Age-related differences of bone mass, geometry, and strength in treatment-naïve postmenopausal women. A tibia pQCT study

The Impact of Different Modes of Exercise Training on Bone Mineral Density in Older Postmenopausal Women: A Systematic Review and Meta-analysis Research

Effectiveness of exercise on bone mass is closely related to the mode of exercise training regimen, as well as the study design. This study aimed to determine the effect of different modes of exercise training on lumbar spine and femoral neck bone mineral density (BMD) in older postmenopausal women (PMW). PubMed, CINAHL, Medline, Google Scholar, and Scopus databases and reference lists of included studies were searched up until March 25, 2019 for randomized controlled trials (RCTs) that evaluated the effectiveness of various modes of exercise training in PMW. Sixteen RCTs with 1624 subjects were included. Our study found no significant change in both lumbar spine and femoral neck BMD following exercise training (MD: 0.01 g/cm²; 95% confidence interval (CI) [- 0.01, 0.02] and MD: 0.00 g/cm²; 95% CI [- 0.01, 0.01], respectively). However, subgroup analysis by type of exercise training revealed that lumbar spine BMD (MD: 0.01; 95% CI [0.00, 0.02]) raised significantly when whole-body vibration (WBV) was employed as intervention compared with RCTs that utilized aerobic (MD: - 0.01; 95% CI [- 0.02, - 0.01]), resistance (MD: 0.01; 95% CI [- 0.04, 0.06]), and combined training (MD: 0.03; 95% CI [- 0.01, 0.08]). On the other hand, lumbar spine BMD (MD: - 0.01; 95% CI [- 0.02, - 0.01]) reduced significantly when aerobic exercise training was used as intervention compared with RCTs that utilized resistance training, combined training, and WBV. By contrast, these analyses did not have significant effect on change in femoral neck BMD. WBV is an effective method to improve lumbar spine BMD in older PMW.

Effect of surgical and natural menopause on proximal femur morphometry in obese women

The purpose of this study is to determine whether there are differences in proximal femur parameters of women subjected to menopause surgically or naturally. In this study, 10 parameters belonging to proximal femur of a total of 60 women cases of whom 30 had a mean age of 55.53 ± 4.57 years; body mass index, 33.06 ± 4.21 kg/m²; menopause age, 48.10 ± 5.92; and menopause years, 7.50 ± 4.58; and who were subjected to natural menopause; and 30 women whose mean age was 56.10 ± 6.87 years; body mass index, 33.33 ± 3.76 kg/m²; menopause age, 48.00 ± 4.64 years and menopause year, 8.10 ± 7.29; who were subjected to surgical menopause, and who did not use hormone replacement, were examined by radiography. Their anthropometric measurements, body compositions, blood hormone analyses (FSH, LH, estradiol, progesterone) and bone mineral densities (femur neck, femur total, lumbar t-score) were evaluated. It was found that there was no difference between surgical and natural menopause with respect to proximal femur parameters (p > 0.05). It was also found that FSH levels were high in the surgical menopause group and there were significant differences between the groups (p < 0.040). No significant difference was found even though bone mineral density t-score tests were lower in the surgical menopause group (p > 0.05). It was found that the difference in low bone mineral density level and high FSH values in the surgical menopause group do not have a relationship with proximal femur morphometry. It was determined that even though the women did not have ovaries, there was no difference between surgical menopause women and natural menopause women with respect to proximal femur morphometry.

Peripheral Quantitative Computed Tomography (pQCT) Measures Contribute to the Understanding of Bone Fragility in Older Patients With Low-trauma Fracture

