Early smoking is associated with peak bone mass and prevalent fractures in young, healthy men

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Low areal bone mass is a risk factor for fractures in men. Limited data are available on fractures and bone geometry in men, and the relation with sex steroids is incompletely understood. We investigated prevalent fractures in relation to peak bone mass, bone geometry, and sex steroids in healthy young men. Healthy male siblings (n ¼ 677) at the age of peak bone mass (25 to 45 years) were recruited in a cross-sectional population-based study. Trabecular and cortical bone parameters of the radius and cortical bone parameters of the tibia were assessed using peripheral quantitative computed tomography (pQCT). Areal bone mineral density (aBMD) was determined using dual-energy X-ray absorptiometry (DXA). Sex steroids were determined using immunoassays, and fracture prevalence was assessed using questionnaires. Fractures in young men were associated with a longer limb length, shorter trunk, lower trabecular BMD, smaller cortical bone area, and smaller cortical thickness ( p < .005) but not with bone-size-adjusted volumetic BMD (vBMD). With decreasing cortical thickness [odds ratio (OR) 1.4/SD, p .001] and decreasing cortical area (OR 1.5/SD, p .001), fracture odds ratios increased. No association between sex steroid concentrations and prevalent fractures was observed. Childhood fractures ( 15 years) were associated with a thinner bone cortex (À5%, p .005) and smaller periosteal size (À3%, p .005). Fractures occurring later than 15 years of age were associated with a thinner bone cortex (À3%, p .05) and larger endosteal circumference (þ3%, p .05) without differences in periosteal bone size. In conclusion, prevalent fractures in healthy young men are associated with unfavorable bone geometry and not with cortical vBMD when adjusting for bone size. Moreover, the data suggest different mechanisms of childhood fractures and fractures during adult life. ß 2010 American Society for Bone and Mineral Research. KEY WORDS: pQCT; PEAK BONE MASS; OSTEOPOROSIS; MEN; BONE GEOMETRY; FRACTURE IntroductionB one mass at any stage in adult life is determined by the growth and mineralization of the skeleton during the first two decades of life leading to the peak bone mass (PBM) and by subsequent net changes in bone mass, usually bone loss, starting in the middle of the third decade. (1) Although fracture risk in old age is lower in men than in women, fracture risk is higher in boys and young men than in girls or young women. (2,3) In both young and older subjects, low areal bone mineral density (aBMD) has been associated with increased fracture prevalence, although most evidence has been obtained in women (4,5) or elderly men, (6) and only limited data are available in boys or young men. (7)(8)(9) An important limitation of dual-energy X-ray absorptiometry (DXA) is that it measures projected aBMD and not volumetric BMD (vBMD). In determining PBM and future facture risk, this has important clinical implications because bone strength depends not only on the amount of bone tissue but also on the diameter, shape, and volumetric bone...

Section: Discussionsupporting

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Section: Study Design and Populationmentioning

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Section: Pqctmentioning

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Section: General Characteristicsmentioning

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Section: General Characteristicsmentioning

confidence: 99%

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Prevalent fractures are related to cortical bone geometry in young healthy men at age of peak bone mass

Taes

Lapauw

Vanbillemont

et al. 2010

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Smoking is associated with impaired bone mass development in young adult men: A 5-year longitudinal study

