A distributed anti-rotation fixation device in the femoral intramedullary bone

Abstract

The invention discloses a femoral intramedullary decentralized anti-rotation fixation device, comprising a medullary nail fixed to the center of the femur, a screw traversing the medullary nail, the medullary nail being hollow, comprising an inclined top and a vertically arranged bottom, the diameter of the medullary nail top being greater than the diameter of the bottom; a through hole is arranged on the side of the medullary nail, the screw traverses the through hole, the through hole is of decentralized design, the through hole is inclined, and comprises a first through hole, a second through hole, a third through hole and a fourth through hole; the screw is an anti-rotation hollow pressurized screw, comprising a fixing part and an anti-rotation part, the end of the fixing part is provided with a thread, the end of the anti-rotation part is provided with a tail cap, and the anti-rotation part is hollow; further, the first through hole, the second through hole, the third through hole and the fourth through hole are arranged in sequence from top to bottom at the top of the medullary nail. The invention can significantly improve the accuracy of screw placement, enable the bone block to obtain immediate stability, increase the probability of fracture block healing, and reduce the probability of bone and bone nail breakage.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, in particular to a femoral intramedullary dispersed anti-rotation fixation device. Background Art

[0002] Every year, many patients in my country suffer from femoral neck and intertrochanteric fractures. Currently, hollow compression screw fixation is a commonly used and effective internal fixation treatment for femoral neck fractures; PFNA fixation is a commonly used and effective internal fixation treatment for intertrochanteric fractures. However, both fixation methods have drawbacks.

[0003] Disadvantages of hollow compression screw fixation: ① Each compression screw rotates, and the threads can apply longitudinal pressure to the femoral head, creating instant stability between the bone fragments. However, this force is static and cannot be sustained. Once the screw tail becomes loose, this force disappears immediately. ② The screw has weak pressure bearing capacity: When the femoral head is subjected to weight from above, shear force is generated between the two fracture fragments. To resist this shear force, the hollow screw must have anti-rotational ability in the vertical direction beyond the fracture line. Unfortunately, due to the low bone density in the medullary cavity of the femoral neck and the relatively thin proximal femoral cortex, the hollow screw cannot provide anti-rotational ability in the vertical direction. When the femoral head is subjected to weight from above, the hollow screw will rotate downward like the bamboo pieces of the folding fan on the right, and the fracture fragments will shift as shown below, resulting in fixation failure.

[0004] Disadvantages of PFNA: ① A spiral blade can achieve anti-rotation and angular stability with one implant. However, success and failure are both due to the same factor. A spiral blade will inevitably cause stress concentration, which will lead to cutting of the femoral head, including oblique upward cutting toward the weight-bearing area and "central" cutting. Some authors point out that "central" cutting is an important reason for the failure of PFNA. The reason for this phenomenon is that the secondary nail (spiral blade) needs to pass through the through hole of the main nail. In order to facilitate installation, the secondary nail can only be designed to be circular or quasi-circular, and the diameter cannot be too large. Therefore, this disadvantage is unavoidable. ② The spiral blade enters the femoral neck and femoral head by knocking, so this fixation has no pressure effect, but there is a risk of separation between the bone fragments.

[0005] Therefore, it is imperative to develop a new method and fixation device to properly resolve femoral neck and intertrochanteric fractures, reduce patients' bed rest time, and enable patients to integrate into society as soon as possible. Summary of the Invention

[0006] To solve the above existing problems, the present invention provides a femoral intramedullary dispersed anti-rotation fixation device. The present invention is implemented through the following technical solutions.

[0007] A femoral intramedullary decentralized anti-rotation fixation device comprises a medullary nail fixed to the center of the femur, a screw passing through the medullary nail, the medullary nail being hollow and comprising an inclined top and a vertically arranged bottom, the diameter of the medullary nail top being larger than the diameter of the bottom; a through hole is provided on the side of the medullary nail, the screw passing through the through hole, the through holes being of decentralized design, being inclined and comprising a first through hole, a second through hole, a third through hole and a fourth through hole; the screw being an anti-rotation hollow pressurized screw, comprising a fixing portion and an anti-rotation portion, the end of the fixing portion being provided with a thread, the end of the anti-rotation portion being provided with a tail cap, and the anti-rotation portion being hollow.

