How Does Bone Quality Differ Between Healthy-weight and Overweight Adolescents and Young Adults?

• Published in: Clinical orthopaedics and related research 2013-04, Vol.471 (4), p.1214-1225
• Main Authors: Hoy, Christa L., Macdonald, Heather M., McKay, Heather A.
• Format: Article
• Language: English
• Subjects: Absorptiometry, Photon; Adaptation, Physiological; Adolescent; Anthropometry; Body Weight; Bone Density; British Columbia; Conservative Orthopedics; Cross-Sectional Studies; Female; Humans; Longitudinal Studies; Male; Medicine; Medicine & Public Health; Orthopedics; Overweight - physiopathology; Pediatrics; Radius - diagnostic imaging; Radius - physiology; Regression Analysis; Sports Medicine; Surgery; Surgical Orthopedics; Surveys and Questionnaires; Symposium: Childhood Obesity and Musculoskeletal Problems; Tibia - diagnostic imaging; Tibia - physiology; Tomography, X-Ray Computed; Young Adult
• ISSN: 0009-921X; 1528-1132
• DOI: 10.1007/s11999-012-2576-0

Background Overweight youth have greater bone mass than their healthy-weight peers but sustain more fractures. However, it is unclear whether and how excess body fat influences bone quality in youth. Questions/purposes We determined whether overweight status correlated with three-dimensional aspects of bone quality influencing bone strength in adolescent and young adult females and males. Methods We categorized males (n = 103; mean age, 17 years) and females (n = 85; mean age, 18 years) into healthy-weight and overweight groups. We measured lean mass (LM) and fat mass (FM) with dual-energy x-ray absorptiometry (DXA). We used high-resolution peripheral quantitative CT to assess the distal radius (7% site) and distal tibia (8% site). Bone quality measures included total bone mineral density (Tt.BMD), total area (Tt.Ar), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), separation (Tb.Sp), and thickness (Tb.Th). We used multiple regression to compare bone quality between healthy-weight and overweight adolescents adjusting for age, ethnicity, limb length, LM, and FM. Results Overweight males had higher (10%–21%) Tt.BMD, BV/TV, and Tb.N and lower Tb.Sp at the tibia and lower Tt.Ar at the radius than healthy-weight males. No differences were observed between overweight and healthy-weight females. LM attenuated the differences in bone quality between groups in males while FM negatively predicted Tt.BMD, BV/TV, Tb.N, and Tb.Th. Conclusions Our data suggest overweight males have enhanced bone quality compared with healthy-weight males; however, when group differences are interpreted in the context of the mechanostat theory, it appears bone quality of overweight adolescents adapts to LM and not to greater FM.