Abraham A C, Pauly H M, Donahue T L Haut
Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA.
School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA.
Osteoarthritis Cartilage. 2014 Feb;22(2):275-83. doi: 10.1016/j.joca.2013.11.013. Epub 2013 Dec 5.
The ability of menisci to prevent osteoarthritis (OA) is dependent on the integrity of the complex meniscal entheses, the attachments of the menisci to the underlying subchondral bone (SB). The goal of this study was to determine mechanical and structural changes in meniscal entheses after the onset of OA.
Healthy and osteoarthritic meniscal entheses were evaluated for changes in histomorphological characteristics, mineralization, and mechanical properties. Glycosaminoglycans (GAG) and calcium in the insertion were evaluated with histological staining techniques. The extent of calcium deposition was assessed and tidemark (TM) integrity was quantified. Changes in the mineralized zone of the insertion were examined using micro-computed tomography (μCT) to determine bone mineral density, cortical zone thickness, and mineralization gradient. Mechanical properties of the entheses were measured using nano-indentation techniques to obtain material properties based on viscoelastic analysis.
GAG thickness in the calcified fibrocartilage (CFC) zone and calcium content were significantly greater in osteoarthritic anterior meniscal entheses. TM integrity was significantly decreased in OA tissue, particularly in the medial anterior (MA) enthesis. The mineralized zone of osteoarthritic meniscal entheses was significantly thicker than in healthy entheses and showed decreased bone mineral density. Fitting of mineralization data to a sigmoidal Gompertz function revealed a lower rate of increase in mineralization in osteoarthritic tissue. Analysis of viscoelastic mechanical properties revealed increased compliance in osteoarthritic tissue.
These data suggest that significant changes occur at meniscal enthesis sites with the onset of OA. Mechanical and structural changes in meniscal entheses may contribute to meniscal extrusion, which has been shown to increase the progression of OA.
半月板预防骨关节炎（OA）的能力取决于复杂半月板附着点的完整性，即半月板与下方软骨下骨（SB）的附着。本研究的目的是确定OA发病后半月板附着点的力学和结构变化。
对健康和骨关节炎半月板附着点的组织形态学特征、矿化和力学性能变化进行评估。采用组织学染色技术评估插入部位的糖胺聚糖（GAG）和钙。评估钙沉积程度并量化潮标（TM）完整性。使用微型计算机断层扫描（μCT）检查插入部位矿化区的变化，以确定骨矿物质密度、皮质区厚度和矿化梯度。使用纳米压痕技术测量附着点的力学性能，以基于粘弹性分析获得材料性能。
骨关节炎前半月板附着点钙化纤维软骨（CFC）区的GAG厚度和钙含量显著更高。OA组织中的TM完整性显著降低，尤其是在内侧前（MA）附着点。骨关节炎半月板附着点的矿化区明显比健康附着点厚，且骨矿物质密度降低。将矿化数据拟合为S形Gompertz函数显示，骨关节炎组织中矿化增加率较低。粘弹性力学性能分析显示骨关节炎组织的顺应性增加。
这些数据表明，随着OA的发生，半月板附着点部位发生了显著变化。半月板附着点的力学和结构变化可能导致半月板挤出，这已被证明会加速OA的进展。
