DUAL-ENERGY X-RAY ABSORPTIOMETRY DERIVED STRUCTURAL GEOMETRY FOR STRESS-FRACTURE PREDICTION IN MALE US-MARINE-CORPS RECRUITS

A total of 626 U.S. male Marine Corps recruits underwent anthropometri c measurements and dual-energy X-ray absorptiometry (DXA) scans of the femoral midshaft and the distal third of the tibia prior to a 12 week physical training program, Conventionally obtained frontal plane DXA scan data were used to measure the bone mineral density (BMD) as well as to derive the cross-sectional area, moment of inertia, section modu lus, and bone width in the femur, tibia, and fibula, During training, 23 recruits (3.7%) presented with a total of 27 radiologically confirm ed stress fractures in various locations in the lower extremity, After excluding 16 cases of shin splints, periostitis, and other stress rea ctions that did not meet fracture definition criteria, we compared ant hropometric and bone structural geometry measurements between fracture cases and the remaining 587 normals, There was no significant differe nce in age (p = 0.8), femur length (p = 0.2), pelvic width (p = 0.08), and knee width at the femoral condyles (p = 0.06), but fracture cases were shorter (p = 0.01), lighter (p = 0.0006), and smaller in most an thropometric girth dimensions (p < 0.04), Fracture case bone cross-sec tional areas (p < 0.001), moments of inertia (p < 0.001), section modu li (p < 0.001), and widths (p < 0.001) as well as BMD (p < 0.03) were significantly smaller in the tibia and femur, After correcting for bod y weight differences, the tibia cross-sectional area (p = 0.03), secti on modulus (p = 0.05), and width (p = 0.03) remained significantly sma ller in fracture subjects, We conclude that both small body weight and small diaphyseal dimensions relative to body weight are factors predi sposing to the development of stress fractures in this population, The se results suggest that bone structural geometry measurements derived from DXA data may provide a simple noninvasive methodology for assessi ng the risk of stress fracture.