When it comes to “transplantation”, many people think of bone marrow transplantation, liver transplantation, kidney transplantation and so on. In fact, transplantation is sometimes needed to treat osteochondral injuries of the talus. Such transplantation includes autologous osteochondral transplantation, autologous periosteal transplantation, autologous osteochondral cell transplantation, and allogeneic osteochondral transplantation. Autologous osteochondral transplantation is one of the more commonly used methods of graft treatment mentioned above. As the name implies, autologous osteochondral transplantation involves obtaining healthy articular cartilage from other parts of the patient’s own body and transplanting it to the talar osteochondral injury. This type of transplantation is the body’s original hyaline cartilage, which has better elasticity and quality and is closer to the pre-injury state than the fibrocartilage that grows after microfracture surgery. Cartilage grafts can repair the defect and maintain the height and shape of the joint, making them a good option for patients with high mobility requirements. Most of the cartilage used for these grafts originates from the non-weight-bearing area of the knee joint. A number of patients are concerned about whether this will have an effect on the location of the cartilage taken. Admittedly, theoretically this effect does exist. In the knee joint, for example, after cartilage is removed from the non-weight-bearing area of the knee, approximately 10-30% of patients will experience swelling and pain in the knee joint. So, if this injury exists, why is this surgery done? In fact, this surgery is similar to tearing down an east wall to repair a west wall; if a load-bearing wall is broken, you need to dig up some bricks elsewhere to remedy the situation. The cartilage in the knee is so large that the surgeon will “take” from the margins during surgery. This marginal cartilage is relatively unimportant to the knee joint, but can be a lifesaver for the damage to the osteochondral cartilage of the talus. Therefore, it is the lesser of two evils. As for the pain and swelling at the knee joint after surgery, you need to consult your doctor for symptomatic treatment. So, are all patients with osteochondral injuries of the talus suitable for autologous osteochondral transplantation? The answer is no. The following cases should be considered: 1. If the result is still not good through arthroscopic cleanup of the lesion or after microfracture surgery, autologous osteochondral transplantation can be considered; 2. Due to the limitation of the extraction material, autologous osteochondral transplantation is not yet able to treat large cartilage defects. It is generally considered that an injury of more than 2 square centimeters, which is considered large, is not recommended for this surgery. The procedure can also be considered if the cartilage injury is within 2 cm2 and the lesion is relatively large. In patients with osteochondral injuries of the talus accompanied by cystic lesions, autologous osteochondral grafts are currently used in foreign countries. In China, arthroscopic debridement can be performed when the cystic lesion is small; when the cystic lesion is particularly large, autologous osteochondral transplantation can also be used, in which the periosteum and cancellous bone from the ilium are taken for transplantation (the periosteum is derived from undifferentiated mesodermal cells, which also have the ability to form cartilage). The advantage of autologous periosteal grafts is that they are not restricted in their use and do not cause damage to the normal joint. There is also an autologous graft that transplants only chondrocytes and not directly cartilage. This approach is not limited by the area of damage and can be done even if the defect is more than 2 cm2. This type of graft is called autologous osteochondrocyte transplantation. In the first generation of autologous osteochondrocyte transplantation, normal cartilage is taken from the knee or ankle joint, processed and chondrocytes are isolated and cultured in vitro to increase them to a certain number. Then the periosteum is taken at the non-weight-bearing part of the knee joint and covered over the injury site. Finally, the chondrocytes in the culture medium are injected into the injury site and sealed with fibrous gel. With the development of technology, the third generation of autologous osteochondrocyte transplantation, i.e. matrix-induced autologous osteochondrocyte transplantation, is currently used. It involves taking the obtained chondrocytes, pre-culturing them on a biological scaffold that can be degraded and absorbed, and then transplanting the scaffold along with the chondrocytes to the injury site. This scaffold is processed so that it has the same shape and size as the defect site. This eliminates the need to take the periosteum from the healthy site and to cover it with a collagen membrane. Also, this biological scaffold can be gradually degraded and absorbed in the body without the need to take it out again. Allogeneic osteochondral grafts can be performed abroad when the lesion damage is extensive. This technique is not very different from autologous osteochondral transplantation, except that the source of cartilage is different – a donation from the deceased is required. This type of transplantation is very weak, although there is rejection present. However, this treatment technique is not currently available in the country.