Knee joint prosthesis
By installing gaskets on the tibial rotary part of the knee prosthesis to share the weight pressure when standing, the problem of excessive pressure under hinge bearings and wear of polyethylene pads is solved, and the service life of the prosthesis is extended.
Patent Information
- Application Number
- CN202421473381.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-25
- Publication Date
- 2025-05-30
- Estimated Expiration
- 2034-06-25
AI Technical Summary
The existing hinge-type knee prosthesis has excessive pressure when standing, which may lead to deformation, and the ankle surface of the femoral ankle is in full fit and in contact with the polyethylene liner, which is prone to wear and affects the service life.
A knee prosthesis is designed. When a gasket is provided on the support part of the tibial rotating member in a standing position, the distal surface of the condyle body is in contact with the top surface of the gasket, and the weight is shared, and the pressure is evenly distributed through the design of the hinge mechanism.
It effectively avoids excessive burden and deformation of the hinge shaft, extends the service life of the knee prosthesis, and reduces the wear of the polyethylene liner.
Smart Images
Figure CN222917675U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of medical devices, and particularly relates to a knee joint prosthesis. Background Art
[0002] Total knee arthroplasty refers to a surgery that replaces the surface of the knee joint that has been severely damaged and cannot perform normal functions with an artificial prosthesis, so as to eliminate pain, correct knee joint deformity, restore knee joint stability and mobility, improve knee joint movement function, and improve the quality of life of patients.
[0003] The hinge-type knee joint is a commonly used prosthesis in total knee arthroplasty. The hinge-type knee joint prosthesis usually uses a hinge mechanism to connect the femoral component to one or both of the bearing component and the tibial component, so as to restrain the components of the knee joint prosthesis and mechanically connect them together. Most of the hinge-type knee joint prostheses in the prior art rely on the hinge shaft to bear the upper and lower hinge structures. When the patient stands upright, the hinge shaft is under the greatest pressure at this time, which may cause an excessive burden on the hinge shaft and lead to deformation of the hinge shaft, thereby affecting the normal use of the knee joint prosthesis. In addition, the ankle surface of the femoral condyle of the existing knee joint prosthesis is in complete contact with the polyethylene liner, and it is easy to wear the polyethylene liner when the knee joint rotates, affecting the service life of the polyethylene liner. Summary of the Utility Model
[0004] The purpose of the utility model is to provide a knee joint prosthesis that can share the pressure on the connecting shaft in the standing position.
[0005] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:
[0006] A knee joint prosthesis, characterized in that it includes:
[0007] A femoral component, the femoral component includes a femoral condyle main body, the femoral condyle main body has two condyles spaced apart in the coronal plane direction, a condylar fossa is defined between the two condyles, and the femoral condyle main body also has an axial hole penetrating through the two condyles in the coronal plane direction;
[0008] A tibial component, the tibial component includes a tibial rotating member, the tibial rotating member has a platform portion and a rod-shaped portion, the rod-shaped portion is connected to the bottom of the platform portion and extends distally, the top of the platform portion is provided with a ridge protruding proximally and corresponding to the position of the condylar fossa, the ridge is provided with a bushing hole penetrating through the ridge in the coronal plane direction, and the top surface of the platform portion has a supporting portion on both sides of the ridge in the coronal plane direction, and the two supporting portions are respectively arranged corresponding to the two condyles of the femoral condyle main body;
[0009] A hinge mechanism, the hinge mechanism includes a pin shaft and a bushing, the bushing is located in the bushing hole of the convex ridge, the pin shaft is located in the shaft hole and the bushing hole, enabling the femoral condyle main body and the tibial rotating part to rotate around the pin shaft;
[0010] Wherein, gaskets are respectively arranged on the top surfaces of the two supporting parts of the platform part, the top surface of the gasket is matched with the surface of the corresponding condyle body, and is set such that in the standing position, the distal surface of the condyle body is in surface contact with the top surface of the corresponding gasket.
