ULTRASOUND TRANSMISSION AS A SENSITIVE INDICATOR OF BONE CHANGE IN JAPANESE WOMEN IS THE PERIMENOPAUSAL PERIOD

Apparent velocity of ultrasound (AVU) through the patella was measured in 160 Japanese women without specific diseases affecting the skeletal system. AVU averaged 1955 +/- 64 m/s (mean +/- S.D.) in healthy premenopausal women. Twenty patients with postmenopausal osteoporosis over the age of 50 years with at least one atraumatic vertebral fracture had significantly lower average AVU (1757 +/- 89.6 m/s) than that of the same age group without compression fracture (1838 +/- 78.0 m/s, P < 0.05). Perimenopausal women without vertebral fracture in their 50s were divided into two groups, premenopausal (n=11), and postmenopausal (n = 28), and both AW through the patella and spinal BMD (L-2-4) using DXA were measured. A significant difference was found in AVU between the two groups (premenopausal, 1953 +/- 58 m/s; postmenopausal, 1885 +/- 73 m/s, P < 0.01), in the absence of a difference either in the mean age (premenopausal, 52.7 +/- 2.0; menopausal, 54.2 +/- 2.4) or in the spinal BMD as assessed by DXA (premenopausal, 0.930 +/- 0.080 g/cm(2); postmenopausal, 0.851 +/- 0.148 g/cm(2)). The apparent difference in AVU without corresponding difference in BMD suggests that perhaps AVU measures something about the bone that is not reflected in BMD in women in their 50s in the immediate postmenopausal period. When AVU of our test subjects was compared with that in Caucasians reported by Heaney RP et al. (Osteoporotic bone fragility: detection by ultrasound transmission velocity. J Am Med Assoc 1989;261:2986-2990)no difference was found in AVU between Japanese and Caucasians. Since AVU is said to be proportional to the product of bone quantity (density) and bone quality, and bone quantity measured as bone mineral density was shown to be lower in Japanese than in Caucasians, there might possibly be some difference in bone quality between the two populations. Cross-cultural exploration of the bone properties and causes of differences in the incidence of hip fracture may help in understanding the causes and background of osteoporosis.