. Summary of the Invention

[0005] The purpose of this invention is to provide a combined patellar fracture fixation device.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A modular patellar fracture fixation device includes Kirschner wires with threads at both ends, a cap, and a two-hole steel plate. The Kirschner wires are trimmed to a suitable length as needed. The cap and the two-hole steel plate are connected to the ends of the Kirschner wires to form the modular patellar fracture fixation device. The modular patellar fracture fixation device is used in pairs, and cables are arranged in a figure-eight pattern and then fixed in front of the patella for fixation.

[0007] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the Kirschner wires with threads at both ends, the tail cap, and the two-hole small steel plate are all made of titanium alloy.

[0008] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the diameter of the threaded Kirschner wire should not be less than 2 mm.

[0009] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the threaded portion of the Kirschner wire is located at both ends, with a 1.5cm-2cm unthreaded section in the middle. The threaded portion, located at both ends of the patella, integrates tightly with the bone and is not easily loosened. The unthreaded portion is positioned at the fracture site, facilitating sliding compression of the fracture.

[0010] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the tail cap body has a longitudinal channel with an inner diameter approximately equal to that of the Kirschner wire. The inner wall of the channel is threaded, and the threads match the threads at both ends of the Kirschner wire. The thinner end connects to both ends of the Kirschner wire, achieving stability through thread matching, while the thicker end has a diameter larger than the inner diameter of the two-hole steel plates, preventing slippage after the steel plates are connected.

[0011] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the inner diameter of the two-hole steel plate is slightly larger than the diameter of the narrower end of the cap. The two ends of the steel plate have different widths; the hole on the wider end connects to the cap, while the hole on the narrower end allows the tension cable to pass through.

[0012] In the aforementioned combined patellar fracture fixation device, as a preferred embodiment, the Kirschner wire, tail cap, and two-hole small steel plate are assembled to form a combined patellar fracture fixation device, which can be used individually. However, the device can be used in pairs and further configured with cables to give full play to the advantages of tension band technology, resulting in better effects and avoiding the defects of traditional tension band technology.

[0013] The advantages of this invention are: Guided by the "AO" principle, this invention retains the core of traditional tension band techniques while avoiding their drawbacks, such as Kirschner wire loosening, cable slippage leading to tension band failure, irritation of surrounding tissues, or skin puncture causing infection. The device provides sufficiently strong fixation, facilitating early functional exercises, shortening rehabilitation time, reducing patient suffering, and improving the surgeon's skill level, offering a novel fixation method for patellar fractures. Furthermore, the invention's "split-unit design and combined use" addresses the innovative development of tension band techniques. Attached Figure Description

[0014] Appendix Figure 1This is a schematic diagram of the overall and exploded structure of the combined patellar fracture fixation device described in this invention; Appendix Figure 2 This is a frontal view of the combined patellar fracture fixation device of the present invention, in which two Kirschner wires are inserted into the patella perpendicular to the patellar fracture line and parallel to the long axis of the patella. Appendix Figure 3 This is a frontal view of the combined patellar fracture fixation device of the present invention after the two Kirschner wires have been inserted into the patella and trimmed to an appropriate length; Appendix Figure 4 This is a front view of the combined patellar fracture fixation device of the present invention, in which two Kirschner wires are inserted into the patella and a two-hole small steel plate is placed and connected. Appendix Figure 5 This is a front view of the combined patellar fracture fixation device of the present invention, after the two Kirschner wires are inserted into the patella and the two-hole small steel plate and the tail cap are placed and connected. Appendix Figure 6 This is a front view of the combined patellar fracture fixation device of the present invention, showing the two Kirschner wires inserted into the patella, and the placement and connection of the two-hole small steel plate, the tail cap, and the cable. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments. It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0016] The reference numerals and components involved in the accompanying drawings are shown below: Overall and exploded structural diagrams of a modular patellar fracture fixation device; Overall design of a modular patellar fracture fixation device; 1.1.1 - Kirschner wires with threads at both ends; 1.1.2a - Front view of the two-hole small steel plate; 1.1.2b - Side view of the two-hole small steel plate; 1.1.3a - Front view of the tail cap; 1.1.3b - Side view of the tail cap; 2-Patent; 2.1 - Patellar fracture line; 3-Femur; 4-Tibia; 5-Cables; Example 1: A combined patellar fracture fixation device Please see the appendix Figure 1-6 As stated in the appendix Figure 1As shown, a combined patellar fracture fixation device is 1.1. The device, when disassembled, consists of three parts: 1.1.1 Kirschner wires with threads at both ends, 1.1.2 a small steel plate with two holes, and 1.1.3 a tail cap.

