Barrier to material transfer at the bone-cartilage interface: measurement with hydrogen gas in vivo.

Hydrogen gas was used as a tracer to identify the barrier to material transfer at bone-cartilage interface in the rabbit knees in vivo. The transfer of hydrogen molecules from subchondral bone to articular cartilage was detected by means of platinum electrodes which were placed in varying depths in articular cartilage and subchondral bone. Hydrogen transfer was obstructed at the osteochondral junction in mature animals, while in immature animals there was no such barrier present in the bone-cartilage interface. The metabolism of articular cartilage in mature animals may be isolated from that of the underlying bone. All layers of the mature cartilage including those in the zone of calcified cartilage can receive nourishment and be maintained from the synovial fluid alone.