**5.2 Cartilage repair techniques**

Cartilage repair techniques intend to stimulate the subchondral bone marrow (marrowstimulation techniques, MST) to induce mesenchymal stem cell infiltration into a chondral defect with formation of a clot that may differentiate into repair tissue. This tissue is generally fibrocartilage, with a ratio of Type II to I collagen that is less than that of normal hyaline articular cartilage. The biomechanical properties and durability of fibrocartilage are inferior to that of hyaline cartilage. Microfracture, subchondral bone drilling, and abrasion arthroplasty are MSTs.
