Modular distal femoral tumor bionic prosthesis with universal component

Abstract

The present invention relates to an assembled tumor-type bionic prosthesis for the distal femur with a universal component, which comprises the following components: a femur component, the femur component includes the distal femur, a first groove is formed at the lower end of the distal femur and two through holes are located at both ends of the first groove; a tibia component, the tibia component includes a tibial plateau, and a second groove is arranged on the tibial plateau; a buffer component, the buffer component includes a gasket, and the gasket is arranged on the upper end of the tibial plateau; a universal component, the universal component includes a universal shaft and a pin shaft, the upper end of the universal shaft is installed in the first groove, the lower end is installed in the second groove, and the pin shaft is arranged between the two through holes for connecting the distal femur and the tibial plateau together. The present invention adds an integrated universal component to the tumor-type prosthesis for the distal femur, effectively dispersing the stress on the prosthesis and improving the service life of the prosthesis.

Description

Technical Field

[0001] The present invention relates to an assembled distal femoral tumor - type bionic prosthesis with a universal component, belonging to the technical field of medical devices. Background Art

[0002] The distal femur is a common site for malignant bone tumors. Currently, the main method for treating malignant bone tumors in this area is segmental resection of the tumor, completely removing the tumor, and then reconstructing the defect bone with an artificial hinge knee joint prosthesis.

[0003] Currently, the commercially available distal femoral tumor - type hinge knee joints have the following two major drawbacks:

[0004] 1. From the design perspective: Currently, the commercially available distal femoral prostheses for tumors only have two types, namely simple hinge and rotating hinge. These two simple structural designs greatly limit the movement of the knee joint prosthesis in all directions, showing a large difference from the movement of a normal knee joint (flexion - extension, rotation, etc.) and failing to fully achieve bionics. Therefore, this type of prosthesis has potential risks such as fracture, fatigue failure, severe wear, and periprosthetic fracture. This is especially true in cases of children and adolescents. The knee joint activity of children and adolescents is greater than that of adults. Coupled with the gradual development and maturity of the bones, ordinary hinge knee joints are affected by the stress in all directions of the bones during the knee joint movement of up to one million times. Ordinary hinge knee joints prevent knee joint dislocation by restricting the movement of the knee joint in all directions, but this stability comes at the cost of movement. Although this metal hinge "blocks" the movement of the knee joint mechanically, the forces in all directions still exist during human activities. Therefore, in the long - term movement process, this prosthesis that does not conform to human kinematics will experience metal fatigue fracture, wear, and even periprosthetic fracture. The rotating hinge knee joint works on the same principle. It only has an additional rotating function compared to the ordinary hinge knee joint, and this rotation is mainly platform rotation, unable to truly achieve the bionic purpose. Eventually, under the action of stress in different directions, fatigue fracture will occur at the junction of the platform and the liner.

[0005] 2. From the material perspective: Commercially available distal femoral prostheses for tumors mainly consist of a distal femur made of cobalt - chromium - molybdenum (CoCrMo) alloy, a tibial plateau and a medullary rod made of medical titanium alloy (Ti6Al4V), and a liner made of polyethylene (PE). These two materials have excellent anti - wear performance and mechanical strength, and can provide immediate joint stability after implantation. However, as an implant prosthesis used in orthopedic oncology, it still has some deficiencies. First, the CoCrMo alloy (density: 8.9 g / cm 3), the prepared prosthesis is too heavy, which will accelerate the load on the surrounding bone mass and may cause fractures and wear; second, the metal particles generated during the wear process of CoCrMo alloy will cause inflammatory reactions and osteolysis in the surrounding tissues; third, the elastic modulus of CoCrMo alloy (220 GPa) is much greater than that of human bone (3 - 20 GPa). After implantation, it will cause the "stress shielding" effect, resulting in fatigue fracture of the prosthesis and fractures around the prosthesis; finally, CoCrMo alloy will scatter after being irradiated by radiation on its surface, generating metal artifacts. On the one hand, these artifacts affect doctors' observation of tiny recurrent lesions during CT or X-ray examinations, causing irreparable consequences. On the other hand, during tumor radiotherapy, they will affect the estimation of radiation dose, and the scattered rays will also damage the surrounding normal tissues. Therefore, we urgently need a distal femoral tumor prosthesis with suitable mechanical properties, lightweight, and good light transmittance.

