Effect of Low-Magnitude Mechanical Stimuli on Bone Density and Structure in Pediatric Crohn's Disease: A Randomized Placebo-Controlled Trial

Association between vitamin D level and pediatric inflammatory bowel disease: A systematic review and meta-analysis

Background

Previous studies have reported that the incidence of pediatric inflammatory bowel disease (IBD) is related to vitamin D, but it is still unclear. This study intends to calculate the relationship between pediatric IBD and vitamin D.

Methods

A comprehensive literature search from inception to January 2023 was performed in the PubMed, EMBASE, Medline, Web of Science, and Google Scholar databases. Relevant data were extracted as required and used for subsequent calculations.

Results

Sixteen papers were included, and there was no significant difference between the average vitamin D level in IBD patients and healthy controls. In addition, the overall pooled results showed that C-reactive protein (CRP) was 2.65 higher before vitamin D supplementation than after supplementation [SMD = 2.65, 95% CI = (2.26, 3.04)]. Moreover, patients with IBD in remission were 0.72 higher before vitamin D supplementation than after supplementation [OR = 0.72, 95% CI = (0.52, 1.00)].

Conclusion

This study suggested that there was no obvious relationship between pediatric IBD and vitamin D, while vitamin D supplementation can improve disease activity. Therefore, follow-up still needs many prospective studies to confirm the relationship between pediatric IBD and vitamin D.

Deficits in the Functional Muscle-Bone Unit in Youths with Fontan Physiology

OBJECTIVE

To determine whether dual energy X-ray absorptiometry (DXA), a clinically available tool, mirrors the magnitude of deficits in trabecular and cortical bone mineral density (BMD) demonstrated on peripheral quantitative computed tomography in youth with Fontan physiology.

STUDY DESIGN

We aimed to describe DXA-derived BMD at multiple sites and to investigate the relationship between BMD and leg lean mass, a surrogate for skeletal muscle loading. Subjects with Fontan (n = 46; aged 5-20 years) underwent DXA in a cross-sectional study of growth and bone and muscle health as described previously. Data from the Bone Mineral Density in Childhood Study were used to calculate age-, sex-, and race-specific BMD z-scores of the whole body, lumbar spine, hip, femoral neck, distal one-third radius, ultradistal radius, and leg lean mass z-score (LLMZ).

RESULTS

Fontan BMD z-scores were significantly lower than reference at all sites-whole body, -0.34 ± 0.85 (P = .01); spine, -0.41 ± 0.96 (P = .008); hip, -0.75 ± 1.1 (P < .001); femoral neck, -0.73 ± 1.0 (P < .001); distal one-third radius, -0.87 ± 1.1 (P < .001); and ultradistal radius. -0.92 ± 1.03 (P < .001)-as was LLMZ (-0.93 ± 1.1; P < .001). Lower LLMZ was associated with lower BMD of the whole body (R² = 0.40; P < .001), lumbar spine (R² = 0.16; P = .005), total hip (R² = 0.32; P < .001), femoral neck (R² = 0.47; P < .001), and ultradistal radius (R² = 0.35; P < .001).

CONCLUSIONS

Patients with Fontan have marked deficits in both cortical (hip, distal one-third radius) and trabecular (lumbar spine, femoral neck, ultradistal radius) BMD. Lower LLMZ is associated with lower BMD and may reflect inadequate skeletal muscle loading. Interventions to increase muscle mass may improve bone accrual.

Effect of Low-Intensity Vibration on Bone Strength, Microstructure, and Adiposity in Pre-Osteoporotic Postmenopausal Women: A Randomized Placebo-Controlled Trial

There has been evidence that cyclical mechanical stimulation may be osteogenic, thus providing opportunities for nonpharmacological treatment of degenerative bone disease. Here, we applied this technology to a cohort of postmenopausal women with varying bone mineral density (BMD) T-scores at the total hip (-0.524 ± 0.843) and spine (-0.795 ± 1.03) to examine the response to intervention after 1 year of daily treatment with 10 minutes of vibration therapy in a randomized double-blinded trial. The device operates either in an active mode (30 Hz and 0.3 g) or placebo. Primary endpoints were changes in bone stiffness at the distal tibia and marrow adiposity of the vertebrae, based on 3 Tesla high-resolution MRI and spectroscopic imaging, respectively. Secondary outcome variables included distal tibial trabecular microstructural parameters and vertebral deformity determined by MRI, volumetric and areal bone densities derived using peripheral quantitative computed tomography (pQCT) of the tibia, and dual-energy X-ray absorptiometry (DXA)-based BMD of the hip and spine. Device adherence was 83% in the active group (n = 42) and 86% in the placebo group (n = 38) and did not differ between groups (p = .7). The mean 12-month changes in tibial stiffness in the treatment group and placebo group were +1.31 ± 6.05% and -2.55 ± 3.90%, respectively (group difference 3.86%, p = .0096). In the active group, marrow fat fraction significantly decreased after 12 months of intervention (p = .0003), whereas no significant change was observed in the placebo group (p = .7; group difference -1.59%, p = .029). Mean differences of the changes in trabecular bone volume fraction (p = .048) and erosion index (p = .044) were also significant, as was pQCT-derived trabecular volumetric BMD (vBMD; p = .016) at the tibia. The data are commensurate with the hypothesis that vibration therapy is protective against loss in mechanical strength and, further, that the intervention minimizes the shift from the osteoblastic to the adipocytic lineage of mesenchymal stem cells. © 2020 American Society for Bone and Mineral Research (ASBMR).

