3D printing technology is also called "rapid prototyping technology" or "additive manufacturing technology". It is a technology based on digital model files, using bondable materials such as powdered metal or plastic, to construct objects by layer-by-layer printing. Since its appearance in the mid-1990s, 3D printing has been widely used in the manufacture of models in the fields of mold manufacturing and industrial design, and has been gradually used in direct manufacturing of products.
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In recent years, the development of 3D printing technology has made great contributions in the medical field. For example, making medical models, props, prosthetics, surgical guides, bones, cartilage, or supports or substitutes for blood vessels, biliary tract, trachea, urethra, and various tissues and organs. So, what is the principle of 3D printing to realize the art of Bian Que? What is the significance of its existence to the medical industry? What are the problems facing its development?
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Academician Dai Kerong (hereinafter referred to as "Academician Dai"), academician of the Chinese Academy of Engineering and tenured professor of the Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, gave a more detailed answer to the above questions.

Using 3D printing to solve a century-old problem in the medical field - "individualized needs"
"3D printing is a means. Through 3D printing technology, a variety of unique products can be created. The fundamental reason for promoting the close connection between medicine and 3D printing is the huge problem that medicine has faced since ancient times. Demand - 'individualization'." When Academician Dai talked about 3D printing, he started talking, and the rest of his life was inextricably linked with 3D printing.
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According to Academician Dai's recollection, 37 years ago, he came into contact with a tumor patient who needed a total talus resection. At that time, there was no prosthesis to replace the talus in the world, and the attending physician team could only customize an artificial talus for the patient. This is also the first time that Academician Dai has come into contact with the case of "personalized" customization of foot bones.

“The talus is the most important piece among the dozen or so bones located in the ankle. This artificial talus also has the upper, lower and front articular surfaces, and it also needs to have sufficient bearing capacity and stability. The size and shape of the talus are unique to everyone. Different." Through multiple data calculations and revisions, the team finally succeeded in replacing the resected talus with a custom-made artificial talus. Today, the patient can still move freely without limping, can ride a bicycle, and even Light physical labor.
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The successful completion of the "personalized" customized case for the first time gave Academician Dai great encouragement. After 1982, Academician Dai led a team to custom-made knee joints, hip joints, shoulder joints, and even half a pelvis for some patients.

As time progressed to the 1990s, artificial customization to meet the "individualized" needs of patients gradually became the norm. At this time, Academician Dai encountered a difficult case.
 

A chief accountant was born with congenital abnormality of both hip joints since childhood, and serious dislocation of both hip joints caused severe pain on both sides, which seriously affected work and life. Finally, he could only travel by wheelchair. Academician Dai recalled that the anatomical structure and geometric shape of the patient's hip were very different from those of the normal people, and were accompanied by serious secondary lesions. All medical device companies were unable to provide joint prostheses that met the requirements, which made him feel helpless for the first time.
 
When it was difficult to advance or retreat, Professor Wang Chengtao of Shanghai Jiaotong University brought Academician Dai good news. "Professor Wang Chengtao told us for the first time that there was a device in the world called 'rapid prototype', which can easily 'copy' the size, position and correlation of the patient's joints and bone cavity accurately with a model." 

At that time, Academician Dai felt that the "rapid prototyping machine" was simply a product tailored for this difficult case! In order to find out, the attending team installed the customized joint prosthesis on the artificial limb model through the rapid prototyping machine for repeated practice, and then arranged the operation for the patient after confirming that there was no error. Finally, with the help of the model, the patient obtained a truly customized prosthesis.
 
After the successful operation, the patient who was unable to walk at that time not only resumed his job as chief accountant, but also visited Tiananmen Square and climbed the Great Wall in person. Now he has become a tourist enthusiast traveling around the world.
 
After this matter, 3D printing personalized customization has gradually developed into an indispensable medical technology for the Dai Kerong team. At the same time, Academician Dai, who has handled hundreds of cases, deeply realized that in the medical industry, "personalized" demand is a development direction with a huge market.

In his words: "There are only 5-7 sizes of each part of the bone plate for fixing fractures and artificial prosthesis for different joints. These only sizes will meet the needs of hundreds of thousands of people or even millions of people every year, resulting in many cases are just about to be used. Therefore, meeting personalized needs will become an important direction of efforts to improve medical quality."
 
Looking back on the entire medical development path, the "personalized" demand has always been one of the biggest problems in the industry. The progress and promotion of 3D printing technology is tantamount to opening a door full of imagination and hope for personalized medical treatment. Today, Academician Dai often sighs: "3D printing is really amazing, it deeply attracts us, because many doctors' dreams can be realized by it. If most of the things put into patients can be customized, what is it?"

 
In 2003, the cooperative company of Shanghai Jiuyuan won the first production license of customized artificial joint in China. In 2013, Academician Dai and the engineering professor of Shanghai Jiaotong University jointly established the clinical transformation research and development center of 3D printing technology of Shanghai Jiuyuan Hospital; In 2015, the collaborative innovation center for clinical transformation of 3D printing technology in Shanghai Jiaotong University Medical College was established; It was upgraded to Shanghai Jiaotong University Medical 3D Printing Technology Innovation Research Center in 2016, and was supported by three national key research and development projects during the "13th Five-Year Plan".
 
