Bionic bones strengthen future of orthopedic implants

Chinese researchers are designing bionic bones with improved biological compatibility and mechanical strength, which will bring new possibilities for future orthopedic implants.

Researchers from Northwestern Polytechnical University have spent more than 15 years developing artificial bones that are highly consistent with the composition, structure and mechanical properties of natural bones.

Bone defects are one of the most common conditions in orthopedics, and scientists have been exploring new methods to fabricate bone scaffolds to repair the defects.

Wang Yan'en from the university, which is based in Xi'an, Shaanxi province, said most bone implants are made of polymer and metals such as titanium. However, they lack biocompatibility and do not match human bones' mechanical strength, which can lead to abrasion and dislocation after they are implanted.

"If the implants cannot be well fused with natural bones, they may need secondary surgery," Wang said.

Wang's team used hydroxyapatite, a medical bioceramic material, to fabricate bone scaffolds. Wang said that though it is considered one of the most suitable materials for bone scaffold fabrication, bonding the powderlike material into a strong and robust scaffold remains difficult.

"Acidic binders used previously made the bone scaffold acidic, which adversely affected the environment for the growth of bone cells and brought agony to the patient after implantation," Wang said.

The team experimented with hundreds of different solutions to create a binder that would not only result in a strong and robust scaffold but also adapt to the biological environment. The research was published in the journal Polymer.

After researching the material, Wang's team also explored how to use 3D printing technology to make customized bone scaffolds. They cooperated with companies in developing 3D bionic bone printing machines.

Natural bones have complex internal structures, which require the printing system to boast special mechanical technology.

"With ultrafine droplet-spraying technology, the printing equipment can precisely regulate the proportion of printing materials, including the powder, the binder, the cell culture liquid and protein original fluid," Wang said.

The research team cooperated with the Air Force Medical University, which is also in the city of Xi'an, to conduct animal tests. After 3D-printed bionic bones were implanted in rabbits, they developed well in their bodies, with the bionic bones well-integrated with the natural bones.

Wang's team is also working on the 3D printing of skin, including sweat glands and hair follicles. "These technologies, with the potential for clinical application, may bring hope to patients with bone defects and skin damage," Wang said.