56 research outputs found

    High-Frequency, Low-Magnitude Vibration Does Not Prevent Bone Loss Resulting from Muscle Disuse in Mice following Botulinum Toxin Injection

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    High-frequency, low-magnitude vibration enhances bone formation ostensibly by mimicking normal postural muscle activity. We tested this hypothesis by examining whether daily exposure to low-magnitude vibration (VIB) would maintain bone in a muscle disuse model with botulinum toxin type A (BTX). Female 16–18 wk old BALB/c mice (N = 36) were assigned to BTX-VIB, BTX-SHAM, VIB, or SHAM. BTX mice were injected with BTX (20 µL; 1 U/100 g body mass) into the left hindlimb posterior musculature. All mice were anaesthetized for 20 min/d, 5 d/wk, for 3 wk, and the left leg mounted to a holder. Through the holder, VIB mice received 45 Hz, ±0.6 g sinusoidal acceleration without weight bearing. SHAM mice received no vibration. At baseline and 3 wk, muscle cross-sectional area (MCSA) and tibial bone properties (epiphysis, metaphysis and diaphysis) were assessed by in vivo micro-CT. Bone volume fraction in the metaphysis decreased 12±9% and 7±6% in BTX-VIB and BTX-SHAM, but increased in the VIB and SHAM. There were no differences in dynamic histomorphometry outcomes between BTX-VIB and BTX nor between VIB and SHAM. Thus, vibration did not prevent bone loss induced by a rapid decline in muscle activity nor produce an anabolic effect in normal mice. The daily loading duration was shorter than would be expected from postural muscle activity, and may have been insufficient to prevent bone loss. Based on the approach used in this study, vibration does not prevent bone loss in the absence of muscle activity induced by BTX

    The influence of muscular action on bone strength via exercise

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    Mechanical stimuli influence bone strength, with internal muscular forces thought to be the greatest stressors of bone. Consequently, the effects of exercise in improving and maintaining bone strength have been explored in a number of interventional studies. These studies demonstrate a positive effect of high-impact activities (i.e. where large muscle forces are produced) on bone strength, with benefits being most pronounced in interventions in early pubertal children. However, current studies have not investigated the forces acting on bones and subsequent deformation, preventing the development of optimised and targeted exercise interventions. Similarly, the effects of number and frequency of exercise repetitions and training sessions on bone accrual are unexplored. There are conflicting results as to gender effects on bone response to exercise, and the effects of age and starting age on the osteogenic effects of exercise are not well known. It also appears that exercise interventions are most effective in physically inactive people or counteracting conditions of disuse such as bed rest. Bone strength is only one component of fracture risk, and it may be that exercise resulting in improvements in, e.g., muscle force/power and/or balance is more effective than those whose effects are solely osteogenic. In summary, exercise is likely to be an effective tool in maintaining bone strength but current interventions are far from optimal. © Springer Science+Business Media 2013

    The Role of Whole-body Vibration in the Prevention of Postmenopausal Osteoporosis

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    Whole-body vibration (WBV) was recently introduced as a potential modality for strengthening bones, and this thesis was set out to investigate whether it plays a role in the prevention of postmenopausal bone loss. First, effects of WBV on bone mineral density (BMD) were systematically evaluated in previous randomized controlled trials (RCTs) in postmenopausal women. Second, a RCT of 202 postmenopausal women with primary osteopenia not on bone medications was conducted to investigate the effects of WBV at 0.3g and 90 Hz versus 0.3g and 30 Hz versus controls on various bone outcomes, as measured by dual-energy x-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and quantitative ultrasound (QUS). In the systematic evaluation of previous RCTs, statistically significant increase in areal BMD (aBMD) at the hip was found in postmenopausal women receiving WBV versus controls, but the effect was small and may have been due to study bias. Also, WBV was not found to influence aBMD at the lumbar spine or volumetric BMD (vBMD) at the distal tibia in the systematic evaluation. In the RCT conducted in this thesis, no statistically significant effects of WBV were found on aBMD at the femoral neck, total hip or lumbar spine, as measured by DXA, or on vBMD or bone structure parameters at the distal tibia or distal radius, as measured by HR-pQCT. Further in this RCT, a statistically significant decrease was observed in QUS attenuation at the calcaneus in women receiving 90 Hz or 30 Hz WBV compared to controls. This may have been due to heel bone or soft tissue damage, although the effect was small and may not be clinically important. In conclusion, this investigation of postmenopausal women did not find clinically relevant benefits of WBV on osteoporotic-prone skeletal sites, including the hip, spine, tibia or radius, while potentially harmful effects on heel bone and/or soft tissue was observed in response to WBV. Thus based on this thesis, WBV is currently not recommended for the prevention of bone loss in community-dwelling postmenopausal women with primary osteopenia.Ph

    Effects of vertical and side-alternating vibration training on fall risk factors and bone turnover in older people at risk of falls

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    Background: Whole body vibration training may improve neuromuscular function, falls risk and bone density, but previous studies have had conflicting findings. Objective: This study aimed to evaluate the influence of vertical and side-alternating vibration on musculoskeletal health in older people at risk of falls. Design: Single blind randomised controlled trial comparing vibration training to sham vibration in addition to usual care. Participants: Participants were 61 older people (37 women and 24 men), aged 80.2 + 6.5y, referred to an outpatient falls prevention service. Methods: Participants were randomly assigned to vertical vibration (VV), side-alternating vibration (SV) or sham vibration (Sham) in addition to the usual falls prevention programme. Participants were requested to attend three vibration sessions per week for 12 weeks, with sessions increasing to six, 1 minute bouts of vibration. Falls risk factors and neuromuscular tests were assessed, and blood samples collected for determination of bone turnover, at baseline and following the intervention. Results: Chair stand time, timed-up-and-go time, fear of falling, NEADL index and postural sway with eyes open improved in the Sham group. There were significantly greater gains in leg power in the VV than Sham group and in bone formation in SV and VV compared to the Sham vibration group. Conversely, body sway improved less in the VV than Sham group. Changes in falls risk factors did not differ between groups. Conclusions: Whole body vibration increased leg power and bone formation, but did not provide any additional benefits to balance or fall risk factors beyond a falls prevention programme in older people at risk of falls

