CN114259327A - Method for reconstructing acetabular bone defect based on 3D printing - Google Patents

Abstract

The invention discloses a method for reconstructing an acetabular bone defect based on 3D printing, which comprises the following steps: s1, preparing and characterizing the titanium metal implant subjected to electron beam melting and 3D printing and detecting cell compatibility; s2, performing electron beam melting 3D printing on the in-vitro characterization of the biological characteristics of the titanium implant; s3, performing electron beam melting on the in vivo representation of the biological characteristics of the 3D printed titanium implant; s4, clinical study of electron beam melting of 3D printed titanium metal implants. The scheme is based on CT three-dimensional reconstruction of the acetabulum bone defect form, a digital cushion block filler model is established by means of Computer Aided Design (CAD), and an electron beam melting (EMB)3D printing technology is utilized to manufacture personalized metal cushion block plants with good biological characteristics so as to realize effective reconstruction of the acetabulum bone defect, thereby bringing a new solution to the bone defect problem in the hip revision surgery.

Description

Method for reconstructing acetabular bone defect based on 3D printing

Technical Field

The invention belongs to the technical field of medical treatment, and particularly relates to a method for reconstructing an acetabular bone defect based on 3D printing.

Background

The hip bone consists of three parts, namely ilium, ischium and pubis, and a large and deep socket called acetabulum is arranged on the outer side surface of the hip bone to form a hip joint with the femoral head. The acetabulum is an important component of the hip joint, and the hip joint is easy to damage due to heavy load and large mobility.

With the accelerating aging process of the population in China and the continuous improvement of the living quality of the people in China, the number of patients who receive joint replacement due to hip joint diseases is increased year by year and the patients are in a trend of being young; according to incomplete statistics, the number of patients who receive hip joint replacement per year in China is nearly 30 thousands of times, and the number of the consequent hip joint revision is increased day by day; common causes of hip revision include aseptic loosening of the prosthesis, infection, abrasion of the polyethylene lining, osteolysis, fractures around the prosthesis, etc.; in hip revision surgery, the treatment of severe bone defects can be the most challenging problem; bone defects are usually seen from the acetabulum side, too much acetabulum bone defects directly cause that an acetabular cup in the revision operation cannot be effectively supported, the press fit fails, and the stability of the prosthesis is difficult to ensure; according to Johanson, 17% of the acetabular bone defects combined in the hip revision surgery, but the failure rate of the surgery is as high as 30%; therefore, whether the acetabulum bone defect can be effectively reconstructed or not can directly influence the success or failure of the hip revision operation;

correct assessment and treatment of acetabular bone defects is critical to the success of hip revision surgery; paprosky typing was proposed by Paprosky et al in 1994, and is increasingly used clinically because this typing method can judge prognosis and guide treatment; the Paprosky type is mainly used for classifying the acetabular bone defect into three types according to the ischial bone dissolving degree, the tear drop damage degree and the femoral head center inward-moving and upward-moving degree; wherein, Paprosky I and IIA type acetabular bone defects are small in bone defects, and extra bone grafting is not needed; structural bone grafting is needed for the bone defect types of Paprosky IIB and above, and autologous bone blocks, allogeneic bone blocks or finished metal cushion blocks are usually needed for filling; however, the defect form of the acetabular bone is changeable, and for structural bone grafting, no matter autologous/allogeneic bone or finished metal cushion blocks are adopted, the defect form of the structural bone grafting cannot be matched with the defect part of the host bone completely from the aspect of appearance, extra finishing, grinding and rubbing are needed in the operation, the operation is complicated, and the purpose of anatomical reconstruction cannot be achieved; meanwhile, the allogeneic bone blocks or finished metal cushion blocks are very expensive and difficult to popularize clinically; therefore, the conventional clinical filler which is convenient, effective, economical and practical is not available for the problem of reconstruction of the acetabular lateral bone defect in the hip revision surgery;

the 3D printing technology is one of Rapid Prototyping (RP) technologies, and is based on a three-dimensional data model, a series of module designs and digital slicing processes are completed through Computer Aided Design (CAD), and information of the slices is transmitted to a 3D printer, and a solid object, also called "additive manufacturing", is constructed by using a powdered or liquid metal, plastic and other bonding materials as raw materials through layered processing and stack molding;

an electron beam melting technology (EBM), which is a rapid prototyping manufacturing technology emerging in recent years, introduces three-dimensional model data into EBM printing equipment, uses metal powder as a raw material in a vacuum environment, melts metal particles through high energy generated by high-energy electron beams after deflection focusing induced by a magnetic field, forms a metal thin layer through solidification and fusion, and completes construction of a metal entity in a layer-by-layer laying manner; at present, some titanium alloy endophytes (shown in figure 1) printed by EBM technology in 3D mode are used for clinic, the short-term curative effect is satisfactory, but effective reconstruction of acetabular bone defects is difficult to achieve by the method.

With the continuous development and innovation of the 3D printing technology in the medical field, the eosin is brought to the application of the individualized artificial implant for the bone joint surgery; the problem is to reconstruct the acetabulum bone defect form in a three-dimensional way based on CT, establish a digital cushion block filler model by means of Computer Aided Design (CAD), and manufacture a personalized metal cushion block plant with good biological characteristics by utilizing an electron beam melting (EMB)3D printing technology so as to realize effective reconstruction of the acetabulum bone defect, thereby bringing a new solution to the problem of bone defect in hip revision surgery.

It is therefore desirable to devise a method for acetabular bone defect reconstruction based on 3D printing.

Disclosure of Invention

The object of the present invention is to provide a method for acetabular bone defect reconstruction based on 3D printing to solve the problems set forth in the background art above.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for acetabular bone defect reconstruction based on 3D printing, comprising the steps of:

s1, preparing and characterizing the titanium metal implant subjected to electron beam melting and 3D printing and detecting cell compatibility;

a1, preparation of electron beam melting 3D printed titanium metal implant:

an engineer respectively draws a three-dimensional digital model diagram of a cylindrical artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and the diameter of 0.4cm and the height of 0.15cm in UG software, saves the data in an STL format, guides the data into a 3D printing main program for layered slicing, guides the obtained fault data into EBM equipment, and prints and manufactures the product;

titanium alloy (Ti6Al4V) powder is filled in the powder bin and is uniformly paved on a working platform by a powder rake, and the thickness of the powder bin is 0.5-1 mm; closing the cabin door, and vacuumizing the working cabin until the vacuum degree reaches 10 & lt-4 & gt-10 & lt-5 & gt mbar; the electron beam gun emits high-energy electron beams under the control of a computer program and focuses the high-energy electron beams on a working platform, titanium metal powder particles irradiated by the high-energy electron beams are heated and melted instantly and then cooled and solidified, and required metal customized objects are printed out in a layered processing and overlapping forming mode; removing unfused metal powder, performing subsequent treatments such as polishing processing and the like to obtain a final personalized metal cushion block finished product, and performing sterile storage for later use after disinfection;

b1, detecting the porosity of the 3D printed titanium metal implant by electron beam melting;

determination of porosity: measuring the porosity by adopting a liquid discharge method; taking a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, immersing the artificial cushion block and the traditional finished artificial cushion block in absolute ethyl alcohol with a known volume (V1), and reducing the pressure to enable all pores in the bracket to be filled with the ethyl alcohol, wherein the total volume is V2; after a period of time, the scaffolds were gently removed and the volume of remaining ethanol was labeled V3; the porosity is obtained by formula (a);

