الفهرس 
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Abstract
Objectives: In the current investigation, magnesium- based alloys were fabricated and assessed in an attempt to establish a novel biodegradable biomedical alloy for orthopedic applications. Methods: Nine experimental alloys were fabricated. They made up of magnesium (Mg) as the balanced element; to which, zinc (Zn) and calcium (Ca) were added. Zn was added in 1, 4, and 6 wt. % while Ca was added in 0.3, 0.6 and 1 wt. % to form nine alloys (I to IX). The composition, microstructure and mechanical properties of the alloys were characterized using X–ray fluorescence (XRF), X-ray diffractometer (XRD), optical microscopy and tensile strength test. Electrochemical corrosion behavior and biomechanical integrity were also evaluated. Based on the results of the in-vitro study, Type I (Mg1Zn0.3Ca) and Type VII (Mg6Zn0.3Ca) were selected for continuing the in-vivo study. A total of eight cylindrical rods with 15 ± 0.4 mm length and 4 ± 0.2 mm diameter were machined from each selected alloy and implanted surgically in the femur bone of the mongrel dogs. Assessment was performed periodically throughout the predetermined study period (12 weeks) via follow up analysis of blood biochemistry and pre and post-operative radiography. Finally, histopathological examinations and spectroscopic quantitative and qualitative analysis of the newly formed bone were performed. Results: For all the investigated alloys, corrosion rate values were increased with increasing amount of Zn and Ca up to 6 and 1 wt. %, respectively. The highest ultimate tensile strength value was recorded when wt. % Ca was the least (0.3). During in vivo study, biochemical blood analysis for implanted Mg-alloys revealed overall stabilization in electrolytes (Mg, Zn and Ca). Adding to that, kidney and liver function parameters were fallen within the normal range. The histopathological observation at the end of the experimental periods showed discrete islands of a newly formed bone around Type I Mg-alloy. Meanwhile, Type VII Mg-alloy showed well-developed trabecular pattern of the newly formed bone. Qualitative and quantitative analysis of the newly formed bone around both implanted types of Mg alloys revealed that a significant increase in the amount of PO4 mineral at first and second time intervals exceeding that of normal bone. Conclusions: Evidently, the fabricated Mg6Zn0.3Ca alloy is a novel biodegradable platform apt for biomedical orthopedic application.