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

Does Whole-Body Vibration Treatment Make Children's Bones Stronger?

PURPOSE OF REVIEW

To summarize the last 10 years of literature regarding the effects of whole-body vibration (WBV) on bone in children, and if WBV results in increased bone acquisition.

RECENT FINDINGS

WBV intervention appears to be a safe intervention with beneficial effects on bone mass in some diseases and syndromes, but there is still low evidence for WBV in clinical practice. The positive effects on muscle strength, balance, and walking speed are more conclusive. One of the takeaways of this review is that well-trained individuals may not further improve bone mass with WBV; thus, interventions are more beneficial in pediatric individuals with Down syndrome or severe motor disabilities with low bone mass and reduced activity levels. WBV appears to be a safe non-pharmacological anabolic approach to increase bone mass in some pediatric populations; however, longer (> 6 months) and larger prospective studies are needed to elucidate the efficacy of WBV on bone health in young individuals.

The long-term residual effects of low-magnitude mechanical stimulation therapy on skeletal health

Background

Low-magnitude mechanical stimulation (LMMS) may improve skeletal health. The objective of this research was to investigate the long-term residual effects of LMMS on bone health. 10-week old female mice were given LMMS for 8 weeks; SHAM did not receive LMMS. Some groups remained on study for an additional 8 or 16 weeks post treatment (N = 17).

Results

Epiphyseal trabecular mineralizing surface to bone surface ratio (MS/BS) and bone formation rate (BFR/BS) were significantly greater in the LMMS group compared to the SHAM group at 8 weeks by 92 and 128% respectively. Mineral apposition rate (MAR) was significantly greater in the LMMS group 16 weeks post treatment by 14%.

Metaphyseal trabecular bone mineral density (BMD) increased by 18%, bone volume tissue volume ratio (BV/TV) increased by 37%, and trabecular thickness (Tb.Th.) increased by 10% with LMMS at 8 weeks post treatment. Significant effects 16 weeks post treatment were maintained for BV/TV and Tb.Th. The middle-cortical region bone volume (BV) increased by 4% and cortical thickness increased by 3% with 8-week LMMS.

Conclusions

LMMS improves bone morphological parameters immediately after and in some cases long-term post LMMS. Results from this work will be helpful in developing treatment strategies to increase bone health in younger individuals.

The risk of fracture to the tibia from a fragment simulating projectile

Penetrating injuries due to fragments energised by an explosive event are life threatening and are associated with poor clinical and functional outcomes. The tibia is the long bone most affected in survivors of explosive events, yet the risk of penetrating injury to it has not been quantified. In this study, an injury-risk assessment of penetrating injury to the tibia was conducted using a gas-gun system with a 0.78-g cylindrical fragment simulating projectile. An ovine tibia model was used to generate the injury-risk curves and human cadaveric tests were conducted to validate and scale the results of the ovine model. The impact velocity at 50% risk (±95% confidence intervals) for EF1+, EF2+, EF3+, and EF4+ fractures to the human tibia - using the modified Winquist-Hansen classification - was 271 ± 30, 363 ± 46, 459 ± 102, and 936 ± 182 m/s, respectively. The scaling factor for the impact velocity from cadaveric ovine to human was 2.5. These findings define the protection thresholds to improve the injury outcomes for fragment penetrating injury to the tibia.

Quantitative ultrasound imaging monitoring progressive disuse osteopenia and mechanical stimulation mitigation in calcaneus region through a 90-day bed rest human study

Background

Osteoporosis parallels aging and functional mechanical unloading (e.g., space flight and bed rest), jeopardizing mineral density, microstructure, and integrity of bone and leading to an increased risk of fracture. A way to combat this deterioration is to harness the sensitivity of bone to mechanical signals.

Objective

This study evaluates the longitudinal effect of a dynamic mechanical loading through the heel on human bone in vivo during 90-day bed rest, monitored by quantitative ultrasound (QUS) imaging and dual-energy X-ray absorptiometry (DXA) in localized regions of interests, i.e., calcaneus.

Methods

A total of 29 bed rest individuals were evaluated (11 control and 18 treatment) with a brief (10-minute) daily low-intensity (0.3g), high-frequency (30Hz) dynamic mechanical stimulation countermeasure through vibrational inhibition bone erosion (VIBE). Both QUS and DXA detected longitudinal bone density and quality changes.

Results

Ultrasound velocity (UV) decreased in the control group and increased in the group treated with low-intensity loading. The UV increased by 1.9% and 1.6% at 60- and 90-day bed rest (p=0.01) in VIBE over control groups. A trend was found in broadband ultrasound attenuation (BUA), with a VIBE benefit of 1.8% at day 60 and 0.5% at day 90 in comparison with control (p=0.5). Bone mineral density (BMD) assessed by DXA decreased -4.50% for control individuals and -2.18% for VIBE individuals, showing a moderate effect of the mechanical intervention (p=0.19). Significant correlations between QUS and DXA were observed, with a combined BUA and UV vs. BMD: r²=0.70.

