CN114831780A

CN114831780A - Cobalt alloy bone trabecula femur condyle prosthesis containing nitride layer and preparation method thereof

Info

Publication number: CN114831780A
Application number: CN202210307421.3A
Authority: CN
Inventors: 周宗科; 罗振宇
Original assignee: West China Hospital of Sichuan University
Current assignee: West China Hospital of Sichuan University
Priority date: 2022-03-25
Filing date: 2022-03-25
Publication date: 2022-08-02

Abstract

The invention discloses a cobalt alloy bone trabecula femur condyle prosthesis containing a nitride layer and a preparation method thereof, wherein the preparation method comprises the following steps: taking cobalt alloy powder as a raw material, carrying out 3D printing and integral forming to obtain an intermediate product of the nitride layer-containing cobalt alloy trabecular femoral condyle prosthesis, and carrying out hot isostatic pressing and surface nitriding to prepare the nitride layer-containing cobalt alloy trabecular femoral condyle prosthesis; the invention realizes that the micro-strain of most areas of the bone tissues of the femoral condyle is between the minimum effective strain threshold and the super-physiological strain threshold, is beneficial to bone ingrowth and improves the long-term stability. The invention has good biocompatibility, induces cell proliferation, prevents the cytotoxic reaction caused by the matrix ion precipitation of the trabecular metal porous cobalt alloy after long-time use, and the joint prosthesis made of the same material can simultaneously meet the osteoinductive property and the wear-resisting property, thereby avoiding the problem that the coating falls off after long-time use because two components are conventionally utilized or the coating technology is adopted in the matrix to complete two interface functions.

Description

Cobalt alloy bone trabecula femur condyle prosthesis containing nitride layer and preparation method thereof

Technical Field

The invention relates to the technical field of medical implant materials, in particular to a trabecular femoral condyle prosthesis containing a cobalt alloy bone with a nitride layer and a preparation method thereof.

Background

Total knee replacement is currently an effective treatment mode for end-stage knee joint diseases in clinic, and the damaged knee joint tissue is replaced by an artificially designed joint prosthesis, so that pain of patients is relieved, the knee joint function of the patients is recovered, and the life quality of the patients is improved. Corresponding to the anatomical structure of human body, the knee joint prosthesis comprises a femoral condyle, a tibial plateau and a platform pad. With the rapid development of medical instrument technology and the continuous improvement of requirements of people on the safety and effectiveness of prosthesis products, the design and manufacturing technology of knee joint prostheses needs to be continuously optimized and improved.

Currently, clinically used knee prostheses include two major classes, bone cement type and biologic type (non-cement fixation). Wherein the bone cement type prosthesis mechanically fixes the joint prosthesis and the bone tissue by means of the solidification and filling of the bone cement. However, years of clinical application show that bone cement fixation can bring about a plurality of safety and effectiveness problems: the bone cement monomer is polymerized to release heat, so that surrounding tissues are damaged; bone cement particles, if introduced into the blood or during filling, cause high pressure in the medullary cavity, leading to pulmonary embolism and fat embolism.

The biological knee joint prosthesis can effectively eliminate the safety and effectiveness risks brought by bone cement, and generally utilizes a surface porous structure to promote bone ingrowth so as to obtain long-term stability. But the surface porous structure is usually prepared by surface treatment processes such as sand blasting, coating, sintering and the like, has low bonding strength with an entity, is easy to fall off, and reduces the service life of the prosthesis. And, according to Wolff's law: after the stress causes the bone to generate deformation (also called micro-strain), the original signal can be started to regulate the synthesis and the catabolism of the bone, and the strain range can promote the bone growth only between the minimum effective strain threshold and the supraphysiological strain threshold. Therefore, the knee joint femoral condyle prosthesis is designed, the micro strain of most areas of bone tissues is realized between the minimum effective strain threshold and the super physiological strain threshold, the bone ingrowth is facilitated, and the knee joint femoral condyle prosthesis has important significance.

Cobalt alloy is a clinically common implant metal prosthesis material, has high wear resistance and fatigue resistance, but is manufactured by casting and forging. The 3D printing technology can realize a product design concept oriented to performance, solve the problem that complex parts are difficult to integrally form, and reduce the waste of raw materials and energy sources caused by machining and manufacturing. 3D prints metal trabecula and solid structure one shot forming, can avoid the drawback that the coating easily drops. But the micro-nano structure of the metal trabecula can increase the surface pressure of the cobalt alloy so as to increase the ion precipitation.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a cobalt alloy trabecular femoral condyle prosthesis containing a nitride layer.

