Three-dimensional characterization of cortical bone microstructure by microcomputed tomography: validation with ultrasonic and microscopic measurements

Background. The porosity of human cortical bone is one of the major parameters conditioning bone strength. The purpose of this study was to validate the characterization of human cortical bone microarchitecture using microcomputed tomography (mu CT). To validate this mu CT technique, the structural measurements were compared with other methods such as ultrasonic techniques and scanning electron microscopy (SEM). Methods. Nineteen cortical samples were extracted from the superior, middle, and inferior shaft of three human femurs (FI, FII, FIII). The samples were scanned by mu CT with an isotropic resolution of 8 mu m. Most of the structural parameters used for trabecular microarchitecture were calculated to characterize the network of pores. On the same cortical samples, ( 1) ultrasound measurements were performed using contact transmission emitter-receptor to determine elastic coefficient and Young's modulus; ( 2) SEM was performed on femoral cross sections from FII to evaluate the porosity. Results. The morphological parameters showed a wide range of variation depending of the level of the diaphysis. Porosity measured by mu CT was significantly correlated with porosity measured by SEM (r = 0.91, P < 0.05). Moreover, all the morphological parameters showed high correlation coefficients with the elastic coefficient and Young's modulus, leading to validation of our three-dimensional analysis. Conclusions. The strong correlations between the structural and mechanical properties obtained with the three techniques allowed us to validate the mu CT technique used to characterize cortical bone microstructure. Porosity measurements might be of importance for clinicians and researchers to obtain a better understanding and evaluation of bone fracture in elderly patients.