The route of nutrients going to articular cartilage was studied by
determining the diffusion of hydrogen molecules from the subchondral
circulation to the articular cartilage in rabbits. In all immature animals
there was diffusion of hydrogen from subchondral bone into articular
cartilage, while in the older immature animals the results were variable.
None of the mature animals showed any diffusion of hydrogen into articular
cartilage. The rate of diffusion of hydrogen was significantly lower in the
articular cartilage than in the subchondral bone in the immature animals
while the concentrations of hydrogen in the articular cartilage were only
fractions of those in the subchondral bone at the same instant.
Histologically, the deep layers of immature cartilage are penetrated
extensively by vascular buds from the ossified portion of the epiphysis,
while in adults the articular cartilage is separated from subchondral
vascular spaces by an end-plate of bone. Blood vessels penetrating into the
basilar layer of articular cartilage in immature animals appear to play an
important role in the nutrition of articular cartilage coming from the
subchondral region.