    Effects of Whole‐Body Vibration Therapy on Distal Tibial Myotendinous Density and Volume: A Randomized Controlled Trial in Postmenopausal Women

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    ABSTRACT Whole‐body vibration (WBV) therapy has been proposed as a therapy to reduce sarcopenia and improve muscle strength. The purpose of this study was to explore whether 12 months of WBV therapy increases myotendinous density and volume of the distal tibia as measured by HR‐pQCT in postmenopausal women in a parallel group, randomized controlled trial with 1:1:1 allocation to three arms. Postmenopausal women (N = 202) with low hip BMD were randomized to 20 min daily of 0.3g 30‐Hz WBV therapy, 0.3g 90‐Hz WBV therapy using the Juvent platform (Juvent, Somerset, NJ, USA), or no WBV. The main outcome measure was myotendinous density (HU) and volume (mm3) at the distal tibia measured at baseline and 12 months with HR‐pQCT. There were no significant effects on myotendinous density or volume at the distal tibia after 12 months of daily 30‐ or 90‐Hz WBV therapy compared with no WBV therapy. Mean change (SD) in myotendinous density from baseline was 4.6 (5.7) HU in the 30‐Hz WBV group, 3.9 (6.1) HU in the 90‐Hz WBV group, and 3.9 (5.4) HU in the control group (p = 0.70). Mean change (SD) in myotendinous volume from baseline was −7 (503) mm3 in the 30‐Hz WBV group, 111 (615) mm3 in the 90‐Hz WBV group, and 35 (615) mm3 in the control group (p = 0.50). In conclusion, WBV therapy at 30‐ or 90‐Hz for 12 months had no significant effects on myotendinous density or volume at the distal tibia as measured by HR‐pQCT in postmenopausal women. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research

    Mortality in older adults following a fragility fracture: real-world retrospective matched-cohort study in Ontario

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    Abstract Background Recent studies are lacking reports on mortality after non-hip fractures in adults aged > 65. Methods This retrospective, matched-cohort study used de-identified health services data from the publicly funded healthcare system in Ontario, Canada, contained in the ICES Data Repository. Patients aged 66 years and older with an index fragility fracture occurring at any osteoporotic site between 2011 and 2015 were identified from acute hospital admissions, emergency and ambulatory care using International Classification of Diseases (ICD)-10 codes and data were analyzed until 2017. Thus, follow-up ranged from 2 years to 6 years. Patients were excluded if they presented with an index fracture occurring at a non-osteoporotic fracture site, their index fracture was associated with a trauma code, or they experienced a previous fracture within 5 years prior to their index fracture. This fracture cohort was matched 1:1 to controls within a non-fracture cohort by date, sex, age, geography and comorbidities. All-cause mortality risk was assessed. Results The survival probability for up to 6 years post-fracture was significantly reduced for the fracture cohort vs matched non-fracture controls (p < 0.0001; n = 101,773 per cohort), with the sharpest decline occurring within the first-year post-fracture. Crude relative risk of mortality (95% confidence interval) within 1-year post-fracture was 2.47 (2.38–2.56) in women and 3.22 (3.06–3.40) in men. In the fracture vs non-fracture cohort, the absolute mortality risk within one year after a fragility fracture occurring at any site was 12.5% vs 5.1% in women and 19.5% vs 6.0% in men. The absolute mortality risk within one year after a fragility fracture occurring at a non-hip vs hip site was 9.4% vs 21.5% in women and 14.4% vs 32.3% in men. Conclusions In this real-world cohort aged > 65 years, a fragility fracture occurring at any site was associated with reduced survival for up to 6 years post-fracture. The greatest reduction in survival occurred within the first-year post-fracture, where mortality risk more than doubled and deaths were observed in 1 in 11 women and 1 in 7 men following a non-hip fracture and in 1 in 5 women and 1 in 3 men following a hip fracture

    Fragility fracture identifies patients at imminent risk for subsequent fracture: real-world retrospective database study in Ontario, Canada

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    Abstract Background The secondary fracture prevention gap in the osteoporosis field has been previously described as a ‘crisis’. Closing this gap is increasingly important in the context of accumulating evidence showing that an incident fragility fracture is associated with an increased risk of subsequent fracture within 1–2 years, known as imminent fracture risk. The objective of this study was to use health services data to characterize the time between index fragility fractures occurring at different osteoporotic sites and subsequent fractures. Methods This retrospective observational study used de-identified health services data from the publicly funded healthcare system in Ontario, the largest province of Canada. Patients aged > 65 with an index fragility fracture occurring between 2011 and 2015 were identified from the ICES Data Repository using International Classification of Diseases (ICD)-10 codes. We examined median time to subsequent fragility fractures for osteoporotic fracture sites until the end of follow-up (2017). BMD assessment and use of osteoporosis therapies following index fracture were also characterized. Results Among 115,776 patients with an index fragility fracture, 17.8% incurred a second fragility fracture. Median time between index and second fracture occurring at any site was 555 days (interquartile range: 236–955). For each index fracture site examined, median time from index to second fracture was  3 years post index fracture. Conclusions This cohort of Canadian patients aged > 65 years who experienced a fragility fracture at any site are at imminent risk of experiencing subsequent fracture within the next 2 years and should be proactively assessed and treated
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