The invention also provides a preparation method of the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer.

The technical scheme of the invention is summarized as follows:

the preparation method of the cobalt alloy bone trabecula femur condyle prosthesis containing the nitride layer comprises the following steps:

1) taking cobalt alloy powder as a raw material, carrying out 3D printing and integral forming to obtain a first intermediate product, putting the first intermediate product into a hot isostatic pressing furnace, heating to 1165-1170 ℃ under the protection of inert gas, standing at a constant temperature for 1-3 h at 130-140 MPa, cooling to normal pressure, cooling to room temperature along with the furnace, and taking out to obtain a second intermediate product;

2) sequentially carrying out ultrasonic cleaning on the second intermediate product by using deionized water and absolute ethyl alcohol to remove surface impurities, and drying; putting the mixture into a vacuum chamber of a plasma immersion implanter, and vacuumizing; negative high pressure, injection volume ratio (2-1): 1, injecting the mixed gas of nitrogen and argon for 5-45 min, and taking out after injection is finished to obtain a third intermediate product;

3) machining, trimming, polishing, cleaning and drying the third intermediate product to obtain a nitride layer-containing cobalt alloy trabecular femoral condyle prosthesis;

the first intermediate product, the second intermediate product and the third intermediate product have the same structure as the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer.

Preferably, the cobalt alloy powder comprises, by mass, 60% -67% of Co, 27% -30% of Cr, 5% -7% of Mo, and the balance of impurity elements; the particle size of the cobalt alloy powder is 45-106 μm.

Step 2) is preferably: sequentially carrying out ultrasonic cleaning on the second intermediate product by using deionized water and absolute ethyl alcohol to remove surface impurities, and drying; placing into a vacuum chamber of a plasma immersion implanter, and vacuumizing to 5 × 10 ^-4 Pa; the negative high voltage is 10kV-15kV, and the injection volume ratio is (2-1): 1, injecting the mixed gas of nitrogen and argon for 5-45 min, and taking out after injection is finished to obtain a third intermediate product.

Preferably, the cobalt alloy bone trabecular femoral condyle prosthesis comprising the nitride layer comprises a medial condyle 11 and a lateral condyle 12 which are arranged left and right, wherein a medial condyle front end 1101 of the medial condyle 11 and a lateral condyle front end 1102 of the lateral condyle 12 are integrated, and a rear end of the medial condyle 11 is connected with a rear end of the lateral condyle 12 through a limit stop 15; the lateral wall of the medial condyle 11 and the lateral wall of the lateral condyle 12 are both provided with holding grooves 16, the medial condyle 11 is provided with a medial condyle fixing surface 110, and the lateral condyle is provided with a lateral condyle fixing surface 120; the medial condyle fixing surface 110 comprises a first fixing surface 111, a second fixing surface 112, a third fixing surface 113, a fourth fixing surface 114 and a fifth fixing surface 115 which are connected in sequence, and the lateral condyle fixing surface 120 comprises a sixth fixing surface 121, a seventh fixing surface 122, an eighth fixing surface 123, a ninth fixing surface 124 and a tenth fixing surface 125 which are connected in sequence; the middle parts of the third fixing surface 113 and the eighth fixing surface 123 are provided with mounting holes 17, and the first fixing surface 111 and the second fixing surface 112 intersect to form a first intersection line 181; the second fixing surface 112 and the third fixing surface 113 intersect to form a second intersection line 182; the third fixing surface 113 and the fourth fixing surface 114 intersect to form a third intersection line 183; the fourth fixing surface 114 and the fifth fixing surface 115 form a fourth intersection line 184; the intersection line of the sixth fixing surface 121 and the seventh fixing surface 122 is collinear with the first intersection line 181; the intersection line of the seventh fixing surface 122 and the eighth fixing surface 123 is collinear with the second intersection line 182; the intersection line of the eighth fixing surface 123 and the ninth fixing surface 124 is collinear with the third intersection line 183; the line of intersection of the ninth fixation surface 124 and the tenth fixation surface 125 is collinear with the fourth line of intersection 184; the first intersection line 181, the second intersection line 182, the third intersection line 183 and the fourth intersection line 184 are parallel to each other;

