Site‐specific variation in cortical porosity and histomorphometry as a reflection of growth and mechanical adaptation in the human tibia (541.12)

Abstract

Previous research has shown that individuals with more slender (narrow relative to length) tibiae may suppress remodeling as a means of increasing tissue stiffness. To test this hypothesis, we quantified cortical porosity (using µCT) and histomorphometry (using light microscopy) in human cadaveric tibia samples (N=10; obtained from 38% and 66% distance proximal to distal endplate) and examined correlations with robustness (total cross‐sectional area/length) and elastic modulus (determined by finite element analysis). Data were analyzed for whole cross‐sections and by anatomically determined regions of interest (ROIs) to determine site‐specific variability. Porosity and histomorphometric variables correlated significantly with robustness (at 66%) and elastic properties, suggesting that remodeling was modulated relative to robustness and affected bone properties at a local level. In addition, anatomical location was a significant (p < 0.001) predictor of variability in all histological measures. This variation could be explained by expected anterior‐posterior [AP] bending loading, as well as by variation in tissue age due to medial drift patterns during growth. Both loading and growth history need to be considered, in addition to global regulators of remodeling such as robustness, when interpreting intra and inter‐individual variability in bone structure and properties. Grant Funding Source: Supported by US Department of Defense