Femoral stem capable of automatically aligning during femoral head assembling

Abstract

The utility model discloses a femoral stem capable of being automatically aligned when a femoral head is assembled, and belongs to the technical field of medical instruments. The defect that in the prior art, a femoral head and a femoral stem cannot be firmly locked when a traditional femoral head is aligned with the femoral stem is overcome. A main body structure of the device comprises a femoral stem and a femoral head matched with the femoral stem, a cylindrical middle shaft is arranged at the top end of a conical head of the femoral stem, a cylindrical hole and an inner conical hole which are communicated with each other are formed in the femoral head, and the outer conical surface of the conical head on the femoral stem is matched with the inner conical hole in the femoral head. And the cylindrical middle shaft on the femoral stem is matched with the cylindrical hole in the femoral head. The thighbone side hip joint replacement device is mainly used for thighbone side hip joint replacement surgery.

Description

Technical Field

[0001] This utility model belongs to the field of medical device technology, and more specifically, it relates to a femoral stem that can automatically align when assembling a femoral head. Background Technology

[0002] Patients with avascular necrosis of the femoral head and femoral neck fractures require femoral hip replacement surgery. Currently, the most commonly used femoral hip replacement products on the market are separate femoral heads and stems. The femoral head is primarily made of cobalt-chromium-molybdenum alloy or ceramic, while the femoral stem is primarily made of titanium alloy or cobalt-chromium-molybdenum alloy. Due to the high hardness of the metal or ceramic materials used in the femoral head and stem, to ensure a high bonding strength after assembly, common femoral head products on the market are designed with an internal conical hole, and femoral stem products are designed with an external conical head. The conical head of the femoral stem connects to the internal conical hole of the femoral head through a tapered connection to achieve locking and fixation of the femoral stem and femoral head.

[0003] During lateral femoral replacement surgery, the femoral stem conical head and the femoral head conical foramen often fail to be installed correctly in one go; that is, the femoral stem conical head tilts during installation. Figure 8 As shown. In actual surgery, doctors need to make multiple adjustments to ensure the femoral head and stem are properly aligned, which inevitably prolongs the operation. When the femoral head and stem are installed at an angle, the outer conical surface of the femoral stem and the inner conical surface of the femoral head cannot fully contact each other. Therefore, when the doctor taps the femoral head, they cannot achieve a locking connection between the femoral stem and stem. If the femoral head and stem cannot be securely locked, dislocation of the femoral head and stem is highly likely during lower limb movement. Furthermore, micro-movements between the femoral head and stem can generate abrasive debris, which can enter the body's tissues and cause rejection, endangering the patient's life and health.

[0004] For example, Chinese utility model patent with authorization announcement number CN 2580920Y discloses a femoral head for artificial hip replacement surgery. Its shortcomings are that the conical part of the femoral stem cannot be completely locked with the inner conical surface of the femoral head. When the femoral head is struck, the femoral stem and femoral head cannot be precisely matched and installed, which easily leads to the phenomenon of dislocation of the femoral head and femoral stem. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a femoral stem that can automatically align when assembling the femoral head.

[0006] To achieve the above objectives, this utility model employs the following technical solution:

[0007] A femoral stem that can automatically align when assembling a femoral head includes a femoral stem and a femoral head that is fitted with the femoral stem. The top of the conical head of the femoral stem is provided with a cylindrical central shaft. The femoral head is provided with a cylindrical hole and an inner conical hole that are connected to each other. The outer conical surface of the conical head on the femoral stem is fitted with the inner conical hole on the femoral head, and the cylindrical central shaft on the femoral stem is fitted with the cylindrical hole on the femoral head.

[0008] Preferably, the side of the femoral stem is provided with a threaded hole, and a ball-head plunger is provided in the threaded hole to prevent the femoral stem cone from being pulled out and twisted.

[0009] Preferably, the ball plunger includes a threaded outer sleeve, inside which a spring and a steel ball are disposed, with one end of the spring connected to the steel ball.

[0010] Preferably, the end of the threaded outer sleeve away from the steel ball is provided with an internal hexagonal hole.

[0011] Preferably, the threaded outer sleeve is connected to the threaded hole by a thread.