the included angle between the first fixing surface 111 and the second fixing surface 112 is equal to the included angle between the sixth fixing surface 121 and the seventh fixing surface 122, and is 130-140 degrees; the included angle between the second fixing surface 112 and the third fixing surface 113 is equal to the included angle between the seventh fixing surface 122 and the eighth fixing surface 123, and is 130-140 degrees; the included angle between the third fixing surface 113 and the fourth fixing surface 114 is equal to the included angle between the eighth fixing surface 123 and the ninth fixing surface 124, and is 130-140 degrees; the included angle between the fourth fixing surface 114 and the fifth fixing surface 115 is equal to the included angle between the ninth fixing surface 124 and the tenth fixing surface 125, and is 130-140 degrees;

the first fixing surface 111, the fifth fixing surface 115, the sixth fixing surface 121 and the tenth fixing surface 125 are provided with a first bone trabecula 191;

the second fixing surface 112, the fourth fixing surface 114, the seventh fixing surface 122 and the ninth fixing surface 124 are provided with second bone trabeculae 192;

the third fixing surface 113 and the eighth fixing surface 123 are provided with a third trabecula 193;

the first trabecular bone 191 has a smaller pore size and porosity than the second 192 and third 193 trabecular bone in turn.

The aperture of the first bone trabecula 191 is 0.74mm-0.85mm, the porosity is 70.0% -74.7%, and the through porosity is 100%;

the aperture of the second bone trabecula 192 is 0.86mm-0.99mm, the porosity is 74.8% -77.5%, and the through porosity is 100%;

the third trabecula 193 has a pore diameter of 1.00-1.10 mm, a porosity of 77.6-85% and a through-hole porosity of 100%.

The first, second and

third bone trabeculae

191, 192 and 193 are of equal thickness, 0.5mm-3 mm.

The joint of the second fixing surface and the seventh fixing surface is provided with a rectangular first solid structure 21; and a semicircular second solid structure 20 is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure 21 and the thickness of the second solid structure 20 are equal to the thickness of the trabecula and are 0.5-3 mm.

Preferably, the side walls 22 are provided at the edges of the fixation surfaces formed by the medial condyle fixation surface 110, the lateral condyle fixation surface 120 and the positive stop 15.

According to another aspect of the invention, the cobalt alloy bone trabecular femoral condyle prosthesis containing the nitride layer prepared by the method is also provided.

The invention has the advantages that according to the cobalt alloy bone trabecula femur condyle prosthesis containing the nitride layer, the micro-strain of most areas of the femur condyle bone tissue is between the minimum effective strain threshold and the super-physiological strain threshold, the bone ingrowth is facilitated, and the long-term stability is improved.

Secondly, the invention adopts 3D printing and integrated molding, solves the problem that the complex structure cannot be prepared by traditional machining, has high bonding strength between the trabecular bone and the solid body, is not easy to fall off, and prolongs the service life of the prosthesis.

Moreover, the trabecular bone (namely the trabecular bone layer) of the cobalt alloy trabecular bone femoral condyle prosthesis containing the nitride layer has good biocompatibility, induces cell proliferation, and prevents cytotoxic reaction caused by matrix ion precipitation after long-term use; the friction interface utilizes the good wear-resisting property of the cobalt alloy, and can still keep the low wear rate of the joint prosthesis. Therefore, the joint prosthesis made of the same material can simultaneously meet the osteoinductive property and the wear-resisting property, and the problem that the coating falls off due to the fact that two components are conventionally utilized or a coating technology is adopted in a matrix to complete two interface functions and the coating is used for a long time is solved.

Drawings

FIG. 1 is an isometric view of a cobalt nitride-containing alloy trabecular femoral condyle prosthesis of the present invention as viewed from the lateral condyle.

FIG. 2 is an isometric view of a cobalt nitride-containing alloy trabecular femoral condyle prosthesis (including a first solid structure and a second solid structure) of the present invention as viewed from the medial condyle.

FIG. 3 is an isometric view of a cobalt nitride containing alloy trabecular femoral condyle prosthesis of the present invention as viewed from the anterior aspect of the femoral condyle.

FIG. 4 is a strain cloud for finite element analysis of the nitride layer containing cobalt alloy trabecular femoral condyle prosthesis of example 1 viewed from the anterior aspect of the femoral condyle.

