CN110575289A - A 3D printing method for bone defect prosthesis - Google Patents

Abstract

The invention relates to a 3D printing method for a bone defect prosthesis, which belongs to the technical field of bone prosthesis production, including: building a bone defect model: using CT or MRI technology to construct a three-dimensional mathematical model of a bone defect; establishing a prosthesis model; compiling a printing program ;Trial printing: printing: print the prosthesis layer by layer; turn on the heat preservation device in the printing table to keep the temperature of the contact surface with the prosthesis consistent with the temperature of the prosthesis; cooling: after the printing is completed, rotate the printing table for air cooling; Lower the prosthesis, and the printing is finished. The present invention supports the gradient structure of the skeleton layer and the fusion layer, on the one hand to ensure its structural strength and realize its functionality, and on the other hand to increase its bonding strength through the combination between the fusion layer and the natural bone. This gradient design , it is easy to realize the purpose of cost saving and weight reduction through the selection of materials, and it is helpful to promote the clinical application of bone prosthesis.

Description

A 3D printing method for bone defect prosthesis

technical field

The invention relates to the technical field of bone prosthesis production, in particular to a 3D printing method for a bone defect prosthesis.

Background technique

3D printing is a kind of direct digital manufacturing, which has fast forming and low production cost, and has been widely used in model manufacturing in mold manufacturing, industrial design and other fields. In recent years, with the rapid development of biotechnology, the medical field has gradually adopted 3D printing technology to improve product molding efficiency and shorten the recovery cycle.

However, 3D printing technology only gives a general idea: gradually form products through material accumulation. In specific applications, there are still many problems. For example, the heat generated during printing may form thermal stress, causing deformation problems such as product warping, and serious quality problems such as cracks and shrinkage may occur. There may also be the same material or different materials. The problem of insufficient cohesion.

When the above problems exist in the bone prosthesis, it may cause the prosthesis to fail to fit with the defect of the human body, resulting in poor fixation, or the mechanical properties of the prosthesis are insufficient to perform functional replacement.

At the same time, the bone prosthesis in the prior art basically uses titanium or tantalum for printing. If only titanium is used, the binding force with human body defects may be insufficient due to insufficient affinity with the human body; if only tantalum is used, the There are problems of being too heavy and too expensive.

Contents of the invention

In view of this, the purpose of the present invention is to provide a 3D printing method for bone defect prosthesis, using titanium and tantalum for composite gradient printing, and adding anti-stress measures to solve the lack of affinity of a single material in the prior art Or the weight is too heavy, the price is expensive, and the problems of deformation, cracks and shrinkage caused by thermal stress.

The present invention is realized through the following technical solutions:

A 3D printing method for a bone defect prosthesis, comprising the following steps:

1) Establish bone defect model: use CT or MRI technology to construct a three-dimensional mathematical model of bone defect;

2) Establishing a prosthesis model: constructing a prosthesis model according to the defect of the three-dimensional mathematical model, the prosthesis model is a multi-layer composite structure, the composite structure at least includes a support skeleton layer and a fusion layer arranged outside the support skeleton layer, and the support skeleton Interlocking connectors are arranged between the layer and the fusion layer;

3) Compile the printing program: import the STL file of the prosthetic model into the 3D printing device, perform slice processing, obtain the cross-sectional graphics that need to be printed at present, and design the plane printing path according to the cross-sectional graphics;

4) Preparation of printing toner: After the supporting skeleton layer material and the fusion layer material are proportioned separately, they are loaded into two mutually independent toner storage areas, and communicated with the toner nozzle through two mutually independent conveying systems ;

5) Pre-preparation: In an argon atmosphere, print the fusion layer in the first layer along the printing path first, then use laser or electron beam heating to melt and consolidate the fusion layer, and then print the fusion layer in the first layer along the printing path The supporting skeleton layer is finally heated and consolidated by laser, so that the supporting skeleton layer is fused and solidified on the fusion layer to form the first consolidated layer; after that, on the basis of the first consolidated layer, continue to laminate the second consolidated layer. knot layer, the third consolidation layer, until the formation of the prosthesis;

6) Detection: After the prosthesis is completely cooled, measure the size of each key part and compare it with the three-dimensional mathematical model to determine the deformation ratio;

7) Adjust the prosthesis model: adjust the prosthesis model according to the deformation ratio;

8) Re-preparation: reprint according to the adjusted prosthesis model;

9) Retesting: correcting the deformation ratio;

10) Repeat 5)-9) until the deformation ratio is 1, stop the trial printing:

11) Preparation: Repeat 5) to print the prosthesis layer by layer; turn on the heat preservation device in the printing table to keep the contact surface with the prosthesis consistent with the temperature of the prosthesis;

12) Cooling: After printing is completed, the printing table is rotated for air cooling;

13) After the cooling is completed, remove the prosthesis and the printing is finished.

