The main pathological changes in osteoarthritis (OA) include the formation of osteoid and the degeneration of cartilage and the eventual exposure of sclerotic subchondral bone. The recent view is that cartilage and subchondral bone are a functional unit and that osteoarthritis is a disease of this functional unit; however, it remains unclear which of the two precedes the disease. radin suggests that the early cartilage degeneration in OA is related to changes in the ability of the subchondral bone to absorb energy for impingement, suggesting that the subchondral bone precedes the cartilage lesion. The McKinley study found that cartilage defects altered the stress distribution of trabeculae, suggesting that off-chondral degeneration affects the subchondral bone structure. Repair of articular cartilage damage is difficult because of the complex structural and biomechanical function of articular cartilage and its very limited ability to repair and regenerate. Cartilage damage can exacerbate and lead to degenerative arthritis, so a number of surgical techniques have been developed both domestically and internationally to repair lost articular cartilage, and among these, the knee arthroscopic microfracture technique is the most widely used technique to repair total cartilage damage, which is not only comparable in efficacy to other techniques (osteochondral transplantation, chondrocyte transplantation), but also minimally invasive, simple in technique, with minimal complications and low cost. It has many advantages compared to other techniques (osteochondral grafting, chondrocyte grafting). Microfracture surgery involves cleaning the broken cartilage, removing the calcified cartilage, drilling through the cortical bone to cause intraosseous bleeding and clotting, and forming fibrocartilage with type II collagen from undifferentiated mesenchymal stem cells in the clot, which is less hard and wear-resistant than hyaline cartilage, but with partial postoperative weight-bearing and passive functional exercise will achieve excellent results. According to foreign research literature, the efficacy at 2 years after surgery is very positive, and the excellent rate at 7 years is 80%.