Leonard Mary B, Zemel Babette S, Wrotniak Brian H, Klieger Sarah B, Shults Justine, Stallings Virginia A, Stettler Nicolas
Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Biostatistics and Epidemiology, Perelman School of Medicine at the University of Pennsylvania, USA.
Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
Bone. 2015 Apr;73:69-76. doi: 10.1016/j.bone.2014.12.002. Epub 2014 Dec 10.
Childhood obesity is associated with biologic and behavioral characteristics that may impact bone mineral density (BMD) and structure. The objective was to determine the association between obesity and bone outcomes, independent of sexual and skeletal maturity, muscle area and strength, physical activity, calcium intake, biomarkers of inflammation, and vitamin D status. Tibia and radius peripheral quantitative CT scans were obtained in 91 obese (BMI>97th percentile) and 51 non-obese adolescents (BMI>5th and <85th percentiles). Results were converted to sex- and race-specific Z-scores relative to age. Cortical structure, muscle area and muscle strength (by dynamometry) Z-scores were further adjusted for bone length. Obese participants had greater height Z-scores (p<0.001), and advanced skeletal maturity (p<0.0001), compared with non-obese participants. Tibia cortical section modulus and calf muscle area Z-scores were greater in obese participants (1.07 and 1.63, respectively, both p<0.0001). Tibia and radius trabecular and cortical volumetric BMD did not differ significantly between groups. Calf muscle area and strength Z-scores, advanced skeletal maturity, and physical activity (by accelerometry) were positively associated with tibia cortical section modulus Z-scores (all p<0.01). Adjustment for muscle area Z-score attenuated differences in tibia section modulus Z-scores between obese and non-obese participants from 1.07 to 0.28. After multivariate adjustment for greater calf muscle area and strength Z-scores, advanced maturity, and less moderate to vigorous physical activity, tibia section modulus Z-scores were 0.32 (95% CI -0.18, 0.43, p=0.06) greater in obese, vs. non-obese participants. Radius cortical section modulus Z-scores were 0.45 greater (p=0.08) in obese vs. non-obese participants; this difference was attenuated to 0.14 with adjustment for advanced maturity. These findings suggest that greater tibia cortical section modulus in obese adolescents is attributable to advanced skeletal maturation and greater muscle area and strength, while less moderate to vigorous physical activities offset the positive effects of these covariates. The impact of obesity on cortical structure was greater at weight bearing sites.
儿童肥胖与可能影响骨矿物质密度（BMD）和骨骼结构的生物学及行为特征相关。本研究的目的是确定肥胖与骨骼结局之间的关联，该关联独立于性别和骨骼成熟度、肌肉面积和力量、身体活动、钙摄入量、炎症生物标志物以及维生素D状态。对91名肥胖青少年（BMI>第97百分位数）和51名非肥胖青少年（BMI>第5百分位数且<第85百分位数）进行了胫骨和桡骨外周定量CT扫描。结果转换为相对于年龄的性别和种族特异性Z分数。皮质结构、肌肉面积和肌肉力量（通过测力计测量）的Z分数进一步根据骨长度进行了调整。与非肥胖参与者相比，肥胖参与者的身高Z分数更高（p<0.001），骨骼成熟度更高（p<0.0001）。肥胖参与者的胫骨皮质截面模量和小腿肌肉面积Z分数更高（分别为1.07和1.63，均p<0.0001）。两组之间胫骨和桡骨的小梁和皮质体积骨密度无显著差异。小腿肌肉面积和力量Z分数、骨骼成熟度提高以及身体活动（通过加速度计测量）与胫骨皮质截面模量Z分数呈正相关（均p<0.01）。对肌肉面积Z分数进行调整后，肥胖与非肥胖参与者胫骨截面模量Z分数的差异从1.07降至0.28。在对更大的小腿肌肉面积和力量Z分数、更高的成熟度以及较少的中度至剧烈身体活动进行多变量调整后，肥胖参与者的胫骨截面模量Z分数比非肥胖参与者高0.32（95%CI -0.18, 0.43, p=0.06）。肥胖参与者的桡骨皮质截面模量Z分数比非肥胖参与者高0.45（p=0.08）；在对更高的成熟度进行调整后，这一差异降至0.14。这些发现表明，肥胖青少年更大的胫骨皮质截面模量归因于骨骼成熟度提高以及更大的肌肉面积和力量，而较少的中度至剧烈身体活动抵消了这些协变量的积极影响。肥胖对皮质结构的影响在负重部位更大。
