Intra‐element variation in osteocyte lacunar density and morphology in healthy young male cortical bone

We previously reported considerable intra‐element variation in osteocyte lacunar properties, with density differences up to 30% across a cross‐section of the male (20 yrs) femoral cortex related to the biomechanical axes. The purpose of this research was to determine whether this pattern of variation occurs in a larger sample. Anterior (A), posterior (P), medial (M) and lateral (L) blocks (2×2 mm) were prepared from the proximal femoral shaft of 7 healthy males aged 20–34 and synchrotron micro‐CT imaged. Average lacunar density (± sd) from the APML regions were 22,961 ± 1991, 28,264 ± 4186, 32,082 ± 7731 and 30,525 ± 1977 per mm3 of bone, respectively. Consistent with the pattern observed in the previous study, density was significantly different between the A and the L region (p<0.05). The density of the combined A and P regions was also lower (p=0.006) than that of the combined M and L regions. The differences in density were mirrored by shape differences; with the combined AP region having more elongate (p=0.004) and flattened (p=0.001) lacunae, than those of the ML region. The consistent appearance of this pattern of variation in a larger sample suggests considerable normal variation occurs in the lacunar properties of healthy young males. The underlying functional significance of the observed differences likely relates to localized variations in loading conditions as the pattern corresponds well with mechanical axes. Grant Funding Source : Saskatchewan Health Research Fund