The research examined the roles of collagen cross-links and structures of osteon collagen/lamellar in the third metacarpal bones of horses during tension and compression tests, and it found that these aspects, along with collagen fiber orientation, have significant impact on the bones’ mechanical properties and ability to handle tension and compression.

Objectives of the Research

• The primary goals of this research were to determine the significance of osteon collagen/lamellar ‘morphotypes’ and intermolecular collagen cross-links (CCLs) on the mechanical properties of bone, especially during tension and compression.
• The researchers were driven to conduct these studies due to a lack of comprehensive understanding of how these factors play roles in the bone’s ability to handle tension and compression, which leads to increased fracture risk in many bones.

Methodology

• In the study, third metacarpal bones (MC3s) from adult horses were tested for their mechanical properties under compression and tension.
• The tests provided data on several characteristics, such as elastic modulus, yield and ultimate strength, and energy absorption.
• Bone fragments from the tested specimens were also analyzed to identify characteristics relating to collagen fiber orientation, osteon morphotype score, mineralization, porosity and other histological features.
• By using a different limiting approach, CCLs were only studied in the specimens tested for compression.

Findings

• The research revealed a significant correlation between specific CCLs and mechanical parameters. For instance, lysylpyridinoline (LP) cross-links were related to energy absorption, and a ratio of hydroxylysylpyridinoline to LP (HP/LP) corresponded with elastic modulus.
• Furthermore, the HP/LP ratio indicated a trend with energy absorption and showed a stronger correlation with osteon density and mineralization than collagen fiber orientation or osteon morphotype score.
• The researchers noted a stronger relationship between collagen fiber orientation and energy absorption compared to osteon morphotype score during both compression and tension tests.

Conclusion

• The research concludes that collagen cross-links, especially HP/LP, and collagen fiber orientation have significant impact on the mechanical properties of bone in tension and compression scenarios, which might serve as crucial factors aiding in the adaptation and reduction of fracture risk in bones.