Goh Megan H, Anderson Dennis E
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, 02215, United States.
Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, 02115, United States.
JBMR Plus. 2024 Dec 3;9(1):ziae153. doi: 10.1093/jbmrpl/ziae153. eCollection 2025 Jan.
Costal cartilage plays an important functional role in the rib cage, but its mechanical properties have not been well characterized. The objective of this study is to characterize the properties of human costal cartilage and examine the effects of age, sex, rib level, and degree of calcification. We obtained cadaveric costal cartilage samples of ribs 3-6 with intact perichondrium from 24 donors (12 females and 12 males) evenly distributed by age (range 47-94 yr). Peripheral QCT scans were used to quantify geometric properties (area moments) and tissue calcification (as volume, length, and classified as central, peripheral, and mixed). Four-point bending tests were performed on each sample, and bending stiffness and modulus outcomes were evaluated by fitting data from mechanical testing with non-linear pseudo-elastic models (composed of linear and cubic components, separated into loading and unloading regimes). Effects of sex, age, rib level, and cartilage calcification on bending stiffness and modulus outcomes were assessed with mixed-effects regression models. Cartilage size (area moment) was larger in males than females and positively associated with age, while there was more calcification volume in cartilage of females than males. During loading, stiffness (linear and cubic) was larger in males, while modulus (linear and cubic) was larger in females. Linear stiffness and modulus were both negatively associated with age, positively associated with calcification, and varied between rib levels. Cubic (nonlinear) components of stiffness and modulus were positively associated with calcification and varied by rib, while modulus (but not stiffness) was negatively associated with age. During unloading, the linear stiffness and modulus values were much lower, though some similar associations were found. Overall, this study adds to our understanding of the behavior of costal cartilage as a nonlinear visco-elastic material, and the effects of sex, aging, and calcification on mechanical behavior.
肋软骨在胸廓中起着重要的功能作用，但其力学性能尚未得到充分表征。本研究的目的是表征人类肋软骨的特性，并研究年龄、性别、肋骨水平和钙化程度的影响。我们从24名捐赠者（12名女性和12名男性）中获取了第3 - 6肋的尸体肋软骨样本，软骨膜完整，年龄分布均匀（范围47 - 94岁）。使用外周定量CT扫描来量化几何特性（面积矩）和组织钙化（以体积、长度表示，并分为中央型、外周型和混合型）。对每个样本进行四点弯曲试验，并通过将力学测试数据与非线性伪弹性模型（由线性和立方成分组成，分为加载和卸载阶段）拟合来评估弯曲刚度和模量结果。使用混合效应回归模型评估性别、年龄、肋骨水平和软骨钙化对弯曲刚度和模量结果的影响。男性的软骨尺寸（面积矩）大于女性，且与年龄呈正相关，而女性软骨中的钙化体积比男性更多。在加载过程中，男性的刚度（线性和立方）更大，而女性的模量（线性和立方）更大。线性刚度和模量均与年龄呈负相关，与钙化呈正相关，且在不同肋骨水平之间有所变化。刚度和模量的立方（非线性）成分与钙化呈正相关，且因肋骨而异，而模量（但不是刚度）与年龄呈负相关。在卸载过程中，线性刚度和模量值要低得多，不过也发现了一些类似的关联。总体而言，本研究增进了我们对肋软骨作为非线性粘弹性材料的行为以及性别、衰老和钙化对力学行为影响的理解。