Porosity＝(V1–V3)/(V2–V3) (a)

c1, surface structure observation of the 3D printed titanium metal implant by electron beam melting;

the appearance and the structure are as follows: respectively spraying gold on the 3D printed artificial cushion block and the traditional finished artificial cushion block for 2min under the condition of 20mA to prepare samples, and observing the surface structure, the size of pores and the like of the samples by using a scanning electron microscope;

d1, testing the compressive strength of the 3D printed titanium metal implant by electron beam melting;

respectively taking 6 patterns of a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, curing for 72 hours at 37 ℃ in a 100% relative humidity environment, polishing the upper surface and the lower surface to be flat, and placing the flat on a universal testing machine for compression testing; the loading rate is 1mm/min, and a load-displacement curve is recorded; calculating the compressive strength value of the pattern according to the following formula (b):

P＝4NπD2 (b)

wherein P represents the compressive strength of the pattern, N represents the peak load value, and D represents the diameter of the pattern;

s2, performing electron beam melting 3D printing on the in-vitro characterization of the biological characteristics of the titanium implant;

a2, culturing osteoblasts;

digesting and counting an MC3T3-E1 cell line by using 0.25% Trypsin-EDTA, taking 1 × 107 cells, inoculating the cells into a cell culture dish with the diameter of 75cm2, culturing at 37 ℃ under the condition of 5% CO2, adding 8-10 mL of culture medium into each dish, and changing the culture medium every other day; after 90% of cells are fused, digesting and passaging by using 0.25% Trypsin-EDTA;

b2, morphologic detection of adhesion and proliferation of cells on the surface of the material;

performing irradiation sterilization on a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block for biological tests; placing 30 cushion blocks into a 24-hole plate respectively, placing one cushion block corresponding to one hole, adding cells for culture, soaking for 3 days at 37 ℃ under the condition of 5% CO2, implanting 1 × 105 MC3T3-E1 cells into each hole, and implanting 1 × 105 MC3T3-E1 cells into another 15-hole material-free hole as a blank control;

removing culture medium from each group by suction in 3 holes on days 1, 3, 7, 14 and 21 respectively, cleaning with PBS solution, and fixing with 4% paraformaldehyde for 10 min; then blocking for 2 hours by using 2% BSA solution, sequentially adding FITC-phalloidin solution with the working concentration of 5 mu g/mL and DAPI solution in a dark environment after blocking, reacting for 20 minutes, and absorbing and removing the reaction solution and washing by using PBS solution after the reaction is finished; the stained sample is placed under a fluorescence microscope to observe the cell morphology and the number of the surface cells of each group of materials and the growth condition of the cells in pores, and the cell morphology is compared with the cell morphology of a blank control group;

performing SEM detection on each group of cell-cushion block compound at each time point; 3 samples of the artificial cushion block group and the traditional finished artificial cushion block group are respectively taken out and washed by PBS on days 1, 3, 7, 14 and 21, and are fixed for 4 hours at 4 ℃ by 1 percent osmic acid, and then the dehydration is carried out by adopting alcohol gradient, wherein the dehydration time of each concentration is not less than 20 minutes; after dehydration, air drying, vacuumizing, spraying gold, and observing the number and quantity of cells on the surface of the cushion block and the growth condition of cells in pores by adopting SEM (scanning Electron microscope);

c2, quantitative detection of cushion block biocompatibility;

placing the printed artificial cushion block with the diameter of 0.4cm and the height of 0.15cm3D and the traditional finished artificial cushion block into a 96-well plate, arranging a material-free control group, implanting 1 × 104 MC3T3-E1 cells into each well for culturing, and taking days 1, 3, 7, 14 and 21 as observation points for detection and analysis by an MTS method; taking 3 holes from each group at each time point, completely sucking out the culture medium in the holes, cleaning the holes by using PBS (phosphate buffer solution), adding 100mL of cell complete culture medium and 20 mu L of MTS (methanol-to-sulfur) solution with the concentration of 1.90mg/mL into each hole, incubating the holes in a cell incubator for 3 hours, sucking out 100 mu L of the cell complete culture medium and the MTS solution into each hole, detecting the OD (optical density) value at the wavelength of 490nm by using an ultraviolet spectrophotometer, recording the result, and drawing a cell growth curve of each group;

s3, performing electron beam melting on the in vivo representation of the biological characteristics of the 3D printed titanium implant;

a3, establishing a goat femoral defect model and preparing a titanium metal cushion block with the diameter of 1cm multiplied by 1 cm/diameter of 3cm multiplied by 3 cm/diameter of 5cm multiplied by 5cm by adopting an electron beam melting 3D printing technology before material implantation, and performing irradiation sterilization and aseptic storage for later use;

selecting green goats weighing 20-25 kG; the animals are sent to the center of the animals in advance and are raised in cages for one week to adapt to the environment; after the experiment starts, the right lateral position of the goat is fixed on a laboratory table after the anterior muscle is successfully anesthetized by fast-asleep (0.15mL/kG), the hind limb is preserved, and the goat is sterilized and paved by 2.5 percent iodine tincture and 75 percent alcohol cotton balls; taking a longitudinal incision with the length of about 5cm at the lower end of the outer side of the femur, sequentially incising skin, subcutaneous tissue and fascia lata to expose the outer femoral condyle, and taking out defects with the diameter of 1cm multiplied by 1 cm/3 cm multiplied by 3 cm/5 cm multiplied by 5cm by adopting an electric drill; and placing each group of aseptically preserved materials into the defect site; wherein, the traditional finished product artificial cushion group is suitable for filling the defects as far as possible by using finished cushion blocks with various sizes; in the sham operation group, only incision and suture of skin and muscle are performed, and femoral condyle drilling and sample placement are not performed; then, normal saline is adopted to wash the wound, the wound is sutured layer by layer, and the wound is wrapped by sterile dressing without external fixation and free movement; 8 ten thousand units of penicillin is intramuscularly injected before, during and after 3 days, and the streptomycin is 0.5 g; high protein green feed is kept in captivity, and stitches are removed after 12 days of operation;

