van der Harst Mark R, Brama Pieter A J, van de Lest Chris H A, Kiers Geesje H, DeGroot Jeroen, van Weeren P René
Faculty of Veterinary Medicine, Department of Equine Sciences, Utrecht University, The Netherlands.
Osteoarthritis Cartilage. 2004 Sep;12(9):752-61. doi: 10.1016/j.joca.2004.05.004.
In articular joints, the forces generated by locomotion are absorbed by the whole of cartilage, subchondral bone and underlying trabecular bone. The objective of this study is to test the hypothesis that regional differences in joint loading are related to clear and interrelated differences in the composition of the extracellular matrix (ECM) of all three weight-bearing constituents.
Cartilage, subchondral- and trabecular bone samples from two differently loaded sites (site 1, dorsal joint margin; site 2, central area) of the proximal articular surface of 30 macroscopically normal equine first phalanxes were collected. Collagen content, cross-linking (pentosidine, hydroxylysylpyridinoline (HP), lysylpyridinoline (LP)) hydroxylation, and denaturation, as well as glycosaminoglycan (GAG) and DNA content were measured in all three tissues. In addition, bone mineral density (BMD), the percentage of ash and the mineral composition (calcium, magnesium and phosphorus) were determined in the bony samples.
For pentosidine cross-links there was an expected correlation with age. Denatured collagen content was significantly higher in cartilage at site 1 than at site 2 and was higher in trabecular bone compared to subchondral bone, with no site differences. There were significant site differences in hydroxylysine (Hyl) concentration and HP cross-links in cartilage that were paralleled in one or both of the bony layers. In subchondral bone there was a positive correlation between total (HP+LP) cross-links and Ca content. For Ca and other minerals there were corresponding site differences in both bony layers.
It is concluded that there are distinct differences in distribution of the major biochemical components over both sites in all three layers. These differences show similar patterns in cartilage, subchondral bone and trabecular bone, stressing the functional unity of these tissues. Overall, differences could be interpreted as adaptations to a considerably higher cumulative loading over time at site 2, requiring stiffer tissue. Turnover is higher in trabecular bone than in subchondral bone. In cartilage, the dorsal site 1 appears to suffer more tissue damage.
在关节中，运动产生的力由整个软骨、软骨下骨和下方的小梁骨吸收。本研究的目的是检验以下假设：关节负荷的区域差异与所有三种负重成分的细胞外基质（ECM）组成中明显且相互关联的差异有关。
从30个宏观正常的马第一指骨近端关节面的两个不同负荷部位（部位1，背侧关节边缘；部位2，中心区域）采集软骨、软骨下骨和小梁骨样本。测量所有三种组织中的胶原蛋白含量、交联（戊糖苷、羟赖氨酰吡啶啉（HP）、赖氨酰吡啶啉（LP））、羟基化和变性，以及糖胺聚糖（GAG）和DNA含量。此外，测定骨样本中的骨矿物质密度（BMD）、灰分百分比和矿物质组成（钙、镁和磷）。
对于戊糖苷交联，与年龄存在预期的相关性。部位1软骨中的变性胶原蛋白含量显著高于部位2，小梁骨中的变性胶原蛋白含量高于软骨下骨，且无部位差异。软骨中羟赖氨酸（Hyl）浓度和HP交联存在显著的部位差异，在一层或两层骨组织中也存在类似差异。在软骨下骨中，总交联（HP+LP）与钙含量呈正相关。钙和其他矿物质在两层骨组织中均存在相应的部位差异。
得出结论，所有三层中两个部位的主要生化成分分布存在明显差异。这些差异在软骨、软骨下骨和小梁骨中呈现相似模式，强调了这些组织的功能统一性。总体而言，这些差异可解释为对部位2随时间累积负荷显著更高的适应性变化，需要更坚硬的组织。小梁骨的周转率高于软骨下骨。在软骨中，背侧部位1似乎遭受更多组织损伤。