FIG. 5 is a strain cloud for finite element analysis of the nitride layer containing cobalt alloy trabecular femoral condyle prosthesis of example 1, as viewed from the posterior aspect of the femoral condyle.

FIG. 6 is a scanning electron microscope image and relative element contents of the sample of cobalt alloy trabecular bone of the control group 1.

FIG. 7 is the SEM image and the relative element contents of the sample of the trabecular bone containing cobalt nitride alloy of example 1.

Fig. 8 shows MTT proliferation test results of trabecular bone specimen, specifically comparing MTT values (OD) of coculture of cobalt alloy trabecular bone specimen of the nitrogen-containing layer of example 1 and cobalt alloy trabecular bone specimen of the control group 1 with osteoblasts.

Detailed Description

The invention is further described below with reference to the figures and examples.

Example 1

1) taking cobalt alloy powder as a raw material, carrying out 3D printing and integral forming to obtain a first intermediate product, putting the first intermediate product into a hot isostatic pressing furnace, heating to 1168 ℃ under the protection of inert gas, standing at a constant temperature of 135MPa for 2h, reducing the temperature to normal pressure, cooling to room temperature along with the furnace, and taking out to obtain a second intermediate product;

2) sequentially using deionized water and absolute ethyl alcohol to carry out the second intermediate productUltrasonic cleaning, removing surface impurities, and drying; placing into a vacuum chamber of a plasma immersion implanter (Woods Co., Ltd., D700) to 5 × 10 ^-4 Pa; the negative high voltage is 13kV, the injection volume ratio is 1.5: 1, injecting the mixed gas of nitrogen and argon for 25min, and taking out after injection is finished to obtain a third intermediate product;

the first intermediate product, the second intermediate product and the third intermediate product have the same structure as the cobalt alloy bone trabecula femur condyle prosthesis containing the nitride layer.

The cobalt alloy powder comprises 65% of Co, 28% of Cr, 6% of Mo and the balance of impurity elements according to mass percentage; the particle size of the cobalt alloy powder is 75 μm.

The cobalt alloy bone trabecular femoral condyle prosthesis containing the nitride layer comprises a medial condyle 11 and a lateral condyle 12 which are arranged on the left and right sides, wherein a medial condyle front end 1101 of the medial condyle 11 and a lateral condyle front end 1102 of the lateral condyle 12 are integrated, and a rear end part of the medial condyle 11 is connected with a rear end part of the lateral condyle 12 through a limit stop 15; the lateral wall of the medial condyle 11 and the lateral wall of the lateral condyle 12 are both provided with holding grooves 16, the medial condyle 11 is provided with a medial condyle fixing surface 110, and the lateral condyle is provided with a lateral condyle fixing surface 120; the medial condyle fixing surface 110 comprises a first fixing surface 111, a second fixing surface 112, a third fixing surface 113, a fourth fixing surface 114 and a fifth fixing surface 115 which are connected in sequence, and the lateral condyle fixing surface 120 comprises a sixth fixing surface 121, a seventh fixing surface 122, an eighth fixing surface 123, a ninth fixing surface 124 and a tenth fixing surface 125 which are connected in sequence; the middle parts of the third fixing surface 113 and the eighth fixing surface 123 are provided with mounting holes 17, and the first fixing surface 111 and the second fixing surface 112 intersect to form a first intersection line 181; the second fixing surface 112 and the third fixing surface 113 intersect to form a second intersection line 182; the third fixing surface 113 and the fourth fixing surface 114 intersect to form a third intersection line 183; the fourth fixing surface 114 and the fifth fixing surface 115 form a fourth intersection line 184; the intersection line of the sixth fixing surface 121 and the seventh fixing surface 122 is collinear with the first intersection line 181; the intersection line of the seventh fixing surface 122 and the eighth fixing surface 123 is collinear with the second intersection line 182; the intersection line of the eighth fixing surface 123 and the ninth fixing surface 124 is collinear with the third intersection line 183; the line of intersection of the ninth fixation surface 124 and the tenth fixation surface 125 is collinear with the fourth line of intersection 184; the first intersection line 181, the second intersection line 182, the third intersection line 183 and the fourth intersection line 184 are parallel to each other;

the included angle between the first fixing surface 111 and the second fixing surface 112 is equal to the included angle between the sixth fixing surface 121 and the seventh fixing surface 122, and is 135 degrees; the included angle between the second fixing surface 112 and the third fixing surface 113 is equal to the included angle between the seventh fixing surface 122 and the eighth fixing surface 123, and is 135 degrees; the included angle between the third fixing surface 113 and the fourth fixing surface 114 is equal to the included angle between the eighth fixing surface 123 and the ninth fixing surface 124, and is 135 degrees; the included angle between the fourth fixing surface 114 and the fifth fixing surface 115 is equal to the included angle between the ninth fixing surface 124 and the tenth fixing surface 125, and is 135 degrees;