b3, detecting the defect filling and repairing in vivo;

b31, Micro-CT detection:

after 4, 8 and 12 weeks after operation, rapidly sleeping new sheep is adopted to anaesthetize the Qingshan sheep, CT detection is carried out, meanwhile, relevant software is used for analyzing indexes such as bone volume fraction (Bonevolume/Totalvolume, BV/TV), bone density (BoneMineralDensity, BMD) and the like, and three-dimensional reconstruction of defect parts is carried out to visually know the defect filling, bone ingrowth and defect repairing conditions;

b32, histomorphological observation:

the goats were sacrificed at weeks 4, 8 and 12 and the tissues containing the samples were removed to prepare sections; respectively carrying out H & E and MASSON trichrome dyeing, and observing defect filling, bone ingrowth and defect repair conditions under an optical microscope;

the H & E dyeing comprises the following specific steps: carrying out gradient dehydration on the slices again, adding the slices into a hematoxylin solution for dyeing for 5 minutes, washing the slices with running water, treating the slices with 1% hydrochloric acid ethanol for 3 seconds, washing the slices with water for bluing for 30 minutes, carrying out alcohol gradient dehydration, dyeing with eosin for 20 seconds, dehydrating with pure ethanol, enabling the slices to be transparent through xylene, and sealing with neutral gum;

the MASSON trichrome dyeing method comprises the following specific steps: performing chromatization on the slices, then dyeing for 10 minutes by using Weiger iron hematoxylin, differentiating by using an acidic ethanol differentiation solution, and turning blue by using a MASSON bluing solution; then, the fuchsin staining solution is adopted for staining for 10 minutes, then the solution is differentiated for 2 minutes by using phosphomolybdic acid solution, and then aniline blue staining solution is adopted for staining for 2 minutes; dehydrating 95% ethanol and anhydrous ethanol in sequence, making the slices transparent with xylene, and sealing with neutral gum;

s4, performing clinical research on the 3D printed titanium metal implant by electron beam melting;

a4, manufacturing an individualized porous metal cushion block by Electron Beam Melting (EBM)3D printing;

according to the preoperative planning result of a surgeon, preparing an electron beam melting 3D printing individualized porous metal cushion block by the method, and performing irradiation sterilization and sterile sealing for use in the operation;

b4, after the earlier-stage experiments are successful, the ethics committee approves, reports relevant procedures, establishes a traditional finished product artificial cushion block control group and carries out clinical implantation experiments;

screening of study subjects:

shooting a pelvis correction X-ray film before a patient operates, and performing Paprosky typing evaluation on the acetabulum lateral bone defect according to the conditions of the acetabulum rotation center upward movement degree of the X-ray film, ischial bone dissolution, tear drop bone dissolution, whether a Kohler line is damaged and the like;

and (3) inclusion standard: paprosky iib and above severe bone defect types;

exclusion criteria: (1) paprosky I and IIA type bone defects are small, and bone grafting is not needed generally; (2) those allergic to metal implants; (3) patients with other serious diseases or intolerance of systemic evaluation; (4) those with hip joint infection or active infection elsewhere in the body; (5) severe osteoporosis; (6) in addition to hip joint, the functional impairment caused by other joint (knee, ankle) diseases of lower limb affects the lower limb functional evaluators; (7) 6 months before screening, the patient has history of abuse of alcohol or drugs; (8) pregnant or lactating women, or women desiring to give birth;

c4, establishing digital pelvis three-dimensional model

A metal artifact removing technology is adopted before operation, and a thin layer with the thickness of 1mm is scanned on the pelvis of a patient by using 64 layers of spiral CT; the CT image file is stored in a DICOM format and is imported into an interactive medical image control system to reconstruct a digital three-dimensional model diagram of the pelvis of a patient;

d4, manufacturing a 1:1 half pelvis 3D model;

importing digital three-dimensional pelvis model data established by MIMICS software into industrial design software UG for further drawing and processing, and finally importing the digital three-dimensional pelvis model data into a main program of a 3D printer to manufacture a pelvis model with a size of 1:1 of the real person in a layer-by-layer printing mode by taking polylactic acid as a raw material;

e4, assessment of bone defects and planning of surgical protocols;

further evaluating the acetabulum bone defect conditions of the patient according to the three-dimensional reconstruction image obtained by MIMICS software and the 1:1 half pelvis 3D entity model, wherein the bone defect conditions comprise the bone defect amount, the appearance, the residual host bone amount and the like of the front wall, the rear wall, the inner wall, the acetabulum top and the like of the acetabulum; according to the bone defect condition, a three-dimensional model of the personalized cushion block is planned by using computer aided design, the appearance, the size and the optimal placement position of the cushion block, the fixed number and the direction of screws and the like are drawn on a reconstructed image, and meanwhile, the size and the installation position of the metal acetabular outer cup of the revision prosthesis are determined, and a three-dimensional effect graph is generated; after confirming satisfaction with the surgeon, the solid spacer model was created using an EBM3D printer based on computer-aided designed spacer patterns, and the surgeon performed the following procedures at 1:1, performing preoperative surgical operation simulation on a half-pelvis model, and evaluating the pre-filling effect of acetabular bone defects;

f4, placing the 3D printed inner plant into the revision surgery to reconstruct the bone defect;

approved by the ethics committee of hospitals, the patients are informed and signed with informed consent for surgery and implants; the operation is completed by the doctor in the subject group; the operation is performed by cutting and exposing an improved Harding access, the wound is thoroughly debrided in the operation, the loosened prosthesis is taken out, and the bone dissolution and bone defect around the acetabular cup are consistent with those shown by a preoperative 3D printed half pelvic model; after the acetabulum side is ground and rubbed, a 3D printing titanium metal cushion block is arranged at the acetabulum bone defect position according to a preoperative plan scheme, and a screw is arranged in the nail hole direction designed and manufactured preoperatively for fixation; placing a metal mortar cup, installing a polyethylene lining after firm press fit, and finally placing the biological femoral stem prosthesis and installing a ceramic ball head;

g4, postoperative clinical efficacy and biomechanical assessment:

firstly, establishing contrast with allograft structural bone grafting and a revision surgery using a finished product metal cushion block, and comparing the time, the amount of bleeding and the complications in the surgery;

follow-up visits were performed on patients 1, 3, 6, 9, 12 months after surgery to assess VAS pain scores, Harris functional scores;

shooting a pelvis X-ray plain film and a thin CT (computed tomography), and evaluating the position of an implant and the bone ingrowth condition;

fourthly, detecting the concentration of V, Al and other related metal ions in the blood of the patient and evaluating the biological toxicity of the prosthesis.