Conclusion

These results indicated that low-intensity, high-frequency loading has the potential to mitigate regional bone loss induced by long-term bed rest and that QUS imaging may be able to assess the subtle changes in bone alteration.

Translational potential of this article

Quantitative ultrasound has shown the efficacy of noninvasively assessing bone mass and structural properties in cadaver and isolated trabecular bone samples. While its ability in measuring in vivo bone quality and density is still unclear, a scanning confocal ultrasound imaging is developed and can perform an instant assessment for the subtle changes of such bone loss. This ultrasound imaging modality can potentially be used in the clinical assessment of bone mass. Moreover, physical stimulation has shown the ability to prevent bone loss induced by functional disuse and estrogen deficiency in animal models. However, its treatment capability is unclear. This study has shown that low-magnitude mechanical signals, introduced using low-intensity vibration (LIV), can mitigate regional bone loss caused by functional disuse. Thus localized mechanical treatment, and the quantitative ultrasound imaging have shown translational potential to noninvasively attenuate bone loss, and assess bone mass in the clinic, e.g., in an extreme condition such as long-term space mission, and long-term bedrest such as in case of spinal cord injury.

Combating osteoporosis and obesity with exercise: leveraging cell mechanosensitivity

Osteoporosis, a condition of skeletal decline that undermines quality of life, is treated with pharmacological interventions that are associated with poor adherence and adverse effects. Complicating efforts to improve clinical outcomes, the incidence of obesity is increasing, predisposing the population to a range of musculoskeletal complications and metabolic disorders. Pharmacological management of obesity has yet to deliver notable reductions in weight and debilitating complications are rarely avoided. By contrast, exercise shows promise as a non-invasive and non-pharmacological method of regulating both osteoporosis and obesity. The principal components of exercise - mechanical signals - promote bone and muscle anabolism while limiting formation and expansion of fat mass. Mechanical regulation of bone and marrow fat might be achieved by regulating functions of differentiated cells in the skeletal tissue while biasing lineage selection of their common progenitors - mesenchymal stem cells. An inverse relationship between adipocyte versus osteoblast fate selection from stem cells is implicated in clinical conditions such as childhood obesity and increased marrow adiposity in type 2 diabetes mellitus, as well as contributing to skeletal frailty. Understanding how exercise-induced mechanical signals can be used to improve bone quality while decreasing fat mass and metabolic dysfunction should lead to new strategies to treat chronic diseases such as osteoporosis and obesity.

Recovery of stem cell proliferation by low intensity vibration under simulated microgravity requires LINC complex

Mesenchymal stem cells (MSC) rely on their ability to integrate physical and spatial signals at load bearing sites to replace and renew musculoskeletal tissues. Designed to mimic unloading experienced during spaceflight, preclinical unloading and simulated microgravity models show that alteration of gravitational loading limits proliferative activity of stem cells. Emerging evidence indicates that this loss of proliferation may be linked to loss of cellular cytoskeleton and contractility. Low intensity vibration (LIV) is an exercise mimetic that promotes proliferation and differentiation of MSCs by enhancing cell structure. Here, we asked whether application of LIV could restore the reduced proliferative capacity seen in MSCs that are subjected to simulated microgravity. We found that simulated microgravity (sMG) decreased cell proliferation and simultaneously compromised cell structure. These changes included increased nuclear height, disorganized apical F-actin structure, reduced expression, and protein levels of nuclear lamina elements LaminA/C LaminB1 as well as linker of nucleoskeleton and cytoskeleton (LINC) complex elements Sun-2 and Nesprin-2. Application of LIV restored cell proliferation and nuclear proteins LaminA/C and Sun-2. An intact LINC function was required for LIV effect; disabling LINC functionality via co-depletion of Sun-1, and Sun-2 prevented rescue of cell proliferation by LIV. Our findings show that sMG alters nuclear structure and leads to decreased cell proliferation, but does not diminish LINC complex mediated mechanosensitivity, suggesting LIV as a potential candidate to combat sMG-induced proliferation loss.

Vitamin D therapy in children with inflammatory bowel disease: A systematic review

BACKGROUND

Vitamin D deficiency is highly prevalent in children with inflammatory bowel disease (IBD). This may contribute to an increased risk of poor bone health and may also influence the course of disease. An optimal treatment strategy of vitamin D therapy in children with IBD has not yet been established.

AIM

To analyse the published intervention studies of vitamin D therapy in children with IBD.

METHODS

A systematic review was conducted of clinical studies involving children with IBD (including Crohn disease or ulcerative colitis) who had received vitamin D therapy. Studies up to March 31st 2018 were identified through MEDLINE, PubMed, EMBASE and the Cochrane Library. Search terms included synonyms of the following terms: vitamin D, paediatric, supplementation, IBD. References of included articles based on abstract were searched for other relevant articles. All relevant articles were accessed and reviewed in full text. Studies fitting the set criteria were included and the remainder were excluded.

