CN115227460A - A kind of variable curvature unicondylar knee joint prosthesis and its manufacturing method - Google Patents

Abstract

The invention discloses a unicondylar knee joint prosthesis with variable curvature and a manufacturing method thereof, comprising two parts, a femoral unicondyle and a tibial lining prosthesis; , the instantaneous center of rotation formed by each curved surface changes in a "J" shape to ensure a smooth transition between each curved surface; the tibial liner prosthesis is designed based on the femoral unicondyle, and the lower surface of the liner is designed with a microporous structure Realize biological fixation with bone tissue; prepare femoral unicondyle and tibial pad by 3D printing process, design the printing path based on the principal stress trace of finite element analysis, and enhance the wear resistance and mechanical strength of the knee joint prosthesis. The variable curvature unicondylar knee joint prosthesis and its manufacturing method provided by the present invention not only have high shape matching and motion stability, but also have excellent wear resistance and biological fixation performance, and improve the motion of the unicondylar knee joint prosthesis stability and longevity.

Description

A kind of variable curvature unicondylar knee joint prosthesis and its manufacturing method

technical field

The invention belongs to the technical field of artificial joints, and in particular relates to a variable curvature unicondylar knee joint prosthesis and a manufacturing method thereof.

Background technique

As the most complex and largest joint in the human body, the knee joint is the hinge between the two longest bones (femur and tibia) of the lower extremity, and is mainly responsible for the body's weight-bearing and movement functions. However, the complex anatomical structure and mechanical environment of the knee joint make it vulnerable to diseases such as trauma and osteoarthritis, resulting in a pathological process that evolves from unicondylar wear to total knee wear, which affects the patient's life, economy, physical and mental health. Health brings great stress.

Existing knee products use injection-molded single-curvature femoral condyles and tibial pads to form knee prostheses. However, the simple femoral condyle surface and the patient's joint have poor matching, which is prone to over-covering or under-covering problems. At the same time, during the flexion movement, due to the sudden change of the joint surface, the problem of motion instability will occur. The tibial pad and the bone tissue are used between The mechanical fixation is prone to fatigue failure.

Therefore, it is increasingly difficult for current knee joint products to meet the patient's demand for long-life, safe and reliable implanted prostheses.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a variable-curvature unicondylar knee joint prosthesis and a manufacturing method thereof in view of the above-mentioned deficiencies in the prior art. stability, improve the long-term safety and service life of the joint.

The present invention adopts following technical scheme:

A variable-curvature unicondylar knee joint prosthesis comprises a tibial pad, a groove is formed on the tibial pad, the inner contour of the groove matches the femoral unicondyle, and the outer contour of the femoral unicondyle includes a plurality of variable curvature curved surfaces, a plurality of variable curvature surfaces. The instantaneous rotation center composed of the curved surface is distributed in a J-shape, and the inner surface of the femoral unicondyle is provided with a fixed column for connecting the bone tissue.

Specifically, the variable curvature surface includes five curved surfaces, namely, the front end surface of the femur, the oblique front end surface of the femur, the distal end surface of the femur, the oblique rear end surface of the femur, and the rear end surface of the femur. The end surfaces decrease sequentially.

Specifically, the fixed column includes a short fixed column and a long fixed column, the long fixed column is perpendicular to the curved surface corresponding to the oblique front end of the femur, and the short fixed column is located on the curved surface corresponding to the front end of the femur.

Further, the length ratio of the long fixed column and the short fixed column is 4:(2-3).

Specifically, the grooves sequentially include the curved surface of the front end of the tibia, the curved front surface of the oblique front of the tibia, and the curved surface of the distal end of the tibia.

Specifically, the nadir of the groove coincides with the nadir of the outer surface of the unicondyle of the femur.

Specifically, the tibial pad is aligned with the joint line formed by the femoral unicondyle and the natural joint line.

Specifically, the femoral unicondyle and tibial pad were prepared by 3D printing.

Specifically, a microporous structure is provided where the lower surface of the tibial pad contacts the bone tissue.

Another technical solution of the present invention is to provide a method for manufacturing a unicondylar knee joint prosthesis with variable curvature. A 3D printing process is used to prepare a femoral unicondyle and a tibial pad respectively; Based on the traces, the outer layer is designed as a concentric circle path to improve wear resistance, the inner layer is divided into 4 areas, and is designed to be divided into vertical line paths to improve mechanical strength, and the fixed column is printed in a criss-cross manner; Keeping parallel to the outer contour path of the femoral unicondyle, the printed path on the lower surface of the tibial pad is designed as a microporous structure.

