Fixation plates are used to accelerate the biological healing process in the damaged area by providing mechanical stabilization for fractured bones. However, they may cause mechanical and biological complications such as aseptic loosening, stress shielding effect and necrosis during the treatment process. The aim of this study, therefore, was to reduce mechanical and biological complications observed in conventional plate models. For this purpose, an optimum plate geometry was obtained using the finite element based topology optimization approach. An optimum and functionally graded porous model were obtained for the plates used for transverse fractures of diaphysis in long bones. This model was combined with a functional graded porous cage structure, and thus a new generation porous implant model was proposed for fixation plates. In order to determine the performance of the optimum plate model, it was produced by additive manufacturing. Three models; i.e. conventional, optimum and porous fixation plates were statically tested, and they were compared experimentally and numerically using the finite element analysis (FEA). The porous model can be considered as the most suitable option since it requires less invasive inputs, and might lead minimum necrosis formation due to having lesser contact surface with the bone.

Akkal O, et al. J Adv Prosthodont. 2023 Aug;15(4):179-188. https://doi.org/10.4047/jap.2023.15.4.179

Conventional fixation plates permanently attached to the body can lead to complications, such as stress shielding and aseptic loosening, due to their contact with the bone, resulting in bone loss. The contact between these solid fixation plates and the bone surface inhibits blood flow, potentially leading to necrosis at the interface. To overcome this challenge, a porous implant featuring a gyroid lattice structure for humerus bone fixation is proposed. However, designing such an implant typically involves deterministic approaches, which do not account for uncertainties in design parameters, loadings on the plate, and additive manufacturing process parameters. Consequently, the actual conditions experienced by the plate may not be accurately modeled. Herein, both deterministic and probabilistic analyses of a porous implant with a gyroid lattice structure positioned on the humeral bone is conducted. The findings are compared to the failure probabilities of both the conventional fixation plate and the optimal plate derived from a previous study. The study reveals that uncertainties in design parameters significantly influence the plate's failure probability compared to deterministic analysis, emphasizing the importance of probability‐based analyses for a reliable plate design.