The invention has the technical effects and advantages that: compared with the prior art, the method for reconstructing the acetabular bone defect based on 3D printing has the following advantages:

the scheme is based on CT three-dimensional reconstruction of the acetabulum bone defect form, a digital cushion block filler model is established by means of Computer Aided Design (CAD), and an electron beam melting (EMB)3D printing technology is utilized to manufacture personalized metal cushion block plants with good biological characteristics so as to realize effective reconstruction of the acetabulum bone defect, thereby bringing a new solution to the bone defect problem in the hip revision surgery.

Drawings

FIG. 1 is a schematic structural view of an electron beam melting 3D printed titanium metal implant;

FIG. 2 is a schematic structural view of an electron beam melting 3D printer and its internal construction;

FIG. 3 is a schematic structural diagram of an integrated metal inner plant manufactured by printing titanium alloy powder layer by layer;

FIG. 4 is a schematic structural diagram of the construction of a pelvis three-dimensional digital model by using MIMICS software;

FIG. 5 is a schematic structural diagram of a 1:1 hemi-pelvic model of polylactic acid made with a 3D printer;

FIG. 6 is a diagram showing the effect of the pre-placement positions of a cushion block and a prosthesis designed by computer-aided design on 1 example of Paprosky IIB type bone defect and a schematic diagram of a 3D printed model entity;

FIG. 7 is a schematic view of 1 example of a Paprosky IIIA bone defect, pre-operative planning and surgical simulation using a 3D printed physical model with computer-aided cushion configuration and pre-installation location design;

FIG. 8 is a format diagram of Harris functional scoring;

fig. 9 is a flow chart of a method for acetabular bone defect reconstruction based on 3D printing.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to fig. 2 to 9 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely illustrative of the invention and do not delimit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 2-9, the present invention provides a method for acetabular bone defect reconstruction based on 3D printing, comprising the steps of:

s1, preparing and characterizing the titanium metal implant subjected to electron beam melting and 3D printing and detecting cell compatibility;

a1, preparation of electron beam melting 3D printed titanium metal implant:

an engineer draws a three-dimensional digital model diagram of a cylindrical artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and the diameter of 0.4cm and the height of 0.15cm in UG software respectively, stores the data in an STL format, guides the data into a 3D printing main program for layered slicing treatment, guides obtained fault data into EBM equipment for printing and manufacturing a product, and as shown in FIG. 2, the left side in the diagram is Sweden Arcam, and the right side is the internal structure;

titanium alloy (Ti6Al4V) powder is filled in the powder bin and is uniformly paved on a working platform by a powder rake, and the thickness of the powder bin is 0.5-1 mm; closing the cabin door, and vacuumizing the working cabin until the vacuum degree reaches 10 & lt-4 & gt-10 & lt-5 & gt mbar; the electron beam gun emits high-energy electron beams under the control of a computer program and focuses the high-energy electron beams on a working platform, titanium metal powder particles irradiated by the high-energy electron beams are heated and melted instantly and then cooled and solidified, and a required metal customized object is printed out in a layered processing and overlapping forming mode, as shown in figure 3; removing unfused metal powder, performing subsequent treatments such as polishing processing and the like to obtain a final personalized metal cushion block finished product, and performing sterile storage for later use after disinfection;

b1, detecting the porosity of the 3D printed titanium metal implant by electron beam melting;

determination of porosity: measuring the porosity by adopting a liquid discharge method; taking a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, immersing the artificial cushion block and the traditional finished artificial cushion block in absolute ethyl alcohol with a known volume (V1), and reducing the pressure to enable all pores in the bracket to be filled with the ethyl alcohol, wherein the total volume is V2; after a period of time, the scaffolds were gently removed and the volume of remaining ethanol was labeled V3; the porosity is obtained by formula (a);

Porosity＝(V1–V3)/(V2–V3) (a)

c1, surface structure observation of the 3D printed titanium metal implant by electron beam melting;

the appearance and the structure are as follows: respectively spraying gold on the 3D printed artificial cushion block and the traditional finished artificial cushion block for 2min under the condition of 20mA to prepare samples, and observing the surface structure, the size of pores and the like of the samples by using a scanning electron microscope;

d1, testing the compressive strength of the 3D printed titanium metal implant by electron beam melting;

respectively taking 6 patterns of a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, curing for 72 hours at 37 ℃ in a 100% relative humidity environment, polishing the upper surface and the lower surface to be flat, and placing the flat on a universal testing machine for compression testing; the loading rate is 1mm/min, and a load-displacement curve is recorded; calculating the compressive strength value of the pattern according to the following formula (b):

P＝4NπD2 (b)

wherein P represents the compressive strength of the pattern, N represents the peak load value, and D represents the diameter of the pattern;

s2, performing electron beam melting 3D printing on the in-vitro characterization of the biological characteristics of the titanium implant;

a2, culturing osteoblasts;

digesting and counting an MC3T3-E1 cell line by using 0.25% Trypsin-EDTA, taking 1 × 107 cells, inoculating the cells into a cell culture dish with the diameter of 75cm2, culturing at 37 ℃ under the condition of 5% CO2, adding 8-10 mL of culture medium into each dish, and changing the culture medium every other day; after 90% of cells are fused, digesting and passaging by using 0.25% Trypsin-EDTA;

b2, morphologic detection of adhesion and proliferation of cells on the surface of the material;

performing irradiation sterilization on a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block for biological tests; placing 30 cushion blocks into a 24-hole plate respectively, placing one cushion block corresponding to one hole, adding cells for culture, soaking for 3 days at 37 ℃ under the condition of 5% CO2, implanting 1 × 105 MC3T3-E1 cells into each hole, and implanting 1 × 105 MC3T3-E1 cells into another 15-hole material-free hole as a blank control;

removing culture medium from each group by suction in 3 holes on days 1, 3, 7, 14 and 21 respectively, cleaning with PBS solution, and fixing with 4% paraformaldehyde for 10 min; then blocking for 2 hours by using 2% BSA solution, sequentially adding FITC-phalloidin solution with the working concentration of 5 mu g/mL and DAPI solution in a dark environment after blocking, reacting for 20 minutes, and absorbing and removing the reaction solution and washing by using PBS solution after the reaction is finished; the stained sample is placed under a fluorescence microscope to observe the cell morphology and the number of the surface cells of each group of materials and the growth condition of the cells in pores, and the cell morphology is compared with the cell morphology of a blank control group;

