Quantifying Changes in the Spatial Structure of Trabecular Bone

We apply recently introduced measures of complexity for the structural quantfication of distal tibial bone. For the first time, we are able to investigate the temporal structural alteration of trabecular bone. Based on four patients, we show how bone may alter due to temporal immobilisation

Balance Performance across the Lifespan Assessed by the Leonardo Mechanograph®: A Cross-Sectional Study

Reference values of sway parameters have not been published for the Leonardo mechanograph® so far. The aim of this cross-sectional study was to determine normative values on postural control measured by the force plate Leonardo Mechanograph® and to analyze the influence of age and sex on balance performance. A set of standardized standing positions with eyes opened (Romberg, semi-tandem, tandem, unipedal standing) was carried out. Analysis of covariance (ANCOVA) was used to detect age-and sex-related differences in center of pressure (COP) parameters (path length, velocity, elliptical area, anterior-posterior, and medio-lateral directions). Measurements were available for 570 subjects aged 20–86 years. Statistical analysis showed a high effect of age group on postural control (partial n² between 0.1 and 0.4) with a U-shaped dependency between postural control and age for all area- and path-related COP parameters, with the largest sway in the youngest (aged 20–40) and the oldest age group (aged 60–86). For velocity of COP, a linear deterioration with increasing age was found. Medio-lateral components of COP are likely to indicate the extent of postural control. Significant sex differences were not clearly supported by current findings. Age- and sex-related normative values are a useful resource for diagnostic, research, and training

Changes in lower extremity muscle function after 56 days of bed rest

Preservation of muscle function, known to decline in microgravity and simulation (bed rest), is important for successful spaceflight missions. Hence, there is great interest in developing interventions to prevent musclefunction loss. In this study, 20 males underwent 56 days of bed rest. Ten volunteers were randomized to do resistive vibration exercise (RVE). The other 10 served as controls. RVE consisted of muscle contractions against resistance and concurrent whole-body vibration. Main outcome parameters were maximal isometric plantar-flexion force (IPFF), electromyography (EMG)/force ratio, as well as jumping power and height. Measurements were obtained before and after bed rest, including a morning and evening assessment on the first day of recovery from bed rest. IPFF (-17.1%), jumping peak power (-24.1%), and height (-28.5%) declined (P < 0.05) in the control group. There was a trend to EMG/force ratio decrease (-20%; P < 0.051). RVE preserved IPFF and mitigated the decline of countermovement jump performance (peak power -12.2%; height -14.2%). In both groups, IPFF was reduced between the two measurements of the first day of reambulation. This study indicates that bed rest and countermeasure exercises differentially affect the various functions of skeletal muscle. Moreover, the time course during recovery needs to be considered more thoroughly in future studies, as IPFF declined not only with bed rest but also within the first day of reambulation. RVE was effective in maintaining IPFF but only mitigated the decline in jumping performance. More research is needed to develop countermeasures that maintain muscle strength as well as other muscle functions including power

an RCT

Physical inactivity leads to a deconditioning of the skeletal, neuromuscular and cardiovascular system. It can lead to impaired quality of life, loss of autonomy, falls and fractures. Regular exercise would be a logical remedy, but the generally recommended high-volume endurance and strength training programs require a lot of time and equipment. In this randomized controlled study with 23 healthy participants, we established that a short, intensive jump training program can prevent the large musculoskeletal and cardiovascular deconditioning effects caused by two months of physical inactivity during bed rest, particularly the loss of bone mineral mass and density, lean muscle mass, maximal leg strength and peak oxygen uptake. The jump training group showed no significant changes with respect to these indicators of musculoskeletal and cardiovascular health after 60 days of bed rest, whereas the control group exhibited substantial losses: up to −2.6% in tibial bone mineral content and density, −5% in leg lean mass, −40% in maximal knee extension torque and −29% in peak oxygen uptake. Consequently, we recommend jump training as a very time-efficient and effective type of exercise for astronauts on long-term space missions, the elderly and sedentary populations in general

Effects of strontium ranelate and alendronate on bone microstructure in women with osteoporosis: Results of a 2-year study