Compared with the prior art, the present invention at least has the following beneficial effects:

A variable-curvature unicondylar knee prosthesis, aiming at the problems of poor matching and motion instability caused by the current clinical use of single-curvature or three-curvature knee prostheses, multiple sets of variable-curvature surfaces are used to form femoral condyle and tibial pads, On the one hand, it can maintain high matching with natural joints, avoid uneven stress transmission and bone loss caused by over- or under-covering of the prosthesis, and on the other hand, reduce the span difference between the surfaces, and improve the knee joint flexion movement. The smooth transition between the curved surfaces ensures the stability of movement; the variable curvature knee joint prosthesis designed by the present invention has high matching with the bone tissue in appearance, and can have good movement stability at high and low flexion angles during movement. At the same time, it also has excellent friction resistance and reliable bonding strength with bone tissue, which improves the overall service life, safety and comfort of the patient after implantation.

Further, the femoral condyle prosthesis adopts but is not limited to five curved surfaces with variable curvature, which improves the matching between the prosthesis and the bone tissue, and avoids the failure of the prosthesis caused by uneven matching. The radius of the femoral unicondyle decreases sequentially from the anterior surface of the femur to the posterior surface of the femur, which can make the instantaneous center of rotation in a J-shaped distribution, which is in line with the movement characteristics of the natural knee joint of ordinary people, and improves the movement stability of patients after prosthesis replacement. sex and comfort.

Further, the long fixed column is perpendicular to the curved surface corresponding to the oblique front end of the femur, and the short fixed column is located on the curved surface corresponding to the front end of the femur, which ensures that the knee joint can bear external loads in different directions at low and high flexion angles, and improves the false positive. The overall mechanical strength of the body. At the same time, the long fixation column and the short fixation column fix the femoral condyle prosthesis from the horizontal plane and the 30° oblique anterior surface respectively, so that it is not easy to fall off.

Further, the ratio of the length of the long fixation column and the short fixation column is 4:3 to 4:2, which ensures that the femoral condyle prosthesis can be firmly combined with the bone tissue, and the fixation column will not occur at high flexion angles. fracture.

Further, the grooves sequentially include the front end surface of the tibia, the oblique front end surface of the tibia, and the surface of the distal end of the tibia, and the three curved surfaces are matched with the curved surface of the femoral condyle prosthesis to form a motion friction surface, so that the two have high shape matching. It increases the contact area, reduces the stress concentration, and improves the friction resistance of the joint. The radius of the anterior tibial surface, the oblique anterior surface of the tibia and the distal surface of the tibia are all larger than the surface radius of the matching femoral unicondyle, ensuring that the femoral The condylar prosthesis can move smoothly in the groove of the tibial lining prosthesis, which ensures the freedom of movement of the joint prosthesis.

Further, the lowest point of the groove coincides with the lowest point of the outer surface of the femoral unicondyle, which ensures that there is no transition fit between the femoral condyle and the tibial liner prosthesis.

Further, the joint line formed by the tibial pad and the unicondyle of the femur is consistent with the natural joint line, which ensures that the position of the knee joint prosthesis during exercise is consistent with the natural knee joint, which is beneficial to the patient's postoperative force line and movement posture. Change.

Further, the variable curvature unicondylar knee joint prosthesis is prepared by 3D printing process, and the principal stress trace of finite element analysis is used as the printing path, which improves the overall mechanical strength of the joint and the wear resistance during exercise.

Further, the microporous structure on the tibial pad can realize biological fixation with the bone tissue, which improves the long-term joint strength of the joint.

The invention discloses a method for manufacturing a unicondylar knee joint prosthesis with variable curvature, which adopts a 3D printing process to prepare the prosthesis, and uses the principal stress trace of finite element analysis as a printing path, thereby improving the overall mechanical strength of the joint and the wear resistance during exercise.

To sum up, the present invention can not only maintain high compatibility with natural joints, avoid uneven stress transmission and bone loss caused by over-covering or under-covering, but also improve the smooth transition between curved surfaces during knee flexion movement. Ensure the stability of movement; the microporous structure on the tibial pad can achieve biological fixation with the bone tissue, improving the long-term joint strength of the joint.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the variable curvature unicondylar knee joint prosthesis of the present invention;

2 is a side view of the variable curvature femoral unicondylar prosthesis of the present invention;

Figure 3 is a side view of the variable curvature tibial pad prosthesis of the present invention;

4 is a bottom view of the variable curvature tibial pad prosthesis of the present invention;

FIG. 5 is a schematic diagram of the 3D printing path of the variable curvature femoral unicondylar prosthesis of the present invention;

Figure 6 is a fitted sagittal diagram.

