Estimating the density of femoral head trabecular bone from hip fracture patients using computed tomography scan data

The purpose of this study was to compare computed tomography density (rCT) obtained using typical clinical computed tomography scan parameters to ash density (rash), for the prediction of densities of femoral head trabecular bone from hip fracture patients. An experimental study was conducted to investigate the relationships between rash and rCT and between each of these densities and rbulk and rdry . Seven human femoral heads from hip fracture patients were computed tomography'scanned ex vivo, and 76 cylindrical trabecular bone specimens were collected. Computed tomography density was computed from computed tomography images by using a calibration Hounsfield units-based equation, whereas rbulk , rdry and rash were determined experimentally. A large variation was found in the mean Hounsfield units of the bone cores (HUcore) with a constant bias from rCT to rash of 42.5 mg/cm3. Computed tomography and sh densities were linearly correlated (R2 = 0.55, p < 0.001). It was demonstrated that rash provided a good estimate of rbulk (R2 = 0.78, p < 0.001) and is a strong predictor of rdry (R2 = 0.99, p < 0.001). In addition, the rCT was linearly related to rbulk (R2 = 0.43, p < 0.001) and rdry (R2 = 0.56, p < 0.001). In conclusion, mineral density was an appropriate predictor of rbulk and rdry, and rCTwas not a surrogate for rash. There were linear relationships between rCT and physical densities; however, following the experimental protocols of this study to determine rCT, considerable scatter was present in the rCT relationships.