Weight bearing controls glycosaminoglycan concentration and articualr cartilage thickness in the knee joints of young beagle dogs

Abstract

Casting of the right knee (stifle) joints of young beagle dogs for 11 weeks caused up to 48% reduction in the glycosaminoglycan (GAG) concentration of the uncalcified articular cartilage, as assessed by a new microspectrophotometric method. The GAGS were depleted mainly in the superficial zone of the cartilage. Although the thickness of the uncalcified cartilage was not decreased, the calcified cartilage under the tidemark was thinned by 6 2 5 % at the femoral condyles. The increased weight-bearing in the limb opposite the one in the splint caused uncalcified cartilage thickness to be augmented by 19% and GAG concentration by 25-35 % in the intermediate, deep, and calcified zones of the summits of the femoral condyles; the changes were smaller in other, less loaded parts of the joint. It is concluded that in young dogs, increased weight-bearing augments local proteoglycan content of the articular cartilage matrix, while unloading reduces it.

Of Mice, Men and Elephants: The Relation between Articular Cartilage Thickness and Body Mass

“…Thus far, little is known about how articular cartilage deals with the challenges posed by increases in body mass [9]. The biochemical composition of the cartilage varies significantly over different topographical locations of the joint surface [10], [11], [12], and glycosaminoglycan (GAG) content appears to be dependent on local tissue loading [10], [13], [14]. While some significant differences in cartilage biochemical composition have been demonstrated between species [15], it is not known to what extent a similar mechanism would be necessary and may indeed exist to accommodate for the much larger differences in loading generated by the size differences between species.…”

Stimulation of Aggrecan Synthesis in Cartilage Explants by Cyclic Loading Is Localized to Regions of High Interstitial Fluid Flow1

“…animal, tissue, and cell levels. Whether in animal (9,10) or tissue explant (11)(12)(13)(14) studies, loading conditions which do not contain dynamic time-varying components were seen to reduce synthesis and deposition of matrix molecules. In contrast, dynamic time-varying loads in animals (15,16) and in tissue explants (17)(18)(19)(20)(21)(22) can stimulate chondrocytes to increase matrix synthesis and deposition.…”

Hsp70 accumulation in chondrocytic cells exposed to high continuous hydrostatic pressure coincides with mRNA stabilization rather than transcriptional activation

“…As in all connective tissues, there is a relationship between mechanical factors and tissue behavior in articular cartilage. At present, it is widely accepted that joint loading is an essential requirement for the maintenance of normal composition of articular cartilage (20)(21)(22)(23). Moderate exercise appears to support maintenance of the biological properties of cartilage (24,25), whereas strenuous exercise may eventually induce adverse reactions in the joint (26).…”