Porous Metal Block Based on Topology Optimization to Treat Distal Femoral Bone Defect in Total Knee Revision

Metal block augmentations are common solutions in treating bone defects of total knee revision. However, the stress shielding and poor osteointegration resulted by metal block augmentation could not be neglected in restoration. In this study, a novel porous metal block was designed with topology optimization to improve biomechanical performance. The biomechanical difference of the topologically optimized block, solid Ti6Al4V block, and porous Ti6Al4V block in treating bone defects of total knee revision was compared by finite element analysis. The inhomogeneous femoral model was created according to the computed tomography data. Combined with porous structures, minimum compliance topology optimization subjected to the volume fraction constraint was utilized for the redesign of the metal block. The 10 mm area of the distal femur underneath the contacting surface was defined as the region of interest. The biomechanical performance of daily motions was investigated. The von Mises stress, the strain energy density of the region of interest, and the von Mises stress of metal blocks were recorded. The results were analyzed in SPSS. In terms of the region of interest, the maximum von Mises stress of the topological optimized group increased obviously, and the average stress of this group was significantly higher than other groups (p < 0.05). Meanwhile, the maximum strain energy density of the topologically optimized block group was the highest among the three groups, and the lowest maximum stress of block was found in the topological optimized group. In this study, the stress shielding reduction and stress transfer capability was found obviously improved through topology optimization. Therefore, the topological optimized porous block is recommended in treating bone defects of total knee revision. Meanwhile, this study also provided a novel approach for the mechanical optimization in block designing.