Khaled M. Hijazi

Affiliations: School of Biomedical Engineering, Bone and Joint Institute
Thesis Title: Porous Titanium Alloy Constructs for Mandibular Reconstruction
Advisor: Dr. Amin S. Rizkalla

Affiliations: Division of Engineering
Thesis Title: Effect of Creep Loading on the Nanostructure of Tendons
Advisor: Dr. Samuel P. Veres

Affiliations: School of Applied Medical Science
Graduation Project: Prosthetic Foot for Inclined Surfaces: Structural Design and Kinematic Study
Advisor: Dr. Nasim Al Numan

Study title: Porous Titanium Alloy Constructs for Mandibular Reconstruction
Description: Finite element analysis (FEA) was employed to simulate the mechanical behavior of LPBF-built porous titanium alloy constructs, which mimic bone properties. These constructs were evaluated using mechanical tests, computed tomography, and scanning electron microscopy, with findings integrated into the FEA models to account for internal defects and surface roughness. The FEA methodologies were then utilized to design patient-specific intraosseous mandibular implants, assessed under physiological loads.
Main Results: Successfully validated the implant designs through rigorous testing, significantly improving the design process for patient-specific implants. Produced numerical models for building novel implant designs that are accurate by 90% to real-life SLM-built constructs. These models were notable for their ability to simulate real-world mechanical behaviour on standard computing resources efficiently.

• Led new product design by coordinating with cross-functional teams of surgeons and engineers, researching customer needs, reviewing relevant literature and patents, and selecting appropriate materials to meet design requirements.
• Leveraged additive manufacturing and 3D CAD for designing over 100 porous titanium constructs and conducted preliminary evaluation through CT scans and mechanical tests to ensure bone biocompatibility.
• Enhanced product development and quality control inspection of product procedures by developing FEA computational models of porous 3D-printed constructs, achieving over 90% accuracy and reducing analysis time by 80%.
• Applied design for manufacturability principles to create a customized mandibular implant with optimized inspection and a 60-year lifespan, using static and dynamic FEA modeling techniques.
• Streamlined data analysis with MATLAB and macro scripting, enhancing efficiency by 40%.
• Presented research findings and technical documents in the medical device industry via group discussions, conferences, and reports, demonstrating efficient knowledge translation and presentation skills. 

Study title: Effect of Creep Loading on the Nanostructure of Tendons
Description: Explored the effects of sustained creep loading on tendons’ fibrils and collagen at overload and suboverload loading levels using SEM and DSC. This research combined detailed microstructural analysis and biomechanical assessments to understand tendon behavior under prolonged stress. Loading on tendons was applied using a customized mechanical testing rig controlled using LabVIEW code.
Main Results: Revealed that tensile failures are primarily due to fibril rupture rather than slippage, challenging prevailing theories and informing better rehabilitation strategies. Provided evidence of heavy damage forming due to sustained creep loading, when compared static ramp loading to beyond the yield. This insight has significant implications for the design of rehabilitation protocols and preventive measures in sports medicine.

• Assembled an electromechanical testing rig using SolidWorks 3D CAD, and controlled it using LabVIEW-scripted code to automatically perform static creep loading on more than 50 tendon specimens for up to 6 hours.
• Utilized scanning electron microscopy and differential scanning calorimetry to analyze tendon samples, assessing collagen damage due to prolonged loading and contributing to significant findings in tendon microstructural damage due to sustained loading.
• Performed sample size determination (power analysis) and analyzed biomechanical and differential scanning calorimetry data using JMP statistics analysis software, confirming trends in tendon research and supporting the publication of significant findings.
• Collaborated with cross-functional research teams and presented findings at international conferences, contributing to the advancement of knowledge in tendon biomechanics 

• KM Hijazi, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, AS Rizkalla, 2023. 3D-Printed Porous Titanium Alloy Constructs for Mandibular Reconstruction, Canadian Biomaterials Society Annual Meeting, Halifax, NS, Canada
• KM Hijazi, YK Hosein, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, AS Rizkalla, 2019. Finite Element Analysis of Porous Titanium Alloy Constructs Matching the Mechanical Properties of Mandibular Bone: A Pilot Study, Joint Congress of The Canadian Society for Mechanical Engineering and the CFD Society of Canada, London, ON, Canada 

Poster Presentations

• KM Hijazi, YK Hosein, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, A Rizkalla, 2021. Optimizing Design of Porous Ti6Al4V Constructs for Mandibular Reconstruction, 99th General Session of the International Association of Dental Research General Session, Virtual
• KM Hijazi, YK Hosein, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, AS Rizkalla, 2021. Porous Titanium Alloy Constructs for Mandibular Reconstruction, London Health Research Day, Virtual
• KM Hijazi, YK Hosein, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, AS Rizkalla, 2020. Optimizing Porous Titanium Constructs for Mandibular Reconstruction, Canadian Bone and Joint
  Conference, Virtual
• KM Hijazi, YK Hosein, H Mao, DW Holdsworth, SJ Dixon, JE Armstrong, AS Rizkalla, 2019. Finite Element Analysis of Porous Titanium Alloy Constructs for Implementation in Intraosseous Mandibular Implants: Pilot Study, London Health Research Day, London, ON, Canada
• KM Hijazi, SP Veres, 2018. Effects of Stress Level and Loading Duration on Mechanical Damage to Tendon Collagen, Canadian Biomechanics Society, Halifax, NS, Canada 
• KM Hijazi, YK Hosein, J Armstrong, H Mao, TG Ivanov, DW Holdsworth, AS Rizkalla, 2018. Development of Porous Titanium Constructs that Mimic the Mechanical Properties of Native Bone, Canadian Bone and Joint Conference, London, ON, Canada
• KM Hijazi, KK Murdymootoo, KL Singfield, SP Veres, 2017. Low Strain-Rate Overextension Injury Causes Massive Nano-Scale Disruption to Tendon Collagen, Orthopaedic Research Society’s Annual Meeting, San Diego, CA, USA
• KM Hijazi, KL Singfield, SP Veres, 2016. Creep Loading of Tendons Causes Extensive and Severe Fibril and Molecular-Level Damage, Biomedical Engineering Society’s Annual Meeting, Minneapolis, MN, USA