Osteochondral damage of the talus cartilage due to ankle injury is often difficult to detect in the early stage. Some patients have long-term swelling and pain in the ankle joint, which affects the function. Depending on the extent of the cartilage damage, arthroscopic debridement, homologous osteochondral grafting or allogeneic osteochondral grafting may be used. If the damage is large (>1.5mm) or the disease history is long, after cleaning the damaged cartilage, a large area of subchondral bone is exposed or subchondral bone necrosis forms a cyst, arthroscopic surgery is difficult to obtain a better clinical effect. Cartilage transplantation is a more effective and feasible method. From February 2002 to February 2006, 22 patients with talus cartilage injury were treated with onlay plasty in our hospital. The report is as follows. I. Clinical materials 22 patients, 9 males and 13 females. The age of the patients ranged from 34 to 56 years old (average 45 years old). Left side 8 cases, right side 14 cases. The history of ankle swelling and pain ranged from 2 to 6 years. All had a history of trauma (sprain). 2 cases had combined lateral ankle instability. All cases were medial lesions. Surgical method: Osteotomy of the medial ankle was used for exposure. After entering the ankle joint, the cartilage of the talus surface was examined, and it was often seen that the cartilage on the medial side of the talus was peeled off or the surface was not smooth, and the luster of the normal cartilage was lost. Resection of the damaged cartilage and exploration of the subchondral bone should be combined with the preoperative CT or MRI, and sometimes necrosis and cystic degeneration of the subchondral bone cannot be seen from the surface. The extent of the lesion is measured, and the size and number of bones to be removed are designed. Bone grafting is done with specialized osteochondral grafting instruments (Arthrex, OATS). A suitable bone grafting instrument is used to remove the lesion bone, and the graft should be kept as perpendicular to the cartilage surface as possible, and the graft is snapped into the subchondral bone to a depth of about 10-15 mm, and then rotated to remove the graft together with the lesion bone. Repeat the process for 1 to 3 times as needed. On the lateral condylar surface of the knee joint, an implant with a diameter 1mm larger than that of the bone graft is used to cut the cartilage and bone to a depth about 1mm shorter than that of the talus. After the implant is removed, the grafted cartilage and bone are implanted into the talus defect. The cartilage surface of the grafted bone is made parallel to the cartilage surface of the talus. The inner ankle was reset and fixed. Two cases with combined lateral ankle instability were treated with modified Chrisman-Snook surgery. After 3 weeks of postoperative cast immobilization, the patients started to practice activities without weight bearing, and could partially bear weight after 6 weeks, and could bear weight after 8 to 12 weeks. The lesion size was measured intraoperatively: 10mm in 2 cases, 10mm~15mm in 6 cases, 15mm~20mm in 14 cases. Results: 20 patients were followed up from 12 months to 5 years. 8 cases of ankle swelling and pain completely disappeared, 9 cases of ankle swelling and pain were significantly reduced, 3 cases of ankle swelling and pain still existed, 3 cases of knee discomfort, 2 cases of combined lateral ankle instability disappeared after the operation, 1 case of ankle pain underwent arthroscopic debridement, 1 case of ankle non-healing, and 1 case of complex localized pain syndrome. There were 4 cases of fracture of the talus or femoral rim during surgery. Discussion Osteochondral lesions of the talus (OLT) are often called osteochondritis dissecans, osteochondral fracture, osteochondral defect, and osteochondritis dissecans. osteochondral defect (OCD), etc. Several different names have been used for this disease. The use of several different names has caused confusion in the clinical diagnosis of this disease. It is true that talus osteochondral fracture may occur after acute trauma to the ankle joint, and a series of pathological changes such as cartilage degeneration and separation, subchondral bone necrosis, and cyst formation may occur later. All of the patients in this group had a history of obvious ankle sprains and recurrent ankle swelling after the injury. However, some patients can develop the same pathologic changes without significant trauma. This is often referred to as exfoliative osteochondritis dissecans of the talus. The authors believe that it is more appropriate to use the term talus osteochondral injury, and in order to differentiate between the different pathologic processes, it can be divided into acute and chronic phases. Trauma is the main cause of talus osteochondral injuries. Osteochondral injuries of the talus can occur in any part of the cartilaginous surface of the talus, but typical injuries are located in the posterior medial or anterolateral aspect of the talar talocalcaneal joint surface. Posteromedial talocalcaneal injuries occur when the foot is dorsiflexed due to inversion and