Fig. 5

Shell thickness effect on fracture loads and stiffness using the Keller-vertebra equation. a Fracture load with a 0.4-mm shell thickness. (Mechanical load) = 1.037 × (FEA-predicted fracture load) + 331.1, R² = 0.76, p < 0.001. b Fracture load with a 0.5-mm shell thickness. (Mechanical load) = 1.047 × (FEA-predicted fracture load) + 194.8, R² = 0.66, p < 0.001. c Stiffness with a 0.4-mm shell thickness. (Mechanical stiffness) = 0.903 × (FEA-predicted stiffness) + 331.1, R² = 0.54, p < 0.001. d Stiffness with a 0.5-mm shell thickness. (Mechanical stiffness) = 0.843 × (FEA-predicted stiffness) + 395.1, R² = 0.52, p < 0.001