[0012] Preferably, the inner diameter of the inner conical hole is larger than the inner diameter of the cylindrical hole.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] 1. By setting a cylindrical central axis at the top of the cone-shaped end of the femoral stem and setting interconnected cylindrical holes and inner cone holes in the femoral head, the femoral stem and femoral head can be automatically aligned during assembly, which can improve the assembly accuracy, reduce errors caused by manual operation, and ensure the precision and reliability of the surgical procedure.

[0015] 2. By setting a threaded hole with a ball-head plunger on the side of the femoral stem, which consists of a threaded outer sleeve, a spring and a steel ball, the femoral stem cone can be effectively prevented from being pulled out and twisted after the femoral stem and femoral head are assembled, thereby greatly enhancing the stability and safety of the prosthesis and reducing the risk of postoperative complications.

[0016] 3. The ball plunger has an internal hexagonal hole at one end of its threaded outer sleeve, which facilitates the installation and removal of the ball plunger using standard tools;

[0017] 4. The inner diameter of the conical hole is larger than that of the cylindrical hole. This not only facilitates a close fit between the femoral stem and the femoral head, but also disperses stress to a certain extent, reduces material fatigue caused by excessive local pressure, and extends the service life of the prosthesis.

[0018] In summary, this invention enables complete contact between the outer conical surface of the cone on the femoral stem and the inner conical surface of the inner conical hole on the femoral head. Tapping the femoral head locks the femoral stem and femoral head together. By assembling and installing the femoral stem with a cylindrical central axis and the femoral head with a cylindrical hole, one-time alignment and installation can be achieved, shortening the installation time of the operation. It effectively avoids the femoral head dislocation caused by the tilting of the femoral stem and femoral head during installation, and avoids the generation of abrasive debris due to micro-movement between the femoral stem and femoral head, thus preventing injury to the human body. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the femoral stem structure in this utility model;

[0020] Figure 2 This is a schematic diagram of the femoral head structure in this utility model;

[0021] Figure 3 This is a diagram illustrating the assembly process of the femoral stem and femoral head in this utility model.

[0022] Figure 4 for Figure 3 A partial sectional view at point A in the middle;

[0023] Figure 5 This is a schematic diagram of the ball-head plunger in this utility model;

[0024] Figure 6 This is a diagram showing the completed assembly of the femoral stem and femoral head in this utility model.

[0025] Figure 7 for Figure 6 A partial sectional view at point B in the middle;

[0026] Figure 8 This is a schematic diagram illustrating the tilted installation of the femoral stem cone and femoral head in the prior art.

[0027] In the diagram: 1. Cylindrical central shaft; 2. Cylindrical hole; 3. Femoral stem; 4. Femoral head; 5. Outer conical surface of the cone head; 6. Inner conical hole; 7. Ball plunger; 8. Threaded hole; 71. Steel ball; 72. Hexagonal socket; 73. Threaded outer sleeve; 74. Spring. Detailed Implementation

[0028] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0029] Example 1:

[0030] like Figure 1-3As shown, a femoral stem that automatically aligns when assembling a femoral head includes a femoral stem 3 and a femoral head 4 that mates with the femoral stem 3. The femoral stem 3 has a cylindrical central shaft 1 at its conical tip. The femoral head 4 has a cylindrical hole 2 and an inner conical hole 6 that communicate with each other. The inner diameter of the inner conical hole 6 is larger than the inner diameter of the cylindrical hole 2. The outer conical surface 5 of the conical head on the femoral stem 3 mates with the inner conical hole 6 on the femoral head 4, and the cylindrical central shaft 1 on the femoral stem 3 mates with the cylindrical hole 2 on the femoral head 4. In this embodiment, the outer conical surface 5 of the conical head on the femoral stem 3 and the inner conical hole 6 on the femoral head 4 are connected by a Morse taper. This Morse taper connection provides anti-rotation for the femoral stem 3. Simultaneously, the stem body coating of the femoral stem 3 is a hydroxyapatite coating, which promotes bone ingrowth.

[0031] Example 2:

[0032] like Figure 4 As shown, the difference from Embodiment 1 is that the femoral stem 3 has a threaded hole 8 on its side, and a ball-head plunger 7 is provided in the threaded hole 8 to prevent the femoral stem 3 cone from being pulled out and twisted.

