Restoration of Injured or Degenerated Articular Cartilage.

Intra-articular fractures, ligamentous and meniscal injuries, and articular cartilage breakdown are major causes of degenerative joint disease. Lesions on the articular surface seem to have a limited capacity for repair and often progress inexorably toward osteoarthritis. Recent studies on joint immobilization and cartilage atrophy, however, have shown that repair and remodeling of articular cartilage may be possible. Currently used clinical methods of stimulating cartilage repair and remodeling include alteration of the loading on degenerated joints (primarily by using osteotomies), introduction of new cartilage-forming cells by perforation of subchondral bone, and soft-tissue arthroplasty. These procedures provide temporary relief in selected patients, but they often do not predictably restore long-term joint function. Experimentally, cartilage repair has been stimulated successfully with the use of allografts of periosteum and perichondrium, which serve as sources of cells with chondrogenic potential; introduction of cells grown in culture (stem cells or chondrocytes); stimulation by fibrin clot formation; artificial collagen matrices combined with cell transplants; and chondrogenic growth factors. The long-term success of all these methods has not been explored thoroughly, even in animal studies. Nevertheless, some research results are sufficiently encouraging to suggest that repair of the degenerating articular cartilage may be possible in the future.