Abstract：
Many bones experience bending, placing one side in net compression and the other in net tension. Because bone mechanical properties are relatively reduced in tension compared with compression, adaptations are needed to reduce fracture risk. Several toughening mechanisms exist in bone, yet little is known of the influences of secondary osteon collagen/lamellar \'morphotypes\' and potential interplay with intermolecular collagen cross-links (CCLs) in prevalent/predominant tension- and compression-loaded regions. Paired third metacarpals (MC3s) from 10 adult horses were prepared for mechanical testing. From one MC3/pair, 5 mm cubes were tested in compression at several mid-shaft locations. From contralateral bones, dumbbell-shaped specimens were tested in tension. Hence, habitual/natural tension- and compression-loaded regions were tested in both modes. Data included: elastic modulus, yield and ultimate strength, and energy absorption (toughness). Fragments of tested specimens were examined for predominant collagen fiber orientation (CFO; representing osteonal and non-osteonal bone), osteon morphotype score (MTS, representing osteonal CFO), mineralization, porosity and other histological characteristics. As a consequence of insufficient material from tension-tested specimens, CCLs were only examined in compression-tested specimens (HP, hydroxylysylpyridinoline; LP, lysylpyridinoline; PE, pentosidine). Among CCLs, only LP and HP/LP correlated significantly with mechanical parameters: LP with energy absorption, HP/LP with elastic modulus (both r=0.4). HP/LP showed a trend with energy absorption (r=-0.3, P=0.08). HP/LP more strongly correlated with osteon density and mineralization than CFO or MTS. Predominant CFO more strongly correlated with energy absorption than MTS in both testing modes. In general, CFO was found to be relatively prominent in affecting regional toughness in these equine MC3s in compression and tension.
摘要：
许多骨头会弯曲，将一侧置于净压缩状态，另一侧置于净张力状态。因为与压缩相比，骨的机械性能在拉伸方面相对降低，需要进行适应性调整以降低骨折风险。骨中存在几种增韧机制，然而,在普遍/主要的张力和压缩负荷区域,继发性骨胶原/层状“形态型”的影响以及与分子间胶原交联(CCL)的潜在相互作用鲜为人知。准备来自10匹成年马的配对第三掌骨（MC3s）进行机械测试。从一个MC3/对，在几个中轴位置处测试5mm立方体的压缩。从对侧骨骼，哑铃形试样进行拉伸试验。因此，在两种模式下测试了习惯性/自然张力和压缩负荷区域。数据包括：弹性模量，屈服和极限强度，和能量吸收（韧性）。检查受试标本的片段的主要胶原纤维取向（CFO；代表骨骼和非骨骼骨骼），骨形态评分(MTS，代表骨CFO)，矿化,孔隙度和其他组织学特征。由于拉伸试样的材料不足，仅在压缩试验样品中检查CCL(HP，羟基吡啶啉;LP,甲基吡啶；PE，戊糖苷）。在CCL中，只有LP和HP/LP与机械参数显着相关：LP与能量吸收，HP/LP具有弹性模量(均r=0.4)。HP/LP呈能量吸收趋势(r=-0.3,P=0.08)。与CFO或MTS相比，HP/LP与骨骼密度和矿化的相关性更强。在两种测试模式下，与MTS相比，主要CFO与能量吸收的相关性更强。总的来说,发现CFO在影响这些马MC3的压缩和拉伸区域韧性方面相对突出。