Among them: 1. Unicondyle of femur; 2. Tibia pad; 3. Anterior surface of femur; 4. Oblique anterior surface of femur; 5. Surface of distal femur; 6. Oblique posterior surface of femur; .Short fixation post; 9. Long fixation post; 10. Instantaneous center of rotation; 11. Tibia pad groove; 12. Tibia anterior curved surface; 13. Tibia oblique anterior curved surface; ; 16. Principal stress traces.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "center", "portrait", "horizontal", "top", "bottom", "front", "rear", "left", "right", " The orientation or positional relationship indicated by "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side", etc. The orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Also, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

It is to be understood that, when used in this specification and the appended claims, the terms "comprising" and "comprising" indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or The presence or addition of a number of other features, integers, steps, operations, elements, components, and/or sets thereof.

It should also be understood that the terminology used in the present specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise.

It should further be understood that, as used in this specification and the appended claims, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items .

Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. The figures are not to scale, some details have been exaggerated for clarity, and some details may have been omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and in practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art should Regions/layers with different shapes, sizes, relative positions can be additionally designed as desired.

The invention provides a unicondylar knee joint prosthesis with variable curvature and a manufacturing method thereof. The femoral unicondylar prosthesis formed by the curved surface with variable curvature has high matching with bone tissue, and the instantaneous rotation center formed by each curved surface is also "J" ” shape changes to ensure a smooth transition between the surfaces; the tibial liner prosthesis is designed based on the unicondyle of the femur, and the lower surface of the liner is designed with a micro-porous structure to achieve biological fixation with the bone tissue; 3D The femoral unicondyle and tibial pad are prepared by the printing process, and the printing path is designed based on the principal stress traces of finite element analysis to enhance the wear resistance and mechanical strength of the knee prosthesis. The invention not only has high shape matching and motion stability, but also has excellent wear resistance and biological fixation performance, and improves the motion stability and service life of the unicondylar knee joint prosthesis.

Referring to FIG. 1 , a variable curvature unicondylar knee joint prosthesis of the present invention includes a femoral unicondyle 1 and a tibial liner 2 ;

Please refer to Figure 2, the outer contour of the femoral unicondyle 1 includes but is not limited to five variable curvature surfaces, including the anterior femoral surface 3, the oblique anterior surface of the femur 4, the distal femoral surface 5, the oblique posterior femoral surface 6 and the posterior femoral surface End surface 7, the radius size of femoral unicondyle 1 decreases in turn from the anterior end of the femur to the posterior end, the anterior femoral surface 3, the oblique anterior surface of the femur 4, the distal surface of the femur 5, the oblique posterior surface of the femur 6 and the posterior surface of the femur 7 The formed instantaneous rotation center 10 is distributed in a "J" shape to improve motion stability, and two fixed posts are arranged on the inner surface of the femoral unicondyle 1 for connecting the bone tissue.

Referring to Fig. 6, the center point of the radius of the front sagittal plane corresponds to the top of the J-shape, and the center of the radius of the rear end of the sagittal plane corresponds to the bottom end of the J-shape.

The two fixed columns include a short fixed column 8 and a long fixed column 9, the long fixed column 9 is perpendicular to the front end surface 4 of the oblique femur corresponding to the oblique front end of the femur, and the short fixed column 8 is located on the front surface 3 of the femur corresponding to the front end of the femur. The length ratio of the fixed column 9 and the short fixed column 8 is 4:(2-3).

Please refer to FIG. 3 , there is a groove structure on the tibial pad 2. The groove is composed of the front end surface of the tibia 12, the oblique front end surface of the tibia 13 and the distal end surface of the tibia 14. The lowest point of the groove and the outer surface of the femoral unicondyle 1 The lowest point coincides.

The radius of each curved surface in the tibial liner 2 is larger than the radius of the curved surface of the femoral unicondylar prosthesis matched with it. The tibial liner 2 is inverted by 3° on the whole and tilted back by 7° to ensure that the tibial liner 2 and the femoral unicondyle are inseparable. The joint line formed by 1 is the same as the natural joint line.