[0017] From the appendix Figure 2 - Appendix Figure 6 The specific usage methods are recorded as follows according to the process.

[0018] Following a patellar fracture, the fracture line is shown in Figure 2.1. Figure 2 As shown, after patellar fracture reduction, the reduction forceps maintain the reduction while two threaded Kirschner wires are inserted perpendicularly to the fracture line from the superior border of the patella and exit from the inferior border. Both Kirschner wires are parallel to the long axis of the patella. The unthreaded portion of the Kirschner wire is located at the fracture line. The ends of the Kirschner wires are trimmed to the appropriate length as shown in the attached diagram. Figure 3 As shown, it protrudes slightly above the patellar bone by 2mm.

[0019] Connect the wider hole on the two-hole steel plate to the threaded Kirschner wire as shown in the attached diagram. Figure 4 As shown in the attached diagram. The narrower side of the cap extends beyond the wider hole of the two-hole steel plate and engages with the Kirschner wire. A hollow drill is used to pre-drill holes along both ends of the threaded Kirschner wire into the patellar bone, facilitating the embedding of the narrower end of the cap into the patellar bone. Figure 5 As shown. The tail cap and Kirschner wires are connected tightly by threads, which can provide pressure fixation for the fracture. The two-hole steel plate is located between the tail cap and the patellar bone. The two combined patellar fracture fixation devices are now assembled.

[0020] As attached Figure 6 As shown, cable 5 is routed through the narrower hole of the two-hole steel plate. The cable can be titanium wire, titanium cable, or non-absorbable wire. After crossing the patella in a figure-eight pattern at the anterior edge of the patella, it is tightened and fixed to form a tension band fixation.

[0021] As described in this specification, references to terms such as "an embodiment" indicate that a specific structure, feature, or material described in connection with that embodiment is included in at least one embodiment of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific structures, features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0022] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to well understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents. The above descriptions are merely preferred embodiments of the invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the principles of the invention, and these improvements and additions should also be considered within the scope of protection of the invention.

Claims

1. A combined patellar fracture fixation device, characterized in that, It includes Kirschner wires with threads at both ends, a tail cap, and a small steel plate with two holes. After trimming, the tail cap and the steel plate are connected to the two ends of the Kirschner wire to form a combined patellar fracture fixation device. This device is used in pairs, and then a cable is arranged around it in a figure-eight pattern and fixed in front of the patella.

2. A combined patellar fracture fixation device according to claim 1, characterized in that, The Kirschner wire with threads at both ends, the tail cap, and the small steel plate with two holes are all made of titanium alloy.

3. A combined patellar fracture fixation device according to claim 1, characterized in that, The Kirschner wire described above has threads at both ends, but the middle 1.5-2cm section is unthreaded.

4. A combined patellar fracture fixation device according to claim 1, characterized in that, The Kirschner wire with threads at both ends has a sharp end that can penetrate bone and a flat end that can be connected to a power device.

5. A combined patellar fracture fixation device according to claim 1, characterized in that, The tail cap has a longitudinal channel in its body, the inner diameter of which is equivalent to the inner diameter of the Kirschner wire, and the inner wall of the channel is provided with threads that match the threads at both ends of the Kirschner wire.

6. A combined patellar fracture fixation device according to claims 1 and 3, characterized in that, The tail cap has a thinner end that connects to both ends of the Kirschner wire and is stabilized by thread matching, while the thicker end has a diameter larger than the inner diameter of the two-hole steel plates to prevent the steel plates from slipping after connection.

7. A combined patellar fracture fixation device according to claim 1, characterized in that, The thinner end of the cap is embedded in the patellar bone, while the thicker end remains outside the patellar bone.

8. A combined patellar fracture fixation device according to claim 1, characterized in that, The inner diameter of the two-hole steel plate is slightly larger than the diameter of the thinner end of the cap.

9. A combined patellar fracture fixation device according to claims 1 and 7, characterized in that, The two-hole steel plate has different widths at both ends. The hole on the wider end is connected to the tail cap, and the hole on the narrower end is connected to and passes through the tension cable.

10. A combined patellar fracture fixation device according to claim 1, characterized in that, The aforementioned threaded Kirschner wires, tail caps, and two-hole steel plates are assembled to form a combined patellar fracture fixation device. This device is usually used in pairs, but can also be used alone. It requires the configuration of cables to form a tension band.

Images