Femoral head prosthesis adaptive to multi-taper femoral stem revision

Abstract

The utility model relates to the technical field of medical instruments, in particular to a femoral head prosthesis for revision of a multi-taper femoral stem, which comprises a femoral head prosthesis, an inverted-cone-shaped mounting cavity is arranged in the femoral head prosthesis, an inverted-cone-shaped bearing cylinder is arranged in the mounting cavity in a sliding manner, and the bearing cylinder is connected with the femoral head prosthesis. A gap is formed between the mounting cavity and the bearing cylinder, the diameter of the gap is gradually increased upwards in the axial direction of the femoral head prosthesis, six through holes are formed in the conical surface of the bearing cylinder, the six through holes are arranged circumferentially, a ball is slidably mounted in each through hole, the balls are attached to the mounting cavity, and the bearing cylinder is in conical insertion connection with the head. According to the femoral stem prosthesis, the conicity of the head cone is not limited, the fixing mode can be achieved as long as the head cone has the conicity and the arc-shaped surface, the design of the conical stem of the femoral stem prosthesis conforms to the characteristic, and therefore the fixing mode can be matched with the femoral stem prosthesis with multiple conicity.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, specifically designing a femoral head prosthesis adapted for revision of multi-tapered femoral stems. Background Technology

[0002] In hip replacement surgery, the femoral head prosthesis is usually made of metal, ceramic, or polymer materials. It is designed to match the acetabular prosthesis to replace the diseased or damaged femoral head. In hip replacement surgery, the diseased femoral head is removed and then replaced by the femoral head prosthesis to restore the normal function of the hip joint. The femoral stem prosthesis is a long strip of metal or ceramic component that is inserted into the medullary cavity of the femur to replace the diseased or damaged part of the femur. The femoral stem prosthesis is usually designed to match the femoral head prosthesis and is fixed to the femur by bone cement, compression fitting, or biological fixation.

[0003] Currently, an increasing number of patients require revision surgery due to prosthesis loosening caused by wear or infection. Current revision procedures typically retain the original femoral stem prosthesis and replace it with a compatible femoral head prosthesis. However, due to the diverse shapes and lack of standardized prostheses in the past, patients using prostheses from different manufacturers have received femoral stem prostheses with different tapers. This makes it impossible for the femoral head prosthesis used in revision to achieve a high degree of fit with the original femoral stem, necessitating the removal of all prosthesis components during revision, resulting in high surgical difficulty, significant trauma, substantial bleeding, and a higher risk of complications such as fractures. Conversely, using an incompatible femoral head prosthesis without removing the femoral stem prosthesis fails to achieve early initial stability and carries a high risk of recurrence of loosening. Therefore, the inventors have purposefully provided a highly compatible, multi-tapered femoral stem revision femoral head prosthesis. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a highly compatible femoral head prosthesis for revision of multi-tapered femoral stems, thereby solving the problem that existing femoral head prostheses used in revision cannot be highly adapted to the existing femoral stem.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] A femoral head prosthesis adapted for revision of multi-tapered femoral stems includes a femoral head prosthesis with an inverted conical mounting cavity. An inverted conical support cylinder is slidably disposed within the mounting cavity, with a gap between the mounting cavity and the support cylinder. The diameter of this gap increases upwards along the axial direction of the femoral head prosthesis. Six through holes are arranged circumferentially on the conical surface of the support cylinder, and a ball bearing is slidably mounted in each through hole. The ball bearing fits snugly against the mounting cavity. The support cylinder is inserted into the conical head, which is provided with... It has an arc-shaped surface for connecting with the conical neck. The bottom surface of the bearing cylinder is connected to the mounting cavity via a spring. When the head cone is inserted into the bearing cylinder, the conical surface of the head cone abuts against the ball bearing. The ball bearing is compressed and slides along the mounting cavity within the through hole, causing the bearing cylinder to move upward. The gap continuously increases until the head cone is fully inserted into the bearing cylinder, reaching its maximum gap. The spring then pushes the bearing cylinder back to its original position, causing the ball bearing to slide off from the connection between the head cone and the arc-shaped surface. At this point, the arc-shaped surface abuts against the mounting cavity via the ball bearing, and the head cone is completely fixed.