Rudäng

Darelid

Nilsson

et al. 2012

It has previously been shown that smoking is associated with reduced bone mass and increased fracture risk, but no longitudinal studies have been published investigating altered smoking behavior at the time of bone mass acquisition. The aim of this study was to investigate the development of bone density and geometry according to alterations in smoking behavior in a 5-year, longitudinal, population-based study of 833 young men, age 18 to 20 years (baseline). Furthermore, we aimed to examine the cross-sectional, associations between current smoking and parameters of trabecular microarchitecture of the radius and tibia, using high-resolution peripheral quantitative computed tomography (HR-pQCT), in young men aged 23 to 25 years (5-year follow-up). Men who had started to smoke since baseline had considerably smaller increases in areal bone mineral density (aBMD) at the total body (mean AE SD, 0.020 AE 0.047 mg/cm 2 versus 0.043 AE 0.040 mg/cm 2 , p < 0.01) and lumbar spine (0.027 AE 0.062 mg/cm 2 versus 0.052 AE 0.065 mg/cm 2 , p ¼ 0.04), and substantially greater decreases in aBMD at the total hip (À0.055 AE 0.058 mg/cm 2 versus À0.021 AE 0.062 mg/cm 2 , p < 0.01) and femoral neck (À0.077 AE 0.059 mg/cm 2 versus À0.042 AE 0.070 mg/cm 2 , p < 0.01) than men who were nonsmokers at both the baseline and follow-up visits. At the tibia, subjects who had started to smoke had a smaller increment of the cortical cross-sectional area (CSA) than nonsmokers (8.1 AE 4.3 mm 2 versus 11.5 AE 8.9 mm 2 , p ¼ 0.03), and a larger decrement of trabecular volumetric BMD (vBMD) than nonsmokers (À13.9 AE 20.5 mg/mm 3 versus À4.1 AE 13.9 mg/mm 3 , p < 0.001). In the cross-sectional analysis at follow-up (23-25 years of age), smokers had significantly lower trabecular vBMD at the tibia (7.0%, p < 0.01) due to reduced trabecular thickness (8.9%, p < 0.001), as assessed using HR-pQCT, than nonsmokers. In conclusion, this study is the first to report that men who start to smoke in young adulthood have poorer development of their aBMD at clinically important sites such as the spine and hip than nonsmokers, possibly due to augmented loss of trabecular density and impaired growth of cortical cross-sectional area. ß

Determinants of Transitional Zone Area and Porosity of the Proximal Femur Quantified In Vivo in Postmenopausal Women

Shigdel

Osima

Lukic

et al. 2015

Bone architecture as well as size and shape is important for bone strength and risk of fracture. Most bone loss is cortical and occurs by trabecularization of the inner part of the cortex. We therefore wanted to identify determinants of the bone architecture, especially the area and porosity of the transitional zone, an inner cortical region with a large surface/matrix volume available for intracortical remodeling. In 211 postmenopausal women aged 54 to 94 years with nonvertebral fractures and 232 controls from the Tromsø Study, Norway, we quantified femoral subtrochanteric architecture in CT images using StrAx1.0 software, and serum levels of bone turnover markers (BTM, procollagen type I N-terminal propeptide and C-terminal cross-linking telopeptide of type I collagen). Multivariable linear and logistic regression analyses were used to quantify associations of age, weight, height, and bone size with bone architecture and BTM, and odds ratio (OR) for fracture. Increasing age, height, and larger total cross-sectional area (TCSA) were associated with larger transitional zone CSA and transitional zone CSA/TCSA (standardized coefficients [STB] ¼ 0.11 to 0.80, p 0.05). Increasing weight was associated with larger TCSA, but smaller transitional zone CSA/TCSA and thicker cortices (STB ¼ 0.15 to 0.22, p < 0.01). Increasing height and TCSA were associated with higher porosity of the transitional zone (STB ¼ 0.12 to 0.46, p < 0.05). Increasing BTM were associated with larger TCSA, larger transitional zone CSA/TCSA, and higher porosity of each of the cortical compartments (p < 0.01). Fracture cases exhibited larger transitional zone CSA and higher porosity than controls (p < 0.001). Per SD increasing CSA and porosity of the transitional zone, OR for fracture was 1.71 (95% CI, 1.37 to 2.14) and 1.51 (95% CI, 1.23 to 1.85), respectively. Cortical bone architecture is determined mainly by bone size as built during growth and is modified by lifestyle factors throughout life through bone turnover. Fracture cases exhibited larger transitional zone area and porosity, highlighting the importance of cortical bone architecture for fracture propensity.