Articular cartilage: injuries and potential for healing.

Impact and torsional joint loading can injure articular cartilage, causing pain, joint dysfunction and effusions, and, in some instances, progressive joint degeneration. Differences in the type of injury and the repair response distinguish three classes of articular surface injuries: 1) damage to the joint surface that leaves the articular surface intact but causes internal chondral damage and may cause subchondral bone injury, 2) mechanical disruption of the articular surface limited to articular cartilage, and 3) mechanical disruption of articular cartilage and subchondral bone. A variety of treatments has the potential to improve healing of articular surfaces, including perforation of subchondral bone, altered joint loading, periosteal and perichondrial grafts, cell transplantation, growth factors, and artificial matrices. Selection of treatment for a patient with an articular cartilage injury should be guided by an understanding of the type of injury, the potential for healing, and the effects of treatment on joint surface restoration.