Spine prosthesis optimization using MOPSO method an‎d finite element analysis

9/22/2026 12:00:00 AM

In this thesis, the extent of the impact of materials used in lumbar spine prostheses is investigated to enhance the implantʹs lifespan an‎d reduce Von Mises stress in the vertebral bones of the spine, the implant endplates, an‎d its core. For this purpose, the ProDisc-L was utilized due to its success an‎d patient satisfaction. Since the type of material an‎d its properties have a direct correlation with Von Mises stress, a wide range of materials was eva‎luated. For example, for the implant endplates, materials such as carbon fiber-reinforced polyetheretherketone, titanium, stainless steel, cobalt-chrome, an‎d tantalum were considered, while for the core, 12 different formulations of ultra-high molecular weight polyethylene were employed. In the next step, due to the computational intensity, Design of Experiments (DOE) was used to derive equations for Von Mises stress in the bone, endplate, an‎d core for four motion states: flexion, extension, torsion, an‎d bending. Each equation served as an optimization objective, utilizing the multi-objective particle swarm optimization method for this researchʹs optimization. The results from the optimization process yielded the top ten responses, specified as the elastic modulus for the endplates an‎d the elastic modulus for the core. Among these, the top five responses were selec‎ted as the final optimization outcomes an‎d further examined using finite element software to identify the optimal response. The results were compared with those from the manufacturerʹs model, an‎d ultimately, titanium for the endplates an‎d GUR-1020 AO for the core were selec‎ted as the optimal materials for the implant. This material combination optimized Von Mises stress by up to 17.55% in the bone region, up to 10.77% in the endplates, an‎d up to 27.13% in the core. This research, employing commonly used materials in biomechanics an‎d optimization tools, determined the best material combination for the implant to minimize Von Mises stress an‎d maximize the implantʹs lifespan.

تحليل بيومكانيكي , ديسك بين مهره اي مصنوعي , بهينه سازي , ستون فقرات كمري , مهندسي مواد , شبيه سازي المان محدود , تنش ون مايزس

Biomechanical analysis , Artificial intervertebral disk , Optimization , Lumbar spine , Material engineering , Finite element simulation , von Mises stress

Amirali Kashani

Siavash Kazemirad