RESULTS

Two hundred and seventy-seven discrete articles were identified. Following assessment of these articles included in the initial search and application of inclusion and exclusion criteria, ten published studies were included in this review. The included studies showed a heterogeneity in study design, inclusion and exclusion criteria, baseline demographics and treatment strategies. Treatment regimens differed in length, supplemented form of vitamin D and factors based upon which dosage was adjusted. Each of the reports included in this review concluded their vitamin D regimens to be safe and well-tolerated. Few of the included studies reported secondary outcomes on the efficacy of vitamin D treatment upon the clinical course of disease or markers of inflammation. The majority of included trials were not sufficient in raising serum vitamin D levels to an adequate level (30 ng/mL) in children with IBD with vitamin D deficiency.

CONCLUSION

The included trials featured diverse treatment regimens that were predominantly insufficient in correcting vitamin D deficiency or maintaining adequate levels in children with IBD. Better treatment regimens are required for the management of vitamin D deficiency in children with IBD.

Pediatric Bone Mineral Accrual Z-Score Calculation Equations and Their Application in Childhood Disease

Annual gains in BMC and areal bone mineral density (aBMD) in children vary with age, pubertal status, height-velocity, and lean body mass accrual (LBM velocity). Evaluating bone accrual in children with bone health-threatening conditions requires consideration of these determinants. The objective of this study was to develop prediction equations for calculating BMC/aBMD velocity SD scores (velocity-Z) and to evaluate bone accrual in youth with health conditions. Bone and body compositions via DXA were obtained for up to six annual intervals in healthy youth (n = 2014) enrolled in the Bone Mineral Density in Childhood Study (BMDCS) . Longitudinal statistical methods were used to develop sex- and pubertal-status-specific reference equations for calculating velocity-Z for total body less head-BMC and lumbar spine (LS), total hip (TotHip), femoral neck, and 1/3-radius aBMD. Equations accounted for (1) height velocity, (2) height velocity and weight velocity, or (3) height velocity and LBM velocity. These equations were then applied to observational, single-center, 12-month longitudinal data from youth with cystic fibrosis (CF; n = 65), acute lymphoblastic leukemia (ALL) survivors (n = 45), or Crohn disease (CD) initiating infliximab (n = 72). Associations between BMC/aBMD-Z change (conventional pediatric bone health monitoring method) and BMC/aBMD velocity-Z were assessed. The BMC/aBMD velocity-Z for CF, ALL, and CD was compared with BMDCS. Annual changes in the BMC/aBMD-Z and the BMC/aBMD velocity-Z were strongly correlated, but not equivalent; LS aBMD-Z = 1 equated with LS aBMD velocity-Z = -3. In CF, BMC/aBMD velocity-Z was normal. In posttherapy ALL, BMC/aBMD velocity-Z was increased, particularly at TotHip (1.01 [-.047; 1.7], p < 0.0001). In CD, BMC/aBMD velocity-Z was increased at all skeletal sites. LBM-velocity adjustment attenuated these increases (eg, TotHip aBMD velocity-Z: 1.13 [0.004; 2.34] versus 1.52 [0.3; 2.85], p < 0.0001). Methods for quantifying the BMC/aBMD velocity that account for maturation and body composition changes provide a framework for evaluating childhood bone accretion and may provide insight into mechanisms contributing to altered accrual in chronic childhood conditions. © 2018 American Society for Bone and Mineral Research.

Children with Crohn's Disease Frequently Consume Select Food Additives

OBJECTIVE

Certain food additives may promote the pathogenesis of Crohn's disease (CD), but thus far the evaluation of food additive exposures in humans has been limited. The objective of this study was to quantify food additive exposures in children with CD.

METHODS

In a trial for bone health in CD, children were followed over 24 months with evaluation of disease characteristics, dietary intake, and body composition. At baseline, participants completed three 24-h dietary recalls. Foods were categorized, and the ingredient list for each item was evaluated for the presence of select food additives: polysorbate-80, carboxymethylcellulose, xanthan gum, soy lecithin, titanium dioxide, carrageenan, maltodextrin, and aluminosilicates. The frequency of exposures to these food additives was described for study participants and for food categories.

RESULTS

At study baseline, 138 participants, mean age 14.2 ± 2.8 years, 95% having inactive or mild disease, were enrolled and dietary recalls were collected. A total of 1325 unique foods were recorded. Mean exposures per day for xanthan gum was 0.96 ± 0.72, carrageenan 0.58 ± 0.63, maltodextrin 0.95 ± 0.77, and soy lecithin 0.90 ± 0.74. The other additives had less than 0.1 exposures per day. For the 8 examined food additives, participants were exposed to a mean (SD) of 3.6 ± 2.1 total additives per recall day and a mean (SD) of 2.4 ± 1.0 different additives per day.

CONCLUSION

Children with CD frequently consume food additives, and the impact on disease course needs further study.