[0007] This can be considered as a further optimization or improvement to the solution.

[0008] The inner wall of the mounting cavity is provided with six limiting grooves, each of which is slidably connected to a ball bearing.

[0009] This can be considered as a further optimization or improvement to the solution.

[0010] A protrusion is fixedly connected to the bottom surface of the mounting cavity. When the conical head is fully inserted into the bearing cylinder, the conical head abuts against the protrusion.

[0011] This can be considered as a further optimization or improvement to the solution.

[0012] The contact point between the ball and the through hole is located between the axis of the bearing cylinder and the axis of the ball.

[0013] This can be considered as a further optimization or improvement to the solution.

[0014] The mounting cavity has a groove, and the diameter of the groove is larger than the diameter of the bottom surface of the bearing cylinder.

[0015] The beneficial effects of this utility model are:

[0016] 1. When the head cone is fully inserted into the support cylinder, the ball bearing will slide off the edge of the head cone. At this time, the ball bearing contacts the arc-shaped surface, which makes the ball bearing tightly abut against the mounting cavity. When the patient's hip joint moves, the head cone on the femoral stem prosthesis will also be moved by force. The inverted cone design of the mounting cavity restricts the head cone from loosening in the femoral head prosthesis because the force of the ball bearing increases with the force on the head cone, thus avoiding the loosening of the head cone in the femoral head prosthesis caused by frequent hip joint movements. Moreover, this fixation method does not limit the taper of the head cone. As long as the head cone has a taper and an arc-shaped surface, it can be achieved. The tapered stem design of the femoral stem prosthesis meets this feature, thus making this fixation method compatible with femoral stem prostheses with multiple tapers.

[0017] 2. This utility model does not use bone cement to connect the femoral head prosthesis and the head cone, which makes the connection between the femoral stem prosthesis and the femoral head prosthesis more flexible and allows for more flexible hip joint rotation. When the hip joint rotates, the head cone can rotate slightly within the bearing cylinder, and the friction force experienced by the head cone during rotation can be reduced through the ball bearings and protrusions.

[0018] 3. In this invention, when separating the head cone and the femoral head prosthesis, a guide rod is used to directly push the support cylinder, causing the support cylinder to move within the mounting cavity. This increases the gap between the support cylinder and the mounting cavity, allowing the ball bearing to move along the arc-shaped surface and the mounting cavity. Finally, the ball bearing passes the connection point between the arc-shaped surface and the head cone and comes into contact with the head cone. At this point, the head cone and the femoral head prosthesis can be separated. Doctors can then easily disassemble and repair or replace both without needing to perform surgery again. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0021] Figure 2 This is a schematic diagram of the sectional structure of the femoral head prosthesis.

[0022] Figure 3 This is a schematic diagram of the femoral head prosthesis and the cone-shaped structure of the head.

[0023] Figure 4 This is a schematic diagram of the limiting groove structure.

[0024] Figure 5 This is a diagram showing the fit between the through hole and the ball bearing.

[0025] The diagram indicates:

[0026] 1. Femoral head prosthesis; 2. Conical head; 3. Support cylinder; 4. Ball bearing; 5. Mounting cavity; 6. Through hole; 7. Spring; 8. Protrusion; 9. Limiting groove; 10. Arc-shaped surface; 11. Groove. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0028] See Figures 1-5 A femoral head prosthesis adapted for revision of multi-tapered femoral stems includes a femoral head prosthesis 1. The femoral head prosthesis 1 has an installation cavity 5, which is inverted conical in shape. An inverted conical support cylinder 3 is slidably disposed within the installation cavity 5, and a gap exists between the installation cavity 5 and the support cylinder 3. The diameter of the gap increases upwards along the axial direction of the femoral head prosthesis 1. Six through holes 6 are formed on the conical surface of the support cylinder 3, arranged circumferentially. A ball bearing 4 is slidably installed in each through hole 6, and the ball bearing 4 fits against the installation cavity 5. The support cylinder 3 is inserted into a head cone 2, which is provided with a... The arc-shaped surface 10 connected to the conical neck is connected to the mounting cavity 5 via the spring 7. When the head cone 2 is inserted into the mounting cavity 3, the conical surface of the head cone 2 abuts against the ball 4. The ball 4 is squeezed and slides along the mounting cavity 5 in the through hole 6, which drives the mounting cavity 3 to move upward. The gap increases continuously. When the head cone 2 is fully inserted into the mounting cavity 3, the gap is at its maximum. The spring 7 pushes the mounting cavity 3 to reset, so that the ball 4 slides off the connection between the head cone 2 and the arc-shaped surface 10. At this time, the arc-shaped surface 10 abuts against the mounting cavity 5 via the ball 4, and the head cone 2 is in a completely fixed state.