rotational stresses and when the lateral talocalcaneal articular surface strikes the fibular articular surface; and when the foot is plantarflexed due to inversion stresses and when the distal tibial articular surface crushes the medial talocalcaneal articular surface. David reported that 98% of patients with lateral lesions had a history of trauma, while only 70% of patients with medial lesions had a history of trauma. However, in other studies, it was found that in 80% of the medial injuries, there was no clear history of trauma, and McCullough and Venugopal suggested that this could be the result of mild stress. In addition, some scholars have proposed other causes of talus osteochondral injury: hereditary ossification defects, paraphyseal bone formation, vascular embolism, vascular anomalies, spontaneous osteonecrosis, hormonal disorders, endocrine diseases, and abnormal stresses on the limbs with poor lines of force, etc. All 22 patients in our group had no history of trauma. All 22 patients in our group had a history of ankle sprains. Ninety percent of the patients seen in the authors’ clinic had medial talar lesions. It may be related to the susceptibility of the ankle to inversion injuries. Some patients had a combination of lateral ankle ligament injuries, resulting in chronic ankle instability. In symptomatic patients with chronic injuries, non-operative treatment is often ineffective and surgery is required. Smaller superficial cartilage injuries can be treated arthroscopically by removing the cartilage and drilling the cartilage defect. However, in larger cartilage injuries or when there is limited necrosis or cystic degeneration of the subchondral bone, simply removing the diseased cartilage will leave a large area of cartilage defect. This will affect the function of the ankle joint. In foreign literature, cartilage lesions >1.5 cm are considered as indications for mosaic osteochondral transplantation and autologous chondrocyte culture transplantation (ACT). For combined injuries should also be treated at the same time. If there is combined lateral ankle instability, reconstruction of the lateral ligament is required. However, in older patients, the cartilage of the knee and ankle joints has degenerated. However, for older patients with degeneration of the cartilage in the knee and ankle joints, or for those with lesions in the distal part of the tibia at the ankle point, mosaic osteochondral grafting is not appropriate. For the combined hindfoot deformity, the deformity should be corrected before surgery. If combined with chronic instability of the lateral ankle joint, the lateral ligament should be repaired or strengthened at the same time. The indications for onlay plasty in the treatment of osteochondral injury of the talus are as follows: 1. Lesions larger than 1.5 cm or still symptomatic after previous arthroscopic surgery. 2. Age less than 60 years old. 3. No arthritis or joint instability, and no “mirror image” lesions on the articular surface of the distal tibia. The limb axis should be normal. The advantages of this treatment are: 1. large coverage area; 2. quicker functional recovery. Generally after 4 months can return to sports. 3, 90% of the results are good. The disadvantages are: 1, the knee joint causes lesions. Although the foreign literature has not reported a significant impact on the knee joint function, but the knee joint has caused damage, the long-term impact of this damage on the knee joint needs to be observed. 2, several pieces of transplanted cartilage surface may have a defective area. 3, close to the edge of the talus medial and lateral articular surface of the lesion, the cutting of the lesion can cause fracture. 4, the coverage of the transplanted cartilage is limited, and can not be used for large-area injuries. 5, the internal ankle osteotomy may not heal. There is a possibility of non-healing. The soft tissues of the inner ankle should be protected as much as possible during the operation, and the inner ankle should be strongly immobilized after the operation. The direction and size of osteotomy should be determined according to the location and scope of the talus cartilage injury; if the osteotomy is inappropriate, it will bring difficulties to cartilage grafting. 2. When the lesion is cut and the bone is removed, it should be as much as possible to keep the fixator and cartilage surface perpendicular to each other and at the same depth to keep the grafted cartilage surface and the surrounding cartilage in the same plane. However, sometimes it is difficult to do so due to the location of the lesion, and the angle of bone extraction and bone grafting should be designed to make the cartilage flush as much as possible.3. The soft tissues of the inner ankle should be protected as much as possible during the operation to minimize the influence on the blood flow of the inner ankle, and the inner ankle should be strongly immobilized after the operation. Onlay plasty has become one of the standard methods for the treatment of osteochondral injury of the talus. The near-term treatment results are satisfactory, but the long-term efficacy needs to be observed.