Prevalence of vitamin D insufficiency among adolescents and its correlation with bone parameters using high-resolution peripheral quantitative computed tomography.

UNLABELLED: Vitamin D deficiency and insufficiency are highly prevalent among adolescents in Hong Kong, which is a sub-tropical city with ample sunshine. Vitamin D level is significantly correlated with key bone density and bone quality parameters. Further interventional studies are warranted to define the role of vitamin D supplementation for improvement of bone health among adolescents. INTRODUCTION: The relationship between bone quality parameters and vitamin D (Vit-D) status remains undefined among adolescents. The aims of this study were to evaluate Vit-D status and its association with both bone density and bone quality parameters among adolescents. METHODS: Three hundred thirty-three girls and 230 boys (12-16 years old) with normal health were recruited in summer and winter separately from local schools. Serum 25(OH) Vit-D level, bone density and quality parameters by Dual Energy X-ray Absorptiometry (DXA) and High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), dietary calcium intake, and physical activity level were assessed. RESULTS: Sixty-four point seven percent and 11.4 % of subjects were insufficient [25 ≤ 25(OH)Vit-D ≤ 50 nmol/L] and deficient [25(OH)Vit-D < 25 nmol/L] in Vit-D, respectively. The mean level of serum 25(OH)Vit-D in summer was significantly higher than that in winter (44.7 ± 13.6 and 35.9 ± 12.6 nmol/L, respectively) without obvious gender difference. In girls, areal bone mineral density (aBMD) and bone mineral content (BMC) of bilateral femoral necks, cortical area, cortical thickness, total volumetric bone mineral density (vBMD), and trabecular thickness were significantly correlated with 25(OH)Vit-D levels. In boys, aBMD of bilateral femoral necks, BMC of the dominant femoral neck, cortical area, cortical thickness, total vBMD, trabecular vBMD, BV/TV, and trabecular separation were significantly correlated with 25(OH)Vit-D levels. CONCLUSION: Vit-D insufficiency was highly prevalent among adolescents in Hong Kong with significant correlation between Vit-D levels and key bone density and bone quality parameters being detected in this study. Given that this is a cross-sectional study and causality relationship cannot be inferred, further interventional studies investigating the role of Vit-D supplementation on improving bone health among adolescents are warranted.

Abnormal Bone Mechanical and Structural Properties in Adolescent Idiopathic Scoliosis: A Study with Finite Element Analysis and Structural Model Index.

Previous studies found adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density (BMD) and abnormal bone quality, whilst the association between AIS and their bone strength is unknown. From high-resolution peripheral quantitative computed tomography-generated images, bone mechanical properties can be evaluated with finite element analysis (FEA), and trabecular rod-plate configuration related to trabecular bone strength can be quantified by structure model index (SMI). This study aimed to compare trabecular configuration and bone mechanical properties between AIS and the controls. 95 AIS girls aged 12-14 years and 97 age- and gender-matched normal controls were recruited. Bilateral femoral necks and non-dominant distal radius were scanned by dual-energy X-ray absorptiometry for areal BMD and HR-pQCT for SMI and FEA, respectively. Subjects were further classified into osteopenic and non-osteopenic group based on their areal BMD. Bone mechanical properties (stiffness, failure load and apparent modulus) were calculated using FEA. Linear regression model was used for controlling age, physical activity and calcium intake. AIS was associated with lower failure load and apparent modulus after adjusting for age, whereas AIS was associated with lower apparent modulus after adjusting for all confounders. Osteopenic AIS was associated with more rod-like trabeculae when compared with non-osteopenic AIS, whereas no difference was detected between osteopenic and non-osteopenic controls. This might be the result of abnormal regulation and modulation of bone metabolism and bone modelling and remodelling in AIS which will warrant future studies with a longitudinal design to determine the significance of micro-architectural abnormalities in AIS.

Feasibility and effects of 6-month home-based digitally supported E-Fit program utilizing high-intensity interval exercises in girls with adolescent idiopathic scoliosis: a randomized controlled pilot study.

Adolescent idiopathic scoliosis (AIS) patients have lower physical activities when compared with healthy controls, and are associated with lower bone mineral density (BMD), muscle strength and poorer quality of life (QoL). We aimed to assess the feasibility and effects of 6-month home-based digitally supported E-Fit comprised of high-intensity interval exercises for AIS patients. 40 AIS girls aged 11-14 were randomly assigned to E-Fit or control group. E-Fit group participated in an online 6-month home-based exercise program. At baseline, 6-months and 12-months follow-up, BMD using dual-energy X-ray absorptiometry, muscle functions, physical activity using Modified Baecke Questionnaire (MBQ), and QoL using Scoliosis Research Society-22 (SRS-22r) and feedback questionnaire were investigated. 14 in E-Fit and 16 in control group completed the study. Both groups had similar baseline characteristics. At 6-months, E-Fit group showed better improvement and significant interaction effect in left femoral neck bone mineral content (p=0.021) and isometric curl up test (p=0.04). Left arm lean mass showed better improvement between 6-months and 12-months follow-up (p=0.046) and whole-body areal BMD had significant interaction effect at 12-months follow-up (p=0.077). Improvement on self-image, work and sports participation were noted in E-Fit group across time. 70% of E-Fit participants were positive towards domestic application via online platform. E-Fit showed some benefits on bone health, muscle functions, physical activity and QoL measures. Current study indicated some potential physical and psychological benefits of E-Fit for AIS girls. E-Fit was feasible to conduct online at home and might have value of promoting exercise habits among relatively inactive AIS girls.