A weighted osteon morphotype score outperforms regional osteon percent prevalence calculations for interpreting cortical bone adaptation.

The research presents and evaluates the efficacy of a new method for quantifying secondary osteon morphotypes in bone using circular polarized light microscopy, which could provide better accuracy in interpreting bone adaptation due to compression and tension compared to older methods based mainly on percent prevalence calculations.

Research Methodology

• The researchers developed a weighted-scoring method for quantifying the regional distributions of six secondary osteon morphotypes in cortical bone, called the Osteon Morphotype Score (MTS).
• They hypothesized that the MTS would be a more effective measure than the percent prevalence (PP) of osteon morphotypes for interpreting bone adaptation.
• Tests were conducted in the proximal femoral diaphyses of adult chimpanzees and habitually bent bones. Various animal bones, including calcanei from sheep, deer, and horses, radii from sheep and horses, and third metacarpsals (MC3s) from horses, were used.
• Sheep tibiae were examined, as they would not necessitate regional variations in osteon morphotypes due to their greater torsion/shear properties.

Findings

• The researchers found that osteon MTS and PP calculations had strong correlation in confirming the collagen fiber orientation (CFO) differences between tension and compression cortices of the examined bones.
• However, PP calculations failed to show a compression/tension difference in equine MC3s and sheep radii, whereas the MTS method showing more consistent and positive correlations with the predominant CFO.
• Thus, the researchers concluded that the osteon MTS method outperforms regional variations in the PP of osteon morphotypes as a predictor of non-uniform strain distributions caused by bending.

Implications

• The findings demonstrate that the proposed osteon MTS method could be a superior approach for exploring bone adaptation in relation to compression and tension, providing more reliable and significant data compared to the conventional PP method.
• This could potentially lead to better understanding of bone health and disease, and potentially inform the development of new therapies or interventions for bone-related conditions.