"In the whole development process, the orthopedics, stomatology, ophthalmology, orthopedics, otolaryngology and even neurology departments of the Ninth Academy of Sciences have all been inextricably bound up with 3D printing. 3D printing is a manufacturing technology, but looking at the depth, the core guarantee of its medical application should be 'combination of medicine and industry' or 'combination of medicine and industry and industry'." Academician Dai, who has applied 3D printing to medicine for more than 20 years, said his heart.
 
Academician Dai further explained that "medical and industrial integration" is the only way to promote 3D printing in the medical industry. If doctors don't understand 3D printing technology, how can rapid prototyping come from? And if engineers master 3D printing technology, but do not know what role it can play in medical treatment and how to play its role, how to "personalize" customization?

 

 

▲ Academician Dai Qirong studied and made shape memory medical products in his early years
 
As we all know, 3D printing technology was mainly used in mold manufacturing, industrial design and other processes in the manufacturing industry at the beginning of its birth. At that time, this technology was regarded as "a turning point that could reverse the decline of the US manufacturing industry". Former US President Barack Obama also said in his State of the Union address that "3D printing may revolutionize the way we manufacture almost all products".
 
Academician Dai was also deeply impressed by this, "From ancient times to the present, all the manufacturing and processing we do belong to 'reduced material manufacturing' or 'added material manufacturing'. A large piece of wood is cut with an axe, carved with a knife, and finally produced a product we need, wasting a lot of materials. To make a metal bowl, we need to use a lathe, milling machine, and grinder to cut a bowl on a three-dimensional metal block, which may only account for about 20% of the whole material, which causes a lot of material waves A lot of extra processing. "
 
3D printing technology is relatively faster, simpler and more environmentally friendly. For 3D printing, only the first layer of material powder needs to be paved on a platform with nothing, and then the second, third and fourth layers of material powder are paved and bonded layer by layer after being fixed by heating or adhesive. After all the materials are completed, the surplus material powder will be collected for secondary use. More than 90% of the material powder used may be utilized.
 
Therefore, the innovative application of 3D printing in the medical field and manufacturing industry is considered a revolutionary subversion. Many supporters of 3D printing believe that "3D printing is a subversion of the old processing technology and an unprecedented revolution in the manufacturing industry. Its emergence can be compared with steam engines and the Internet." 

 
Corresponding to the rapid development of 3D printing technology, China is facing the embarrassing situation of massive import of 3D printing equipment and materials and low conversion rate of scientific and technological achievements.
 
"No matter how high-end this technology is, if it is to truly become an outstanding scientific and technological achievement in everyone's mind, it must be implemented. Only by achieving clinical transformation can science reflect the greatness of science, and using science for the benefit of the people is our ultimate goal." Academician Dai said that clinical transformation has always been the core theme of the development of 3D printing, and is also the direction that the country is currently actively promoting.
 
Academician Dai regretted and worried about the high proportion of imported 3D printing equipment and materials. Although there are many domestic 3D printers in China, they are often used to produce medical devices directly into the body. It is gratifying that the application rate of domestic equipment and materials is rising.
 
"Now the country attaches great importance to the development of 3D printing, and has invested a lot of attention and financial resources in the industry. We hope that China's 3D printing industry can be at the forefront of the world. We should" open the green light "for new technologies, new equipment and new products, but this" green light "must be scientific and serious, because the products are used for patients." Academician Dai said that any reform and innovation of science and technology should go to the end, It is the only way to 'turn on the green light' to encourage the healthy and rapid development of the domestic 3D printing industry.
 
It is reported that in the field of biomedicine, 3D printing has now developed to 4D and 5D printing. 5D printing adds two variables of time and tissue formation. After printing, active cells gradually form a piece of skin, a section of trachea or an organ. Academician Dai believes that bioprinting is the most possible way to solve the problem of tissue and organ sources in the development of regenerative medicine, and the prospect of its application in regenerative medicine is very attractive.
 
Dai Qirong is a tenured professor of the Ninth People's Hospital affiliated to the School of Medicine of Shanghai Jiaotong University, an academician of the CAE Member, and a foreign communication academician of the French National Academy of Medical Sciences. At present, he serves as the director of the Medical 3D Printing Innovation Research Center of Shanghai Jiaotong University and the director of the stem cell and regenerative medicine transformation base of the Institute of Translational Medicine of Shanghai Jiaotong University.
 
He has successively served as the President of the Chinese Orthopaedic Society, the President of the Asia-Pacific Association of Artificial Joints, the Vice President of the World Multidisciplinary Biomaterials Society, and the Director of the World Internal Fixation (AO) Foundation. He has been elected as a communication member of the American Orthopaedic Society and an official member of the International Hip Association. Academician Dai Qirong has developed new orthopedic implants and new technologies through cross-cooperation between medicine and engineering, biology and materials science, and actively promoted basic research and clinical technology such as 3D printing in medical applications, artificial joints and bone regeneration.
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