Department of Orthopaedic Surgery, University of California at Davis, Sacramento, CA, USA.
Bone. 2012 Jun;50(6):1275-80. doi: 10.1016/j.bone.2012.02.018. Epub 2012 Feb 25.
We recently developed a method to measure cortical bone fracture initiation toughness using a double-notched beam in four-point bending. This method was used to test the hypothesis that mineralization around the two notch roots is correlated with fracture toughness and crack extension (physical damage). Total energy absorbed to failure negatively correlated with average mineralization of the beam (r(2)=0.62), but not with notch root mineralization. Fracture initiation toughness was positively correlated to mineralization at the broken notch root (r(2)=0.34). Crack length extension at the unbroken notch was strongly negatively correlated with the average mineralization of the notch roots (r(2)=0.81) whereas crack length extension at the broken notch did not correlate with any of the mineralization measurements. Mineralization at the notch roots and the average mineralization contributed independently to the mechanical and damage properties. The data are consistent with a hypothesis that a) high notch root mineralization results in less stable crack length extension but high force to initiate unstable crack propagation while b) higher average mineralization leads to low post-yield (and total) energy absorption to failure.
我们最近开发了一种使用四点弯曲双切口梁测量皮质骨断裂起始韧性的方法。该方法用于检验以下假设：两个切口根部周围的矿化与断裂韧性和裂纹扩展（物理损伤）有关。破坏总能量与梁的平均矿化程度呈负相关（r²=0.62），但与切口根部矿化无关。断裂起始韧性与破损切口根部的矿化程度呈正相关（r²=0.34）。未破损切口处的裂纹扩展长度与切口根部的平均矿化程度呈强烈负相关（r²=0.81），而破损切口处的裂纹扩展长度与任何矿化测量均无关。切口根部矿化和平均矿化独立地影响机械和损伤性能。数据与以下假设一致：a）高切口根部矿化导致不稳定裂纹扩展的长度扩展减少，但启动不稳定裂纹扩展的力增加，而 b）较高的平均矿化导致屈服后（和总）能量吸收到故障减少。