[0008] Furthermore, the first through hole, the second through hole, the third through hole and the fourth through hole are arranged in sequence from top to bottom on the top of the medullary nail.

[0009] Furthermore, the inclination angle of the first through hole can make the entry point of the screw passing through it to the femoral head be located at the center position of the femoral head, and this entry point is the first entry point; the inclination angle of the second through hole can make the entry point of the screw passing through it to the femoral head be located at the front and upper part of the femoral head, and this entry point is the second entry point; the inclination angle of the third through hole can make the entry point of the screw passing through it to the femoral head be located at the back and upper part of the femoral head, and this entry point is the third entry point; the inclination angle of the fourth through hole can make the entry point of the screw passing through it to the femoral head be located at the lower part of the femoral head, and this entry point is the fourth entry point.

[0010] Furthermore, the second entry point, the third entry point, and the fourth entry point are located on the same circle.

[0011] Furthermore, the diameter of the anti-rotation portion is larger than the diameter of the fixing portion.

[0012] Furthermore, the outer diameter of the thread at the end of the screw is larger than the diameter of the fixing portion.

[0013] Furthermore, the end face of the tail cap is elliptical, and a rotating through hole is provided at the center of the tail cap; and a hexagonal groove is provided at the open end of the rotating through hole.

[0014] Furthermore, raised reinforcement parts are provided on both sides of the tail cap.

[0015] Beneficial effects of the present invention:

[0016] (1) Uniquely designed angled side holes. The angle of the side holes is pre-designed. With the help of an external aimer, screws can be quickly and easily placed into the femoral head, ensuring that multiple screws are reasonably distributed within the femoral head. This design significantly improves the accuracy of screw placement, reduces uncertainty during screw placement, significantly shortens surgical time, and reduces the number of fluoroscopy sessions.

[0017] (2) The through hole on the side of the medullary nail is a unique decentralized design, which allows three to four screws to be placed in the femoral head through the medullary nail, distributing the force from the femoral head to multiple screws (three or four, the surgeon can freely choose according to the specific situation), which can significantly reduce the chance of the screw cutting the femoral head and the chance of the screw breaking.

[0018] (3) The unique hollow tension screw design, when used in conjunction with the medullary nail, can produce multiple advantages: a. It can generate tension, so that the bone fragments can obtain immediate stability, increase the chance of fracture healing, and reduce femoral head necrosis; b. The distal part of the screw (the anti-rotation part of the screw) is contained and held by the medullary nail, which can provide support for the screw and prevent the screw from swinging in all directions; c. The distal part of the screw (the anti-rotation part of the screw) is contained by the medullary nail, which means that the presence of the medullary nail can shorten the screw force arm, making it more capable of resisting shear force and less likely to break.

[0019] In summary, the femoral intramedullary dispersed anti-rotation fixation device of the present invention can provide stability to bone fragments, increase the probability of fracture healing, and reduce the probability of internal fixation failure such as bone cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing a state of use of a femoral intramedullary distributed anti-rotation fixation device according to the present invention;

[0021] Figure 2 This is a structural diagram of a femoral intramedullary nail of a distributed anti-rotation fixation device according to a specific embodiment 1 of the present invention;

[0022] Figure 3 This is a diagram of the screw structure of a distributed anti-rotation fixation device for the femoral intramedullary region according to the first embodiment of the present invention;

[0023] Figure 4 This is a partial view of a screw in a femoral intramedullary distributed anti-rotation fixation device according to a specific embodiment 1 of the present invention;

[0024] Figure 5 This is a schematic diagram of the structure of the entry points of four screws on the femoral head in specific embodiment 1 of the present invention.

[0025] Among them: 1. Femur; 2. Medullary nail; 201. Top; 202. Bottom; 3. Screw; 301. Anti-rotation part; 302. Fixing part; 303. Thread; 304. Tail cap; 3041. Rotation through hole; 3042. Reinforcement part; 4. Through hole; 401. First through hole; 402. Second through hole; 403. Third through hole; 404. Fourth through hole; 5. Femoral head; 501. First entry point; 502. Second entry point; 503. Third entry point; 504. Fourth entry point. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1-5 The technical solution of the present invention is described in more detail and completely.

