Combined patella needle
By using a modular design for the patellar pin, the problems of stability and soft tissue irritation in the fixation of patellar fractures using traditional Kirschner wires are solved, achieving more efficient fixation of patellar fractures and early mobilization protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 孟祥飞
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional Kirschner wire tension band technique for treating patellar fractures has problems such as Kirschner wire displacement, wire slippage, soft tissue irritation, and postoperative pain, leading to surgical failure and increased medical costs.
The modular patellar pin features a split design, consisting of a threaded Kirschner wire and a tail cap. By trimming the threaded Kirschner wire and connecting the tail cap, a tension band is formed, preventing the Kirschner wire from irritating soft tissues. The tail cap design also increases fixation stability.
This method achieves stable fixation of patellar fractures, reduces postoperative pain and infection risk, improves fixation effectiveness, and lowers the likelihood of reoperation.
Smart Images
Figure CN122251102A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of medical device design technology, and is a modular patellar pin. Background Technology
[0002] The patella, located superficially at the front of the knee joint, is prone to fracture. A patellar fracture disrupts the integrity of the knee extensor mechanism, limiting knee extension and requiring surgical treatment. This involves first reducing the patella and then applying strong fixation. Domestic epidemiological surveys indicate that patellar fractures account for approximately 2.53% of all fractures in adults, with transverse fractures being the most common. For transverse patellar fractures, various fixation methods exist, but the Kirschner wire tension band technique introduced by the AO (Aggregate Osteoarthritis) is a classic method. This involves using two parallel Kirschner wires perpendicular to the fracture line, with the wire looped in a figure-eight pattern around the wires and fixed to the anterior side of the patella. The tension band technique converts tension into compressive stress, promoting fracture healing. However, studies show that approximately 25%-42% of patients treated with Kirschner wire tension band fixation experience poor results and postoperative pain or irritation. While early postoperative functional exercises help accelerate knee joint function recovery, cases of tension band laxity and Kirschner wire displacement leading to surgical failure frequently occur, often requiring repeat surgery, increasing both patient suffering and medical costs. Analysis of literature reveals the following problems with Kirschner wire tension band fixation: wire slippage after Kirschner wire displacement leads to tension band failure; sharp or excessively long Kirschner wire ends can irritate or puncture surrounding soft tissues, causing pain or infection; the ends of the Kirschner wires require manual bending to prevent slippage, but wire slippage and wire detachment still occur during postoperative exercises. These are all critical issues urgently needing clinical resolution. The root cause lies in the inherent defects of the Kirschner wire itself. To address these problems, we have invented a modular patellar pin that achieves tension band fixation while avoiding the defects of traditional Kirschner wires. This invention relates to a modular patellar pin with a modular design. When used in combination, it achieves stable fixation of the tension band without irritating surrounding soft tissues, conforming to the biomechanics of early knee joint movement and providing sufficient time for patellar fracture healing. No reports have yet documented this modular patellar pin. Summary of the Invention
[0003] The purpose of this invention is to provide a combined patellar pin.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A composite patellar pin includes a threaded Kirschner wire and caps at both ends. The threaded Kirschner wire is trimmed as needed. The trimmed threaded Kirschner wire is connected to the caps at both ends, forming the composite patellar pin. The caps at both ends have the same structure; the caps are cylindrical or hexagonal prisms with rounded ends. One end of the cap has a longitudinal channel along the longitudinal axis of the prism, the inner diameter of which is the same as the diameter of the threaded Kirschner wire, and the threads within the longitudinal channel match the threads of the threaded Kirschner wire. The other end of the cap has a transverse channel perpendicular to the longitudinal axis, allowing tension band cables to pass through. The composite patellar pin connects to the cables to form a tension band.
[0005] In the aforementioned combined patellar pin, as a preferred embodiment, both the threaded Kirschner wire and the end cap are made of titanium alloy.
[0006] In the aforementioned combined patellar pin, as a preferred option, the diameter of the threaded Kirschner wire is between 1.5 and 2.0 mm, with 1.5 mm and 2 mm being common.
[0007] In the aforementioned combined patellar pin, as a preferred embodiment, the body of the threaded Kirschner wire is designed with full threads, which match the threads in the longitudinal channel of the tail cap.
[0008] In the aforementioned combined patellar pin, as a preferred embodiment, one end of the threaded Kirschner wire is blunt for connection to a power drill or hammer, while the other end has a sharp structure that can penetrate bone.
[0009] In the aforementioned combined patellar pin, as a preferred embodiment, the body of the tail cap is a cylinder or a hexagonal prism, with rounded ends.