Further, the prosthesis model is provided with a plurality of outwardly protruding stress-relieving convex hulls, and the stress-relieving convex hulls are evenly arranged on the outer circumference of the contact surface between the prosthesis model and the printing platform.

Further, the supporting skeleton layer is a hollow titanium structure.

Further, the fusion layer is porous tantalum, the thickness of the porous tantalum is 1.5-3mm, the pore diameter is 0.3-0.9mm, the wire diameter is 0.3-0.6mm, and the porosity is 75%-85%.

Further, the particle proportioning includes vibration separation and particle remixing process.

Further, the toner is conveyed by a hybrid method of vibrating separation and blade conveying.

The beneficial effects of the present invention are:

1. By supporting the gradient structure of the skeleton layer and the fusion layer, the present invention can on the one hand ensure its structural strength and realize its functionality; on the other hand, it can increase its bonding strength by combining the fusion layer with the natural bone, making it Fixed stable and reliable. In addition, this gradient design is easy to achieve the purpose of saving cost and reducing weight through the selection of materials. For example, some materials with high strength, light weight and low price can be considered for the support skeleton layer, such as titanium materials, and some pro-friendly materials can be considered for the fusion layer. Materials with good compatibility and good bone ingrowth, such as tantalum materials. In this way, the bonding strength is ensured, and the weight and cost are reduced, which is helpful for promoting the clinical application of the bone prosthesis.

2. By independently preparing the support skeleton layer and fusion layer in the same layer, sufficient melting and bonding can be carried out, thereby avoiding the problem of no melting and mutual incompatibility caused by the different melting temperatures of the two.

3. By adjusting the proportion of large particles and small particles in the material through the particle ratio, on the one hand, the fluidity of the material is enhanced, on the other hand, the melting level of the material can be ensured, and the melting efficiency and consolidation level of the material can be improved.

4. Through the heat preservation operation, the overall temperature of the prosthesis can be kept within a certain range, and defects such as warping and shrinkage caused by excessive temperature differences in the partial section can be avoided.

Description of drawings

Fig. 1 is a flowchart of the present invention;

Fig. 2 is the structural representation of prosthetic model;

Fig. 3 is another schematic diagram of the prosthesis model;

Fig. 4 is the structural representation of the prosthetic model without selenium layer;

Fig. 5 is another schematic diagram of the phantom model without selenium layer;

Fig. 6 is a structural schematic diagram of a supporting skeleton layer;

Fig. 7 is a schematic structural diagram of a printing station involved in the present invention;

Fig. 8 is a schematic structural diagram of another printing station involved in the present invention;

Fig. 9 is a sectional view along the wall thickness of the prosthesis model;

Fig. 10 is the block prosthesis of operculum;

Figure 11 is the acetabular spacer prosthesis;

Figure 12 is an integrated acetabular cup prosthesis;

Figure 13 is a 100% full patella prosthesis;

Figure 14 is a 100% fibula tumor replacement prosthesis;

Figure 15 is the prosthesis for 96% fibula tumor replacement;

Fig. 16 is 100% partial patella (leaving the patella shell) replacement prosthesis;

Figure 17 is a 100% patella replacement prosthesis;

Figure 18 is a 100% pelvic tumor replacement prosthesis;

Figure 19 is a 100% iliac bone tumor replacement prosthesis;

Figure 20 is a 100% knee fusion replacement prosthesis;

Figure 21 is the femoral side prosthesis;

Figure 22 is the prosthesis on the radial side.