[0006] In summary, the existing distal femoral tumor hinge knee joints still have the following problems:

[0007] 1) The current hinge knee joint does not match the movement behavior of the normal human knee joint, and multi-directional stress causes the shortening of the service life of the prosthesis components; 2) The elastic modulus of CoCrMo alloy does not match that of the bone. After implantation, it is easy to produce the stress shielding phenomenon, accelerating bone loss while increasing the risk of secondary fractures; 3) The density of CoCrMo alloy is too large. After implantation, it will increase the burden on the host bone, causing fractures or wear and resulting in prosthesis failure; 4) CoCrMo alloy will generate toxic metal wear particles during use, causing inflammatory reactions in the surrounding tissues; 5) CoCrMo alloy materials will produce severe scattering and metal artifacts when irradiated by radiation. Summary of the Invention

[0008] To address the above prominent problems, the present invention provides an assembled distal femoral tumor bionic prosthesis with a universal component. By adding an integrated universal component, the stress on the prosthesis is effectively dispersed, improving the service life of the prosthesis.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] An assembled distal femoral tumor bionic prosthesis with a universal component, comprising the following components:

[0011] Femoral component, the femoral component includes the distal femur, and a first groove is opened at the lower end of the distal femur and two through holes are located at both ends of the first groove;

[0012] Tibial component, the tibial component includes the tibial plateau, and a second groove is provided on the tibial plateau;

[0013] A buffer component, the buffer component includes a gasket, and the gasket is arranged at the upper end of the tibial plateau;

[0014] A universal component, the universal component includes a universal shaft and a pin shaft. The upper end of the universal shaft is installed in the first groove, and the lower end is installed in the second groove. The pin shaft is arranged between the two through holes and is used to connect the distal femur and the tibial plateau together.

[0015] For the modular distal femoral tumorous bionic prosthesis, preferably, the universal shaft includes an upper end portion, an intermediate transition portion, and a lower end portion. The upper end portion is a cylindrical tubular structure, the intermediate transition portion is an arc-shaped curved surface, the lower end portion is a ball head, and the second groove is an arc-shaped groove adapted to the ball head.

[0016] For the modular distal femoral tumorous bionic prosthesis, preferably, the universal component further includes a universal shaft sleeve, and the universal shaft sleeve is assembled between the ball head and the second groove to reduce the friction between the ball head and the second groove.

[0017] For the modular distal femoral tumorous bionic prosthesis, preferably, the buffer component further includes a first shaft sleeve and a second shaft sleeve. The first shaft sleeve and the second shaft sleeve are respectively sleeved at both ends of the pin shaft to reduce the friction between the pin shaft and the through holes.

[0018] Both of the above two shaft sleeves are designed to reduce the friction between CFR-PEEK and metal materials, between metal and CFR-PEEK materials.

[0019] For the modular distal femoral tumorous bionic prosthesis, preferably, the femoral component further includes a femoral medullary cavity rod and an extension rod. The lower end of the extension rod is connected to the upper end of the distal femur, and the upper end of the extension rod is connected to the lower end of the femoral medullary cavity rod.

[0020] For the modular distal femoral tumorous bionic prosthesis, preferably, the tibial component further includes a tibial medullary cavity rod, and the tibial medullary cavity rod is connected to the lower end of the tibial plateau.

[0021] For the modular distal femoral tumorous bionic prosthesis, preferably, the universal shaft and the pin shaft are tightly connected by a fastener.