performing SEM detection on each group of cell-cushion block compound at each time point; 3 samples of the artificial cushion block group and the traditional finished artificial cushion block group are respectively taken out and washed by PBS on days 1, 3, 7, 14 and 21, and are fixed for 4 hours at 4 ℃ by 1 percent osmic acid, and then the dehydration is carried out by adopting alcohol gradient, wherein the dehydration time of each concentration is not less than 20 minutes; after dehydration, air drying, vacuumizing, spraying gold, and observing the number and quantity of cells on the surface of the cushion block and the growth condition of cells in pores by adopting SEM (scanning Electron microscope);

c2, quantitative detection of cushion block biocompatibility;

placing the printed artificial cushion block with the diameter of 0.4cm and the height of 0.15cm3D and the traditional finished artificial cushion block into a 96-well plate, arranging a material-free control group, implanting 1 × 104 MC3T3-E1 cells into each well for culturing, and taking days 1, 3, 7, 14 and 21 as observation points for detection and analysis by an MTS method; taking 3 holes from each group at each time point, completely sucking out the culture medium in the holes, cleaning the holes by using PBS (phosphate buffer solution), adding 100mL of cell complete culture medium and 20 mu L of MTS (methanol-to-sulfur) solution with the concentration of 1.90mg/mL into each hole, incubating the holes in a cell incubator for 3 hours, sucking out 100 mu L of the cell complete culture medium and the MTS solution into each hole, detecting the OD (optical density) value at the wavelength of 490nm by using an ultraviolet spectrophotometer, recording the result, and drawing a cell growth curve of each group;

s3, performing electron beam melting on the in vivo representation of the biological characteristics of the 3D printed titanium implant;

a3, establishing a goat femoral defect model and preparing a titanium metal cushion block with the diameter of 1cm multiplied by 1 cm/diameter of 3cm multiplied by 3 cm/diameter of 5cm multiplied by 5cm by adopting an electron beam melting 3D printing technology before material implantation, and performing irradiation sterilization and aseptic storage for later use;

selecting green goats weighing 20-25 kG; the animals are sent to the center of the animals in advance and are raised in cages for one week to adapt to the environment; after the experiment starts, the right lateral position of the goat is fixed on a laboratory table after the anterior muscle is successfully anesthetized by fast-asleep (0.15mL/kG), the hind limb is preserved, and the goat is sterilized and paved by 2.5 percent iodine tincture and 75 percent alcohol cotton balls; taking a longitudinal incision with the length of about 5cm at the lower end of the outer side of the femur, sequentially incising skin, subcutaneous tissue and fascia lata to expose the outer femoral condyle, and taking out defects with the diameter of 1cm multiplied by 1 cm/3 cm multiplied by 3 cm/5 cm multiplied by 5cm by adopting an electric drill; and each set of aseptically preserved material, as shown in table 1, was placed into the defect site; wherein, the traditional finished product artificial cushion group is suitable for filling the defects as far as possible by using finished cushion blocks with various sizes; in the sham operation group, only incision and suture of skin and muscle are performed, and femoral condyle drilling and sample placement are not performed; then, normal saline is adopted to wash the wound, the wound is sutured layer by layer, and the wound is wrapped by sterile dressing without external fixation and free movement; 8 ten thousand units of penicillin is intramuscularly injected before, during and after 3 days, and the streptomycin is 0.5 g; high protein green feed is kept in captivity, and stitches are removed after 12 days of operation;

TABLE 1 in vivo test grouping

B3, detecting the defect filling and repairing in vivo;

b31, Micro-CT detection:

after 4, 8 and 12 weeks after operation, rapidly sleeping new sheep is adopted to anaesthetize the Qingshan sheep, CT detection is carried out, meanwhile, relevant software is used for analyzing indexes such as bone volume fraction (Bonevolume/Totalvolume, BV/TV), bone density (BoneMineralDensity, BMD) and the like, and three-dimensional reconstruction of defect parts is carried out to visually know the defect filling, bone ingrowth and defect repairing conditions;

b32, histomorphological observation:

the goats were sacrificed at weeks 4, 8 and 12 and the tissues containing the samples were removed to prepare sections; respectively carrying out H & E and MASSON trichrome dyeing, and observing defect filling, bone ingrowth and defect repair conditions under an optical microscope;

the H & E dyeing comprises the following specific steps: carrying out gradient dehydration on the slices again, adding the slices into a hematoxylin solution for dyeing for 5 minutes, washing the slices with running water, treating the slices with 1% hydrochloric acid ethanol for 3 seconds, washing the slices with water for bluing for 30 minutes, carrying out alcohol gradient dehydration, dyeing with eosin for 20 seconds, dehydrating with pure ethanol, enabling the slices to be transparent through xylene, and sealing with neutral gum;

the MASSON trichrome dyeing method comprises the following specific steps: performing chromatization on the slices, then dyeing for 10 minutes by using Weiger iron hematoxylin, differentiating by using an acidic ethanol differentiation solution, and turning blue by using a MASSON bluing solution; then, the fuchsin staining solution is adopted for staining for 10 minutes, then the solution is differentiated for 2 minutes by using phosphomolybdic acid solution, and then aniline blue staining solution is adopted for staining for 2 minutes; dehydrating 95% ethanol and anhydrous ethanol in sequence, making the slices transparent with xylene, and sealing with neutral gum;

s4, performing clinical research on the 3D printed titanium metal implant by electron beam melting;

a4, manufacturing an individualized porous metal cushion block by Electron Beam Melting (EBM)3D printing;

according to the preoperative planning result of a surgeon, preparing an electron beam melting 3D printing individualized porous metal cushion block by the method, and performing irradiation sterilization and sterile sealing for use in the operation;

b4, after the earlier-stage experiments are successful, the ethics committee approves, reports relevant procedures, establishes a traditional finished product artificial cushion block control group and carries out clinical implantation experiments;

screening of study subjects:

the patient shoots a pelvis correction X-ray film before the operation, and the Paprosky typing evaluation is carried out on the acetabulum side bone defect according to the conditions of the acetabulum rotation center upward movement degree of the X-ray film, ischial bone dissolution, tear drop bone dissolution, whether a Kohler line is damaged and the like, and is shown in table 2;

