Prediction of cortical bone porosity in vitro by microcomputed tomography

The high importance of intracortical porosity for mechanical strength of co rtical bone has been established. The contribution of other parameters of m icrostructure such as osteon dimensions for strength is in discussion. The aim of this study was to evaluate the predictive value of micro-computed to mography (mu CT) for porosity and other microstructural parameters of corti cal bone in cortical bone biopsies. Femoral cortical bone specimens from th e middiaphysis of 24 patients were harvested during the procedure of total hip replacement at the location where normally one hole (Phi 4.5 mm) for th e relief of the intramedullary pressure is placed. In vitro intracortical p orosity and bone mineral density (BMD) measurements by mu CT were compared with structural parameters assessed in histological sections of the same sp ecimens. A strong correlation was found between intracortical porosity meas ured by mu CT and histological porosity (r = 0.95, P < 0.0001). Porosity me asured by <mu>CT was also a strong predictor for other parameters describin g dimensions of porous structures. BMD-1 was associated with osteonal area (r = -0.76, P < 0.0001). We consider the measurement of porosity by <mu>CT as a very potent procedure for assessing intracortical porosity and paramet ers related to porous structures of cortical bone nondestructively in vitro .