[0022] For the modular distal femoral tumorous bionic prosthesis, preferably, the distal femur is a distal femoral prosthesis made of CFR-PEEK material, and the buffer component and the universal shaft sleeve are made of PE material or CFR-PEEK material.

[0023] For the modular distal femoral tumor-type bionic prosthesis described above, preferably, the content of carbon fiber in the CFR-PEEK is 20 to 40 wt%.

[0024] For the modular distal femoral tumor-type bionic prosthesis described above, preferably, the weight-average molecular weight of the CFR-PEEK is 80,000 to 120,000, the number-average molecular weight is 20,000 to 40,000, the molecular weight distribution is 3.2 to 3.8, and the degree of polymerization is 100 to 110.

[0025] Due to the above technical solutions adopted by the present invention, it has the following advantages:

[0026] 1. The Carbon Fiber Reinforced-Polyether Ether Ketone (CFR-PEEK) material used in the present invention has good mechanical strength (compressive strength, flexural strength, yield stress, impact strength) and biosecurity. Compared with metals, on the one hand, CFR-PEEK has a lower density. The density of CFR-PEEK is only about 1.38 g / cm 3 or so. As a prosthesis material, it can effectively reduce the weight of the prosthesis, reduce the weight of the implant, relieve the burden on the host bone, and is beneficial to the immediate stability of the prosthesis in the early stage. On the other hand, the elastic modulus of CFR-PEEK (about 18 GPa) is similar to that of human bone (3 - 20 GPa) and lower than that of medical titanium alloy (110 GPa). Therefore, after implantation into the human body, it can effectively avoid the stress shielding effect and reduce the risk of secondary fracture and bone loss. Thirdly, the wear particles of the CFR-PEEK material do not have as strong tissue toxicity as the wear particles of the CoCrMo alloy.

[0027] 2. The CFR-PEEK in the present invention has excellent light transmission performance, making it have very important application value in the field of orthopedics, especially in the field of bone oncology. The CFR-PEEK material eliminates the interference of metal artifacts, which can help doctors detect early tumor recurrence. In addition, the CFR-PEEK material can also solve the problem of ray refraction. After the problem of ray refraction is solved, on the one hand, orthopedic doctors can more accurately judge the radiotherapy dose, and on the other hand, the surrounding tissues are better protected. The emergence of the CFR-PEEK material also provides a very good alternative solution to solve the problem of tissue inflammation caused by the release of metal ions during the wear process of CoCrMo prostheses.

[0028] 3. The universal module in the present invention completely subverts the design of the prosthesis in the prior art. The overall structure from the cylindrical sleeve extending to the ball head below is called the universal shaft, and it adopts an integrated streamlined design, which improves the situation in the prior art where the cylindrical sleeve and the lower connection point are prone to fatigue fracture, and the mechanical design is more reasonable. A screw fixation is added at the connection between the universal shaft and the pin shaft, increasing the stability of the prosthesis during flexion and extension movements.

[0029] 4. The present invention is the first to use CFR-PEEK material to replace the entire distal femoral part of the tumor prosthesis, and for the first time, an integrated universal component is added to the distal femoral tumor prosthesis, effectively dispersing the stress on the prosthesis and improving the service life of the prosthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. 9 is a three-dimensional structural schematic diagram of the distal femur in the modular distal femoral tumor bionic prosthesis with a universal component provided by an embodiment of the present invention;

[0031] Figure 2 FIG. 13 is a side view of the distal femur in the modular distal femoral tumor bionic prosthesis with a universal component provided by this embodiment of the present invention;

[0032] Figure 3 FIG. 17 is an exploded view of the modular distal femoral tumor bionic prosthesis with a universal component provided by this embodiment of the present invention;

[0033] Figure 4 FIG. 21 is an assembled view of the modular distal femoral tumor bionic prosthesis with a universal component provided by this embodiment of the present invention;

[0034] Figure 5 FIG. 25 is a structural schematic diagram of a tumor knee prosthesis provided by the prior art;

