Cortical versus trabecular bone mass: influence of activity on both bone components.

Motivated by the controversy in the literature concerning the influence of activity on bone mass and on its cortical and trabecular components, a study was made using computed peripheral tomography (Stratec XCT 900) of the total, cortical, and trabecular bone mass of the dominant and nondominant upper extremities of 50 apparently normal subjects (average age 26 +/- 6 years). No differences were observed in the trabecular bone compartment, but the cortical compartment was greater (P < 0.001) in the dominant extremity. There was also a significantly greater total bone mass in the dominant extremity which we attributed to greater cortical mass (P < 0.025) given the highly significant correlation (r2 = 0.904, P = 0.0001) between total and cortical bone mass and the less significant correlation between total and trabecular bone mass (r2 = 0.479, P = 0.0001).