title: Finite element analysis and computed tomography based structural rigidity analysis of rat tibia with simulated lytic defects.
abstract: Finite element analysis (FEA), CT based structural rigidity analysis (CTRA) and mechanical testing is performed to assess the compressive failure load of rat tibia with simulated lytic defects. Twenty rat tibia were randomly assigned to four equal groups (n=5). Three of the groups included a simulated defect at various locations: anterior bone surface (Group 1), posterior bone surface (Group 2) and through bone defect (Group 3). The fourth group was a control group with no defect (Group 4). Microcomputed tomography was used to assess bone structural rigidity properties and to provide 3D model data for generation of the finite element models for each specimen. Compressive failure load calculated using CT derived rigidity parameters (FCTRA) was well correlated to failure load recorded in mechanical testing (R(2)=0.96). The relationships between mechanical testing failure load and the axial rigidity (R(2)=0.61), bending rigidity (R(2)=0.71) and FEA calculated failure loads, considering bone as an elastic isotropic (R(2)=0.75) and elastic transversely isotropic (R(2)=0.90) are also well correlated. CTRA stress, calculated adjacent to the defect, were also shown to be well correlated with yield stresses calculated using the minimum density at the weakest cross section (R(2)=0.72). No statistically significant relationship between apparent density and mechanical testing failure load was found (P=0.37). In summary, the results of this study indicate that CTRA analysis of bone strength correlates well with both FEA and results obtained from compression experiments. In addition there exist a good correlation between structural rigidity parameters and experimental failure loads. In contrast, there was no correlation between average bone density and failure load.
authors: Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Department of Mechanical Engineering, Northeastern University, Boston, MA, USA.
authors: John A
authors: JA
authors: Rennick
authors: Ara
authors: A
authors: Nazarian
authors: Vahid
authors: V
authors: Entezari
authors: James
authors: J
authors: Kimbaris
authors: Alan
authors: A
authors: Tseng
authors: Aidin
authors: A
authors: Masoudi
authors: Hamid
authors: H
authors: Nayeb-Hashemi
authors: Ashkan
authors: A
authors: Vaziri
authors: Brian D
authors: BD
authors: Snyder
mesh_terms: D000818:Animals; D015519:Bone Density; D005260:Female; D020342:Finite Element Analysis; D010014:Osteolysis / Q000000981:diagnostic imaging / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology; D016474:Weight-Bearing; D055114:X-Ray Microtomography
keywords: Finite element analysis; Lytic defect; Metastatic disease; Rat; Structural rigidity analysis