Explanation of reference signs:

1 - Prosthesis model; 2 - Supporting skeleton layer; 3 - Fusion layer; 4 - Printing table; 5 - Resistance wire; 6 - Heating equipment; 7 - Rotating motor; 8 - Stress relief convex hull;

Detailed ways

In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the above description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "one side", "the other side" and so on are based on the orientation or positional relationship shown in the drawings, or the Orientation or positional relationship that is conventionally placed is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a reference to the present invention. Invention Limitations. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

Furthermore, terms such as the term "same" do not mean that the components are absolutely identical, but slight differences may exist. The term "vertical" just means that the positional relationship between components is more vertical than "parallel", and does not mean that the structure must be completely vertical, but can be slightly inclined.

The present invention provides a 3D printing method for a bone defect prosthesis, as shown in Figure 1, comprising the following steps:

1) Establish a bone defect model: use CT scan or MRI nuclear magnetic resonance to construct a three-dimensional mathematical model of bone defect;

2) Establishing a prosthesis model: constructing a prosthesis model 1 according to a three-dimensional mathematical model, as shown in Figure 2, the prosthesis model is a multi-layer composite structure, and the composite structure is at least two layers, as shown in Figure 6 and Figure 9, and its The inner layer is the support skeleton layer 2, the outer layer is the fusion layer 3, and a connecting body 9 interlocking with each other is arranged between the supporting skeleton layer and the fusion layer, as shown in FIG. Of course, it can also be a variety of tooth shapes, so that the joint area between the two can be increased to increase its bonding force;

3) Compile the printing program: compile the printing program according to the phantom model;

4) Prepare toner for printing:

First prepare the supporting skeleton layer material: put an appropriate amount of supporting skeleton layer material into the proportioning mechanism, first separate the large and small particles, and then mix and stir the large and small particles according to a certain proportion to form a mixed powder with moderately large and small particles, and place it Stand by in the material storage area of the support frame layer;

Then prepare the material for the fusion layer: put an appropriate amount of material for the fusion layer into the proportioning mechanism, first separate the large and small particles, then mix the large and small particles according to a certain proportion, stir to form a mixed powder with moderate particle size, and place it in the fusion layer The material storage area is ready for use;

The storage area for the above-mentioned supporting frame layer material and the material storage area for the fusion layer are boxes that are isolated from each other or set independently.

5) Trial preparation:

When the melting point of the fusion layer is higher than that of the supporting skeleton layer, in an argon atmosphere, print the fusion layer in the first layer along the printing path first, then use laser heating to melt and consolidate the fusion layer, and then print the first layer along the printing path first The supporting skeleton layer in the middle is finally heated and consolidated by laser, so that the supporting skeleton layer is melted and solidified on the fusion layer to form the first consolidated layer; after that, on the basis of the first consolidated layer, continue to laminate the second consolidated layer. The second consolidation layer and the third consolidation layer until the prosthesis is formed;

Since the melting point of the fusion layer is higher than that of the supporting framework layer, the supporting framework layer will not be overburned during heating and melting, and its performance and the bonding level between the two will not be affected.

Conversely, when the melting point of the supporting skeleton layer is higher than that of the fusion layer, the supporting skeleton layer should be printed first.

6) Detection: After the prosthesis is completely cooled, measure the size of each key part, compare it with the three-dimensional mathematical model, and determine the deformation ratio;

7) Adjust the prosthesis model: adjust the prosthesis model according to the deformation ratio;

8) Re-preparation: reprint according to the adjusted prosthesis model;

9) Retesting: correcting the deformation ratio;

10) Repeat 5), 6), 7), 8) and 9) until the deformation ratio is 1, that is, the printed prosthesis is completely consistent with the 3D model. At this point, stop the trial printing:

11) Printing: Repeat step 5) to print the prosthesis layer by layer; open the heat preservation device in the printing table, as shown in Figure 7, the heat preservation device can be the resistance wire 5 provided in the printing table, and pass the resistance wire to the printing table. Heating to keep the contact surface with the prosthesis consistent with the temperature of the prosthesis, which can keep the prosthesis in a constant temperature range and avoid defects such as stress deformation or material tearing caused by excessive local temperature differences;

Of course, the peripheral space of the printing table may also be heated by the heating device 6 to keep the entire peripheral space within a certain temperature range, as shown in FIG. 8 .

12) Cooling: After the printing is completed, the rotating motor 7 is used to drive the printing table to rotate for air-cooling and cooling. The air-cooling can cool down the whole prosthesis, so that the cooling is uniform, the temperature difference is small, the internal stress is small, the deformation is small, and the size of the prosthesis is small. easy to keep;

13) After the cooling is completed, remove the prosthesis and the printing is finished.