[0011] In one embodiment, the outer surface of the condyle body is divided into a condyle anterior curved surface, a condyle distal curved surface and a malleolus posterior curved surface along the sagittal plane direction, the condyle distal curved surface transitionally connects the condyle anterior curved surface and the malleolus posterior curved surface, wherein, the curvature radii of the condyle anterior curved surface, the malleolus posterior curved surface and the condyle distal curved surface increase in sequence, and the curvature radius of the condyle distal curved surface is at least ten times that of the malleolus posterior curved surface.
[0012] In one embodiment, the top surface of the gasket is a curved surface complementary to the condyle distal curved surface, and the curvature radius of the top surface of the gasket is 0.1 - 0.3 mm larger than that of the condyle distal curved surface.
[0013] In one embodiment, in the standing position, at least half of the area of the condyle distal curved surface is in contact with the top surface of the gasket.
[0014] In one embodiment, in the standing position, at least two-thirds of the area of the condyle distal curved surface is in contact with the top surface of the gasket.
[0015] In one embodiment, two spaced elastic pieces are connected to one end of the pin shaft, one end of the elastic piece is connected to the end of the pin shaft and extends in the axial direction of the pin shaft, a retaining member is arranged at the other end of the elastic piece, a snap ring portion extending radially along the pin shaft is arranged at the edge of the retaining member, a radially recessed blocking groove is arranged in the shaft hole, and the snap ring portion can be snapped into the blocking groove through the elastic deformation of the elastic piece to prevent the pin shaft from being disengaged from the shaft hole.
[0016] In one embodiment, a flange portion is arranged at one end of the bushing located on one side of the intercondylar fossa, the outer diameter of the flange portion is larger than the aperture of the bushing hole, and the flange portion is located between the outer side wall of the convex ridge and the inner side wall of the intercondylar fossa.
[0017] In one embodiment, the knee joint prosthesis further includes a meniscus liner, the bottom surface of the platform part of the tibial rotating part is in curved surface fit with the top surface of the meniscus liner, and allows the tibial rotating part to have an internal and external rotation range of plus or minus 20 degrees.
[0018] In one embodiment, the top surface of the meniscus pad is a concave curved surface, and a relief hole for the rod-shaped portion to pass through is provided in the middle of the concave curved surface. The surface radii on both the inner and outer sides of the concave curved surface are smaller than the surface radius in the middle. The bottom surface of the platform portion is a convex curved surface that mates with the curved surface of the top surface of the meniscus pad.
[0019] In one embodiment, the knee joint prosthesis further includes a tibial shaft sleeve, which is fixed in the cavity of the tibial tray or the tibial proximal substitute, and the rod-shaped portion is inserted into the hole of the tibial shaft sleeve.
[0020] Adopting the above technical solution, the beneficial effect of the present utility model is that the knee joint prosthesis provided by the present utility model is provided with gaskets on both sides of the tibial rotating member, and when in the standing position, the distal surface of the condyle body is in surface contact with the top surface of the corresponding gasket. The surface contact between the gasket and the condyle body and the hinge axis can jointly share the weight of the patient, avoiding deformation of the hinge axis caused by excessive load, and thus extending the service life of the knee joint prosthesis. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 A schematic diagram showing the knee joint prosthesis connected with a medullary cavity extension rod.
[0022] Figure 2 A three-dimensional schematic diagram of the knee joint prosthesis.
[0023] Figure 3 A side schematic diagram of the knee joint prosthesis in the sagittal plane direction.
[0024] Figure 4 Shows Figure 2 An exploded view of the knee joint prosthesis in
[0025] Figure 5 Shows Figure 3 An enlarged view of part A in
[0026] Figure 6 A side schematic diagram of the knee joint prosthesis in the coronal plane direction.
