Shape, Structural Properties, and Cortical Stability Along the Femoral Neck: A Study Using Clinical QCT

Abstract

This study used clinical quantitative computer tomography (QCT) to obtain detailed estimates of the structural properties and cortical dimensions of cross-sections (CSs) along the femoral neck (FN). The computer tomography scans of both proximal femora of 27 postmenopausal women (mean age 81, range 65–86 yr) with osteoporosis were processed and analyzed. The cross-sectional shape, cortical and trabecular bone area, and section moduli under different fall directions were calculated. Furthermore, each CS was divided into 8 sectors and cortical thickness and buckling ratio were estimated for each octant. The cross-sectional shape was found to be increasingly elliptic and both tensile and compressive section moduli increased significantly (by a factor of up to 1.8) from the proximal to distal half of the FN. The section modulus was dependent on the fall direction; it was maximal when falling 20° anterior and at its lowest (reduced by as much as 37%) when falling 50° posterior on the greater trochanter. The cortex was significantly thinner (≤1 mm) in the anterior, superoanterior, superior, superoposterior, and posterior octants than the inferomedial aspect of the FN. In conclusion, multiple site measurements are required for a comprehensive assessment of FN structural properties, which can be studied based on clinical QCT.