Department of Orthopedic Surgery, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
Bone. 2012 May;50(5):1173-83. doi: 10.1016/j.bone.2012.01.022. Epub 2012 Feb 9.
We evaluated site-specific skeletal adaptation to loading during growth, comparing radius (RAD) and femoral neck (FN) DXA scans in young female gymnasts (GYM) and non-gymnasts (NON).
Subjects from an ongoing longitudinal study (8-26yr old) underwent annual DXA scans (proximal femur, forearm, total body) and anthropometry, completing maturity and physical activity questionnaires. This cross-sectional analysis used the most recent data meeting the following criteria: gynecological age ≤2.5yr post-menarche; and GYM annual mean gymnastic exposure ≥5.0h/wk in the prior year. Bone geometric and strength indices were derived from scans for 173 subjects (8-17yr old) via hip structural analysis (femoral narrow neck, NN) and similar radius formulae (1/3 and Ultradistal (UD)). Maturity was coded as M1 (Tanner I breast), M2 (pre-menarche, ≥Tanner II breast) or M3 (post-menarche). ANOVA and chi square compared descriptive data. Two factor ANCOVA adjusted for age, height, total body non-bone lean mass and percent body fat; significance was tested for main effects and interactions between gymnastic exposure and maturity.
At the distal radius, GYM means were significantly greater than NON means for all variables (p<0.05). At the proximal femur, GYM exhibited narrower periosteal and endosteal dimensions, but greater indices of cortical thickness, BMC, aBMD and section modulus, with lower buckling ratio (p<0.05). However, significant interactions between maturity and loading were detected for the following: 1) FN bone mineral content (BMC) and NN buckling ratio (GYM BMC advantages only in M1 and M3; for BMC and buckling ratio, M1 advantages were greatest); 2) 1/3 radius BMC, width, endosteal diameter, cortical cross-sectional area, and section modulus (GYM advantages primarily post-menarche); and 3) UD radius BMC and axial compressive strength (GYM advantages were larger with greater maturity, greatest post-menarche).
Maturity-specific comparisons suggested site-specific skeletal adaptation to loading during growth, with greater advantages at the radius versus the proximal femur. At the radius, GYM advantages included greater bone width, cortical cross-sectional area and cortical thickness; in contrast, at the femoral neck, GYM bone tissue cross-sectional area and cortical thickness were greater, but bone width was narrower than in NON. Future longitudinal analyses will evaluate putative maturity-specific differences.
我们评估了生长过程中特定部位骨骼对负荷的适应性，比较了年轻女性体操运动员（GYM）和非体操运动员（NON）的桡骨（RAD）和股骨颈（FN）DXA 扫描结果。
来自一项正在进行的纵向研究的受试者（8-26 岁）接受了每年一次的 DXA 扫描（股骨近端、前臂、全身）和人体测量，并完成了成熟度和体力活动问卷。本横断面分析使用了最近的数据，符合以下标准：妇科年龄≤初潮后 2.5 年；并且在前一年中，GYM 每年平均体操暴露量≥5.0 小时/周。通过髋关节结构分析（股骨窄颈，NN）和类似的桡骨公式（1/3 和 Ultradistal（UD）），从 173 名受试者（8-17 岁）的扫描中得出了骨几何和强度指数。成熟度编码为 M1（乳房 I 期）、M2（初潮前，≥乳房 II 期）或 M3（初潮后）。方差分析和卡方比较描述性数据。双因素协方差分析调整年龄、身高、全身非骨瘦体重和体脂百分比；测试了体操暴露和成熟度之间的主要效应和相互作用的显著性。
在桡骨远端，GYM 的平均值明显大于 NON 的平均值（p<0.05）。在股骨近端，GYM 表现出更窄的骨膜和骨内膜尺寸，但更大的皮质厚度、BMC、aBMD 和截面模数，以及更低的屈曲比（p<0.05）。然而，在成熟度和负荷之间检测到了显著的相互作用：1）FN 骨矿物质含量（BMC）和 NN 屈曲比（仅在 M1 和 M3 中，GYM 的 BMC 优势；对于 BMC 和屈曲比，M1 的优势最大）；2）1/3 半径 BMC、宽度、骨内膜直径、皮质横截面面积和截面模数（主要在初潮后，GYM 有优势）；3）UD 半径 BMC 和轴向抗压强度（GYM 的优势随着成熟度的增加而增加，最大的是初潮后）。
成熟度特异性比较表明，生长过程中存在特定部位骨骼对负荷的适应性，桡骨的优势大于股骨近端。在桡骨处，GYM 的优势包括更大的骨宽度、皮质横截面面积和皮质厚度；相比之下，在股骨颈处，GYM 的骨组织横截面积和皮质厚度较大，但骨宽度较窄。未来的纵向分析将评估潜在的成熟度特异性差异。