Changes in pediatric DXA measures of musculoskeletal outcomes and correlation with quantitative CT following treatment of acute lymphoblastic leukemia

We previously reported significant gains in pQCT measures of tibia trabecular bone mineral density (BMD) and cortical structure following completion of therapy in children and adolescents with acute lymphoblastic leukemia (ALL). The objective of this study was to examine changes in DXA measures used in clinical practice and expressed as Z-scores using robust national reference data. Children and adolescents, ages 5 to 18 years were enrolled within 2 (median 0.8) years of completing ALL therapy. DXA total-body less-head bone mineral content (TBLH-BMC), and spine, total hip, femoral neck, and 1/3rd radius areal BMD (aBMD) were assessed in 45 participants at enrollment and 12-months later. Linear regression models examined correlates of changes in DXA Z-scores. Changes in DXA outcomes were compared to changes in tibia pQCT trabecular and cortical volumetric BMD (vBMD) and cortical area. At enrollment, DXA TBLH-BMC, spine and radius aBMD Z-scores were not significantly reduced in ALL survivors; however, total hip [median -0.74 (IQ range -1.51 to -0.04)] and femoral neck [-0.51 (-1.24 to 0.14)] aBMD Z-scores were lower (both p < 0.01) compared to reference data. DXA Z-scores at all skeletal sites increased over 12 months. Despite improvement, total hip Z-score remained lower at -0.55 (-1.05 to 0.18). The increases in TBLH-BMC, total hip and femoral neck aBMD Z-scores were more pronounced in those enrolled within 6 months of completing ALL therapy, compared to those enrolled at >6 months. Gains in TBLH-BMC, total hip, femoral neck and radius aBMD Z-scores were significantly associated with gains in tibia cortical area Z-scores (R = 0.56 to 0.67, p ≤ 0.001). Changes in TBLH and proximal femur sites were associated with gains in trabecular vBMD Z-scores (R = 0.37 to 0.40; p ≤ 0.01); these associations were not significant when adjusted for gains in cortical area. In summary, gains in DXA measures were most pronounced in total hip and femoral neck following ALL therapy. The gains in all DXA measures, with the exception of lumbar spine, reflected gains in cortical area. Overall, ALL survivors demonstrate skeletal recovery following completion of therapy; a small sub-group continue to demonstrate deficits and benefit from continued observation to ensure improvement over time.

The Association of Diet and Exercise With Body Composition in Pediatric Crohn's Disease

BACKGROUND

In pediatric Crohn's disease, fat mass improves over time with treatment, but lean mass deficits persist. This observational study of the associations of physical activity and dietary intake with lean mass and muscle strength in children with Crohn's disease was ancillary to a previously reported randomized clinical trial of an intervention to improve bone health.

METHODS

In this study, 138 participants were followed at baseline and at 6, 12, and 24 months with evaluation of lean and fat mass using DXA, muscle strength (peak torque), Crohn's characteristics, dietary intake, time in moderate to vigorous physical activity (MVPA), and serum insulin-like growth factor-1 (IGF-1) and tumor necrosis factor-alpha (TNF-α). Race- and sex-specific Z-scores for leg lean mass and whole body fat mass were generated. Quasi least square regression evaluated determinants of changes in body composition and muscle strength.

RESULTS

Leg lean mass and muscle strength were positively associated with time in MVPA (P < 0.05) and negatively associated with increasing clinical disease activity (P < 0.05). Both leg lean mass and strength were positively associated with IGF-1 Z-score (P ≤ 0.03) but negatively associated with serum TNF-α (P ≤ 0.04). Neither lean mass nor muscle strength was associated with caloric or protein intake.

CONCLUSIONS

Persistence of lean mass deficits was related to ongoing Crohn's disease activity but improved with greater time spent in moderate to vigorous physical activity. Future trials are needed to evaluate the efficacy of physical activity in improving lean mass in pediatric Crohn's disease.

Anabolic Therapy for the Treatment of Osteoporosis in Childhood

PURPOSE OF REVIEW

Numerous forms of osteoporosis in childhood are characterized by low bone turnover (for example, osteoporosis due to neuromuscular disorders and glucocorticoid exposure). Anti-resorptive therapy, traditionally used to treat osteoporosis in the young, is associated with further reductions in bone turnover, raising concerns about the long-term safety and efficacy of such therapy. These observations have led to increasing interest in the role of anabolic therapy to treat pediatric osteoporosis.

RECENT FINDINGS

While growth hormone and androgens appears to be relatively weak anabolic modulators of bone mass, emerging therapies targeting bone formation pathways (anti-transforming growth factor beta antibody and anti-sclerostin antibody) hold considerable promise. Teriparatide remains an attractive option that merits formal study for patients post-epiphyseal fusion, although it must be considered that adult studies have shown its effect is blunted when administered following bisphosphonate therapy. Mechanical stimulation of bone through whole body vibration therapy appears to be much less effective than bisphosphonate therapy for treating osteoporosis in children. New anabolic therapies which target important pathways in skeletal metabolism merit further study in children, including their effects on fracture risk reduction and after treatment discontinuation.

Increases in IGF-1 After Anti-TNF-α Therapy Are Associated With Bone and Muscle Accrual in Pediatric Crohn Disease

CONTEXT

Low levels of insulinlike growth factor 1 (IGF-1) in pediatric and adolescent Crohn disease (CD) likely contribute to bone and muscle deficits.