[0029] In practical use, in order to ensure good matching and stable fixation between the prosthesis and the femoral medullary cavity, the femoral stem is usually designed with one end tapered. This design is called a tapered stem. The tapered stem includes a head tapered 2 and a neck tapered. The head tapered 2 is the end where the femoral stem prosthesis connects to the femoral head prosthesis 1. The diameter of the neck tapered is smaller than the diameter of the head tapered 2. The connection between the neck tapered and the head tapered 2 is an arc-shaped surface 10.

[0030] The working principle of this utility model is as follows: Figure 2Taking the direction shown as an example, when the head cone 2 is inserted upward into the bearing cylinder 3, the conical surface of the head cone 2 first abuts against the ball 4. The ball 4 is compressed and slides along the mounting cavity 5 in the through hole 6. When it slides to the end of the through hole 6, the bearing cylinder 3 moves synchronously with the head cone 2 and continuously compresses the spring 7. During this process, the gap between the bearing cylinder 3 and the mounting cavity 5 continuously increases. Due to the compression of the conical surface of the head cone 2, the ball 4 always adheres to the inner wall of the mounting cavity 5 when it moves. This causes the axis of the ball 4 to gradually move away from the axis of the head cone 2. When the head cone 2 is fully inserted into the bearing cylinder 3, the gap is at its maximum. The edge of the ball 4 is in contact with the head cone 2. The ball 4 contacts the edge of the head cone 2, but the elastic force of the spring 7 is greater than the frictional force at the contact point between the ball 4 and the head cone 2. The spring 7 will push the bearing cylinder 3 to reset, and the ball 4 will slide off the edge of the head cone 2. At this time, the ball 4 contacts the arc surface 10. The arc surface 10 will make the ball 4 tightly abut against the mounting cavity 5. When the patient's hip joint moves, the head cone 2 on the femoral stem prosthesis will also be moved by force. The inverted cone design of the mounting cavity 5 will limit the head cone 2 from loosening in the femoral head prosthesis 1. Because the force of the ball 4 abutting increases with the increase of the force on the head cone 2, it avoids the head cone 2 from loosening in the femoral head prosthesis 1 due to frequent hip joint movements.

[0031] Furthermore, this fixation method does not limit the taper of the head cone 2. It can be achieved as long as the head cone 2 has a taper and an arc surface 10. The early femoral stem prosthesis tapered stem design conforms to this feature, thus making this fixation method adaptable to femoral stem prostheses with multiple tapers.

[0032] Specifically, the inner wall of the mounting cavity 5 is provided with six limiting grooves 9, and each limiting groove 9 is slidably connected to the ball 4.

[0033] In one specific embodiment, when the head cone 2 is inserted, the bearing cylinder 3 will drive the ball 4 to slide along the mounting cavity 5. The setting of the limiting groove 9 restricts the ball 4 to move only along the path of the limiting groove 9. Moreover, when the hip joint rotates, the head cone 2 can rotate slightly within the bearing cylinder 3. When rotating, the friction between the head cone 2 and the ball 4 will drive the ball 4 to rotate. The limiting groove 9 first restricts the ball 4 to rotate only within the limiting groove 9, avoiding the ball 4 from rotating along the circumference of the mounting cavity 5, thus avoiding the ball 4 from driving the bearing cylinder 3 to rotate, ensuring the stability of the position of the bearing cylinder 3.

[0034] More specifically, a protrusion 8 is fixedly connected to the bottom surface of the mounting cavity 5. When the head cone 2 is fully inserted into the bearing cylinder 3, the head cone 2 abuts against the protrusion 8.

