EXPERIMENTAL AND COMPUTATIONAL INVESTIGATIONS ON MAGNESIUM-BASED COMPOSITES FOR BIODEGRADABLE INTERNAL FRACTURE FIXATION

Abstract

The field of biomaterials has experienced a surge in demand driven by factors such as an aging population, increased life expectancy, higher incidence of road accidents, growing expectations for improved quality of life, rising sports-related injuries, and the prevalence of conditions like osteoarthritis and osteoporosis. These trends have led to a greater need for advanced materials that can meet the diverse challenges of the healthcare industry, with growing emphasis on the development of resorbable metals to treat the long bone fractures by stabilizing the broken bone, promoting healing, and restoring their normal function. Among the promising candidates, magnesium-based alloys have gained considerable attention due to their biocompatibility, mechanical properties, and ability to degrade in the physiological environment. However, the inherent limitations of magnesium alloys, such as rapid corrosion rates and insufficient mechanical strength, have prompted extensive research to fully harness their potential for use in resorbable fixation devices. Thus, the current thesis work focuses on addressing these challenges through different comprehensive studies, with the aim of developing innovative strategies to enhance the mechanical strength, corrosion resistance, biocompatibility, and degradation behaviour of magnesium-based materials. In the initial phase of the study, manganese and zinc metals were introduced as alloying elements, alongside Ca10(PO4)6(OH)2 (Hydroxyapatite, HAp) as a reinforcing phase. The HAp powder was chosen because of its chemical and crystallographic similarity with the inorganic component of the bone matrix. The HAp powder was synthesised using wet precipitation method. The Mg-2Mn-1.5Zn (MZ21) and Mg-2Mn-1.5Zn/1HAp (MZ21/HAp) metal matrix nanocomposites were fabricated and their mechanical, microstructural, corrosion, biocompatibility behaviour was comprehensively investigated. Tensile yield and ultimate strengths of the MZ21 (60.31±0.24 MPa, 142.83±18.40 MPa) and MZ21/HAp (73.41±2.24 MPa, 139.65±16.16 MPa) showed around two-fold increase compared to pure Mg (30.36±2.66 MPa, 73±5.74 MPa). In-vitro studies indicated > 65% cell viability for MZ21 and MZ21/HAp, and significant reduction in hemolysis rates with respect to pure Mg.