Microfracture is a surgical technique that has been developed to treat cartilage defects. It is a common procedure used to treat patients with full thickness damage to the articular cartilage that goes all the way down to the bone. Microfracture creates small holes in the bone using a sharp tipped metal awl. These small holes become a channel through the surface layer of bone, called the subchondral bone, which is hard and lacks good blood supply. By penetrating this hard subchondral bone layer, a microfracture channel allows the deeper, more vascular bone to access the surface layer hence forming a super clot. This deeper bone has more blood supply, and the cells can then get to the surface layer and stimulate cartilage growth.