A QCT Based Nonlinear Finite Element Method Proposed for Predicting Failure Initiation Load and Locationin Vertebrae Affected by Tumors

Abstract

The aim of this study was to present an effective specimen-specific approach for predicting failure initiation load and location incadaveric vertebrae with simulated osteo-lytic defects. Nine thoraco-lumbar vertebrae excised from three cadavers were used as the samples in which the defects were simulated. The samples were then scanned using the QCT and their sectional images were segmentated and converted into 3D voxel based finite element models. Then, a large deformation nonlinear analysis was carried out. The equivalent plastic strain was then obtained and used to predict the load and locations of the failure initiation in each vertebra. Subsequently, all the samples were tested under the uniaxial compression condition and their experimental load-displacement diagrams were also obtained. Results showed that in the samples with simulated osteolytic defects, the failure is initiated and occurred at the load levels well below the ultimate strength of the samples. The radiographic images showed that the failure initiation happens in the same portion of the vertebral bodies as predicted by the QCT voxel based FEM. The method developed and verified in this study can be regarded as a valuable tool for predicting vertebral failure load. However more experiments may be required to test the method for the vertebrae affected by real tumors.