As the mechanical competence of trabecular bone is a function of its apparent density and 3-D distribution, assessment of 3-D trabecular structural characteristics may improve our ability to understand the pathophysiology of osteoporosis, to test the efficacy of pharmaceutical intervention, and to estimate bone biomechanical properties. We have studied ovariectomy-induced osteopenia in rats and its treatment with agents such as estrogen and sodium fluoride. We have demonstrated that 3-D micro-computed tomography (microCT) can directly quantify mouse trabecular and cortical bone structure with an isotropic resolution of 6 microm(3). MicroCT is also useful for studying osteoporosis in mice and phenotypes of mice with gene manipulation, such as SHIP-knockout mice, which are severely osteoporotic due to increased numbers of hyperresorptive osteoclasts, PTHrP heterozygous-null mice, and mice with Zmpste24 deficiency. MicroCT can quantify osteogenesis in mouse Ilizarov leg-lengthening procedures, osteoconduction in a rat cranial defect model, and structural changes in arthritic rabbits, rats, and mice. In clinical studies, we evaluated longitudinal changes in the iliac crests. Paired bone biopsies from the same premenopausal and postmenopausal women showed the changes in 3-D trabecular structure, such as decreased trabecular thickness, shifting of trabecular model from platelike structure to rodlike structure, and decreased degree of anisotropy were remarkable. Treatment with PTH in postmenopausal women with osteoporosis significantly improved trabecular morphology with a shift toward a more platelike structure, increased trabecular connectivity density, and increased cortical thickness. Paired bone biopsy specimens from the iliac crest in postmenopausal women with osteoporosis before and an average of 2 years after beginning of estrogen replacement therapy demonstrated that posttreatment biopsies showed a significant change in the ratio of plates to rods and statistically insignificant changes in other 3-D trabecular parameters. Thus, microCT can characterize 3-D structure of various animal models, and the longitudinal changes in 3-D bone microarchitectural integrity that deteriorates in the transmenopausal period, is preserved with HRT, and is improved with PTH treatment in postmenopausal women.

With the progressive aging of the population, osteoporosis has gradually grown into a global health problem for men and women aged 50 years and older because of its consequences in terms of disabilities and fragility fractures. This is especially true in the People’s Republic of China, which has the largest population and an increasing proportion of elderly people, as osteoporosis has become a serious challenge to the Chinese government, society, and family. Apart from the fact that all osteoporotic fractures can increase the patient’s morbidity, they can also result in fractures of the hip and vertebrae, which are associated with a significantly higher mortality. The cost of osteoporotic fractures, moreover, is a heavy burden on families, society, and even the country, which is likely to increase in the future due, in part, to the improvement in average life expectancy. Therefore, understanding the epidemiology of osteoporosis is essential and is significant for developing strategies to help reduce this problem. In this review, we will summarize the epidemiology of osteoporosis in the People’s Republic of China, including the epidemiology of osteoporotic fractures, focusing on preventive methods and the management of osteoporosis, which consist of basic measures and pharmacological treatments.

Osteoporosis is a major public health problem, particularly in women. Bone mineral density (BMD) reference plot is a basic, and the peak BMD (PBMD) an important, parameter in the diagnosis of osteoporosis. In order to establish reference plots of BMD at multiple skeletal sites in Chinese women and improve the diagnostic accuracy for osteoporosis, we measured BMDs at several skeletal regions in 3,378 Chinese women, aged 5-96 years, using a dual-energy X-ray absorptiometry fan-beam bone densitometer. After determining that the cubic regression model best fit all skeletal regions, we utilized the curve-fitting to establish BMD reference plots and utilized the curve-fitting equation to calculate the highest BMDs at all skeletal regions using three different methods of calculation--actual PBMD (method A), PBMD of each 5-year age group (method B), and a cross-section of age (method C). When the three methods were compared, we found significant differences among them at the majority of skeletal regions studied. When we utilized these three methods to determine the prevalence of osteoporosis in 2,120 women aged 40 years and older, except for the Ward's triangle, we observed significant differences among them at all skeletal regions. In the present study, we established new BMD reference plots at multiple skeletal regions for women of mainland China. Our findings also indicate that curve-fitting equations can be employed to calculate actual PBMDs specific to individual regions, and that the use of different methods to calculate PBMD may have a significant impact on both PBMD and the diagnosis of osteoporosis. Therefore, we suggest that a standardized method be established to calculate site-specific PBMDs based on the peak values of best-fit reference curves in appropriate age groups.

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Gonadotropic hormone levels are correlated with the rate of bone turnover in Chinese women: the higher the serum gonadotropic hormone levels in circulation, the higher the levels of bone turnover indicators. FSH has a greater influence on all types of bone turnover indicator than LH; moreover, it has a greater influence on bone formation indicators than on bone resorption indicators.