Implantes biodegradáveis em ferro poroso obtidos por fabrico aditivo

Musculoskeletal disorders, injuries due to diseases such as osteoporosis or due to accidents, affect millions of patients all over the world. To treat the damaged tissues, a fixationprocedure is required, where the insertion of a fixation device, permanent or temporary, is necessary. After bone healing or tissue regeneration, the so-called temporary devices thatare applied in low-weight bearing circumstances, lose their function and remain in the body as strange objects. Due to a large number of factors that affect the well-being of patientssuch as pain, discomfort, prominent devices, infections, implant removal surgery is often recommended. This type of removal surgeries is frequent in orthopaedic departments and isresponsible for high societal costs. Biodegradable devices have the potential to become successful candidates for temporary medical implant devices, as they are able to degrade inthe human body upon tissue healing, reducing the costs of additional removal surgery. Although bioabsorbable polymeric materials are common in the market and are used inclinical practice, they are limited due to the intrinsic polymer properties of low mechanical strength. Recently, metals such as iron (Fe), magnesium (Mg) and zinc (Zn) have beenstudied in medical applications due to their biodegradable properties. Magnesium and its alloys have compatible mechanical properties with the human bone, however, theirdegradation is faster than the host tissue and it is often related to hydrogen release that interferes with the healing process. Zinc and its alloys have an adequate corrosion rate,however, their mechanical properties and high density are not appropriate. Iron, in turn, has higher stiffness when compared with the human bone and a low degradation rate.However, iron is the best option, because it is essential for blood cells, as haemoglobin and myoglobin, to transport oxygen and in the redox reactions of cytochromes. In order toovercome some of the iron limitations, a great effort must be performed to adequate its properties to bone substitutes. Recently the scientific community started to give the firststeps in the use of porous iron scaffolds formed by simple unit cells. Preliminary results seem promising in decreasing the elastic modulus, accelerating the biodegradation rate andoffering good support for bone cell proliferation. Still, the mechanical properties and degradation rate can be improved with the appropriate design of the iron scaffolds. The strategyof this project relies on a new concept of porous iron scaffolds based on graded lattice structures with different unit cells that have never been attempted before for temporaryfixation devices, which degrade at the same rate as the bone or tissue, heal. To accomplish the challenge of producing such complex structures, an advanced method of additivemanufacturing (AM), such as sintered laser melting (SLM) will be used. This new line of research will evaluate the effect of the design of the iron scaffold, produced by additivemanufacturing, in the resulting properties, to obtain the suitable characteristics for temporary bone implants. Prototypes will be developed and submitted to cytocompatibility andmicrobiology assays. The combination of biodegradable iron and additive manufacturing (AM) leads to a revolutionary change of metal implants in many aspects including materials,design, manufacturing, and clinical applications. To accomplish this purpose, a multidisciplinary team of academic researchers from IDMEC, INEGI, CeFEMA, IPS andFMUP/CINTESIS, combining experts from materials, mechanical engineering and microbiology will work in straight collaboration with industrial consultants (BioCeramed) and clinicalconsultants (orthopaedists). The three-way collaboration university-industry-clinicians will be crucial to generate high quality innovative results with scientific impact. The definitionof new research routes with economic viability may have repercussions on technology transfer and, in long term, in the wellness and healthy ageing of the populations.