[0035] In one specific embodiment, when the head cone 2 abuts against the protrusion 8, the contact area is very small, which can reduce the friction between the two, allowing the head cone 2 to rotate easily without restricting the user's hip joint movement.

[0036] It should also be noted that the contact point between the ball 4 and the through hole 6 is located between the axis of the bearing cylinder 3 and the axis of the ball 4.

[0037] In one specific embodiment, when the head cone 2 is not inserted into the bearing cylinder 3, the contact point between the ball 4 and the through hole 6 is located between the axis of the bearing cylinder 3 and the axis of the ball 4. This means that the ball 4 is always restricted by the through hole 6 and abuts against the mounting cavity 5, thus avoiding the ball 4 falling out of the through hole 6 without the restriction of the head cone 2.

[0038] More specifically, a groove 11 is provided inside the mounting cavity 5, and the diameter of the groove 11 is larger than the diameter of the bottom surface of the bearing cylinder 3.

[0039] In one specific embodiment, when the diameter of the groove 11 is greater than the diameter of the bottom surface of the support cylinder 3, it means that the support cylinder 3 can be directly contacted through the groove 11. When separating the head cone 2 and the femoral head prosthesis 1, the support cylinder 3 is directly pushed by the guide rod, so that the support cylinder 3 moves in the mounting cavity 5, increasing the gap between the support cylinder 3 and the mounting cavity 5. This causes the ball bearing 4 to move along the arc surface 10 and the mounting cavity 5, eventually passing the connection between the arc surface 10 and the head cone 2 and abutting against the head cone 2. At this time, the head cone 2 can be separated from the femoral head prosthesis 1.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A femoral head prosthesis for revision of a multi-tapered femoral stem, characterized in that: It includes femoral head prosthesis (1), the installation cavity (5) is opened in the femoral head prosthesis (1), and the installation cavity (5) is inverted cone, the bearing cylinder (3) of shape as inverted cone is slidably arranged in the installation cavity (5), and there is gap between the installation cavity (5) and the bearing cylinder (3), and the gap diameter increases along the femoral head prosthesis (1) axial direction upwards, six through holes (6) are formed on the conical surface of the bearing cylinder (3), and the six through holes (6) are arranged in a circle, the ball (4) is slidably installed in each through hole (6), the ball (4) is attached to the installation cavity (5), the bearing cylinder (3) is inserted with the head cone (2), the arc surface (10) for connecting with the conical neck is arranged on the head cone (2), the bottom surface of the bearing cylinder (3) is connected with the installation cavity (5) through the spring (7), when the head cone (2) is inserted into the bearing cylinder (3), the conical surface of the head cone (2) is abutted on the ball (4), the ball (4) is extruded and slides in the through hole (6) along the installation cavity (5), and the bearing cylinder (3) is driven to move upwards, the gap is continuously increased, the head cone (2) is completely inserted into the bearing cylinder (3), the gap is in the maximum state, the spring (7) drives the bearing cylinder (3) to reset, so that the ball (4) slides off from the edge of the head cone (2), at this time, the arc surface (10) is abutted with the installation cavity (5) through the ball (4), and the head cone (2) is in a completely fixed state.

2. A femoral head prosthesis for revision of a multi-tapered femoral stem according to claim 1, characterized in that: Six limit grooves (9) are formed in the inner wall of the installation cavity (5), and each limit groove (9) is slidably connected with the ball (4).

3. A femoral head prosthesis for revision of a multi-tapered femoral stem according to claim 1, characterized in that: The convex block (8) is fixedly connected to the bottom surface of the installation cavity (5), when the head cone (2) is completely inserted into the bearing cylinder (3), the head cone (2) is abutted to the convex block (8).

4. The femoral head prosthesis for revision of a multi-tapered femoral stem according to claim 1, characterized in that: The contact point of the ball (4) and the through hole (6) is located between the axis of the bearing cylinder (3) and the axis of the ball (4).

5. The femoral head prosthesis for revision of a multi-tapered femoral stem according to claim 1, wherein: The recess (11) is formed in the installation cavity (5), and the diameter of the recess (11) is greater than the diameter of the lower bottom surface of the bearing cylinder (3).

Images