The aperture of the first bone trabecula 191 is 0.80mm, the porosity is 72 percent, and the through porosity is 100 percent; the aperture of the second bone trabecula 192 is 0.92mm, the porosity is 76%, and the through porosity is 100%; the third trabecular bone 193 has a pore diameter of 1.05mm, a porosity of 80% and a through porosity of 100%.

The first, second and

third bone trabeculae

191, 192 and 193 are of equal thickness, 1.7 mm.

The joint of the second fixing surface and the seventh fixing surface is provided with a rectangular first solid structure 21; and a semicircular second solid structure 20 is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure 21 and the second solid structure 20 is equal to that of the trabecula and is 1.7 mm.

The side wall 22 is provided at the edge of the fixation surface formed by the medial condyle fixation surface 110, the lateral condyle fixation surface 120 and the limit stop 15.

Example 2

1) taking cobalt alloy powder as a raw material, carrying out 3D printing and integral forming to obtain a first intermediate product, putting the first intermediate product into a hot isostatic pressing furnace, heating to 1165 ℃ under the protection of inert gas, standing at a constant temperature of 130MPa for 3h, reducing to normal pressure, cooling to room temperature along with the furnace, and taking out to obtain a second intermediate product;

2) sequentially carrying out ultrasonic cleaning on the second intermediate product by using deionized water and absolute ethyl alcohol to remove surface impurities, and drying; placing into a vacuum chamber of a plasma immersion implanter (Woods Co., Ltd., D700) to 5 × 10 ^-4 Pa; the negative high voltage is 10kV, and the injection volume ratio is 2: 1, injecting the mixed gas of nitrogen and argon for 45min, and taking out after injection is finished to obtain a third intermediate product;

The cobalt alloy powder comprises 60% of Co, 30% of Cr, 7% of Mo and the balance of impurity elements according to mass percentage; the particle size of the cobalt alloy powder is 45 mu m.

the included angle between the first fixing surface 111 and the second fixing surface 112 is equal to the included angle between the sixth fixing surface 121 and the seventh fixing surface 122, and is 130 degrees; the included angle between the second fixing surface 112 and the third fixing surface 113 is equal to the included angle between the seventh fixing surface 122 and the eighth fixing surface 123, and is 130 degrees; the included angle between the third fixing surface 113 and the fourth fixing surface 114 is equal to the included angle between the eighth fixing surface 123 and the ninth fixing surface 124, and is 130 degrees; the included angle between the fourth fixing surface 114 and the fifth fixing surface 115 is equal to the included angle between the ninth fixing surface 124 and the tenth fixing surface 125, and is 130 degrees;

The first bone trabecula 191 has a pore diameter of 0.74mm, a porosity of 70.0% and a through porosity of 100%; the aperture of the second bone trabecula 192 is 0.86mm, the porosity is 74.8 percent, and the through porosity is 100 percent; the third trabecular bone 193 has a pore diameter of 1.00mm, a porosity of 77.6% and a through-hole porosity of 100%.

The first, second and

third bone trabeculae

191, 192 and 193 are of equal thickness, 0.5 mm.

The joint of the second fixing surface and the seventh fixing surface is provided with a rectangular first solid structure 21; and a semicircular second solid structure 20 is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure 21 and the thickness of the second solid structure 20 are equal to the thickness of the trabecula and are 0.5 mm.