[0010] In the aforementioned combined patellar pin, as a preferred embodiment, the tail cap has a body diameter of 6 mm and a height of 10 mm.
[0011] In the aforementioned combined patellar pin, as a preferred embodiment, the depth of the longitudinal channel is 5-6 mm, and the diameter can be 1.5 mm or 2.0 mm.
[0012] In the aforementioned combined patellar pin, as a preferred embodiment, the diameter of the transverse channel is 1-1.5 mm, with 1.2 mm or 1.5 mm being acceptable.
[0013] In the aforementioned combined patellar pin, as a preferred embodiment, the longitudinal channel of the tail cap is provided with threads that can match the threads of a threaded Kirschner wire.
[0014] In the aforementioned combined patellar pin, as a preferred embodiment, the inner wall of the transverse channel of the tail cap is smooth, allowing the cable to slide freely through.
[0015] In the aforementioned combined patellar pin, as a preferred embodiment, the tension band cable can be titanium wire, titanium cable, or non-absorbable wire.
[0016] Compared with traditional technologies, this invention, employing the above technical solutions, has the following advantages: The invention, through its separate design and combined use, avoids the bending and loosening issues of traditional Kirschner wires. Traditional Kirschner wires have a smooth body, resulting in poor bone retention and easy loosening and displacement. The threaded Kirschner wire of this invention, with its continuous threads, increases the retention force with surrounding bone, making it less prone to loosening and displacement. The combined patellar pin of this invention, by tightening the caps at both ends, can create initial pressure, providing initial stability to the fracture; the effect is even better after using a tension band. The combined patellar pin of this invention forms a tension band after connecting the cable; the transverse channel designed in the cap allows the cable to pass through, preventing tension band slippage and failure. The rounded ends of the caps in the combined patellar pin of this invention reduce irritation to surrounding tissues and prevent skin puncture and infection. The tension band using the combined patellar pin of this invention is more stable and has fewer complications than traditional Kirschner wire tension bands. Attached Figure Description
[0017] The accompanying drawings are provided to give a preferred understanding of the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 For threaded Kirschner wires Figure 2 For the tail cap Figure 3 Combination patellar pin Figure 4 Frontal view of two parallel insertions of untrimmed threaded Kirschner wires into a fractured patella. Figure 5 Lateral view of an untrimmed threaded Kirschner wire inserted into a fractured patella. Figure 6 Frontal view of two parallel insertions of trimmed threaded Kirschner wires into a fractured patella. Figure 7 Lateral view of a trimmed threaded Kirschner wire inserted into a fractured patella. Figure 8 Front view of a fractured patella with two parallel insertions of a combined patellar pin. Figure 9 Lateral view of a patellar fracture treated with a combination patellar pin. Figure 10 Front view of combined patellar pin tension band Symbol explanation: 1a Untrimmed threaded Kirschner wire 1b Trimmed threaded Kirschner wire 2a Front sectional view of the tail cap Side sectional view of 2b tail cap 2.1 The transverse passage of the tail cap 2.2 Longitudinal channels of the tail cap Front view of 3a combined patellar pin 3b combined patellar pin side view 4 tension belt cable 5 Patella 5.1 Patellar fracture line 6 Tibia 7 femurs Detailed Implementation
[0018] Specific embodiments of the present invention will be described in detail with reference to the usage process and accompanying drawings. The present invention can have many different implementations and should not be construed as being limited to the embodiments presented herein. These embodiments are provided to achieve a full and complete disclosure and to enable those skilled in the art to fully understand the scope of the invention. Furthermore, for layout purposes and to make the drawings clear, the dimensions and relative sizes of the areas may have been enlarged or reduced, resulting in some differences from the actual dimensions.
[0019] Figure 1 The body of the combined patellar pin is shown in Figure 1a, which is an untrimmed threaded Kirschner wire, and Figure 1b is a threaded Kirschner wire that has been shortened as needed.
[0020] Figure 2 This is the end cap of a composite patellar pin, connecting the two ends of a trimmed threaded Kirschner wire. The end caps at both ends have the same structure. The end cap includes a longitudinal channel and a transverse channel, located at each end of the end cap. 2a is a front sectional view of the end cap; 2b is a side sectional view of the end cap; 2.1 is the transverse channel of the end cap, with a smooth inner wall, allowing the tension band cable to pass freely; 2.2 is the longitudinal channel of the end cap, with an inner diameter the same as the diameter of the threaded Kirschner wire, and internal threads that match the threads of the Kirschner wire.