In the present invention, the prosthesis model is provided with a plurality of outwardly protruding stress-relieving convex hulls 8, and the plurality of stress-relieving convex hulls are evenly printed on the outer circumference of the contact surface between the prosthesis model and the printing platform. The convex hull protrudes outwards and is distributed on the outer circumference of the prosthesis model, so the strength of the outer structure can be increased, and the prestress deformation can be better resisted.

In the present invention, the supporting skeleton layer is made of titanium material. Compared with tantalum, titanium has a lighter weight, is relatively cheap, and has higher structural strength. Therefore, the structural strength can be guaranteed while reducing the quality. play a supporting role.

In the present invention, the fusion layer is made of tantalum material and has a porous structure. It has been clinically proven that tantalum is an orthopedic implant with ideal biocompatibility, especially porous tantalum has a porous structure and elastic modulus that can meet the interface bone ingrowth, and has good mechanical properties close to the host bone. Therefore, in this example, the The porous tantalum structure is used as the fusion layer, and the bone ingrowth property is used to integrate with the host bone to strengthen the bonding strength with the bone end.

Porous tantalum can reduce the strength of solid tantalum, so as to achieve mechanical properties similar to human bone. However, in practical applications, not all pore sizes are suitable. If the pore size is too large, its structural strength may be reduced and cannot match human bone; while the pore size If it is too small, it is not conducive to the ingrowth of bone cells and affects the level of integration with human bone. At the same time, it may increase the weight and load. Therefore, it is necessary to choose a suitable pore size range.

At the same time, the strength is also related to the porosity. Long-term research and multiple tests have shown that: the pore diameter is 0.3-0.9mm, the wire diameter is 0.3-0.6mm, and the porosity is 75%-85%, and the cell proliferation ability is better.

In addition, on the basis of ensuring the function, in order to further reduce the operation cost and the weight of the prosthesis, the thickness of the porous structure in this embodiment is preferably 1.5-3mm, which can make the human bone and the prosthesis have sufficient bonding force without excessive waste.

In actual printing, the supporting skeleton layer can be a solid structure or a hollow structure, which is mainly set according to the needs. Usually, as long as sufficient structural strength is ensured, the supporting skeleton layer can be set as a hollow structure. This can further reduce the weight of the prosthesis and can reduce manufacturing costs.

In the present invention, after step 12 and before step 13, the operation of spraying the selenium layer 10 on the surface of the prosthesis is also included, as shown in Fig. 2-Fig. 3 after completion. Selenium is a multifunctional life nutrient, which is widely used in cancer, surgery, radiotherapy and chemotherapy, etc. The selenium layer on the outside of the prosthesis is in full contact with the host bone to supplement the necessary nutrients for the human body and has a certain inhibitory effect on bone tumors.

Application of the above method:

1. The operculum block, as shown in Figure 10.

Wire diameter: 0.5～0.6mm, aperture: 0.3～0.6mm, porosity>75%, length x width x height: 32x46x29mm;

2. The acetabular pad, as shown in Figure 11.

Wire diameter: 0.5~0.6mm, aperture: 0.4~0.6mm, porosity>75%, length x width x height: 43x29x25mm;

3. An integrated acetabular cup, as shown in Figure 12.

Wire diameter: 0.35mm, aperture: 0.65mm, porosity 75%, length x width x height: 45x66x99mm;

4. The patella, as shown in Figure 13.

Wire diameter: 0.5~0.6mm, aperture: 0.4~0.6mm, porosity 75%, length x width x height: 48.85x36.0x28.58mm.

5. Fibula tumor prosthesis, as shown in Figure 14.

Wire diameter: 0.5~0.6mm, aperture: 0.4~0.6mm, porosity>75%, length x width x height: 21x19x131mm.

6. Femoral tumor prosthesis, as shown in Figure 15.

Wire diameter: 0.35mm, aperture: 0.75mm, porosity 85%, length x width x height: 128x58x57mm

7. 100% partial patella replacement (keep the patella shell), as shown in Figure 16.

Wire diameter: 0.5～0.6mm, aperture: 0.4～0.6mm, porosity>75%, length x width x height: 47x48.14x23.44mm

8. 100% (total patella replacement), as shown in Figure 17.