Example 3

1) taking cobalt alloy powder as a raw material, carrying out 3D printing and integral forming to obtain a first intermediate product, putting the first intermediate product into a hot isostatic pressing furnace, heating to 1170 ℃ under the protection of inert gas, standing at 140MPa for 1h at constant temperature, reducing to normal pressure, cooling to room temperature along with the furnace, and taking out to obtain a second intermediate product;

2) sequentially carrying out ultrasonic cleaning on the second intermediate product by using deionized water and absolute ethyl alcohol to remove surface impurities, and drying; placing into a vacuum chamber of a plasma immersion implanter (Woods Co., Ltd., D700) to 5 × 10 ^-4 Pa; the negative high voltage is 15kV, and the injection volume ratio is 1: 1, injecting the mixed gas of nitrogen and argon for 5min, and taking out after injection is finished to obtain a third intermediate product;

The cobalt alloy powder comprises 67% of Co, 27% of Cr, 5% of Mo and the balance of impurity elements according to mass percentage; the particle size of the cobalt alloy powder is 106 mu m.

the included angle between the first fixing surface 111 and the second fixing surface 112 is equal to the included angle between the sixth fixing surface 121 and the seventh fixing surface 122, and is 140 degrees; the included angle between the second fixing surface 112 and the third fixing surface 113 is equal to the included angle between the seventh fixing surface 122 and the eighth fixing surface 123, and is 140 degrees; the included angle between the third fixing surface 113 and the fourth fixing surface 114 is equal to the included angle between the eighth fixing surface 123 and the ninth fixing surface 124, and is 140 degrees; the included angle between the fourth fixing surface 114 and the fifth fixing surface 115 is equal to the included angle between the ninth fixing surface 124 and the tenth fixing surface 125, and is 140 degrees;

The first bone trabecula 191 has a pore diameter of 0.85mm, a porosity of 74.7% and a through porosity of 100%; the aperture of the second bone trabecula 192 is 0.99mm, the porosity is 77.5 percent, and the through porosity is 100 percent; the third trabecular bone 193 has a pore diameter of 1.10mm, a porosity of 85% and a through porosity of 100%.

The first 191, second 192 and third 193 bone trabeculae are 3mm thick and equal.

The joint of the second fixing surface and the seventh fixing surface is provided with a rectangular first solid structure 21; and a semicircular second solid structure 20 is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure 21 and the thickness of the second solid structure 20 are equal to the thickness of the trabecula and are 3 mm.

Control group 1

The preparation method of the cobalt alloy trabecular femoral condyle prosthesis comprises the following steps:

1) taking cobalt alloy powder as a raw material, and obtaining a first intermediate product through 3D printing and integral forming;

2) machining, trimming, polishing, cleaning and drying the first intermediate product to obtain a cobalt alloy trabecular bone femoral condyle prosthesis;

the first intermediate product is identical in structure to the cobalt alloy trabecular femoral condyle prosthesis.

The first, second and

third bone trabeculae

191, 192 and 193 are of equal thickness, 1.7 mm.

A rectangular first solid structure 21 is arranged at the joint of the second fixing surface and the seventh fixing surface; and a semicircular second solid structure 20 is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure 21 and the thickness of the second solid structure 20 are equal to the thickness of the trabecula and are 1.7 mm.

Experimental verification

Finite element analysis is performed on the finite element model of the embodiment 1 of the invention, as shown in fig. 4-5, the strain cloud chart only shows the micro strain (shaded part) in the range of 1000-3000, and the percentage of the 1000-3000 micro strain area on the finite element model of the bone tissue of the femoral condyle of the embodiment 1 of the invention in the finite element model of the bone tissue of the femoral condyle is 61.3%, which indicates that the cobalt nitride-containing alloy trabecular femoral condyle prosthesis of the invention realizes that the micro strain of the large part of the area is between the minimum effective strain threshold and the supraphysiological strain threshold, and has excellent bone in-growth performance.

The trabecular bone specimen containing the cobalt nitride layer alloy of example 1 was observed by a scanning electron microscope (Crossbeam340/550, Zeiss, Germany) to have a filament diameter of about 500 μm and a pore diameter of 800 μm, 950 μm and 1100 μm, respectively. The shape and chemical composition of each scanning point observed by the energy spectrum are shown in figure 7, and the mass percentages of the elements are respectively C: 6.17, N: 26.21, Si: 0.53, Cr: 15.17, Co: 46.68, Mo: 3.93.

the tensile properties of the solid tensile test piece prepared by the same preparation method described in example 1 and the solid tensile test piece prepared by the same preparation method described in control group 1 were tested by an electronic universal tester (UTM5105, shenzhen mitsunshi longitudinal and transverse science and technology ltd., china) (refer to the standard GB/T228.1-2010), and 12 solid tensile test pieces were used in example 1 and control group 1, respectively. As shown in Table 1, the maximum force of example 1 was close to that of control 1(P > 0.05), and the tensile strength and elastic modulus were slightly decreased but were not statistically different from that of control 1(P > 0.05); the non-proportional elongation strength of example 1 is lower than that of control group 1(P <0.05), and the elongation and the reduction of area of example 1 are better than those of control group 1(P <0.05), which indicates that the hot isostatic pressed 3D printed cobalt alloy tensile test bar of the invention has stronger plasticity than that of the tensile test bar prepared without hot isostatic pressing, and the cobalt alloy femoral condyle prepared by the process has enhanced fatigue resistance.