[0035] 1 - femoral medullary cavity rod; 2 - extension rod; 3 - distal femur, 301 - first through hole, 302 - second through hole, 303 - first groove; 4 - universal shaft, 401 - lower end part, 402 - intermediate transition part, 403 - upper end part; 5 - pin shaft; 6 - first bushing; 7 - second bushing; 8 - universal shaft sleeve; 9 - gasket; 10 - tibial plateau; 11 - tibial medullary cavity rod; 12 - screw. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains. The terms "first", "second", "third", "fourth" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0038] As Figure 1 , 2 shown, the present invention provides an assembled modular distal femoral tumor bionic prosthesis with a universal component, comprising the following components: a femoral component, the femoral component including a distal femur 3, a first groove 303 is formed at the lower end of the distal femur 3 and two through holes are located at both ends of the first groove 303; a tibial component, the tibial component including a tibial plateau 10, a second groove is provided on the tibial plateau 10; a buffer component, the buffer component including a gasket 9, the gasket 9 is disposed on the upper end of the tibial plateau 10; a universal component, the universal component including a universal shaft 4 and a pin shaft 5, the upper end of the universal shaft 4 is installed in the first groove 303, the lower end is installed in the second groove, and the pin shaft 5 is passed through between the two through holes for connecting the distal femur 3 and the tibial plateau 10 together.

[0039] In a preferred embodiment of the present invention, the universal shaft 4 includes an upper end portion 403, an intermediate transition portion 402 and a lower end portion 401. The upper end portion 403 is a cylindrical tubular structure, the intermediate transition portion 402 is an arc-shaped curved surface, and the lower end portion 401 is a ball head. The second groove is an arc-shaped groove adapted to the ball head. Since the lower end of the universal shaft 4 is connected to the second groove through the ball head, the universal shaft allows the prosthesis to have slight movements in all directions during the movement process, and can better decompose the stresses borne in all directions compared with traditional hinge knee joint prostheses, thereby improving the service life of the prosthesis.

[0040] In a preferred embodiment of the present invention, the universal component further includes a universal shaft sleeve 8, and the universal shaft sleeve 8 is assembled between the ball head and the second groove for reducing the friction between the ball head and the second groove.

[0041] In a preferred embodiment of the present invention, the buffer component further includes a first shaft sleeve 6 and a second shaft sleeve 7, and the first shaft sleeve 6 and the second shaft sleeve 7 are respectively sleeved at both ends of the pin shaft 5.

[0042] In a preferred embodiment of the present invention, the femoral component further includes a femoral medullary cavity rod 1 and an extension rod 2. The lower end of the extension rod 2 is connected to the upper end of the distal femur 3, and the upper end of the extension rod 2 is connected to the lower end of the femoral medullary cavity rod 1. The femoral medullary cavity rod 1, the extension rod 2, and the tibial plateau 10 are made of traditional Ti6Al4V material. This is because the femoral medullary cavity rod 1 is an immediate stability device after the implantation of the tumor-type knee prosthesis, and the shear force that the prosthesis needs to bear at the junction with the medullary cavity is very large. Therefore, a metal material is still used here. In addition, the femoral medullary cavity rod 1 can be designed in different models according to the length and width of the patient's medullary cavity.

[0043] In a preferred embodiment of the present invention, the tibial component further includes a tibial medullary cavity rod 11, and the tibial medullary cavity rod 11 is connected to the lower end of the tibial plateau 10. The tibial medullary cavity rod 11 is also made of traditional Ti6Al4V material to increase the stability of fixation.

[0044] In a preferred embodiment of the present invention, the universal shaft 4 and the pin shaft 5 are tightly connected by a fastener. Specifically, the universal shaft 4 and the pin shaft 5 are fastened by a screw 12 to enhance the stability between the two.

[0045] In a preferred embodiment of the present invention, the distal femur 3 is a distal femur prosthesis made of CFR-PEEK material, and the buffer component and the universal shaft sleeve 8 are made of PE material or CFR-PEEK material.

