Optimization of the surface thickness an‎d geometric topology of porous hip stems

9/22/2026 12:00:00 AM

In recent years, the rising rate of hip joint replacement surgeries an‎d the growing need to enhance the performance of orthopedic implants have highlighted the importance of innovative designs with high mechanical an‎d biological compatibility. One of the major challenges associated with conventional implants is the occurrence of phenomena such as stress shielding an‎d interfacial contact stresses at the implant–bone interface, which can lead to mechanical failures an‎d a reduction in the service life of the prosthesis. In this study, with the aim of improving the mechanical performance of hip implants, the effects of surface coating thickness an‎d porous topology with three-dimensional triply periodic minimal surface (TPMS) geometry of the gyroid type in the proximal region of the implant were investigated an‎d optimized. For this purpose, models with coating thicknesses of 0.5, 0.75, 1.0, 1.25, an‎d 1.5 mm, as well as porosity levels of 40%, 60%, an‎d 80%, were designed. Finite element analyses were carried out to eva‎luate criteria such as contact stress at the bone–prosthesis interface, stress shielding, an‎d relative deformation. Subsequently, to determine the optimal combination of design parameters, a multi-objective particle swarm optimization (MOPSO) algorithm was employed. The results of the analyses an‎d optimization revealed that the model with a coating thickness of 0.3 mm an‎d 85% porosity (C03P85 model) exhibited superior performance compared to other configurations. This model effectively reduced stress shielding, maintained contact stress within the physiological range, an‎d achieved an appropriate match between the stiffness of the prosthesis an‎d the host bone. Consequently, it can prevent bone resorption an‎d premature loosening. Overall, the findings of this research demonstrate that optimized porous coatings, designed using advanced geometries an‎d numerical methods, can significantly improve initial fixation, enhance long-term stability, an‎d increase the biocompatibility of hip implants. Furthermore, this study provides a practical framework for the design of patient-specific implants, in which the geometric an‎d mechanical properties of the coating can be tailored to meet individual clinical needs.

مفصل ران , ايمپلنت متخلخل , سپر تنشي , تنش تماسي , ساخت افزايشي , بهينه‌سازي چندهدفه , TPMS , تحليل المان محدود , ساختار ژيروئيد

Porous prosthesis , Additive manufacturing , Multi-objective optimization , TPMS , Finite Element Analysis , Gyroid structure , Stress shielding , Contact stress

Reza Piri Hossein Abadi

Dr. Mansour Alizadeh