Reconstruction of Cortical and Cancellous Bone in Tibia with Osteogenesis Imperfecta

Abstract

Osteogenesis Imperfecta (OI) is the bone fragility disorder that leads to long bone bowing. Finite Element Analysis (FEA) has become the tool of choice to assess behaviour structural within bones. Currently, the FEA performed on the tibia is based on the bone constructed without considering different components of the bone, where the bone was created as a single material. In an attempt to further investigate the bone with OI, the present study was conducted to investigate the mechanical stress distribution using finite element model of the OI affected tibia. The model was reconstructed from the CT images composed of cortical and cancellous bones obtained from Osirix database. The segmentation of the cortical and cancellous of the tibia was performed on 346 images using two different methods which are global thresholding and the selection of the binary object. The segmented images were used to develop a three-dimensional model of the tibia using VOXELCON software. The boundary conditions were set to the meshed model in preparation for the finite element analysis using the same software. Displacements ranging from 5 mm to 35 mm were assigned to a point in between the proximal and distal of the tibia model. In the coronal plane, the highest stress levels were recorded on the medial side of the cortical bone, whereas in the sagittal plane, the highest stress levels were recorded on the anterior side of the cortical bone when the model was subjected to 35 mm displacement. The cancellous bone, however, showed lower stress levels on both planes when subjected to similar displacement. With each increment of displacement, the model experienced more stress and caused the higher percentage volume of individual cortical and cancellous that exceed critical stress of 115 MPa. There were no significant differences in the percentage volume of voxels affected between the cortical and cancellous bones for both coronal and sagittal planes with the pvalue of 0.29 and 0.32 respectively (p > 0.05). There was no significant difference obtained for the percentage volume of voxels affected between the coronal and sagittal planes with the p-value is 0.13 (p > 0.05).