Creating Bone Replacements

The researchers have used a computational technique called topological optimization to design a 3-D structure that can withstand the forces of chewing, facilitate speaking and swallowing. The work is focused on the centre of the face, home to the most complicated bony structures in the human head.

The research was led by Ohio State University researchers in collaboration with scientists from the University of Illinois. Eventually, the team plans to use tissue engineering techniques to grow bone around these lightweight structures and implant the new bone during facial reconstruction surgeries.

Current plastic surgery techniques involve using a patient’s own bones to piece together a relatively crude bone replacement during facial reconstruction. “The difference between what is done now and our design is that we take into account all of the loads on the structure. And this is not a generic shape. For each person, we could create a patient-specific design” said Alok Sutradhar, lead author of the paper.

The method puts a computer to work to design the smallest structure needed to accommodate specific spatial boundaries and mechanical loads. The technique combines mathematical equations with advanced 3-D imaging to produce a structure that takes into account both the space to be filled and space that must remain unoccupied to allow for such features as nasal passages and eyes.

“The purpose is to find the most optimized macrostructure to replace the missing bone. It would contain the minimum amount of tissue positioned in three-dimensional space and supported upon remaining uninjured portions of the facial skeleton,” Sutradhar explained.

With the technology developed to date, the researchers start with a sample MRI image of a damaged face to establish the outer boundaries of a rectangular space in which a replacement structure would be placed surgically. They specify spaces that must be left void, and then apply a number of mathematical equations that account for how strong the structure must be and how it should be shaped to support the skull and accommodate the loads of chewing and blunt pressure on the face. “The idea is not to recreate normal anatomy. It is to recreate functional support that is alive and permanent that we will be able to place prosthetics on,” Miller said.; Source: Ohio State University