[0027] Figure 7 Shows Figure 6 An enlarged view of part B in
[0028] Figure 8 A three-dimensional schematic diagram of the pin shaft. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The preferred embodiments of the present utility model will be described in detail below in conjunction with the accompanying drawings, so as to more clearly understand the purpose, features and advantages of the present utility model. It should be understood that the embodiments shown in the drawings are not a limitation on the scope of the present utility model, but only to illustrate the essential spirit of the technical solution of the present utility model.
[0030] In the following description, for the purpose of illustrating the various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other instances, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail so as not to unnecessarily obscure the description of the embodiments.
[0031] Unless the context requires otherwise, throughout the specification and claims, the words "comprising" and its variants, such as "including" and "having", should be understood in an open, inclusive sense, i.e., construed to mean "including, but not limited to".
[0032] References throughout the specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of "in one embodiment" or "in an embodiment" throughout the specification do not necessarily all refer to the same embodiment. Additionally, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.
[0033] As used in this specification and the appended claims, the singular forms "a" and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally used in its inclusive sense of "and / or" unless the context clearly dictates otherwise.
[0034] In the following description, in order to clearly show the structure and working mode of the present utility model, many directional terms will be used for description. However, words such as "front", "rear", "left", "right", "outer", "inner", "outward", "inward", "up", "down", etc. should be understood as convenient terms and should not be understood as limiting terms.
[0035] Furthermore, terms such as "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.
[0036] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "arranged", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0037] As Figures 1-6 shown, this embodiment provides a knee joint prosthesis, which includes a femoral component 1, a tibial component 2, and a hinge mechanism 3. The femoral component 1 is rotatably coupled to the tibial component 2 via the hinge mechanism 3.
[0038] The femoral component 1 includes a femoral condyle main body 11, which is anatomically matched with the femoral condyle of a human. The femoral condyle main body 11 has two condyle bodies 12 spaced apart in the coronal plane direction. An intercondylar fossa 13 is defined between the two condyle bodies 12; the femoral condyle main body 11 also has an axial hole 14 penetrating through the two condyle bodies 12 in the coronal plane direction. The upper part of the femoral condyle main body 11 is used to connect a femoral canal extension rod 7, and the femoral canal extension rod 7 is used to be inserted into the medullary cavity of the femur. The femoral canal extension rod 7 is threadedly connected and fixed to the femoral condyle main body 11. The femoral canal extension rod 7 can be selected as a biological type or a cement type according to actual needs. Among them, the cement type femoral canal extension rod 7 can be used in cooperation with bone cement.
[0039] The tibial component 2 includes a tibial rotating member 21, which has a platform portion 211 and a rod-shaped portion 212. The rod-shaped portion 212 is connected to the bottom of the platform portion 211 and extends distally. The size of the rod-shaped portion 212 is set to be received and defined in the cavity of the tibial tray 4 or the tibial proximal substitute. The bottom of the tibial rotating member 21 is used to connect a tibial canal extension rod 8, and the tibial canal extension rod 8 is used to be inserted into the medullary cavity of the tibia. The tibial canal extension rod 8 is threadedly connected and fixed to the tibial rotating member 21. The tibial canal extension rod 8 can also be selected as a biological type or a cement type according to actual needs. Among them, the cement type tibial canal extension rod 8 can be used in cooperation with bone cement.
[0040] A ridge 213 protruding in the proximal direction is provided on the top of the platform portion 211. The ridge 213 is arranged corresponding to the position of the intercondylar fossa 13, and a bushing hole 214 is provided in the ridge 213 in the coronal plane direction. The top surface of the platform portion 211 has a supporting portion 215 on both sides of the ridge 213 in the coronal plane direction, and the two supporting portions 215 correspond to the two condyle bodies 12 of the femoral condyle main body 11.
