Long-term leisure-time physical activity has a positive effect on bone mass gain in girls.

The purpose of this 7-year prospective longitudinal study was to examine whether the level and consistency of leisure-time physical activity (LTPA) during adolescence affected the bone mineral content (BMC) and bone mineral density (BMD) attained at early adulthood. The study subjects were 202 Finnish girls who were 10 to 13 years of age at baseline. Bone area (BA), BMC, and BMD of the total body (TB), total femur (TF), and lumbar spine (L(2)-L(4)) were assessed by dual-energy X-ray absorptiometry (DXA).

Low volumetric BMD is linked to upper-limb fracture in pubertal girls and persists into adulthood: a seven-year cohort study.

The aetiology of increased incidence of fracture during puberty is unclear. This study aimed to determine whether low volumetric bone mineral density (vBMD) in the distal radius is associated with upper-limb fractures in growing girls, and whether any such vBMD deficit persists into adulthood. Fracture history from birth to 20 years was obtained and verified by medical records in 1034 Finnish girls aged 10-13 years.

Monitoring bone growth using quantitative ultrasound in comparison with DXA and pQCT.

Quantitative ultrasound (QUS) is a safe, inexpensive, and nonradiation method for bone density assessment. QUS correlates with, and predicts fragility fractures comparable to, dual-energy X-ray absorptiometry (DXA)-derived bone mineral density (BMD) in postmenopausal women. However, its validity in monitoring bone growth in children is not well understood.

Ultrasonically determined thickness of long cortical bones: two-dimensional simulations of in vitro experiments.

Previously it has been demonstrated that cortical bone thickness can be estimated from ultrasonic guided-wave measurements, in an axial transmission configuration, together with an appropriate analytical model. This study considers the impact of bone thickness variation within the measurement region on the ultrasonically determined thickness (UTh). To this end, wave velocities and UTh were determined from experiments and from time-domain finite-difference simulations of wave propagation, both performed on a set of ten human radius specimens (29 measurement sites).

Ultrasonically determined thickness of long cortical bones: Three-dimensional simulations of in vitro experiments.

It was reported in a previous study that simulated guided wave axial transmission velocities on two-dimensional (2D) numerically reproduced geometry of long bones predicted moderately real in vitro ultrasound data on the same bone samples. It was also shown that fitting of ultrasound velocity with simple analytical model yielded a precise estimate (UTh) for true cortical bone thickness. This current study expands the 2D bone model into three dimensions (3D).

Assessment of the cortical bone thickness using ultrasonic guided waves: modelling and in vitro study.

Determination of cortical bone thickness is warranted, e.g., for assessing the level of endosteal resorption in osteoporosis or other bone pathologies.

Effects of calcium, dairy product, and vitamin D supplementation on bone mass accrual and body composition in 10-12-y-old girls: a 2-y randomized trial.

Background: Little is known about the relative effectiveness of calcium supplementation from food or pills with or without vitamin D supplementation for bone mass accrual during the rapid growth period.

Objective: The purpose was to examine the effects of both food-based and pill supplements of calcium and vitamin D on bone mass and body composition in girls aged 10-12 y.

Design: This placebo-controlled intervention trial randomly assigned 195 healthy girls at Tanner stage I-II, aged 10-12 y, with dietary calcium intakes <900 mg/d to 1 of 4 groups: calcium (1000 mg) + vitamin D3 (200 IU), calcium (1000 mg), cheese (1000 mg calcium), and placebo.

Differential effects of sex hormones on peri- and endocortical bone surfaces in pubertal girls.

Context: The role of sex steroids in bone growth in pubertal girls is not yet clear. Bone biomarkers are indicators of bone metabolic activity, but their value in predicting bone quality has not been studied in growing girls.

Objective: This study examines the association of sex hormones and bone markers with bone geometry and density in pubertal girls.

Differences in estimates of change of bone accrual and body composition in children because of scan mode selection with the prodigy densitometer.

Girls of age 10-13 yr with Tanner stage I-III maturation status (n = 155) were measured using the Prodigy (GE Lunar) densitometer. Bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were assessed for the whole body, lumbar spine, and proximal femur using the Thin (T) and Standard (S) scan modes at years 1 and 3 of the study. The differences obtained between the T and S mode at year 1 were 1-2% for the lumbar spine and proximal femur and 5-11% for the whole body.

Thickness sensitivity of ultrasound velocity in long bone phantoms.

One approach to bone disease diagnosis such as osteoporosis is to measure the velocity of ultrasound propagating axially along long bones. In this study, the variation in velocity as a function of radial position was assessed using two polyvinyl chloride (PVC) bone phantoms with cross-sectional geometry similar to the human tibia but differing in medullary cavity diameter. Two ultrasonometers were used: these were a commercial device operating at a relatively high frequency (HF) of 1.

Relationship of sex hormones to bone geometric properties and mineral density in early pubertal girls.

This study aimed to evaluate the associations among serum 17beta-estradiol (E2), testosterone (T), sex hormone-binding globulin (SHBG), bone geometric properties, and mineral density in 248 healthy girls between the ages of 10 and 13 yr old. The left tibial shaft was measured by peripheral quantitative computed tomography (Stratec XCT-2000; Stratec Medizintechnik, GmbH, Pforzheim, Germany). The cortical bone and marrow cavity areas were expressed as proportions of the total tibial cross-sectional area (CSA).

Guided ultrasonic waves in long bones: modelling, experiment and in vivo application.

Existing ultrasound devices for assessing the human tibia are based on detecting the first arriving signal, corresponding to a wave propagating at, or close to, the bulk longitudinal velocity in bone. However, human long bones are effectively irregular hollow tubes and should theoretically support the propagation of more complex guided modes similar to Lamb waves in plates. Guided waves are attractive because they propagate throughout the bone thickness and can potentially yield more information on bone material properties and architecture.

Bone marrow influences quantitative ultrasound measurements in human cancellous bone.

Quantitative ultrasound (QUS) transmission and backscatter measurements were made in 46 human cancellous bone specimens from the calcaneus. All QUS measurements were made at 35 degrees C, initially with marrow filling the pores and then repeated after substituting water for marrow. Bone mineral density (BMD) was determined using x-ray absorptiometry.