[0027] A femoral intramedullary decentralized anti-rotation fixation device comprises a medullary nail 2 fixed to the center of a femur 1, a screw 3 being passed through the medullary nail 2, the medullary nail 2 being hollow and comprising an inclined top 201 and a vertically arranged bottom 202, the top diameter of the medullary nail 2 being larger than the diameter of the bottom 1; a through hole 4 being provided on the side of the medullary nail 2, the screw 3 passing through the through hole 4, the through hole 4 being of a decentralized design, being inclined and comprising a first through hole 401, a second through hole 402, a third through hole 403 and a fourth through hole 404; the screw 3 being an anti-rotation hollow pressurized screw, comprising a fixing portion 302 and an anti-rotation portion 301, the end of the fixing portion 302 being provided with a thread 303, the end of the anti-rotation portion 301 being provided with a tail cap 304, and the anti-rotation portion 301 being hollow.

[0028] Furthermore, the first through hole 401 , the second through hole 402 , the third through hole 403 and the fourth through hole 404 are arranged in sequence from top to bottom on the top 201 of the medullary nail.

[0029] Furthermore, the inclination angle of the first through hole 401 can make the entry point of the screw passing through it to the femoral head be located at the center of the femoral head, and this entry point is the first entry point 501; the inclination angle of the second through hole 402 can make the entry point of the screw passing through it to the femoral head be located at the front upper part of the femoral head, and this entry point is the second entry point 502; the inclination angle of the third through hole 403 can make the entry point of the screw passing through it to the femoral head be located at the back upper part of the femoral head, and this entry point is the third entry point 503; the inclination angle of the fourth through hole 404 can make the entry point of the screw passing through it to the femoral head be located at the lower part of the femoral head, and this entry point is the fourth entry point 504; further, the positions of the second entry point 502, the third entry point 503, and the fourth entry point 504 are on the same circumference.

[0030] Furthermore, the diameter of the anti-rotation part 301 is larger than the diameter of the fixing part 302; the outer diameter of the thread 303 at the end of the screw is larger than the diameter of the fixing part 302; the end face of the tail cap 304 is elliptical, and a rotating through hole 3041 is provided in the center of the tail cap 304; the open end of the rotating through hole 3041 is provided with a hexagonal groove; and raised reinforcement parts 3042 are provided on both sides of the tail cap 304.

[0031] Specific embodiment 1 is a distributed intramedullary anti-rotation fixation device for the femur, comprising a medullary nail 2 fixed to the center of a femur 1. The medullary nail 2 is hollow and includes an inclined top portion 201 and a vertical bottom portion 202. The diameter of the top portion 201 is larger than that of the bottom portion 202. A screw 3 is inserted through the interior of the medullary nail 2. The side of the medullary nail 2 is provided with four through-holes, namely a first through-hole 401, a second through-hole 402, a third through-hole 403, and a fourth through-hole 404. These four through-holes are all inclined and distributed throughout the medullary nail. Fixing screws 3 are provided through the four through holes. The inclination angle of the first through hole 401 can make the entry point of the screw passing through it to the femoral head be located at the center position of the femoral head, and the entry point is the first entry point 501; the inclination angle of the second through hole 402 can make the entry point of the screw passing through it to the femoral head be located at the front upper side of the femoral head, and the entry point is the second entry point 502; the inclination angle of the third through hole 403 can make the entry point of the screw passing through it to the femoral head be located at the back upper side of the femoral head, and the entry point is the third entry point 503; the inclination angle of the fourth through hole 404 can make the entry point of the screw passing through it to the femoral head be located at the lower side of the femoral head, and the entry point is the fourth entry point 504; further, the positions of the second entry point 502, the third entry point 503, and the fourth entry point 504 are on the same circumference.

[0032] Screw 3 is an anti-rotation hollow compression screw, comprising a fixing portion 302 and an anti-rotation portion 301. The fixing portion 302 has a threaded end 303, while the anti-rotation portion 301 has a cap 304. The anti-rotation portion 301 is hollow and has a larger diameter than the fixing portion 302. The outer diameter of the threaded end 303 is larger than the diameter of the fixing portion 302, allowing for tension and self-tapping. The cap 304 has an elliptical end face, a rotational through-hole 3041 in its center, and raised reinforcements 3042 on either side.

