Human cortical bone maintenance: does mechanical loading compensate for bone loss associated with metabolic stress?

Cortical bone adapts to environmental factors at macroscopic and microscopic levels by altering mass and shape, and thus strength. As few studies have focused on how these factors interact in humans, researchers continue to investigate mechanical and metabolic influences on bone as if they act independently. This study utilizes an archaeological human juvenile sample from a medieval Lithuanian cemetery. Juvenile bone is favored over adult bone because it responds strongly to both mechanical and metabolic effects. Macroscopic and microscopic bone morphology were assessed in three skeletal elements under different levels of mechanical loading (i.e., femora, humeri, ribs) and compared among individuals under varying amounts of metabolic stress. Analyses evaluated whether, in the presence of bone loss due to metabolic stress, bone mass and strength were preferentially maintained in bones under the highest mechanical demands. Results indicate that such a preferential maintenance may occur, suggesting that systemic metabolic bone loss is compensated by high local loading demands. Results caution researchers against evoking solely mechanical or metabolic causes for variation in cortical bone morphology. Grant Funding Source : NA