Tomoaki Yoshikawa

Bone mineral density of the spine and proximal femur in normal and osteoporotic subjects in Japan.

Bone mineral density (BMD) of the spine and proximal femur in Japanese men and women was investigated with dual photon absorptiometry, using gadolinium-153. Peak bone mass of the spine (L2-4) was 1.20 g/cm2 in women which was lower than that of men by 4.7%, whereas BMD of the femoral neck was 0.91 g/cm2 in women and lower than in men by 13.3%. Bone loss was faster in postmenopausal women than in men of the corresponding age, and the regressions of BMD on age were 6.7-times higher at L2-4 and 5.1-times higher at the femoral neck than in men. Such rates of loss became slower both in the lumbar spine and proximal femur in women after 70 years of age, but the density at the proximal femur kept decreasing in men after 70 years of age. Fracture thresholds of each region were evaluated at the 90th percentile for BMD of L2-4 in patients with vertebral crush fractures and for BMD of the proximal femur in patients with hip fractures. The fracture threshold was 0.97 g/cm2 at the spine and 0.67 g/cm2 at the femoral neck in women. BMD values at the spine and proximal femur in normal Japanese men and women appear to be lower than those in white American control population.

Epidemiology of Osteoporosis in Okinawa

International comparisons of fracture incidence of the femoral neck, bone mineral density of the axial and appendicular bones, calcium intake and daily activities in aged populations are extremely important for identifying preventive measures to be taken against senile osteoporosis. We surveyed the femoral neck fracture rate for four years from 1986 to 1989 in Okinawa Prefecture, and investigated bone mineral density of the lumbar spine and proximal femur by dual photon absortiometry or dual energy quantitative computed tomography in both normal subjects and osteoporotics with spinal compression fractures or hip fractures. Information on past and current daily activities and calcium intakes were collected through interviews or questionnaires on some of these control or osteoporotic subjects.The incidence of hip fracture in Okinawa was relatively higher than that in other prefectures of Japan, but apparently lower than that in Caucasian populations. In normal subjects, the slope of the overall regression line for bone mass vs age in women was 2.2 times steeper than that in men at the lumbar spine, but it was almost identical at the proximal femur in both sexes. Middle aged women lost BMD at both skeltal sites almost 2 times faster than that of overall women. BMD values of the osteoporotics with fractures were significantly lower than those of control subjects before 70 years. The high calcium intake group (more than 600mg/day) showed significantly higher BMD values at both skeltal sites comapred to the low calcium group (less than 600mg/day). Past daily activity level was significantly correlated with BMD values of each skeltal site, but current daily activity level correlated only with BMD for the lumbar spine.In conclusion, one of the important factors of senile fractures must be low BMD, which is influenced by calcium intake and daily activities in both the past and present.

Epidemiology of senile fracture in Japanese population

ConclusionsIn conclusions, The incidence of hip fracture in Okinawa was relatively higher than in other perfecture in Japan, but lower than in caucasian populations. Age-related bone loss occurs both at the trabecular and cortical bone with an accerelation at perimenopausal age in women. Osteoporotics show lower values of bone mineral density than control subjects. But it is difficult to discriminate osteoporotics from control only by BMD values at older age.The most important factor to determine the present bone mineral density must be adequate daily calcium intake and daily activity through life.

A Study of bone Mineral Density of the Proximal Tibia

We reported a comparative study of bone mineral density (BMD) of the proximal tibia with age, sex, weight and height.We measured the BMD of the proximal tibia of 74 healthy men and 76 women from the 2nd to 8th decades, with dual photon absorptiometer, LUNAR DP3, using gadolinium 153.BMD of the proximal tibia decreased according to age particularly in women. Age-related decreases of BMD of the femoral neck and lumbar supine were also recognized. The linear regression coefficient of the proximal tibia on age was greater than that of other skeletal sites. The most relative factor of BMD of the proximal tibia was age in women and weight in men. And BMD at medial and lateral sides of the proximal tibia, which were the weight bearing area, was higher than that of central side, non-weight bearing area. The value of the BMD of the proximal tibia may be influenced by physical activity other than aging.