Over the years, the advancement of orthopedic medical technology has been inseparable from the role of internal fixation devices. In the past, patients with fractures often had to lie in bed for a long time, relying on plaster casts or traction to stabilize the local bones and allow them to heal slowly. After the 1980s, internal fixation metal devices gradually entered clinical use, helping patients reconstruct bone structures and significantly shortening the recovery period. However, limited by traditional technology, only some regular-shaped internal fixation metal devices, either round or square, could be produced. Taking the atlas and axis, the most complex structures in the human spine, as an example, their shapes are irregular, and traditional implants are clearly unable to adapt to the complex structure of human bones.

Over the years, advancements in orthopedic medical technology owe a significant debt to the role of internal fixation devices. In the past, patients with fractures often had to remain in bed for extended periods, relying on casts or traction to stabilize the affected bones and allow for gradual healing. After the 1980s, internal fixation metal devices gradually entered clinical use, aiding in bone structure reconstruction and significantly shortening recovery times. However, limited by traditional manufacturing processes, only regular shapes such as round or square internal fixation metal devices could be produced. Taking the atlas and axis, the most complex structures in the human spine, as an example, their unusual shapes meant that traditional implants were clearly unsuitable for the complex structures of human bones.

Using 3D printing technology to print "bones" surprised even engineering experts who control 3D printing. After all, this involved printing an implant that resembled a bone, with no prior experience to draw upon.

The first implant Liu Zhongjun wanted to develop was an artificial axis, but he encountered problems from the outset. Doctors and engineers were not speaking the same language. Medical terminology and anatomical terms were incomprehensible to engineers; computer and engineering jargon was equally difficult for doctors to understand.

The small artificial axis has a very complex and unique bone anatomical structure. No matter how Liu Zhongjun drew or explained, it was difficult for the engineering experts in charge of 3D printing to understand its external shape and internal structure. After several rounds of communication, Liu Zhongjun had a sudden inspiration. He used modeling clay to create a model of an axis vertebra and gave it to the technicians, saying, "Just make it like this." This clumsy method proved surprisingly effective. The technicians produced a sample accordingly, and after repeated modifications, a standard 3D-printed axis was finally created.

Following this minor incident, cooperation between the two parties became more harmonious. Soon, Liu Zhongjun's team and the 3D printing engineers formed a research group, holding monthly meetings to discuss the progress and planning of 3D printing technology.

The artificial axis became the research team's first "customized" 3D-printed implant. With the 3D-printed artificial axis, after a doctor removes a tumor from a patient, they can use advanced and reliable technology to repair the structure of the cervical spine.