[0046] In a preferred embodiment of the present invention, the content of carbon fiber in CFR-PEEK is 20-40 wt%.

[0047] In a preferred embodiment of the present invention, the weight-average molecular weight of CFR-PEEK is 80,000-120,000, the number-average molecular weight is 20,000-40,000, the molecular weight distribution is 3.2-3.8, and the degree of polymerization is 100-110.

[0048] To further illustrate the role of carbon fiber in modified polyetheretherketone, the following experiments were conducted in the present invention:

[0049] Example 1

[0050] In the CFR-PEEK used in this example, the degree of polymerization of PEEK is 105, the number-average molecular weight is 34,000, the weight-average molecular weight is 100,000, the molecular weight distribution is 3.2-3.8, and the content of carbon fiber is 30 wt%. The mechanical properties and density of CFR-PEEK are shown in Table 1.

[0051] Examples 2-6

[0052] The difference between Examples 2-6 and Example 1 lies in: the content of carbon fiber is different, and the specific test results are shown in Table 1 for details.

[0053] Table 1 shows the effects of different carbon fiber contents on the mechanical properties and density of PEEK

[0054]

[0055] As can be seen from Table 1, as the proportion of carbon fiber gradually increases, the elastic modulus and tensile strength of the prosthesis also gradually increase, the stiffness gradually increases, but the toughness gradually decreases. When the carbon fiber content reaches 60%, the material has completely lost its plastic forming function and is very hard. This material is not suitable for preparing joint prostheses. Therefore, after continuous attempts, it is finally determined that the mechanical properties of 30wt% CFR-PEEK material are most suitable for making knee joint prostheses, which takes into account both rigidity and toughness. In addition, the carbon fiber in the present invention is short fiber, and the fiber distribution direction is randomly distributed.

[0056] Example 7

[0057] This example is the same as Example 3, where the carbon fiber content is 30wt%, the degree of polymerization of PEEK is 105, the number average molecular weight is 34,000, the weight average molecular weight is 100,000, and the molecular weight distribution is 3.2 - 3.8.

[0058] Examples 8 - 12

[0059] The differences between Examples 8 - 12 and Example 7 are that the degree of polymerization and molecular weight distribution of PEEK are different, as shown in Table 2 specifically.

[0060] Table 2 shows the mechanical properties and density of PEEK with different degrees of polymerization

[0061]

[0062] As can be seen from Table 2, as the degree of polymerization and molecular weight distribution gradually increase, the elastic modulus and tensile strength of the prosthesis also gradually increase, and the stiffness gradually increases. When the degree of polymerization is 150, the elastic modulus of CFR-PEEK material has exceeded the elastic modulus bearing range of the human femur. Therefore, it is finally determined that the mechanical properties of CFR-PEEK material with a degree of polymerization of 105 and a molecular weight distribution of 3.2 - 3.8 are most suitable for making knee joint prostheses.

[0063] Such as Figure 5As shown in the figure, it is a tumor-type knee joint prosthesis provided by the prior art. The distal femoral prosthesis 11 includes a prosthesis main body 111 and two protective shells 112 made of PE material and coated on both sides of the prosthesis main body 111. The two protective shells 112 are fixed on the distal femoral prosthesis 11 by titanium alloy screws. During use, it is found that the titanium alloy screws will cut the protective shells 112 and the distal femoral prosthesis 11, causing the protective shells 112 to crack and the distal femoral prosthesis 11 to wear. At the same time, due to the stress shielding effect generated by the contact between the screws and two materials with a large difference in elastic modulus, fatigue fracture occurs.

[0064] On the other hand, there is no universal component on the tibial plateau prosthesis 21 in the prior art. The tibial component 2 and the distal femur are connected by a hinge device with a relatively high restriction. The hinge device and the tibial plateau prosthesis 21 are integrated and cannot be disassembled, and can only move slightly at a preset angle (the preset angle is 3°) and direction, with a very high restriction. Therefore, the human body still cannot meet the requirement of stress dispersion during sudden start running, lateral movement, and rotational movements. The present invention provides a separately assembled universal component, which can produce 360° of micro-movement, perfectly cope with the stress generated during the above-mentioned movement process, greatly enhance the service life of the prosthesis, and more conform to the kinematic law of the normal human knee joint, achieving a fully bionic effect.