[0021] Figure 3 A full view of the combined patellar pin, showing the trimmed threaded Kirschner wire in the center, with two end caps connected to the wire at both ends via longitudinal channels. 3a is a front view of the combined patellar pin. 3b is a side view of the combined patellar pin.
[0022] Step 1: Insertion of Kirschner wires. The specific procedure is as follows: First, reduce the displaced patella to restore the alignment of the fractured patellar fragments and the smoothness of the articular surfaces. Fix the patella with reduction forceps. Connect the blunt end of the Kirschner wire to an electric drill. Place the tip of the Kirschner wire on both sides of the superior pole of the patella, perpendicular to the fracture line, and positioned anteriorly and posteriorly in the center of the patellar body. Insert two Kirschner wires parallel to each other. (Frontal view as shown) Figure 4 As shown, two parallel Kirschner wires are inserted perpendicularly to the transverse fracture line of the patella, entering from both sides of the superior pole of the patella and exiting from both sides of the inferior pole of the patella. Side view as follows. Figure 5 As shown, the threaded Kirschner wire is located anteriorly and posteriorly at the center of the patellar body.
[0023] The second step is to trim the threaded Kirschner wire, as follows: Based on the length of the longitudinal channel, the length of the two ends of the threaded Kirschner wire (exposed outside the patellar bone) should be approximately the length of the longitudinal channel of the tail cap. Trim the two ends of the threaded Kirschner wire. (Front view as shown) Figure 6 As shown, both ends of the threaded guide pin need to be shortened, and the threads of the Kirschner wire should be preserved as much as possible during trimming. Side view as shown... Figure 7 As shown, the position of the Kirschner wire remains unchanged.
[0024] The third step is to connect the tail cap, as follows: Screw the tail cap into both ends of the shortened threaded Kirschner wire, connecting the longitudinal channel to both ends of the threaded Kirschner wire. The tightness should be such that the tail cap contacts the patellar bone and provides slight pressure, ensuring a tight fit and applying some pressure. (Front view as shown) Figure 8 As shown, the tail cap is screwed into both ends of the trimmed threaded Kirkstock pin through the longitudinal channels, as seen in the side view. Figure 9 As shown, the tail cap contacts the patellar bone, providing initial pressure.
[0025] The fourth step is to lay out the tension band cable, as follows: Pass one end of the tension band cable through the transverse channels of the two caps at the upper pole of the patella. Lead the cable diagonally to the lower pole of the patella, passing it through the transverse channels of the two caps at the lower pole. Connect the cable end to end in a figure-eight pattern, and tighten the cable until sufficient tension is achieved. Figure 10 From the front, it shows a complete tension band formed by two combined patellar pins and cables.
[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A combined patellar pin, characterized in that, It includes a threaded Kirschner wire in the middle and tail caps at both ends. The two ends of the threaded Kirschner wire are connected to the tail caps. The tail caps have a longitudinal channel and a transverse channel. The longitudinal channel is connected to the threaded Kirschner wire, and the transverse channel allows the tension band cable to pass freely.
2. The combined patellar pin according to claim 1, characterized in that... The flat-end design of the threaded Kirschner wire in the middle allows it to be connected to a power drill or struck with a hammer to transmit power to the other end.
3. A combined patellar pin according to claim 1, characterized in that... The other end of the threaded Kirschner wire is designed to be pointed, allowing it to drill through bone.
4. A combined patellar pin according to claim 1, characterized in that... The body of the Kirschner wire with a central thread is designed with full thread.
5. A combined patellar pin according to claim 1, characterized in that... The two ends of the threaded Kirschner wire, after being cut short, are connected to the longitudinal channel of the tail cap.
6. A combined patellar pin according to claims 1 and 4, characterized in that... The threads of the threaded Kirschner wire in the middle match the threads in the longitudinal channel of the tail cap, forming a tight and stable meshing structure after connection.
7. A combined patellar pin according to claim 1, characterized in that... The body of the tail cap is cylindrical or hexagonal prism.
8. A combined patellar pin according to claim 1, characterized in that... The two ends of the cap are rounded and blunt.
9. A combined patellar pin according to claims 1 and 7, characterized in that... One end of the tail cap has a channel running longitudinally along the center of the tail cap body, which connects to the shortened threaded Kirschner wire.
10. A combined patellar pin according to claims 1 and 7, characterized in that... The other end of the cap has a transverse channel perpendicular to the longitudinal axis, with a smooth inner wall, allowing the tension band cable to pass freely.
11. A combined patellar pin according to claims 1 and 10, characterized in that... The modular patellar pin can be used alone or in pairs, and when used with cables, it forms a tension band to exert its effect.