Peripheral quantitative computed tomography of the femoral neck in 60 Japanese women

Peripheral quantitative computed tomography (pQCT) is able to evaluate trabecular and cortical bone separately, and to determine geometric properties from cross-sectional images for noninvasive assessments of mechanical strength. In order to assess the diagnostic value of pQCT of the femoral neck, 60 healthy women were examined with a new pQCT machine, XCT- 3000 (Norland-Stratec, Germany), which is suitable for direct measurement of the hip. The region of interest chosen was the center of the femoral neck. pQCT of the distal radius and dual energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck were also performed. The study demonstrated that total bone mineral density (BMD) (femoral MD) and trabecular BMD (femoral-TBD) decreased with advancing age. Percent cortical area showed a small but significant decrease with advancing age and % trabecular area increased slightly. Both the endosteal perimeter and the periosteal perimeter were relatively constant with aging. Bone strength index (BSI) and stress- strain index (SSI), which reflect the mechanical strength of bone, declined with advancing age, especially after menopause. Femoral TBD correlated strongly with femoral neck BMD by DXA and L2-L4 BMD by DXA but femoral-CBD did not correlate with femoral neck BMD by DXA. Volumetric BMD of the femoral neck and distal radius were closely correlated. It is concluded that (1) cortical thinning occurs with aging by endocortical resorption and loss of femoral-TBD; (2) loss of femoral-CBD occurred at a slower rate than radial CBD, perhaps due to the weight-bearing effect; (3) biomechanical parameters such as the BSI and SSI may reflect increasing fragility of the femoral neck in pre- and postmenopausal women; (4) pQCT of the femoral neck had diagnostic value at least equivalent to that of DXA or pQCT of the distal radius.