Cartilage wound healing. An overview.

Cartilage wound healing is a tentative balance between deposition of type I collagen in the form of scar tissue and repair by expression of type II collagen and proteoglycans. Small full-thickness cartilage defects are replaced by fibrocartilage, whereas partial-thickness defects are normally repaired by deposition of fibrous scar tissue. The mechanism of fibrocartilaginous repair appears to be mediated by proliferation and differentiation of mesenchymal cells of the marrow. Biologic grafts such as perichondrium have been successfully used to repair full-thickness defects, probably because they contain progenitor cells that can differentiate into chondroblasts. Other grafts composed of fibrocartilage, such as meniscus, appear potentially useful because they serve as a source for chondrocytes. When graft material is unavailable or cannot be easily fashioned to fit the defect, cell-cultured materials containing chondrocytes or progenitor cells appear promising. Finally, growth factors such as somatomedin-C have growth-promoting effect on cartilage and offer a future means of promoting cartilage repair.