Relationship between nutrition factors and osteopenia: Effects of experimental diets on immature bone quality.

To investigate the influence of experimental diets on morphological and mechanical characteristics of immature bone, this study thoroughly examined the nutrition-bone connection. A non-destructive evaluation method involving high-resolution in-vivo micro-computed tomography and finite element (FE) analysis was used to investigate the relationship between obesity and osteopenia-two disorders of body composition. Correlation of nutritional deficiency with bone characteristics was also investigated. Some recent studies have shown that both obesity and osteopenia share several common genetic and environmental factors. However, there have been few studies correlating these pathologies in-vivo from a structural and biomechanical point of view. In the present study, detailed changes in morphological and mechanical characteristics of trabecular bone architecture were detected and tracked by longitudinal studies of morphometric parameters and simulated compression testing. Rats were randomized into three groups: overeaten diet (OD) for formation of obesity, normal diet (ND), and restricted diet (RD) in which rats received 65% of the normal diet. In the OD and ND groups, all structural parameters changed significantly (p<0.05). The degree of alteration in the structural parameters of the ND group was similar to that of the RD group (p<0.05). In simulated compression tests using FE models, the effective modulus of the OD group significantly decreased, depending on measuring time (p<0.05), whereas that of the ND and RD groups significantly increased (p>0.05). The key finding of the present study is that fat mass is morphologically and mechanically inversely correlated with bone mass when the mechanical loading effects of greater body weight on bone mass are applied.

The effect of hormone treatment on the plastic characteristic of osteoporotic vertebral trabecular bone.

Many researchers have investigated the elastic characteristic of trabecular bones by using the microfinite element (Micro-FE) models based on the microcomputed tomography (micro-CT). However, there were few micro-FE models to account for the plastic characteristic of trabecular bones. The present study analyzed the plastic characteristic as well as the elastic characteristic of the trabecular bone and evaluated the effect of specimen size on the plastic characteristic of vertebral trabecular bones. Previous researchers reported that a cubic specimen with side length 6.5 mm was suggested as a standard specimen for the experimental tests of trabecular bones. The present study examined whether the effects of the specimen size on the experimental tests may be also applied to the simulated compression test of trabecular bone specimens and investigated the effect of voxel resolution on the plastic characteristic of micro-FE models. The results illustrate that in the simulated compression test to analyze mechanical characteristics of vertebral trabecular bones, it is recommended to use a cubic specimen with side length 6.5 mm rather than a cubic specimen with side length 4 mm. It is also found that the hormone therapy is likely to be less effective than the amount reported by previous researcher for 2D models.