Comparative finite element analysis of an osseointegration system in transradial amputation: a proposal of a new design for osseointegration

Purpose: Conventional osseointegration systems have been applied in patients requiring transhumeral or transfemoral amputation. However, the application of these systems to transradial amputation is limited by the small diameter of the radius and ulna. Our study compared the biomechanical stability of a novel osseointegration system with that of a conventional system used in transradial amputation through an analysis of finite element (FE) models.Methods: We established three-dimensional FE models of transradial amputations, which were osseointegrated with both the novel and conventional systems. External loads were applied to the FE models with compressive force and tensile force along the long axis, horizontal shear force, and vertical shear force. The maximum equivalent stress (MES) and the distribution of stress through the radius and ulna were evaluated.Results: The MES of the radius and ulna was higher in the conventional system when compressive, tensile, and vertical shear forces were applied. However, when a horizontal shear force was applied, the opposite result was found. The distribution of stress was more effective in the novel system.Conclusion: Three-dimensional FE modeling showed that the novel system enabled a lower stress level and a more even distribution of stress for osseointegration in transradial amputation.