OBJECTIVE

Assess changes in IGF-1 levels and associations with bone and muscle accrual following initiation of anti-tumor necrosis factor α (TNF-α) therapy in pediatric and adolescent CD.

DESIGN AND PARTICIPANTS

Participants (n = 75, age 5 to 21 years) with CD were enrolled in a prospective cohort study; 63 completed the 12-month visit.

MAIN OUTCOME MEASURES

IGF-1 levels at baseline and 10 weeks, as well as dual-energy x-ray absorptiometry (DXA) and tibia peripheral quantitative computed tomography (pQCT) measures of bone and muscle at baseline and 12 months after initiation of anti-TNF-α therapy. Outcomes were expressed as sex-specific z scores.

RESULTS

IGF-1 z scores increased from a median (interquartile range) of -1.0 (-1.58 to -0.17) to -0.36 (-1.04 to 0.36) over 10 weeks (P < 0.001). Lesser disease severity and systemic inflammation, as well as greater estradiol z scores (in girls), was significantly associated with greater IGF-1 z scores over time. DXA whole-body bone mineral content, leg lean mass, and total hip and femoral neck bone mineral density (BMD) z scores were low at baseline (P < 0.0001 vs reference data) and increased significantly (P < 0.001) over 12 months. Greater increases in IGF-1 z scores over 10 weeks predicted improvement in DXA bone and muscle outcomes and pQCT trabecular BMD and cortical area. Adjustment for changes in muscle mass markedly attenuated the associations between IGF-1 levels and bone outcomes.

CONCLUSIONS

Short-term improvements in IGF-1 z scores predicted recovery of bone and muscle outcomes following initiation of anti-TNF-α therapy in pediatric CD. These data suggest that disease effects on growth hormone metabolism contribute to musculoskeletal deficits in CD.

Low-intensity vibration increases cartilage thickness in obese mice

Obesity is associated with an elevated risk of osteoarthritis (OA). We examined here whether high fat diet administered in young mice, compromised the attainment of articular cartilage thickness. Further, we sought to determine if low-intensity vibration (LIV) could protect the retention of articular cartilage in a mouse model of diet-induced obesity. Five-week-old, male, C57BL/6 mice were separated into three groups (n = 10): Regular diet (RD), High fat diet (HF), and HF + LIV (HFv; 90 Hz, 0.2g, 30 min/d, 5 d/w) administered for 6 weeks. Additionally, an extended HF diet study was run for 6 months (LIV at 15 m/d). Articular cartilage and subchondral bone morphology, and sulfated GAG content were quantified using contrast agent enhanced μCT and histology. Gene expression within femoral condyles was quantified using real-time polymerase chain reaction. Contrary to our hypothesis, HF cartilage thickness was not statistically different from RD. However, LIV increased cartilage thickness compared to HF, and the elevated thickness was maintained when diet and LIV were extended into adulthood. RT-PCR analysis showed a reduction of aggrecan expression with high fat diet, while application of LIV reduced the expression of degradative MMP-13. Further, long-term HF diet resulted in subchondral bone thickening, compared to RD, providing early evidence of OA pathology-LIV suppressed the thickening, such that levels were not significantly different from RD. These data suggest that dynamic loading, via LIV, protected the retention of cartilage thickness, potentially resulting in joint surfaces better suited to endure the risks of elevated loading that parallel obesity. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:751-759, 2018.

Musculoskeletal health in newly diagnosed children with Crohn's disease

We evaluated the impact of Crohn's disease on muscle and bone strength, mass, density, and geometry in children with newly diagnosed CD and found profound muscle and bone deficits; nevertheless, the prevalence of vertebral fractures at this time point was low.

INTRODUCTION

Crohn's disease (CD) is an inflammatory condition of the gastrointestinal tract that can affect the musculoskeletal system. The objective of this study was to determine the prevalence of vertebral fractures and the impact of CD on muscle and bone mass, strength, density, and geometry in children with newly diagnosed CD.

METHODS

Seventy-three children (26 girls) aged 7.0 to 17.7 years were examined within 35 days following CD diagnosis by lateral spine radiograph for vertebral fractures and by jumping mechanography for muscle strength. Bone and muscle mass, density, and geometry were assessed by dual-energy x-ray absorptiometry and peripheral quantitative computed tomography (pQCT).

RESULTS

Disease activity was moderate to severe in 66 (90%) patients. Mean height (Z-score -0.3, standard deviation (SD) 1.1, p = 0.02), weight (Z-score -0.8, SD 1.3, p < 0.01), body mass index (Z-score -1.0, SD 1.3, p < 0.01), lumbar spine areal bone mineral density (BMD; Z-score -1.1, SD 1.0, p < 0.01), total body bone mineral content (Z-score -1.5, SD 1.0, p < 0.01), and total body lean mass (Z-score -2.5, SD 1.1, p < 0.01) were all low for age and gender. pQCT showed reduced trabecular volumetric BMD at the tibial metaphysis, expansion of the bone marrow cavity and thin cortices at the diaphysis, and low calf muscle cross-sectional area. Jumping mechanography demonstrated low muscle power. Only one patient had a vertebral fracture.