[0033] like Figure 5 As shown, the ball plunger 7 includes a threaded outer sleeve 73, inside which a spring 74 and a steel ball 71 are disposed. One end of the spring 74 is connected to the steel ball 71. An internal hexagonal hole 72 is provided at the end of the threaded outer sleeve 73 away from the steel ball 71. The threaded outer sleeve 73 is connected to the threaded hole 8 by threads.

[0034] In this embodiment, when the femoral stem 3 and femoral head 4 are locked together, as follows: Figure 6-7 As shown, under the force of the spring 74, the steel ball 71 presses against the inner conical surface of the inner conical hole 6. Therefore, the spring 74 and the steel ball 71 can play an auxiliary role in preventing pull-out and torsion of the conical head of the femoral stem 3. The threaded hole 8 is used to screw in the ball plunger 7 and fix the ball plunger 7 through the threaded connection. The internal hexagonal hole 72 is used with an internal hexagonal wrench to screw in the ball plunger 7.

[0035] The working principle of this utility model is as follows:

[0036] During the assembly and installation of the femoral stem 3 and femoral head 4, before the outer conical surface 5 of the conical head of the femoral stem 3 contacts the inner conical surface of the inner conical hole 6 of the femoral head 4, the cylindrical central shaft 1 at the tip of the conical head of the femoral stem 3 is already inserted into the cylindrical hole 2 of the femoral head 4. Figure 3-4 As shown, at this point, the cone head of the femoral stem 3 is aligned with the inner cone hole 6 of the femoral head 4. Continuing the installation and movement will allow the outer cone surface 5 of the cone head on the femoral stem 3 to completely fit with the inner cone surface of the inner cone hole 6 on the femoral head 4, as shown. Figure 6-7As shown, tapping the femoral head 4 at this time can lock the femoral stem 3 and the femoral head 4 together. The femoral stem 3 with a cylindrical central shaft 1 and the femoral head 4 with a cylindrical hole 2 can be installed together and aligned in one go, which shortens the installation time of the operation and effectively avoids the femoral head 4 from dislodging due to the tilt of the femoral stem 3 and the femoral head 4. It also avoids the phenomenon of abrasion caused by the femoral stem 3 and the femoral head 4 due to micro-movement, and prevents injury to the human body.

Claims

1. A femoral stem that can automatically align when assembling a femoral head, comprising a femoral stem (3) and a femoral head (4) that is fitted and installed in conjunction with the femoral stem (3), characterized in that: The femoral stem (3) has a cylindrical central shaft (1) at the top of the cone, and the femoral head (4) has a cylindrical hole (2) and an inner cone hole (6) that are connected to each other. The outer cone surface (5) of the cone on the femoral stem (3) is fitted with the inner cone hole (6) on the femoral head (4), and the cylindrical central shaft (1) on the femoral stem (3) is fitted with the cylindrical hole (2) on the femoral head (4).

2. The femoral stem that can automatically align during the assembly of the femoral head according to claim 1, characterized in that: The femoral stem (3) has a threaded hole (8) on its side, and a ball-head plunger (7) is provided in the threaded hole (8) to prevent the femoral stem (3) cone from being pulled out and twisted.

3. The femoral stem that can automatically align during the assembly of the femoral head according to claim 2, characterized in that: The ball plunger (7) includes a threaded outer sleeve (73), and a spring (74) and a steel ball (71) are provided inside the threaded outer sleeve (73). One end of the spring (74) is connected to the steel ball (71).

4. The femoral stem that can automatically align during the assembly of the femoral head according to claim 3, characterized in that: The threaded outer sleeve (73) has an internal hexagonal hole (72) at the end away from the steel ball (71).

5. The femoral stem that can automatically align during the assembly of the femoral head according to claim 3, characterized in that: The threaded outer sleeve (73) is connected to the threaded hole (8) by threads.

6. The femoral stem that can automatically align during the assembly of the femoral head according to any one of claims 1-5, characterized in that: The inner diameter of the inner conical hole (6) is larger than the inner diameter of the cylindrical hole (2).

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