[0041] The hinge mechanism 3 includes a pin shaft 31 and two bushings 32. The two bushings 32 are arranged in the bushing holes 214 of the convex ridge 213. The pin shaft 31 penetrates through the shaft hole 14 and the bushing hole 214, enabling the femoral condyle main body 11 and the tibial rotating member 21 to rotate around the pin shaft 31. The bushing 32 is made of a polymer material meeting the medical implant standard, such as polymer materials like polyethylene and polytetrafluoroethylene. This bushing 32 can avoid the metal-to-metal movement wear between the pin shaft 31 and the tibial rotating member 21 during the flexion and extension of the human body. Preferably, the end of the bushing 32 on the side of the intercondylar fossa 13 is provided with a flange portion 321 located outside the bushing hole 214. The outer diameter of the flange portion 321 is greater than the aperture of the bushing hole 214, such that the flange portion 321 is located between the two side walls of the convex ridge 213 and the inner wall of the intercondylar fossa 13, thereby avoiding the direct contact between the two side walls of the convex ridge 213 and the inner wall of the intercondylar fossa 13, allowing direct contact movement between metal and non-metal, and increasing the service life.
[0042] On the top surfaces of the two supporting portions 215 of the platform portion 211, a groove 216 is respectively provided, and a gasket 217 is fixed in each groove 216. The gasket 217 is made of a non-metal material meeting the medical implant standard, such as polymer materials like polyethylene. The lower part of the gasket 217 is fixed in the groove 216, and the fixing between the lower part of the gasket 217 and the groove 216 is achieved through a clamping structure. The top surface of the gasket 217 is arranged to match the surface of the corresponding condyle body 12. It is set that when in the standing position, the condyle body 12 abuts against the top surface of the corresponding gasket 217, and the contact between the distal surface of the condyle body 12 and the corresponding gasket 217 is a surface contact. When in the maximum compression position, the surface contact between the gasket 217 and the condyle body 12 and the hinge axis can jointly share the weight of the patient.
[0043] See Figures 3-6 , the outer surface of the condyle body 12 of the femoral condyle main body 11 is divided into a condyle anterior curved surface 121, a condyle distal curved surface 122, and a condyle posterior curved surface 123 along the sagittal plane direction. The condyle distal curved surface 122 transitionally connects the condyle anterior curved surface 121 and the condyle posterior curved surface 123 to form a complete outer surface of the condyle body. Among them, the condyle anterior curved surface 121 has the smallest curvature radius, the condyle posterior curved surface 123 has the second smallest curvature radius, and the condyle distal curved surface 122 has the largest curvature radius.
[0044] Preferably, the surface radius of the distal condylar surface 122 is much larger than that of the posterior malleolar surface 123, such that the distal condylar surface 122 is almost a plane. In the standing position, there can be a larger contact area between the distal condylar surface 122 and the spacer 217, which can better share the patient's weight. At the same time, the spacer 217 also has a limiting function. In the standing position, the anterior condylar surface 121 is interfered by the spacer 217 and cannot perform hyperextension movement anymore. Thus, the spacer 217 can not only satisfy the function of sharing pressure but also does not affect the physiological characteristics of normal joint movement. It should be noted that the so-called much larger usually means exceeding an exponential level, that is, greater than or equal to 10 times the surface radius. As can be seen from Figure 4 it can be seen that the distal condylar surface 122 of the condyle body 12 is basically in contact with the top surface of the spacer 217 in the sagittal plane direction. As can be seen from Figure 6 it can be seen that the distal condylar surface 122 of the condyle body 12 is basically in contact with the top surface of the spacer 217 in the coronal plane direction. From this, it can be concluded that most of the distal condylar surface 122 is in surface contact with the top surface of the spacer 217. Preferably, in the standing position, at least half of the area of the distal condylar surface 122 is in contact with the top surface of the spacer 217, and more preferably at least two-thirds of the area of the distal condylar surface 122 is in contact with the top surface of the spacer 217.