Referring to FIG. 4 , the lower surface of the tibial pad 2 in contact with the bone tissue is printed with a microporous structure 15 to improve the biological bonding strength between the interfaces.

The pore size of the microporous structure 15 is 200-500 μm.

Please refer to FIG. 5 , a method for manufacturing a unicondylar knee joint prosthesis with variable curvature of the present invention, comprising the following steps:

The femoral unicondyle and tibial liner prosthesis were prepared by 3D printing process respectively;

The printing path of the femoral unicondyle 1 is based on the principal stress trace 16 of the finite element analysis. The outer layer is designed as a concentric circle path to improve wear resistance. The two fixed columns are printed in a criss-cross pattern to ensure sufficient mechanical strength at different buckling angles.

The printing path of the tibial liner 2 and the outer contour path of the femoral unicondyle 1 are kept parallel to reduce the friction coefficient. The printing path on the lower surface of the tibial liner 2 is designed as a micro-porous structure, which promotes the growth of bone tissue into the porous interior. And improve the bonding strength between the prosthesis and bone tissue.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Take the design and manufacturing process of the variable curvature unicondylar knee prosthesis as an example.

The variable-curvature unicondylar knee joint prosthesis includes a tibial pad 2, a groove is formed on the tibial pad 2, and an inner contour matching the femoral unicondyle 1 is arranged in the groove, and the outer contour of the femoral unicondyle 1 includes a plurality of variable curvature curved surfaces , the instantaneous rotation center 10 composed of a plurality of variable curvature curved surfaces is distributed in a J-shape, and the inner surface of the femoral unicondyle 1 is provided with a fixed column for connecting the bone tissue. The femoral unicondyle 1 and the tibial pad 2 were fabricated by 3D printing.

The design and manufacture of the variable curvature unicondylar knee prosthesis includes the following processes:

(1) First obtain the imaging data of the knee joint, extract the outer contour of the patient's knee joint through Mimics software, establish a triangular face model through Geomagic Wrap software software, and smooth the surface, reduce noise, solidify and mesh the surface. , to obtain a 3D model of the knee joint with high consistency with the original joint;

(2) Establish the datum plane of the coronal and sagittal planes on the medial side of the femoral condyle, fit the sagittal plane with 5 radii of different curvatures, fit the coronal plane with the radii of each curvature, and obtain the initial femoral prosthesis by loft scanning;

(3) Establish the osteotomy reference plane of the femoral condyle. The thickness of the osteotomy in the horizontal position is 10 mm, the thickness of the osteotomy is 7 mm at the front end of the femur with an anterior inclination of 30°, and the thickness of the osteotomy at 45° of the oblique posterior end of the femur is 10 mm. The posterior end of the femur is vertical Directional osteotomy, the thickness of the osteotomy is also 10mm;

(4) Assemble the initial femoral prosthesis and the femoral condyle after osteotomy, obtain the femoral prosthesis by Boolean operation, and design the femoral prosthesis with a diameter of 6 mm and a length of 20 mm and 15 mm, respectively;

(5) Establish the datum plane of the tibial osteotomy, fit the outer contour of the tibia after the osteotomy, and obtain the initial tibial prosthesis with a thickness of 11 mm by stretching;

(6) Establish the lowest point of the tibial plateau and the reference planes of the coronal and sagittal planes, and use 3 but not limited to 3 curves to construct the sagittal plane contour of the groove on the sagittal plane through the lowest point. A single radius of curvature is used to construct the outer contour, and at the same time, the radius of curvature of the tibial prosthesis is larger than that of the corresponding femoral prosthesis;

(7) Part of the solid body is excised by lofting to obtain a groove structure that matches the femoral condyle.

(8) The tibial column is designed to be rectangular, 30mm long, 5mm wide, 6mm high, and the two apertures are 0.75mm.

After the design is completed, the principal stress traces of the femoral condyle and tibial liner prosthesis are obtained through finite element analysis, the printing path is designed, and then the knee joint prosthesis is prepared by a 3D printer.

The radii of curvature of the sagittal plane of the femoral condyle prosthesis were 43.72mm, 35.78mm, 28.45mm, 20.54mm and 16.12mm in turn, and the difference of each radius of curvature showed a uniform decreasing trend. Stability of the knee joint during movement.

The radii of curvature of the sagittal plane of the groove structure on the tibial liner were 87.44mm, 71.56mm and 56.90mm, which were all larger than the radii of curvature of the sagittal plane of the femoral condyle prosthesis, which ensured that the femoral condyle was in the concave tibial liner. The slot has enough freedom of movement to move smoothly.