Dual-energy X-ray absorptiometry (DXA) as currently used has limitations in identifying patients with osteoporosis and predicting occurrence of fracture. We aimed to express peripheral quantitative computed tomography (pQCT) variables of patients with low-trauma fracture as T-scores by using T-score scales obtained from healthy young women, and to evaluate the potential clinical utility of pQCT for the assessment of bone fragility. Fracture patients were recruited from a fracture liaison service at the Royal Melbourne Hospital. Reference pQCT data were obtained from studies on women's health conducted by our group. A study visit was arranged with fracture patients, during which DXA and pQCT were applied to measure their bone strength. A total of 59 fracture patients were recruited, and reference data were obtained from 78 healthy young females. All DXA variables and most pQCT variables were significantly different between healthy young females and fracture patients (p < 0.05), except polar stress-strain index (p = 0.34) and cortical bone density (p = 0.19). Fracture patients were divided into osteoporosis and non-osteoporosis groups according to their DXA T-scores. Significant differences were observed in most pQCT variables (p < 0.05), except trabecular area and cortical density (p > 0.9 and p = 0.5, respectively). By applying pQCT T-scores, 11 (27%) of patients who were classified as having low or medium risk of osteoporosis on DXA T-scores alone were reclassified as high risk. Results of logistic regression suggested trabecular bone density as an independent predictor of osteoporosis status. More patients can be identified with osteoporosis by applying pQCT T-score variables in older people with low-trauma fracture. Peripheral QCT T-scores contribute to the understanding of bone fragility in this population.

Hypothalamic leptin gene therapy reduces body weight without accelerating age-related bone loss

Excessive weight gain in adults is associated with a variety of negative health outcomes. Unfortunately, dieting, exercise, and pharmacological interventions have had limited long-term success in weight control and can result in detrimental side effects, including accelerating age-related cancellous bone loss. We investigated the efficacy of using hypothalamic leptin gene therapy as an alternative method for reducing weight in skeletally-mature (9 months old) female rats and determined the impact of leptin-induced weight loss on bone mass, density, and microarchitecture, and serum biomarkers of bone turnover (CTx and osteocalcin). Rats were implanted with cannulae in the 3rd ventricle of the hypothalamus and injected with either recombinant adeno-associated virus encoding the gene for rat leptin (rAAV-Leptin, n=7) or a control vector encoding green fluorescent protein (rAAV-GFP, n=10) and sacrificed 18 weeks later. A baseline control group (n=7) was sacrificed at vector administration. rAAV-Leptin-treated rats lost weight (-4±2%) while rAAV-GFP-treated rats gained weight (14±2%) during the study. At study termination, rAAV-Leptin-treated rats weighed 17% less than rAAV-GFP-treated rats and had lower abdominal white adipose tissue weight (-80%), serum leptin (-77%), and serum IGF1 (-34%). Cancellous bone volume fraction in distal femur metaphysis and epiphysis, and in lumbar vertebra tended to be lower (P<0.1) in rAAV-GFP-treated rats (13.5 months old) compared to baseline control rats (9 months old). Significant differences in cancellous bone or biomarkers of bone turnover were not detected between rAAV-Leptin and rAAV-GFP rats. In summary, rAAV-Leptin-treated rats maintained a lower body weight compared to baseline and rAAV-GFP-treated rats with minimal effects on bone mass, density, microarchitecture, or biochemical markers of bone turnover.

Fat Infiltration in the Leg is Associated with Bone Geometry and Physical Function in Healthy Older Women

The objective of this study was to estimate the associations between muscular fat infiltration, tibia bone mineral quantity and distribution, and physical function in healthy older women. Thirty-five women (aged 60-75 years, mean 70 years) were recruited from the community. Percent intramuscular fat (%IntraMF) within the right leg tibialis anterior, soleus, and gastrocnemius muscles and total intermuscular fat (IMF) were segmented from magnetic resonance imaging scans at the mid-calf. Intramyocellular lipid (IMCL) content in the right tibialis anterior was measured with proton magnetic resonance spectroscopy. Right tibia bone content, area, and strength were measured at the 4, 14, and 66% sites using peripheral quantitative computed tomography. Physical function was assessed by gait speed on the 20 m walking test. After adjusting for age, body size, and activity level, %IntraMF had a negative association with bone content and area at all tibia sites (r = -0.31 to -0.03). Conversely, greater IMF was associated with increased bone content and area (r = 0.04-0.32). Correlation coefficients for the association between IMCL and bone were negative (r = -0.44 to -0.03). All measures of fat infiltration had a negative association with observed physical function (r = -0.42 to -0.04). Our findings suggest that muscular fat infiltration in the leg of healthy postmenopausal women has a compartment-specific relationship with bone status and physical function. Minimizing fat accumulation within and between muscle compartments may prevent bone fragility and functional decline in women.