By: 21 March 2018
Human bones are incredibly resilient, but when things go wrong, replacing them can be a painful process

OPN speaks to Hossein Montazerian, a research assistant at University of British Columbia Okanagan’s School of Engineering. Hossein has identified a new way to model and create artificial bone grafts that can be custom printed


OPN: Tell us a little about your background and education in the orthopaedic industry?


HM: I am currently a second-year Master student studying mechanical engineering at The University of British Columbia. My work in the area of biomedical engineering goes back to my undergraduate research when I found a big gap between medical doctors and engineers. Since then, I have tried to keep in touch with the medical community by taking internships in the implant and medical instrument manufacturing centres. It has provided me with a great opportunity to observe this gap first-hand by being present in the operating rooms as an engineer and closely identifying the challenges that orthopaedic surgeons are faced with during surgery.


OPN: Could you explain more about your work in the area of artificial bone grafts and custom printing?

HM: Natural bone is intrinsically a smart porous material. The reason I am saying “smart” is that the internal pores dynamically align themselves based on the daily activities of individuals, in a way that the bone’s mechanical integrity under the repeating loads is always kept optimal. It is also porous to let cells grow and keep their biological activities in a biocompatible environment. Mimicking such a complex and crucial material is a big challenge for scientists and almost infeasible by the conventional fabrication methods.

My work is motivated by the emerging 3D printing techniques as they are capable of producing structures as complex as porous bone. Mostly, my research answers the question of what porosity and pore shape patterns would best resemble the natural bone and let the cells feel safe in their 3D printed homes. Cells feel the mechanical loads, which are transferred through bone structure and grow according to the rigidity of their substrate. I have put a primary effort into understanding how different pore designs affect the bone replacement design parameters and subsequently satisfying requirements of a biologically and mechanically similar-to-bone replacement practice. After analysis of a big library of naturally-inspired porosity patterns, and according to their characteristics, I came up with a new way to locally design artificial porous bone replacements with best correspondence to porosity variations in specific patient’s bones.


OPN: Was does this mean for the surgical process?


HM: First of all, using the proposed technology, the surgeons would not need to deal with the current standardised implants anymore. Not all of the size-standardised implants will fit into the patient’s bodies. Besides, the medical doctors sometimes need to harvest surrounding bone or tissues to be able to implant a new artificial replacement. In some cases, the surgeon has no other option but to fill the lost bone volume by the bone taken from patient, this often requires a pre-surgery to harvest that needed bone – this means introducing extra damages to the natural tissues.

The 3D printing allows the doctors to design the final structure of the bone replacement specific to each patient, based on 3D images taken from the damaged tissue with minimal damage to the natural tissues or repeated surgeries.


OPN: And for the patient and their recovery?


HM: Patients who have tumour in their bones or those who are suffering from severe bone fractures and osteoporosis, will undergo less recovery time as the bone healing process is facilitated using the new technique. A porous bone replacement can provide them with a better integrity between their artificial bone and surrounding tissues, while the mismatch between the currently used metallic implants and the natural bone requires long-term secondary surgeries because of issues such as implant loosening. Such secondary surgeries may not only cause a high risk of infection, but are by far more painful and need more difficult surgical processes. The patient-specific nature of the new approach can also bring advantages from aesthetical point of views.


OPN: What is the next stage for your development?


HM: I am about to develop a 3D printing-based fabrication process that will adapt our bone replacement material properties closer to the bone structure. The interface between bone and cartilage is not simply a sharp material change; but it is basically a slight transition in the material properties that make gradual changes from bone to cartilage, and so the main subject of our current research is to introduce the same material transition as in the porous artificial implants.


OPN: What could your research mean for the future of orthopaedics?


HM: The future direction in the field of bone replacement development in my opinion is to grow the cells into the porous bone replacements before implanting them into the human body. The new-fangled bio-printing techniques are rapidly emerging by which the bone replacement material can be printed along with the cells at the same time. Hence, a significant amount of research is currently being conducted to extend and apply 3D printing methods for printing artificial living soft organs such as cartilage.