CONCLUSIONS

Children with newly diagnosed CD have profound muscle and bone deficits; nevertheless, the prevalence of vertebral fractures at this time point was low.

The Efficacy of Low-intensity Vibration to Improve Bone Health in Patients with End-stage Renal Disease Is Highly Dependent on Compliance and Muscle Response

RATIONAL AND OBJECTIVES

Low intensity vibration (LIV) may represent a nondrug strategy to mitigate bone deficits in patients with end-stage renal disease.

MATERIALS AND METHODS

Thirty end-stage renal patients on maintenance hemodialysis were randomized to stand for 20 minutes each day on either an active or placebo LIV device. Analysis at baseline and completion of 6-month intervention included magnetic resonance imaging (tibia and fibula stiffness; trabecular thickness, number, separation, bone volume fraction, plate-to-rod ratio; and cortical bone porosity), dual-energy X-ray absorptiometry (hip and spine bone mineral density [BMD]), and peripheral quantitative computed tomography (tibia trabecular and cortical BMD; calf muscle cross-sectional area).

RESULTS

Intention-to-treat analysis did not show any significant changes in outcomes associated with LIV. Subjects using the active device and with greater than the median adherence (70%) demonstrated an increase in distal tibia stiffness (5.3%), trabecular number (1.7%), BMD (2.3%), and plate-to-rod ratio (6.5%), and a decrease in trabecular separation (-1.8%). Changes in calf muscle cross-sectional area were associated with changes in distal tibia stiffness (R = 0.85), trabecular bone volume/total volume (R = 0.91), number (R = 0.92), and separation (R = -0.94) in the active group but not in the placebo group. Baseline parathyroid hormone levels were positively associated with increased cortical bone porosity over the 6-month study period in the placebo group (R = 0.55) but not in the active group (R = 0.01). No changes were observed in the nondistal tibia locations for either group except a decrease in hip BMD in the placebo group (-1.7%).

CONCLUSION

Outcomes and adherence thresholds identified from this pilot study could guide future longitudinal studies involving vibration therapy.

Mechanical signals protect stem cell lineage selection, preserving the bone and muscle phenotypes in obesity

The incidence of obesity is rapidly rising, increasing morbidity and mortality rates worldwide. Associated comorbidities include type 2 diabetes, heart disease, fatty liver disease, and cancer. The impact of excess fat on musculoskeletal health is still unclear, although it is associated with increased fracture risk and a decline in muscular function. The complexity of obesity makes understanding the etiology of bone and muscle abnormalities difficult. Exercise is an effective and commonly prescribed nonpharmacological treatment option, but it can be difficult or unsafe for the frail, elderly, and morbidly obese. Exercise alternatives, such as low-intensity vibration (LIV), have potential for improving musculoskeletal health, particularly in conditions with excess fat. LIV has been shown to influence bone marrow mesenchymal stem cell differentiation toward higher-order tissues (i.e., bone) and away from fat. While the exact mechanisms are not fully understood, recent studies utilizing LIV both at the bench and in the clinic have demonstrated some efficacy. Here, we discuss the current literature investigating the effects of obesity on bone, muscle, and bone marrow and how exercise and LIV can be used as effective treatments for combating the negative effects in the presence of excess fat.

The Effect of Whole Body Vibration Training on Bone and Muscle Function in Children With Osteogenesis Imperfecta

CONTEXT

Osteogenesis imperfecta (OI) is associated with reduced muscle size, dynamic muscle function, and mobility.

OBJECTIVE

To assess the effect of whole body vibration (WBV) on bone density and geometry, muscle size and function, mobility, and balance in children with OI.

DESIGN

Randomized controlled pilot trial.

SETTING

Tertiary pediatric research center.

PARTICIPANTS

Twenty-four children (5 to 16 years) with OI types 1, 4, and limited mobility [Child Health Assessment Questionnaire (CHAQ) score ≥ 0.13] recruited in sex- and pubertal stage-matched pairs. Incident fractures in two boys (WBV arm) led to exclusion of two prepubertal pairs.

INTERVENTION

Five months of WBV training (3 × 3 minutes twice daily) or regular care.

MAIN OUTCOME MEASURES

Bone and muscle variables measured by dual-energy X-ray absorptiometry (spine, hip, total body) and peripheral quantitative computed tomography (tibia). Mobility assessed by 6-minute walk tests and CHAQ; dynamic muscle function by mechanography.

RESULTS

All participants had reduced walking distances and muscle function (P < 0.001). Body mass index z score was associated with higher CHAQ scores (ρ + 0.552; P = 0.005) and lower walking and two-leg jumping performance (ρ - 0.405 to -0.654, P < 0.05). The WBV and control groups did not differ in the 5-month changes in bone. Total lean mass increased more in the WBV group [+1119 g (+224 to +1744)] compared with controls [+635 g (-951 to +1006)], P = 0.01, without improving mobility, muscle function, or balance.

CONCLUSIONS

The increase in lean mass without changes in muscle function or bone mass suggests reduced biomechanical responsiveness of the muscle-bone unit in children with OI.