TABLE 2 Paprosky typing reference Table

Type (B)	Central shift of femoral head	Dissolution of ischial bones	Kohler wire	Tear drop
					I	Smaller (<3cm)	Is free of	Complete (complete)	Complete (complete)
IIA	Mild (<3cm)	Mild degree of	Complete (complete)	Complete (complete)
					IIB	Moderate (A), (B)<3cm)	Mild degree of	Complete (complete)	Complete (complete)
IIC	Mild (<3cm)	Mild degree of	Destruction of	Moderate osteolysis
					IIIA	Severe (A) to (B)>3cm)	Of moderate degree	Complete (complete)	Moderate osteolysis
IIIB	Severe (A) to (B)>3cm)	Severe severity of disease	Destruction of	Severe osteolysis

And (3) inclusion standard: paprosky iib and above severe bone defect types;

exclusion criteria: (1) paprosky I and IIA type bone defects are small, and bone grafting is not needed generally; (2) those allergic to metal implants; (3) patients with other serious diseases or intolerance of systemic evaluation; (4) those with hip joint infection or active infection elsewhere in the body; (5) severe osteoporosis; (6) in addition to hip joint, the functional impairment caused by other joint (knee, ankle) diseases of lower limb affects the lower limb functional evaluators; (7) 6 months before screening, the patient has history of abuse of alcohol or drugs; (8) pregnant or lactating women, or women desiring to give birth;

c4, establishing digital pelvis three-dimensional model

A metal artifact removing technology is adopted before operation, and a thin layer scan with the layer thickness of 1mm is carried out on the pelvis of a patient by using 64 layers of spiral CT (Siemens, Germany); the CT image file is stored in a DICOM format and is imported into an interactive medical image control system (MIMICS, Belgium), and a digital three-dimensional model diagram of the pelvis of the patient is reconstructed, as shown in FIG. 4;

d4, manufacturing a 1:1 half pelvis 3D model;

the digital three-dimensional pelvis model data established by MIMICS software is introduced into industrial design software UG (Siemens, USA) for further drawing and processing, and finally introduced into a main program of a 3D printer (Archam, Sweden) to prepare a pelvis model of 1:1 of the size of a real person in a layer-by-layer printing mode by taking polylactic acid as a raw material, as shown in FIG. 5;

e4, assessment of bone defects and planning of surgical protocols;

further evaluating the acetabulum bone defect conditions of the patient according to the three-dimensional reconstruction image obtained by MIMICS software and the 1:1 half pelvis 3D entity model, wherein the bone defect conditions comprise the bone defect amount, the appearance, the residual host bone amount and the like of the front wall, the rear wall, the inner wall, the acetabulum top and the like of the acetabulum; according to the bone defect condition, a three-dimensional model of the personalized cushion block is planned by using computer aided design, the appearance, the size and the optimal placement position of the cushion block, the fixed number and the direction of screws and the like are drawn on a reconstructed image, and meanwhile, the size and the installation position of the metal acetabular outer cup of the revision prosthesis are determined, and a three-dimensional effect graph is generated; after confirming satisfaction with the surgeon, the solid spacer model was created using an EBM3D printer based on computer-aided designed spacer patterns, and the surgeon performed the following procedures at 1:1 performing a simulation of a pre-operative surgical procedure on a semi-pelvic model to assess the pre-filling effect of the acetabular bone defect, as shown in fig. 6 and 7;

f4, placing the 3D printed inner plant into the revision surgery to reconstruct the bone defect;

approved by the ethics committee of hospitals, the patients are informed and signed with informed consent for surgery and implants; the operation is completed by the doctor in the subject group; the operation is performed by cutting and exposing an improved Harding access, the wound is thoroughly debrided in the operation, the loosened prosthesis is taken out, and the bone dissolution and bone defect around the acetabular cup are consistent with those shown by a preoperative 3D printed half pelvic model; after the acetabulum side is ground and rubbed, a 3D printing titanium metal cushion block is arranged at the acetabulum bone defect position according to a preoperative plan scheme, and a screw is arranged in the nail hole direction designed and manufactured preoperatively for fixation; placing a metal mortar cup, installing a polyethylene lining after firm press fit, and finally placing the biological femoral stem prosthesis and installing a ceramic ball head;

g4, postoperative clinical efficacy and biomechanical assessment:

firstly, establishing contrast with allograft structural bone grafting and a revision surgery using a finished product metal cushion block, and comparing the time, the amount of bleeding and the complications in the surgery;

follow-up visits were performed on patients at 1, 3, 6, 9, 12 months after surgery, and the VAS pain score and Harris functional score were evaluated, as shown in fig. 8;

shooting a pelvis X-ray plain film and a thin CT (computed tomography), and evaluating the position of an implant and the bone ingrowth condition;

detecting the concentration of V, Al and other related metal ions in the blood of the patient, and evaluating the biological toxicity of the prosthesis;

statistical analysis was performed by the SPSS19.0 software package; data are expressed as mean + -standard deviation, single-factor analysis of variance is adopted for comparison among groups, Student-Newman-Keuls (SNK) test is adopted for pairwise comparison, and p <0.05 shows that difference among groups has statistical significance

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims (1)

1. A method for acetabular bone defect reconstruction based on 3D printing, comprising the steps of:

s1, preparing and characterizing the titanium metal implant subjected to electron beam melting and 3D printing and detecting cell compatibility;

a1, preparation of electron beam melting 3D printed titanium metal implant:

an engineer respectively draws a three-dimensional digital model diagram of a cylindrical artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and the diameter of 0.4cm and the height of 0.15cm in UG software, saves the data in an STL format, guides the data into a 3D printing main program for layered slicing, guides the obtained fault data into EBM equipment, and prints and manufactures the product;

titanium alloy (Ti6Al4V) powder is filled in the powder bin and is uniformly paved on a working platform by a powder rake, and the thickness of the powder bin is 0.5-1 mm; closing the cabin door, and vacuumizing the working cabin until the vacuum degree reaches 10 & lt-4 & gt-10 & lt-5 & gt mbar; the electron beam gun emits high-energy electron beams under the control of a computer program and focuses the high-energy electron beams on a working platform, titanium metal powder particles irradiated by the high-energy electron beams are heated and melted instantly and then cooled and solidified, and required metal customized objects are printed out in a layered processing and overlapping forming mode; removing unfused metal powder, performing subsequent treatments such as polishing processing and the like to obtain a final personalized metal cushion block finished product, and performing sterile storage for later use after disinfection;

b1, detecting the porosity of the 3D printed titanium metal implant by electron beam melting;

determination of porosity: measuring the porosity by adopting a liquid discharge method; taking a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, immersing the artificial cushion block and the traditional finished artificial cushion block in absolute ethyl alcohol with a known volume (V1), and reducing the pressure to enable all pores in the bracket to be filled with the ethyl alcohol, wherein the total volume is V2; after a period of time, the scaffolds were gently removed and the volume of remaining ethanol was labeled V3; the porosity is obtained by formula (a);

