Femoral neck shape and the spatial distribution of its mineral mass varies with its size: Clinical and biomechanical implications

摘要: The femoral neck (FN) is a cantilever with external and internal dimensions determining its size, shape, the spatial distribution of mineralized cortical trabecular bone tissue mass, strength. Geometric indices FN strength are often derived using estimated in vivo from dual X-ray absorptiometry (DXA) assuming that cross section approximates circle or square. As DXA does not measure depth, we examined whether circular, square, elliptical models sections predict so volume, volumetric mineral density (vBMD), geometric We studied paired specimens 13 Caucasian female cadavers (mean age 69 years, range 29 to 85) DXA, micro-computed tomography (mu-CT), direct calliper measurements. accurately measured width (supero-inferior diameter) but circular square overestimated depth (antero-posterior underestimated vBMD by 15.0 +/- 5.8% (circular section) 33.2 4.6% (square (both P < 0.05). was less than width, an model constant depth/width ratio 0.75 reduced accuracy error 14.0 8.5% (P = 0.10). However, as increased, increased relatively less. An quadratic equation mimic this changing shape increasing size 4.4 7.7% (NS). Circular cross-section modulus at mid-FN about 51%. two- three fold. Images micro-CT scanning show cross-sectional resembles ellipse long axis maximum moment inertia (I(max)) oriented supero-inferior direction, mass concentrated inferiorly. larger section, more greater I(max) supero-inferiorly, while I(min) (in antero-posterior direction) remains constant. bone, moments likely be adaptations bending during bipedalism. Assuming produces errors vBMD, Studies needed determine effects age, sex, race on health disease.