Abstract
In this paper, a CT based structural rigidity analysis (CTRA) method that incorporates bone intrinsic local curvature is introduced to assess the compressive failure load of human femur with simulated lytic defects. The proposed CTRA is based on a three dimensional curved beam theory to obtain critical stresses within the human femur model. To test the proposed method, ten human cadaveric femurs with and without simulated defects were mechanically tested under axial compression to failure. Quantitative computed tomography images were acquired from the samples, and CTRA and finite element analysis were performed to obtain the failure load as well as rigidities in both straight and curved cross sections. Experimental results were compared to the results obtained from FEA and CTRA. The failure loads predicated by curved beam CTRA and FEA are in agreement with experimental results. The results also show that the proposed method is an efficient and reliable method to find both the location and magnitude of failure load. Moreover, the results show that the proposed curved CTRA outperforms the regular straight beam CTRA, which ignores the bone intrinsic curvature and can be used as a useful tool in clinical practices.
Highlights
The skeleton is the third most common site of metastatic cancer, and nearly half of all cancers metastasize to bone[1,2,3]
This study evaluated the accuracy of straight and curved beam Computed tomography-based structural rigidity analysis (CTRA) models and Finite Element (FE) analysis to predict failure load, which was determined through mechanical testing in paired femurs with and without simulated lytic lesions
We were able to demonstrate that predicted failure loads from curved beam CTRA and FE analysis were highly correlated with the actual failure load obtained through mechanical testing
Summary
The skeleton is the third most common site of metastatic cancer, and nearly half of all cancers metastasize to bone[1,2,3]. There is a need for a reliable clinical tool to objectively assess fracture risk based on the material and geometric determinants of bone strength. Computed tomography-based structural rigidity analysis (CTRA), which takes into account the material properties and structural organization of bone, can reliably predict failure load in rat and human bones with lytic defects[8,9,10,11,12,13,14]. CTRA calculations are derived from straight beam theory, where the influence of bone curvature on strength has not been considered. This influence has been shown to be significant in calculating bone fracture load[15]. We hypothesize that curved beam CTRA will outperform traditional CTRA in terms of the accuracy of the predicated failure load and the failure location and will correlate well with FEA and mechanical testing results
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