Wire diameter: 0.5~0.6mm, aperture: 0.4~0.6mm, porosity>75%, length x width x height: 48.85x36.0x28.58mm.

9. 100% pelvic tumor, as shown in Figure 18.

Wire diameter: 0.35mm, aperture: 0.65mm, porosity 70%, length x width x height: 163x104x61mm

10. 100% ilium tumor, as shown in Figure 19.

Wire diameter: 0.35mm, aperture: 0.7-0.9mm, porosity 85%, length x width x height: 100% of 66x72x74mm.

11. Knee joint fusion is 100%, as shown in Figure 20.

Wire diameter: 0.5~0.6mm, aperture: 0.4~0.6mm, porosity 75%, length x width x height: 65x43x50m.

12. Femoral side, as shown in Figure 21.

Wire diameter: 0.3-0.4mm, aperture: 0.7-0.8mm, porosity 75.95%, length x width x height: 67x42x65mm.

13. Tibia side, as shown in Figure 22.

Wire diameter: 0.35mm, aperture: 0.7-0.8mm, porosity 75%, length x width x height: 68x60x43mm.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (6)

1. A bone defect prosthesis 3D printing method, characterized in that: comprises the following steps: 1) Establish bone defect model: use CT or MRI technology to construct a three-dimensional mathematical model of bone defect; 2) Establishing a prosthesis model: constructing a prosthesis model according to the defect of the three-dimensional mathematical model, the prosthesis model is a multi-layer composite structure, the composite structure at least includes a support skeleton layer and a fusion layer arranged outside the support skeleton layer, and the support skeleton Interlocking connectors are arranged between the layer and the fusion layer; 3) Compile the printing program: import the STL file of the prosthetic model into the 3D printing device, perform slice processing, obtain the cross-sectional graphics that need to be printed at present, and design the plane printing path according to the cross-sectional graphics; 4) Preparation of printing toner: After the supporting skeleton layer material and the fusion layer material are proportioned separately, they are respectively loaded into two mutually independent toner storage areas, and communicated with the toner nozzle through two mutually independent conveying systems ; 5) Pre-preparation: In an argon atmosphere, print the fusion layer in the first layer along the printing path first, then use laser or electron beam heating to melt and consolidate the fusion layer, and then print the fusion layer in the first layer along the printing path The supporting skeleton layer is finally heated and consolidated by laser, so that the supporting skeleton layer is melted and solidified on the fusion layer to form the first consolidated layer; after that, on the basis of the first consolidated layer, the second consolidated layer is continued to be laminated. knot layer, the third consolidation layer, until the formation of the prosthesis; 6) Detection: After the prosthesis is completely cooled, measure the size of each key part and compare it with the three-dimensional mathematical model to determine the deformation ratio; 7) Adjust the prosthesis model: adjust the prosthesis model according to the deformation ratio; 8) Re-preparation: reprint according to the adjusted prosthesis model; 9) Retesting: correcting the deformation ratio; 10) Repeat 5)-9) until the deformation ratio is 1, stop the trial printing: 11) Preparation: Repeat 5) to prepare the prosthesis layer by layer; turn on the heat preservation device in the printing table to keep the contact surface with the prosthesis consistent with the temperature of the prosthesis; 12) Cooling: After printing is completed, the printing table is rotated for air cooling; 13) After the cooling is completed, remove the prosthesis and the printing is finished. 2. A 3D printing method for a bone defect prosthesis according to claim 1, wherein the prosthesis model is provided with a plurality of outwardly protruding stress-relieving convex hulls, and the stress-relieving convex hulls are uniform It is arranged on the outer circumference of the contact surface between the phantom model and the printing platform. 3. The 3D printing method for bone defect prosthesis according to claim 1, characterized in that: the supporting skeleton layer is a hollow titanium structure. 4. A 3D printing method for a bone defect prosthesis according to claim 1, characterized in that: the fusion layer is porous tantalum, the thickness of the porous tantalum is 0.4-0.6mm, the diameter of the hole is 0.3-0.9mm, and the wire diameter 0.3-0.6mm, porosity 75%-85%. 5. A 3D printing method for bone defect prosthesis according to claim 1, characterized in that: particle proportioning includes vibration separation and particle remixing process. 6. A method for 3D printing of a bone defect prosthesis according to claim 1, characterized in that: the toner is conveyed in a hybrid manner of vibration separation and blade conveyance.