Architecture of the femoral and tibial diaphyses in relation to body mass and composition: Research from whole-body CT scans of adult humans.

OBJECTIVES: Recent investigations have evaluated the influence of body composition on long bones in order to overcome the limits of body mass (BM) estimation methods and eventually lead to studying nutrition in past populations. Knowing how fat mass (FM) and fat-free mass (FFM) impact the skeleton would also enhance the understanding of mobility, activity, and locomotion derived from bone architecture. We investigated the relationship between BM and composition, and the architecture of the entire tibial and femoral diaphyses in an adult sample representative of a wide range of variation in age, BM, and composition.

MATERIALS AND METHODS: Body composition was measured directly from 78 whole-body CT scans for which the age, sex, BM, and stature were recorded. The entire diaphyseal thickness, volume, curvature, and cross-sectional geometry parameters of both the femur and tibia were numerically extracted.

RESULTS: FM correlates with large portions of the femoral thickness in females only. FFM correlates with the femoral diaphysis in males but not in females. FFM correlates with the tibia architecture in both sexes, while FM is correlated in males exclusively.

DISCUSSION: BM and body components influence the architecture of the diaphysis of lower limb long bones in sex-specific patterns that are mostly reflected in their thickness and can be recorded, in some cases, for their strength, rigidity, and volume. Our results suggest that (1) long bone diaphyses should be thoroughly studied, as a whole, when possible; and (2) BM and body components should be accounted for when deriving activity, mobility, or locomotion patterns from cortical bone.