Porosity＝(V1–V3)/(V2–V3) (a)

c1, surface structure observation of the 3D printed titanium metal implant by electron beam melting;

the appearance and the structure are as follows: respectively spraying gold on the 3D printed artificial cushion block and the traditional finished artificial cushion block for 2min under the condition of 20mA to prepare samples, and observing the surface structure, the size of pores and the like of the samples by using a scanning electron microscope;

d1, testing the compressive strength of the 3D printed titanium metal implant by electron beam melting;

respectively taking 6 patterns of a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block, curing for 72 hours at 37 ℃ in a 100% relative humidity environment, polishing the upper surface and the lower surface to be flat, and placing the flat on a universal testing machine for compression testing; the loading rate is 1mm/min, and a load-displacement curve is recorded; calculating the compressive strength value of the pattern according to the following formula (b):

P＝4NπD2 (b)

wherein P represents the compressive strength of the pattern, N represents the peak load value, and D represents the diameter of the pattern;

s2, performing electron beam melting 3D printing on the in-vitro characterization of the biological characteristics of the titanium implant;

a2, culturing osteoblasts;

digesting and counting an MC3T3-E1 cell line by using 0.25% Trypsin-EDTA, taking 1 × 107 cells, inoculating the cells into a cell culture dish with the diameter of 75cm2, culturing at 37 ℃ under the condition of 5% CO2, adding 8-10 mL of culture medium into each dish, and changing the culture medium every other day; after 90% of cells are fused, digesting and passaging by using 0.25% Trypsin-EDTA;

b2, morphologic detection of adhesion and proliferation of cells on the surface of the material;

performing irradiation sterilization on a cylindrical 3D printing artificial cushion block with the diameter of 1.5cm and the height of 0.5cm and a traditional finished artificial cushion block for biological tests; placing 30 cushion blocks into a 24-hole plate respectively, placing one cushion block corresponding to one hole, adding cells for culture, soaking for 3 days at 37 ℃ under the condition of 5% CO2, implanting 1 × 105 MC3T3-E1 cells into each hole, and implanting 1 × 105 MC3T3-E1 cells into another 15-hole material-free hole as a blank control;

removing culture medium from each group by suction in 3 holes on days 1, 3, 7, 14 and 21 respectively, cleaning with PBS solution, and fixing with 4% paraformaldehyde for 10 min; then blocking for 2 hours by using 2% BSA solution, sequentially adding FITC-phalloidin solution with the working concentration of 5 mu g/mL and DAPI solution in a dark environment after blocking, reacting for 20 minutes, and absorbing and removing the reaction solution and washing by using PBS solution after the reaction is finished; the stained sample is placed under a fluorescence microscope to observe the cell morphology and the number of the surface cells of each group of materials and the growth condition of the cells in pores, and the cell morphology is compared with the cell morphology of a blank control group;

performing SEM detection on each group of cell-cushion block compound at each time point; 3 samples of the artificial cushion block group and the traditional finished artificial cushion block group are respectively taken out and washed by PBS on days 1, 3, 7, 14 and 21, and are fixed for 4 hours at 4 ℃ by 1 percent osmic acid, and then the dehydration is carried out by adopting alcohol gradient, wherein the dehydration time of each concentration is not less than 20 minutes; after dehydration, air drying, vacuumizing, spraying gold, and observing the number and quantity of cells on the surface of the cushion block and the growth condition of cells in pores by adopting SEM (scanning Electron microscope);

c2, quantitative detection of cushion block biocompatibility;

placing the printed artificial cushion block with the diameter of 0.4cm and the height of 0.15cm3D and the traditional finished artificial cushion block into a 96-well plate, arranging a material-free control group, implanting 1 × 104 MC3T3-E1 cells into each well for culturing, and taking days 1, 3, 7, 14 and 21 as observation points for detection and analysis by an MTS method; taking 3 holes from each group at each time point, completely sucking out the culture medium in the holes, cleaning the holes by using PBS (phosphate buffer solution), adding 100mL of cell complete culture medium and 20 mu L of MTS (methanol-to-sulfur) solution with the concentration of 1.90mg/mL into each hole, incubating the holes in a cell incubator for 3 hours, sucking out 100 mu L of the cell complete culture medium and the MTS solution into each hole, detecting the OD (optical density) value at the wavelength of 490nm by using an ultraviolet spectrophotometer, recording the result, and drawing a cell growth curve of each group;

s3, performing electron beam melting on the in vivo representation of the biological characteristics of the 3D printed titanium implant;

a3, establishing a goat femoral defect model and preparing a titanium metal cushion block with the diameter of 1cm multiplied by 1 cm/diameter of 3cm multiplied by 3 cm/diameter of 5cm multiplied by 5cm by adopting an electron beam melting 3D printing technology before material implantation, and performing irradiation sterilization and aseptic storage for later use;

selecting green goats weighing 20-25 kG; the animals are sent to the center of the animals in advance and are raised in cages for one week to adapt to the environment; after the experiment starts, the right lateral position of the goat is fixed on a laboratory table after the anterior muscle is successfully anesthetized by fast-asleep (0.15mL/kG), the hind limb is preserved, and the goat is sterilized and paved by 2.5 percent iodine tincture and 75 percent alcohol cotton balls; taking a longitudinal incision with the length of about 5cm at the lower end of the outer side of the femur, sequentially incising skin, subcutaneous tissue and fascia lata to expose the outer femoral condyle, and taking out defects with the diameter of 1cm multiplied by 1 cm/3 cm multiplied by 3 cm/5 cm multiplied by 5cm by adopting an electric drill; and placing each group of aseptically preserved materials into the defect site; wherein, the traditional finished product artificial cushion group is suitable for filling the defects as far as possible by using finished cushion blocks with various sizes; in the sham operation group, only incision and suture of skin and muscle are performed, and femoral condyle drilling and sample placement are not performed; then, normal saline is adopted to wash the wound, the wound is sutured layer by layer, and the wound is wrapped by sterile dressing without external fixation and free movement; 8 ten thousand units of penicillin is intramuscularly injected before, during and after 3 days, and the streptomycin is 0.5 g; high protein green feed is kept in captivity, and stitches are removed after 12 days of operation;

b3, detecting the defect filling and repairing in vivo;

