Mean Bone Material Strength Index Values for Women are Lower Than Those for Men: Data from a Single Geographical Location.

Bone material strength index (BMSi) values are obtained using impact microindentation, which assesses the ability of bone to resist indentation. Differences in BMSi between men and women are unclear, and to date, BMSi sex differences have not been compared for individuals from the same population. Therefore, we compared BMSi values for men and women drawn from the same geographical location in Australia. Participants (n = 220) were from the Geelong Osteoporosis Study. BMSi was measured, following international published guidelines, using an OsteoProbe for participants at recent follow-up phases (women 2022-2023 and men 2016-2022). Women (n = 55) were age matched to men (n = 165) in a 1:3 ratio. A two-sample t test was used to determine the intergroup difference in mean BMSi. Linear regression was also performed, adjusting for weight and height. Median (IQR) ages for men and women were 67.0 (61.7-71.5) and 67.4 (62.0-71.2) years (p = 0.998). Men were heavier (81.0 ± 10.9 vs 71.0 ± 13.9 kg, p < 0.001) and taller (173.9 ± 6.4 vs 161.5 ± 7.5 cm, p < 0.001) than women. Mean (± SD) BMSi for women (75.7 ± 7.4) was lower than for men (82.8 ± 6.8) (p < 0.001). The difference persisted after adjustment for weight and height (mean ± SE: 76.5 ± 1.1 vs 82.5 ± 0.6, p < 0.001). Given the higher fracture risk observed for women, the higher mean BMSi values in men are consistent with cross sectional data suggesting this measure may be useful in fracture prediction.

Peripheral quantitative computed tomography-derived bone parameters in men with impaired fasting glucose and diabetes.

INTRODUCTION: Individuals with type 2 diabetes mellitus (T2DM) are at higher risk of fracture, but paradoxically do not have reduced bone mineral density. We investigated associations between peripheral quantitative computed tomography (pQCT) and glycaemia status. MATERIALS AND METHODS: Participants were men (n = 354, age 33-92 year) from the Geelong Osteoporosis Study. Diabetes was defined by fasting plasma glucose (FPG) ≥ 7.0 mmol/L, self-report of diabetes and/or antihyperglycaemic medication use and impaired fasting glucose (IFG) as FPG 5.6-6.9 mmol/L. Bone measures were derived using pQCT (XCT2000) at 4% and 66% radial and tibial sites. Linear regression was used, adjusting for age, body mass index and socio-economic status. RESULTS: At the 4% site, men with T2DM had lower adjusted bone total area, trabecular area and cortical area at the radius (all - 6.2%) and tibia (all - 6.4%) compared to normoglycaemia. Cortical density was higher for T2DM at the radius (+ 5.8%) and tibia (+ 8.0%), as well as adjusted total bone density at the tibial site (+ 6.1%). At the 66% site, adjusted total bone area and polar stress strain index were lower for T2DM at the radius (- 4.3% and - 8.0%). Total density was also higher for T2DM (+ 1.2%). Only cortical density at the 4% tibial site was different between IFG and normoglycaemia in adjusted analyses (+ 4.5%). CONCLUSION: Men with T2DM had lower total bone area, trabecular area, cortical area and polar stress strain index than the other two groups; however, total density and cortical density were higher. Only one difference was observed between IFG and normoglycaemia; increased tibial cortical density.

The practicality of using bone impact microindentation in a population-based study of women: A Geelong-Osteoporosis Study.

Impact microindentation (IMI) is a minimally invasive technique that allows the assessment of bone material strength index (BMSi) in vivo, by measuring the depth of a micron-sized, spherical tip into cortical bone that is then indexed to the depth of the tip into a reference material. In this study, we aimed to assess the practicality of its application in 99 women aged 42-84 yr from the Geelong Osteoporosis Study. Impact microindentation was performed in the mid-shaft of the right tibia using the OsteoProbe. Immediately following measurement, each participant was requested to rate on a Visual Analogue Scale [0-10] the level of discomfort anticipated and experienced, any initial reluctance towards the measurement and whether they were willing to repeat the measurement. Of 99 potential participants who attended this assessment phase, 55 underwent IMI measurement. Reasons for non-measurement in 44 women were existing skin conditions (n = 8, 18.2 %) and excessive soft tissue around mid-tibial region (n = 32, 72.2 %). An additional four (9.1 %) participants did not provide any reasons for declining. For 55 participants who had underwent IMI, the expectation for pain when briefed about the procedure was low (2.28 ± 2.39), as was pain experienced during the measurement (0.72 ± 1.58). Participants were not reluctant to undergo the measurement (0.83 ± 1.67), and all indicated a willingness to repeat the measurement. Results of this study showed that the IMI technique is well tolerated and accepted by women participating in the Geelong Osteoporosis Study, suggesting that the technique shows promise in a research or clinical setting.

For older individuals there is greater variance in low mean Bone Material Strength Index values obtained with the OsteoProbe.

Purpose: Bone Material Strength Index (BMSi) quantifies the resistance of bone to a specified force in vivo at the mid tibia using impact microindentation (IMI). Anecdotal evidence suggests that within-participant variance in BMSi may be associated with the individual's mean BMSi. This study aimed to investigate associations between mean and variance of IMI measures in a population-based study. Methods: Participants were men (n = 420) and women (n = 55) from the Geelong Osteoporosis Study who underwent BMSi measurement using the OsteoProbe at recent follow-up phases (men 2016-2022; women 2022-2023). Median age was 63.7 yr (IQR 53.0-71.8). BMSi standard deviation was skewed and therefore natural log transformed (referred to as ln-SD). Linear regression models were developed with ln-SD as the dependent variable and mean BMSi as the independent variable adjusting for sex, age, height and weight. Results: In unadjusted models, greater BMSi was associated with lower ln-SD (ß = -1.58, p = 0.042). This association was sustained after adjustment (p = 0.013), and an interaction between BMSi and age was observed (p = 0.004). In those aged 63.7 yr and over (median age), mean BMSi was inversely associated with ln-SD (ß = -3.22, p = 0.002). Sex was not identified as an effect modifier. In younger participants, no BMSi*ln-SD association was observed. Conclusion: In older men and women, there was greater variance in low BMSi values. This suggests that standard deviation of the BMSi measure may provide additional information in the assessment of bone health and is worthy of further investigation. Mini abstract: In older men and women, greater variance is observed when BMSi values are low, reflecting potential variation in the bone surface.