[0045] In one embodiment, the top surface of the spacer 217 is a surface complementary to the distal condylar surface 122, that is, the distal condylar surface 122 is a convex surface, and the top surface of the spacer 217 is a concave surface with almost the same surface diameter. Among them, the surface radius of the top surface of the spacer 217 is slightly larger than that of the distal condylar surface 122. Preferably, the surface radius of the top surface of the spacer 217 is 0.1 - 0.3 mm larger than that of the distal condylar surface 122. Within this range, it can well avoid the wear of the spacer 217 when the femoral condyle main body 11 performs joint activities relative to the tibial component 2, and can also ensure the contact area with the distal condylar surface 122 in the standing position, playing a good supporting role.
[0046] See Figure 3 and, the hinge mechanism 3 is also provided with an anti - withdrawal design to prevent the pin shaft 31 from disengaging from the bushing hole 214. Specifically, one end of the pin shaft 31 is connected with two spaced elastic pieces 311. One end of the elastic piece 311 is connected to the end of the pin shaft 31 and extends in the axial direction of the pin shaft 31. The other end of the elastic piece 311 is provided with a retaining member 312. The edge of the retaining member 312 is provided with a snap - ring portion 313 extending radially along the pin shaft 31. The snap - ring portion 313 can be snapped into the shaft hole 14 through the elastic deformation between the two elastic pieces 311 and into the radially - arranged blocking groove 141 in the shaft hole 14, such that the snap - ring portion 313 at the edge of the retaining member 312 plays a role similar to a snap - ring, effectively playing an anti - withdrawal role.
[0047] SeeFigure 3 , in this embodiment, the knee joint prosthesis further includes a meniscus pad 5. The bottom surface of the platform portion 211 of the tibial rotating member 21 is designed to be in curved surface fit with the top surface of the meniscus pad 5. This curved surface fit can, on the one hand, allow an internal and external rotation range of ±20°, and on the other hand, ensure the stability of internal and external rotation in the standing position. Specifically, the top surface of the meniscus pad 5 is a concave curved surface, and the middle part of the curved surface has a relief hole 51 for the rod-shaped portion 212 to pass through. At the same time, the bottom surface of the platform portion 211 is a convex curved surface that matches the curved surface of the top surface of the meniscus pad 5. The curved surface radii on both the inner and outer sides are smaller than the curved surface radius in the middle, so as to allow an internal and external rotation range of ±20°, and at the same time, it can meet the requirement of ensuring the stability of internal and external rotation in the standing position. During assembly, the bottom surface of the platform portion 211 can be attached to the top surface of the meniscus pad 5, and the rod-shaped portion 212 can pass through the relief hole 51 on the meniscus pad 5 and be received and limited in the cavity of the tibial tray or the tibial proximal substitute. The meniscus pad 5 is fixed in the groove on the top of the tibial tray 4 or the tibial proximal substitute, so that the tibial rotating member 21 and the tibial tray 4 or the tibial proximal substitute are constructed as a whole.
[0048] See Figure 3 , the rod-shaped portion 212 of the tibial rotating member 21 is a long cylindrical structure, and the free end of the rod-shaped portion 212 is hemispherical. At the same time, it further includes a tibial bushing 6. The tibial bushing 6 is fixed in the cavity of the tibial tray or the tibial proximal substitute, and the rod-shaped portion 212 is inserted into the hole of the tibial bushing 6. This design can better avoid the dislocation of the tibial rotating member in the tibial side prosthesis. The rod-shaped portion 212 can achieve effective rotation and unobstructed up and down movement with the non-metallic tibial bushing 6 during normal knee joint movement.
[0049] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims of this application.