Osteoporosis in Children with Chronic Illnesses: Diagnosis, Monitoring, and Treatment

PURPOSE OF REVIEW

Osteoporosis is an under-recognized complication of chronic illness in childhood. This review will summarize recent literature addressing the risk factors, evaluation, and treatment for early bone fragility.

RECENT FINDINGS

Criteria for the diagnosis of pediatric osteoporosis include the presence of low trauma vertebral fractures alone or the combination of low bone mineral density and several long bone fractures. Monitoring for bone health may include screening for vertebral fractures that are common but often asymptomatic. Pharmacologic agents should be offered to those with fragility fractures especially when spontaneous recovery is unlikely. Controversies persist about the optimal bisphosphonate agent, dose, and duration. Newer osteoporosis drugs have not yet been adequately tested in pediatrics, though clinical trials are underway. The prevalence of osteoporosis is increased in children with chronic illness. To reduce the frequency of fragility fractures requires increased attention to risk factors, early intervention, and additional research to optimize therapy and potentially prevent their occurrence.

Whole-body vibration of mice induces progressive degeneration of intervertebral discs associated with increased expression of Il-1β and multiple matrix degrading enzymes

OBJECTIVE

Whole-body vibration (WBV) is a popular fitness trend based on claims of increased muscle mass, weight loss and reduced joint pain. Following its original implementation as a treatment to increase bone mass in patients with osteoporosis, WBV has been incorporated into clinical practice for musculoskeletal disorders, including back pain. However, our recent studies revealed damaging effects of WBV on joint health in a murine model. In this report, we examined potential mechanisms underlying disc degeneration following exposure of mice to WBV.

METHODS

Ten-week-old male mice were exposed to WBV (45 Hz, 0.3 g peak acceleration, 30 min/day, 5 days/week) for 4 weeks, 8 weeks, or 4 weeks WBV followed by 4 weeks recovery. Micro-computed tomography (micro-CT), histological, and gene expression analyses were used to assess the effects of WBV on spinal tissues.

RESULTS

Exposure of mice to 4 or 8 weeks of WBV did not alter total body composition or induce significant changes in vertebral bone density. On the other hand, WBV-induced intervertebral disc (IVD) degeneration, associated with decreased disc height and degenerative changes in the annulus fibrosus (AF) that did not recover within 4 weeks after cessation of WBV. Gene expression analysis showed that WBV for 8 weeks induced expression of Mmp3, Mmp13, and Adamts5 in IVD tissues, changes preceded by increased expression of Il-1β.

CONCLUSIONS

Progressive IVD degeneration induced by WBV was associated with increased expression of Il-1β within the IVD that preceded Mmp and Adamts gene induction. Moreover, WBV-induced IVD degeneration is not reversed following cessation of vibration.

Shear-mediated orientational mineralization of bone apatite on collagen fibrils

Intrafibrillar mineralization of collagen under a 1.5 Pa FSS environment versus the serious extrafibrillar mineralization of collagen under no FSS.

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional 'muscle-bone unit', defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton's health follow-up.

Exercise Regulation of Marrow Adipose Tissue

Despite association with low bone density and skeletal fractures, marrow adipose tissue (MAT) remains poorly understood. The marrow adipocyte originates from the mesenchymal stem cell (MSC) pool that also gives rise to osteoblasts, chondrocytes, and myocytes, among other cell types. To date, the presence of MAT has been attributed to preferential biasing of MSC into the adipocyte rather than osteoblast lineage, thus negatively impacting bone formation. Here, we focus on understanding the physiology of MAT in the setting of exercise, dietary interventions, and pharmacologic agents that alter fat metabolism. The beneficial effect of exercise on musculoskeletal strength is known: exercise induces bone formation, encourages growth of skeletally supportive tissues, inhibits bone resorption, and alters skeletal architecture through direct and indirect effects on a multiplicity of cells involved in skeletal adaptation. MAT is less well studied due to the lack of reproducible quantification techniques. In recent work, osmium-based 3D quantification shows a robust response of MAT to both dietary and exercise intervention in that MAT is elevated in response to high-fat diet and can be suppressed following daily exercise. Exercise-induced bone formation correlates with suppression of MAT, such that exercise effects might be due to either calorie expenditure from this depot or from mechanical biasing of MSC lineage away from fat and toward bone, or a combination thereof. Following treatment with the anti-diabetes drug rosiglitazone - a PPARγ-agonist known to increase MAT and fracture risk - mice demonstrate a fivefold higher femur MAT volume compared to the controls. In addition to preventing MAT accumulation in control mice, exercise intervention significantly lowers MAT accumulation in rosiglitazone-treated mice. Importantly, exercise induction of trabecular bone volume is unhindered by rosiglitazone. Thus, despite rosiglitazone augmentation of MAT, exercise significantly suppresses MAT volume and induces bone formation. That exercise can both suppress MAT volume and increase bone quantity, notwithstanding the skeletal harm induced by rosiglitazone, underscores exercise as a powerful regulator of bone remodeling, encouraging marrow stem cells toward the osteogenic lineage to fulfill an adaptive need for bone formation. Thus, exercise represents an effective strategy to mitigate the deleterious effects of overeating and iatrogenic etiologies on bone and fat.