Medicine & Science in Sports & Exercise:
C-13 Free Communication/Slide - Bone 1: MAY 29, 2008 8:00 AM - 9:45 AM ROOM: 116
Modlesky, Christopher M.1; Kanoff, Sara1; Heaven, Jessica1; Miller, Freeman2
1University of Delaware, Newark, DE. 2AI duPont Hospital for Children, Wilmington, DE.
(No relationships reported)
Recent studies suggest the structural aspects of bone should be considered when evaluating skeletal status. Furthermore, understanding the relationship between bone and muscle may provide insight into fracture risk.
PURPOSE: The purpose of this study was to determine if there are gender differences in trabecular bone structure, cortical bone structure and the muscle-bone unit in children.
METHODS: Fourteen boys and 14 girls between 7 and 12 years of age participated in the study. Pubertal development was assessed by Tanner staging. Magnetic resonance imaging (GE, 1.5 T) was used to determine measures of trabecular bone structure [i.e., apparent trabecular bone volume to total volume (appBV/TV), trabecular number (appTb.N), trabecular thickness (appTb.Th) and trabecular separation (appTb.Sp)] in the lateral half of the distal femur, measures of cortical bone structure (i.e., cortical bone volume, cross-sectional moment of inertia, section modulus and polar moment of inertia) in the middle-third of the femur and muscle mass in the midthigh. Indexes of the muscle-bone unit were calculated by dividing measures of trabecular bone structure and cortical bone structure by midthigh muscle mass.
RESULTS: There were no gender differences in age, height, body mass, BMI, or midthigh muscle mass (p < 0.05). One boy and three girls were early pubertal (Tanner stage 2); the remaining children were prepubertal (Tanner stage 1). Girls and boys were not different in any measure that reflected the distal femur trabecular bone structure, midfemur cortical bone structure or midthigh muscle-bone unit (p < 0.05). Moreover, muscle mass was moderately related (p < 0.05) to appBV/TV, appTb.N and appTb.Sp (r = 0.57, 0.54 and − 0.61, respectively) in boys and moderately to strongly related (p < 0.05) to appBV/TV, appTb.Th and appTb.Sp (r = 0.87, 0.78 and − 0.65, respectively) in girls. Muscle mass was strongly related (p < 0.05) to all measures of cortical bone structure in boys (r = 0.89 to 0.94) and girls (r = 0.92 to 0.96).
CONCLUSIONS: The findings suggest that boys and girls have equally developed trabecular and cortical bone structures in the femur and muscle-bone units in the thigh.
Supported by the National Osteoporosis Foundation and the NIH (HD050530)