Table 1 tensile test results of the solid tensile test pieces of control 1 and example 1: (

n is 12, P <0.05, compare with control 1)

Mouse MC3T3-E1 cells seeded at 75cm ² In the culture flask, the culture medium is filled with a culture medium,at 37 ℃ 5% CO ₂ Culturing in an incubator. After digestion with pancreatin at 2X 10 ⁶ The cell suspension with density is inoculated on the first, second and third trabecular test pieces of the nitrogenous layer and the control group 1. Inoculating 20 μ l of each trabecular bone specimen, incubating at 37 deg.C for 30min, turning over the specimen, incubating for 3h, adding alpha-MEM culture solution (containing 10% fetal calf serum and 1% double antibody), and changing every 2 d. And culturing the cell-trabecular bone specimen compound for 7 days, and taking out the cell-trabecular bone specimen compound for an MTT proliferation experiment. OD measurements at 450nm (TECAN, Austria) were performed according to the protocol, statistically soft using SPSS

And carrying out statistical analysis on the experimental data. Data are expressed as (x ± s), comparisons between groups were analyzed by one-way variance, and pairwise comparisons were performed by LSD. The measured OD value mean values are respectively 0.60, 0.67 and 0.86, and the three test pieces of the trabecular bone containing nitride layer have obvious cell proliferation effect and statistically significant difference (P < 0.05).

Experiments prove that the chemical components, the appearance and the biocompatibility of the nitrided layer of the trabecular bone part of the nitrided layer cobalt alloy trabecular femoral condyle prosthesis prepared in the examples 2 and 3 are similar to those of the nitrided layer cobalt alloy trabecular femoral condyle prosthesis prepared in the example 1 in terms of the mechanical properties of the solid part and the chemical components and the appearance of the nitrided layer of the trabecular bone part.

Claims

1. A preparation method of a cobalt alloy bone trabecular femoral condyle prosthesis containing a nitride layer is characterized by comprising the following steps:

2. The method for preparing the cobalt alloy bone trabecular femoral condyle prosthesis containing the nitride layer as claimed in claim 1, wherein the cobalt alloy powder comprises, by mass, 60% -67% of Co, 27% -30% of Cr, 5% -7% of Mo, and the balance of impurity elements; the grain diameter of the cobalt alloy powder is 45-106 μm.

3. The method for preparing the cobalt alloy bone trabecular femoral condyle prosthesis containing the nitride layer according to claim 1, wherein the step 2) is as follows: sequentially carrying out ultrasonic cleaning on the second intermediate product by using deionized water and absolute ethyl alcohol to remove surface impurities, and drying; placing into a vacuum chamber of a plasma immersion implanter, and vacuumizing to 5 × 10 ^-4 Pa; the negative high voltage is 10kV-15kV, and the injection volume ratio is (2-1): 1, injecting the mixed gas of nitrogen and argon for 5-45 min, and taking out after injection is finished to obtain a third intermediate product.