b31, Micro-CT detection:

after 4, 8 and 12 weeks after operation, rapidly sleeping new sheep is adopted to anaesthetize the Qingshan sheep, CT detection is carried out, meanwhile, relevant software is used for analyzing indexes such as bone volume fraction (Bonevolume/Totalvolume, BV/TV), bone density (BoneMineralDensity, BMD) and the like, and three-dimensional reconstruction of defect parts is carried out to visually know the defect filling, bone ingrowth and defect repairing conditions;

b32, histomorphological observation:

the goats were sacrificed at weeks 4, 8 and 12 and the tissues containing the samples were removed to prepare sections; respectively carrying out H & E and MASSON trichrome dyeing, and observing defect filling, bone ingrowth and defect repair conditions under an optical microscope;

the H & E dyeing comprises the following specific steps: carrying out gradient dehydration on the slices again, adding the slices into a hematoxylin solution for dyeing for 5 minutes, washing the slices with running water, treating the slices with 1% hydrochloric acid ethanol for 3 seconds, washing the slices with water for bluing for 30 minutes, carrying out alcohol gradient dehydration, dyeing with eosin for 20 seconds, dehydrating with pure ethanol, enabling the slices to be transparent through xylene, and sealing with neutral gum;

the MASSON trichrome dyeing method comprises the following specific steps: performing chromatization on the slices, then dyeing for 10 minutes by using Weiger iron hematoxylin, differentiating by using an acidic ethanol differentiation solution, and turning blue by using a MASSON bluing solution; then, the fuchsin staining solution is adopted for staining for 10 minutes, then the solution is differentiated for 2 minutes by using phosphomolybdic acid solution, and then aniline blue staining solution is adopted for staining for 2 minutes; dehydrating 95% ethanol and anhydrous ethanol in sequence, making the slices transparent with xylene, and sealing with neutral gum;

s4, performing clinical research on the 3D printed titanium metal implant by electron beam melting;

a4, manufacturing an individualized porous metal cushion block by Electron Beam Melting (EBM)3D printing;

according to the preoperative planning result of a surgeon, preparing an electron beam melting 3D printing individualized porous metal cushion block by the method, and performing irradiation sterilization and sterile sealing for use in the operation;

b4, after the earlier-stage experiments are successful, the ethics committee approves, reports relevant procedures, establishes a traditional finished product artificial cushion block control group and carries out clinical implantation experiments;

screening of study subjects:

shooting a pelvis correction X-ray film before a patient operates, and performing Paprosky typing evaluation on the acetabulum lateral bone defect according to the conditions of the acetabulum rotation center upward movement degree of the X-ray film, ischial bone dissolution, tear drop bone dissolution, whether a Kohler line is damaged and the like;

and (3) inclusion standard: paprosky iib and above severe bone defect types;

exclusion criteria: (1) paprosky I and IIA type bone defects are small, and bone grafting is not needed generally; (2) those allergic to metal implants; (3) patients with other serious diseases or intolerance of systemic evaluation; (4) those with hip joint infection or active infection elsewhere in the body; (5) severe osteoporosis; (6) in addition to hip joint, the functional impairment caused by other joint (knee, ankle) diseases of lower limb affects the lower limb functional evaluators; (7) 6 months before screening, the patient has history of abuse of alcohol or drugs; (8) pregnant or lactating women, or women desiring to give birth;

c4, establishing digital pelvis three-dimensional model

A metal artifact removing technology is adopted before operation, and a thin layer with the thickness of 1mm is scanned on the pelvis of a patient by using 64 layers of spiral CT; the CT image file is stored in a DICOM format and is imported into an interactive medical image control system to reconstruct a digital three-dimensional model diagram of the pelvis of a patient;

d4, manufacturing a 1:1 half pelvis 3D model;

importing digital three-dimensional pelvis model data established by MIMICS software into industrial design software UG for further drawing and processing, and finally importing the digital three-dimensional pelvis model data into a main program of a 3D printer to manufacture a pelvis model with a size of 1:1 of the real person in a layer-by-layer printing mode by taking polylactic acid as a raw material;

e4, assessment of bone defects and planning of surgical protocols;

further evaluating the acetabulum bone defect conditions of the patient according to the three-dimensional reconstruction image obtained by MIMICS software and the 1:1 half pelvis 3D entity model, wherein the bone defect conditions comprise the bone defect amount, the appearance, the residual host bone amount and the like of the front wall, the rear wall, the inner wall, the acetabulum top and the like of the acetabulum; according to the bone defect condition, a three-dimensional model of the personalized cushion block is planned by using computer aided design, the appearance, the size and the optimal placement position of the cushion block, the fixed number and the direction of screws and the like are drawn on a reconstructed image, and meanwhile, the size and the installation position of the metal acetabular outer cup of the revision prosthesis are determined, and a three-dimensional effect graph is generated; after confirming satisfaction with the surgeon, the solid spacer model was created using an EBM3D printer based on computer-aided designed spacer patterns, and the surgeon performed the following procedures at 1:1, performing preoperative surgical operation simulation on a half-pelvis model, and evaluating the pre-filling effect of acetabular bone defects;

f4, placing the 3D printed inner plant into the revision surgery to reconstruct the bone defect;

approved by the ethics committee of hospitals, the patients are informed and signed with informed consent for surgery and implants; the operation is completed by the doctor in the subject group; the operation is performed by cutting and exposing an improved Harding access, the wound is thoroughly debrided in the operation, the loosened prosthesis is taken out, and the bone dissolution and bone defect around the acetabular cup are consistent with those shown by a preoperative 3D printed half pelvic model; after the acetabulum side is ground and rubbed, a 3D printing titanium metal cushion block is arranged at the acetabulum bone defect position according to a preoperative plan scheme, and a screw is arranged in the nail hole direction designed and manufactured preoperatively for fixation; placing a metal mortar cup, installing a polyethylene lining after firm press fit, and finally placing the biological femoral stem prosthesis and installing a ceramic ball head;

g4, postoperative clinical efficacy and biomechanical assessment:

firstly, establishing contrast with allograft structural bone grafting and a revision surgery using a finished product metal cushion block, and comparing the time, the amount of bleeding and the complications in the surgery;

follow-up visits were performed on patients 1, 3, 6, 9, 12 months after surgery to assess VAS pain scores, Harris functional scores;

shooting a pelvis X-ray plain film and a thin CT (computed tomography), and evaluating the position of an implant and the bone ingrowth condition;

fourthly, detecting the concentration of V, Al and other related metal ions in the blood of the patient and evaluating the biological toxicity of the prosthesis.

Images