[0033] During use, the screw's anti-rotation portion 301 resides within the angled through-hole 4 of the medullary nail. Because it is thicker than the fixing portion, it, together with the angled hole, ensures that the screw 3 enters the femur 1 at a specific angle and resists rotation. The through-hole end of the tail cap is designed with a hexagonal groove, which can be used with a hexagonal screwdriver to rotate the screw 3 in and out of the femoral bone. The elliptical design prevents the tail of the screw from sinking into the bone and generates tension during the final stage of rotation. It also saves space and does not interfere with the use of other screws.

[0034] Specific usage procedure: The patient lies supine on a traction bed and traction is performed for reduction. An incision is made proximal to the greater trochanter of the femur, and an opening is made at the greater trochanter. The "four-hole angled distributed fixed medullary nail 2 (DIS nail, hereinafter)" is connected to an external sight. The sight holder is held and the DIS nail is inserted into the femoral medullary canal. Fluoroscopy is used to confirm the appropriate depth. Through the sight, Kirschner wires are inserted into the four "DIS nail angled side holes." Fluoroscopy is used to confirm that the Kirschner wires are positioned within the femoral head and are of the appropriate length. The length is measured, and an anti-rotational hollow compression screw 3 (ANTI screw, hereinafter) of the appropriate length is selected. A cannulated drill is used to drill the lateral cortex of the femur along the Kirschner wires. Then, a screwdriver is used to rotate the tail of the ANTI screw along the Kirschner wires, allowing the screw to rotate into the femoral head. The external sight is removed, and the incisions are sutured. The operation is complete.

[0035] Obviously, the described embodiments are only individual embodiments of the present invention, not all embodiments. In actual applications, the structure can be adjusted as needed. For example, the inclination angles of the four through holes on the side of the medullary nail can be adjusted as needed, and the entry point of the screw through the through hole into the femoral head can also be changed as needed. These are all within the scope of protection of the present invention. In short, based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without making any creative efforts are also within the scope of protection of the present invention.

Claims

1. A femoral intramedullary decentralized anti-rotation fixation device, comprising a medullary nail fixed to the center of the femur, a screw traversing the medullary nail, the medullary nail being hollow and comprising an inclined top and a vertically arranged bottom, the diameter of the medullary nail top being greater than the diameter of the bottom; a through hole being provided on the side of the medullary nail, the screw traversing the through hole, characterized in that: The through holes are of dispersed design, and are arranged obliquely, and include a first through hole, a second through hole, a third through hole, and a fourth through hole; The screw is an anti-rotation hollow pressurized screw, comprising a fixing portion and an anti-rotation portion, wherein the end of the fixing portion is provided with a thread, the end of the anti-rotation portion is provided with a tail cap, and the anti-rotation portion is hollow; The inclination angle of the first through hole can make the entry point of the screw passing through it to the femoral head be located at the center of the femoral head, and this entry point is the first entry point; the inclination angle of the second through hole can make the entry point of the screw passing through it to the femoral head be located at the front upper side of the femoral head, and this entry point is the second entry point; the inclination angle of the third through hole can make the entry point of the screw passing through it to the femoral head be located at the back upper side of the femoral head, and this entry point is the third entry point; the inclination angle of the fourth through hole can make the entry point of the screw passing through it to the femoral head be located at the lower side of the femoral head, and this entry point is the fourth entry point; The diameter of the anti-rotation portion is greater than the diameter of the fixing portion.

2. The femoral intramedullary decentralized anti-rotation fixation device according to claim 1, characterized in that: The first through hole, the second through hole, the third through hole and the fourth through hole are arranged in sequence from top to bottom on the top of the medullary nail.

3. The distributed anti-rotation fixation device for femoral intramedullary according to claim 1, characterized in that: The second entry point, the third entry point, and the fourth entry point are located on the same circle.

4. The femoral intramedullary decentralized anti-rotation fixation device according to claim 1, characterized in that: The outer diameter of the thread of the screw end is greater than the diameter of the fixing portion.

5. The femoral intramedullary decentralized anti-rotation fixation device according to claim 1, characterized in that: The end surface of the tail cap is elliptical, and a rotation through hole is arranged at the center of the tail cap; and a hexagonal groove is arranged at the opening end of the rotation through hole.

6. The femoral intramedullary decentralized anti-rotation fixation device according to claim 1, characterized in that: Raised reinforcement parts are arranged on both sides of the tail cap.

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