Summary: Strontium ranelate appears to influence more than alendronate distal tibia bone microstructure as assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT), and biomechanically relevant parameters as assessed by micro-finite element analysis (μFEA), over 2years, in postmenopausal osteoporotic women. Introduction: Bone microstructure changes are a target in osteoporosis treatment to increase bone strength and reduce fracture risk. Methods: Using HR-pQCT, we investigated the effects on distal tibia and radius microstructure of strontium ranelate (SrRan; 2g/day) or alendronate (70mg/week) for 2years in postmenopausal osteoporotic women. This exploratory randomized, double-blind trial evaluated HR-pQCT and FEA parameters, areal bone mineral density (BMD), and bone turnover markers. Results: In the intention-to-treat population (n = 83, age: 64 ± 8years; lumbar T-score: −2.8 ± 0.8 [DXA]), distal tibia Cortical Thickness (CTh) and Density (DCort), and cancellous BV/TV increased by 6.3%, 1.4%, and 2.5%, respectively (all P < 0.005), with SrRan, but not with alendronate (0.9%, 0.4%, and 0.8%, NS) (P < 0.05 for all above between-group differences). Difference for CTh evaluated with a distance transformation method was close to significance (P = 0.06). The estimated failure load increased with SrRan (+2.1%, P < 0.005), not with alendronate (−0.6%, NS) (between-group difference, P < 0.01). Cortical stress was lower with SrRan (P < 0.05); both treatments decreased trabecular stress. At distal radius, there was no between-group difference other than DCort (P < 0.05). Bone turnover markers decreased with alendronate; bALP increased (+21%) and serum-CTX-I decreased (−1%) after 2years of SrRan (between-group difference at each time point for both markers, P < 0.0001). Both treatments were well tolerated. Conclusions: Within the constraints of HR-pQCT method, and while a possible artefactual contribution of strontium cannot be quantified, SrRan appeared to influence distal tibia bone microstructure and FEA-determined biomechanical parameters more than alendronate. However, the magnitude of the differences is unclear and requires confirmation with another metho

Strontium ranelate and alendronate have differing effects on distal tibia bone microstructure in women with osteoporosis

The structural basis of the antifracture efficacy of strontium ranelate and alendronate is incompletely understood. We compared the effects of strontium ranelate and alendronate on distal tibia microstructure over 2years using HR-pQCT. In this pre-planned, interim, intention-to-treat analysis at 12months, 88 osteoporotic postmenopausal women (mean age 63.7±7.4) were randomized to strontium ranelate 2g/day or alendronate 70mg/week in a double-placebo design. Primary endpoints were changes in microstructure. Secondary endpoints included lumbar and hip areal bone mineral density (aBMD), and bone turnover markers. This trial is registered with http://www.controlled-trials.com, number ISRCTN82719233. Baseline characteristics of the two groups were similar. Treatment with strontium ranelate was associated with increases in mean cortical thickness (CTh, 5.3%), cortical area (4.9%) and trabecular density (2.1%) (all P<0.001, except cortical area P=0.013). No significant changes were observed with alendronate. Between-group differences in favor of strontium ranelate were observed for CTh, cortical area, BV/TV and trabecular density (P=0.045, 0.041, 0.048 and 0.035, respectively). aBMD increased to a similar extent with strontium ranelate and alendronate at the spine (5.7% versus 5.1%, respectively) and total hip (3.3% versus 2.2%, respectively). No significant changes were observed in remodeling markers with strontium ranelate, while suppression was observed with alendronate. Within the methodological constraints of HR-pQCT through its possible sensitivity to X-ray attenuation of different minerals, strontium ranelate had greater effects than alendronate on distal tibia cortical thickness and trabecular volumetric densit

Establishing reference intervals for bone turnover markers in healthy postmenopausal women in a nonfasting state.

In order to interpret bone turnover markers (BTMs), we need to establish healthy reference intervals. It is difficult to establish reference intervals for older women because they commonly suffer from diseases or take medications that affect bone turnover. The aims of this study were: (1) to identify diseases and drugs that have a substantial effect on BTMs; (2) to establish reference intervals for premenopausal and postmenopausal women; and (3) to examine the effects of other factors on BTMs in healthy postmenopausal women. We studied women aged 30-39 years (n=258) and women aged 55-79 years (n=2419) from a five-European centre population-based study. We obtained a nonfasting serum and second morning void urine samples at a single baseline visit. BTMs were measured using automated immunoassay analysers. BTMs were higher in patients with vitamin D deficiency and chronic kidney disease. Three or more BTMs were higher in women who were osteoporotic and at least two BTMs were lower in women who were oestrogen replete, taking osteoporosis treatments or having diseases known to affect bone turnover. These were used as exclusion criteria for selecting the populations for the reference intervals. The reference intervals for BTMs were higher in postmenopausal than premenopausal women. Levels of BTMs were not dependent on geographical location and increased with age