To sum up, the present invention is a unicondylar knee prosthesis with variable curvature and its manufacturing method. The unicondylar knee prosthesis is constructed by regularly changing multi-curved surfaces, which can achieve high matching with natural bone tissue and avoid traditional The problem of uneven stress distribution and bone loss caused by the knee joint, the instantaneous center of rotation is the J-shaped variable curvature knee joint, which reduces the span difference between the curved surfaces and improves the stability of the knee joint during movement. The microporous structure on the lower surface of the tibial liner can promote the ingrowth of bone tissue, realize the biological integration between the prosthesis and the bone, avoid the thermal damage and unstable fixation problems caused by traditional bone cement fixation, and improve the joint and prosthesis. long-term binding strength. The 3D printing process is used to prepare the prosthesis, and the principal stress trace of the finite element analysis is used as the printing path, which improves the overall mechanical strength of the joint and the wear resistance during exercise.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention all fall within the scope of the claims of the present invention. within the scope of protection.

Claims (10)

1. a variable curvature unicondylar knee joint prosthesis, is characterized in that, comprises tibial pad (2), is provided with groove on tibial pad (2), and the inner contour of groove matches femoral unicondyle (1), femoral The outer contour of the unicondyle (1) includes a plurality of curved surfaces of variable curvature, and the instantaneous center of rotation (10) composed of the plurality of curved surfaces of variable curvature is distributed in a J-shape. Fixed column. 2. The variable curvature unicondylar knee joint prosthesis according to claim 1, wherein the variable curvature curved surface comprises five, which are followed by the femur front end curved surface (3), the femur oblique front end curved surface (4), and the femur distal end curved surface. (5), the oblique posterior end surface of the femur (6) and the posterior end surface of the femur (7), the radius size of the femoral unicondyle (1) decreases sequentially from the anterior surface of the femur (3) to the posterior surface of the femur (7). 3. The variable curvature unicondylar knee joint prosthesis according to claim 1, wherein the fixed column comprises a short fixed column (8) and a long fixed column (9), and the long fixed column (9) is perpendicular to the oblique front end of the femur The corresponding curved surface, the short fixation column (8) is located on the curved surface corresponding to the front end of the femur. 4 . The variable curvature unicondylar knee joint prosthesis according to claim 3 , wherein the length ratio of the long fixing column ( 9 ) and the short fixing column ( 8 ) is 4: (2˜3). 5 . 5. variable curvature unicondylar knee joint prosthesis according to claim 1, is characterized in that, groove comprises tibia front end curved surface (12), tibia oblique front end curved surface (13) and tibia distal end curved surface (14) successively, tibia The radius of the front end curved surface (12), the oblique front end curved surface of the tibia (13) and the curved surface of the distal end of the tibia (14) are all larger than the radius of the curved surface of the cooperating femoral unicondyle (1). 6 . The variable curvature unicondylar knee joint prosthesis according to claim 1 , wherein the lowest point of the groove coincides with the lowest point of the outer surface of the femoral unicondyle ( 1 ). 7 . 7 . The variable curvature unicondylar knee joint prosthesis according to claim 1 , wherein the joint line formed by the tibial pad ( 2 ) and the femoral unicondyle ( 1 ) is consistent with the natural joint line. 8 . 8. The variable curvature unicondylar knee prosthesis according to claim 1, wherein the femoral unicondyle (1) and the tibial pad (2) are prepared by 3D printing. 9 . The variable curvature unicondylar knee joint prosthesis according to claim 1 , wherein a microporous structure ( 15 ) is provided where the lower surface of the tibial pad ( 2 ) contacts the bone tissue. 10 . 10. A method for manufacturing a unicondylar knee joint prosthesis with variable curvature as claimed in claim 1, wherein a 3D printing process is used to prepare the femoral unicondyle (1) and the tibial pad (2) respectively; 1) The printing path is based on the principal stress traces of finite element analysis. The outer layer is designed as a concentric circle path to improve wear resistance. The inner layer is divided into 4 areas, designed as a partitioned vertical line path to improve mechanical strength. The fixed column adopts It is printed in a crisscross manner; the printing path of the tibial pad (2) and the outer contour of the femoral unicondyle (1) are kept parallel, and the printing path of the lower surface of the tibial pad (2) is designed as a microporous structure.

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