Influence of site and age on biochemical characteristics of the collagen network of equine articular cartilage

Abstract

Abstract Objective To determine variations in biochemical characteristics of equine articular cartilage in relation to age and the degree of predisposition for osteochondral disease at a specific site. Sample Population Articular cartilage specimens from 53 horses 4 to 30 years old. Procedure Healthy specimens were obtained from 2 locations on the proximal articular surface of the first phalanx that had different disease prevalences (site 1 at the mediodorsal margin and site 2 at the center of the medial cavity). Water, total collagen, and hydroxylysine contents and enzymatic (hydroxylysylpyridinoline [HP]) and nonenzymatic (pentosidine) crosslinking were determined at both sites. Differences between sites were analyzed by ANOVA (factors, site, and age), and age correlation was tested by Pearson’s product-moment correlation analysis. Significance was set at P < 0.01. Results Correlation with age was not found for water, collagen, hydroxylysine contents, and enzymatic crosslinking. Nonenzymatic crosslinking was higher in older horses and was linearly related to age (r = 0.94). Water and collagen contents and HP and pentosidine crosslinks were significantly higher at site 1. Hydroxylysine content was significantly lower at site 1. Conclusions Except for nonenzymatic glycation, the composition of articular cartilage collagen does not change significantly in adult horses. A significant topographic variation exists in biochemical characteristics of the articular cartilage collagen network in equine metacarpophalangeal joints. These differences may influence local biomechanical properties and, hence, susceptibility to osteochondral disease, as will greater pentosidine crosslinks in older horses that are likely to cause stiffer and more brittle cartilage. (Am J Vet Res 1999;60:341-345)