Claims
1. A knee joint prosthesis, characterized in that: include: A femoral component, the femoral component comprising a femoral condyle body, the femoral condyle body having two condyles spaced apart in a coronal plane direction, an intercondylar fossa defined between the two condyles, and the femoral condyle body also having an axial hole penetrating through the two condyles in a coronal plane direction; A tibial component, the tibial component comprising a tibial rotation member, the tibial rotation member having a platform portion and a rod-shaped portion, the rod-shaped portion being connected to the bottom of the platform portion and extending toward the distal side, the top of the platform portion being provided with a ridge protruding toward the proximal direction and corresponding to the position of the intercondylar fossa, the ridge being provided with a sleeve hole penetrating the ridge along the coronal plane direction, the top surface of the platform portion being provided with a supporting portion on both sides of the ridge along the coronal plane direction, the two supporting portions being respectively provided corresponding to the two condyles of the femoral condyle body; A hinge mechanism, the hinge mechanism comprising a pin and a sleeve, the sleeve being located in the sleeve hole of the convex ridge, the pin being located in the shaft hole and the sleeve hole, so that the femoral condyle body and the tibial rotation member can rotate with the pin as the axis; Wherein, the top surfaces of the two supporting parts of the platform part are provided with gaskets, the top surfaces of the gaskets are matched with the surfaces of the corresponding condyles, and are set so that when in the standing position, the distal surface of the condyle is in surface contact with the top surface of the corresponding gasket.
2. The knee joint prosthesis according to claim 1, characterized in that: The outer surface of the condyle is divided into an anterior condylar curved surface, a distal condylar curved surface and a posterior malleolar curved surface along the sagittal plane, and the distal condylar curved surface transitionally connects the anterior condylar curved surface and the posterior malleolar curved surface, wherein the curvature radii of the anterior condylar curved surface, the posterior malleolar curved surface and the distal condylar curved surface increase successively, and the curvature radius of the distal condylar curved surface is at least ten times the curvature radius of the posterior malleolar curved surface.
3. The knee joint prosthesis according to claim 2, characterized in that: The top surface of the gasket is a curved surface that is complementary to the curved surface of the distal end of the condyle, and the curved surface radius of the top surface of the gasket is 0.1-0.3 mm larger than the curved surface radius of the curved surface of the distal end of the condyle.
4. The knee joint prosthesis according to claim 2, characterized in that: In the standing position, at least half of the area of the distal curved surface of the condyle is in contact with the top surface of the spacer.
5. The knee joint prosthesis according to claim 4, characterized in that: In the standing position, at least two-thirds of the area of the distal curved surface of the condyle is in contact with the top surface of the spacer.
6. The knee joint prosthesis according to claim 2, characterized in that: One end portion of the pin shaft is connected to two spaced-apart spring sheets, one end of the spring sheet is connected to the end portion of the pin shaft and extends in the axial direction of the pin shaft, the other end of the spring sheet is provided with a stop member, the edge of the stop member is provided with a retaining spring portion extending radially along the pin shaft, a radially recessed blocking groove is provided in the shaft hole, the retaining spring portion can be inserted into the blocking groove through the elastic deformation of the spring sheet, and prevents the pin shaft from escaping from the shaft hole.
7. The knee joint prosthesis according to claim 1, characterized in that: The sleeve is provided with a flange at one end portion located at the intercondylar notch. The outer diameter of the flange is larger than the hole diameter of the sleeve hole, and the flange is located between the outer side wall of the ridge and the inner side wall of the intercondylar notch.
8. The knee joint prosthesis according to claim 1, characterized in that: The knee joint prosthesis also includes a meniscus pad. The bottom surface of the platform portion of the tibial rotation component matches the curved surface of the top surface of the meniscus pad, allowing the tibial rotation component to have an internal and external rotation range of plus or minus 20 degrees.
9. The knee joint prosthesis according to claim 8, characterized in that: The top surface of the meniscus pad is an inwardly concave curved surface, the middle part of the concave curved surface has a clearance hole for the rod-shaped portion to pass through, the curved surface radius on both sides of the concave curved surface is smaller than the curved surface radius of the middle part, and the bottom surface of the platform part is a convex curved surface that matches the curved surface of the top surface of the meniscus pad.
10. The knee joint prosthesis according to claim 1, characterized in that: The knee joint prosthesis further comprises a tibial sleeve, which is fixed in a cavity of a tibial tray or a tibial proximal end replacement component, and the rod-shaped portion is inserted into a hole of the tibial sleeve.