[0065] The elastic modulus of the CFR-PEEK provided by the present invention is about 18 GPa, which is similar to the elastic modulus of the human femur of 3-20 GPa and lower than that of medical titanium alloy (110 GPa). Therefore, after being implanted into the human body, it can effectively avoid the stress shielding effect and reduce the risk of secondary fracture. In addition, the density of CFR-PEEK is only 1.38 g / cm 3 or so. As a prosthesis material, it can effectively reduce the weight of the prosthesis; the wear particles of CFR-PEEK material do not have as strong tissue toxicity as CoCrMo wear particles; and the excellent light transmission performance of CFR-PEEK effectively reduces the scattering of radiation and solves the problem of metal artifacts.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modular distal femoral tumorous bionic prosthesis with a universal component, characterized in that, it comprises the following components: A femoral component, the femoral component includes a distal femur (3), a first groove (303) is opened at the lower end of the distal femur (3) and two through holes are located at both ends of the first groove (303); A tibial component, the tibial component includes a tibial plateau (10), and a second groove is provided on the tibial plateau (10); A buffer component, the buffer component includes a gasket (9), and the gasket (9) is arranged on the upper end of the tibial plateau (10); A universal component, the universal component includes a universal shaft (4) and a pin shaft (5), the upper end of the universal shaft (4) is installed in the first groove (303), the lower end is installed in the second groove, and the pin shaft (5) is arranged between the two through holes for connecting the distal femur (3) and the tibial plateau (10) together; The universal shaft (4) includes an upper end portion (403), an intermediate transition portion (402) and a lower end portion (401), the upper end portion (403) is a cylindrical tubular structure, the intermediate transition portion (402) is an arc-shaped curved surface, the lower end portion (401) is a ball head, and the second groove is an arc-shaped groove adapted to the ball head; The universal component further includes a universal shaft sleeve (8), and the universal shaft sleeve (8) is assembled between the ball head and the second groove for reducing the friction between the ball head and the second groove; The distal femur (3) is a distal femoral prosthesis made of CFR-PEEK material, and the buffer component and the universal shaft sleeve (8) are made of PE material or CFR-PEEK material; The weight-average molecular weight of the CFR-PEEK is 80,000 - 120,000, the number-average molecular weight is 20,000 - 40,000, the molecular weight distribution is 3.2 - 3.8, and the degree of polymerization is 100 - 110.

2. The modular distal femoral tumorous bionic prosthesis according to claim 1, characterized in that, the buffer component further includes a first shaft sleeve (6) and a second shaft sleeve (7), and the first shaft sleeve (6) and the second shaft sleeve (7) are respectively sleeved at both ends of the pin shaft (5).

3. The modular distal femoral tumorous bionic prosthesis according to claim 1, characterized in that, the femoral component further includes a femoral medullary cavity rod (1) and an extension rod (2), the lower end of the extension rod (2) is connected to the upper end of the distal femur (3), and the upper end of the extension rod (2) is connected to the lower end of the femoral medullary cavity rod (1).

4. The modular distal femoral tumorous bionic prosthesis according to claim 1, characterized in that, the tibial component further includes a tibial medullary cavity rod (11), and the tibial medullary cavity rod (11) is connected to the lower end of the tibial plateau (10).

5. The modular distal femoral tumorous bionic prosthesis according to claim 1, characterized in that, the universal shaft (4) and the pin shaft (5) are tightly connected by a fastener.

6. The modular distal femoral tumorous bionic prosthesis according to claim 1, characterized in that, The content of carbon fiber in the CFR-PEEK is 20 to 40 wt%.

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