4. The preparation method of the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer according to claim 1, which is characterized in that the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer comprises a medial condyle (11) and a lateral condyle (12) which are arranged on the left and right, wherein the anterior end (1101) of the medial condyle (11) and the anterior end (1102) of the lateral condyle (12) are integrated, and the posterior end of the medial condyle (11) and the posterior end of the lateral condyle (12) are connected through a limit stop (15); the lateral wall of the medial condyle (11) and the lateral wall of the lateral condyle (12) are both provided with holding grooves (16), the medial condyle (11) is provided with a medial condyle fixing surface (110), and the lateral condyle is provided with a lateral condyle fixing surface (120); the medial condyle fixing surface (110) comprises a first fixing surface (111), a second fixing surface (112), a third fixing surface (113), a fourth fixing surface (114) and a fifth fixing surface (115) which are sequentially connected, and the lateral condyle fixing surface (120) comprises a sixth fixing surface (121), a seventh fixing surface (122), an eighth fixing surface (123), a ninth fixing surface (124) and a tenth fixing surface (125) which are sequentially connected; the middle parts of the third fixing surface (113) and the eighth fixing surface (123) are provided with mounting holes (17), and the first fixing surface (111) and the second fixing surface (112) are intersected to form a first intersection line (181); the second fixing surface (112) and the third fixing surface (113) are intersected to form a second intersection line (182); the third fixing surface (113) and the fourth fixing surface (114) are intersected to form a third intersection line (183); a fourth intersection line (184) is formed by the fourth fixing surface (114) and the fifth fixing surface (115); the intersection line of the sixth fixing surface (121) and the seventh fixing surface (122) is collinear with the first intersection line (181); the intersection line of the seventh fixing surface (122) and the eighth fixing surface (123) is collinear with the second intersection line (182); the intersection line of the eighth fixing surface (123) and the ninth fixing surface (124) is collinear with the third intersection line (183); the intersection line of the ninth fixing surface (124) and the tenth fixing surface (125) is collinear with the fourth intersection line (184); the first intersection line (181), the second intersection line (182), the third intersection line (183) and the fourth intersection line (184) are parallel to each other;

the included angle between the first fixing surface (111) and the second fixing surface (112) is equal to the included angle between the sixth fixing surface (121) and the seventh fixing surface (122), and the included angle is 130-140 degrees; the included angle between the second fixing surface (112) and the third fixing surface (113) is equal to the included angle between the seventh fixing surface (122) and the eighth fixing surface (123) and is 130-140 degrees; the included angle between the third fixing surface (113) and the fourth fixing surface (114) is equal to the included angle between the eighth fixing surface (123) and the ninth fixing surface (124), and the included angle is 130-140 degrees; the included angle between the fourth fixing surface (114) and the fifth fixing surface (115) is equal to the included angle between the ninth fixing surface (124) and the tenth fixing surface (125), and the included angle is 130-140 degrees;

the first fixing surface (111), the fifth fixing surface (115), the sixth fixing surface (121) and the tenth fixing surface (125) are provided with a first bone trabecula (191);

the second fixing surface (112), the fourth fixing surface (114), the seventh fixing surface (122) and the ninth fixing surface (124) are provided with second bone trabeculae (192);

the third fixing surface (113) and the eighth fixing surface (123) are provided with a third trabecula (193);

the first trabecular bone (191) has a smaller pore size and porosity than the second (192) and third (193) trabecular bone in that order.

5. The method for preparing the cobalt alloy bone trabecular femoral condyle prosthesis containing the nitride layer according to the claim 4, characterized in that the first bone trabecular (191) has the aperture of 0.74mm-0.85mm, the porosity of 70.0% -74.7% and the through porosity of 100%;

the aperture of the second bone trabecula (192) is 0.86mm-0.99mm, the porosity is 74.8% -77.5%, and the through porosity is 100%;

the third trabecula (193) has the aperture of 1.00-1.10 mm, the porosity of 77.6-85% and the through porosity of 100%.

6. The method for preparing a cobalt alloy bone trabecular femoral condyle prosthesis containing a nitride layer according to claim 4, wherein the thicknesses of the first bone trabecula (191), the second bone trabecula (192) and the third bone trabecula (193) are equal and are 0.5mm to 3 mm.

7. The method for preparing the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer according to claim 4, wherein a rectangular first solid structure (21) is arranged at the joint of the second fixing surface and the seventh fixing surface; and a semicircular second solid structure (20) is arranged at the joint of the first fixing surface and the sixth fixing surface, and the thickness of the first solid structure (21) and the second solid structure (20) is equal to that of the trabecula and is 0.5-3 mm.

8. The method for preparing the cobalt alloy trabecular femoral condyle prosthesis containing the nitride layer according to claim 4, wherein the side wall (22) is arranged at the edge of the fixing surface consisting of the medial condyle fixing surface (110), the lateral condyle fixing surface (120) and the limit stop (15).

9. The cobalt alloy bone trabecular femoral condyle prosthesis containing the nitrogen layer, which is prepared according to the preparation method of the cobalt alloy bone trabecular femoral condyle prosthesis containing the nitrogen layer of any one of claims 1-8.