Autologous osteochondral graft, also known as mosaic graft, is used to repair cartilage defects using osteochondral plugs from non-weight-bearing surfaces at the site of osteochondral defects. 1. Method: A cylindrical measuring rod is selected to determine the number and size of grafts required, followed by the selection of a columnar osteochondral block of 10-15 mm in length taken perpendicular to the articular surface of the donor area with a suitable size retrieval device. There are many different diameters of the graft block, the most commonly used diameter is 6 mm. extraction site: non-weight-bearing areas, such as the medial and lateral talar crests, intercondylar fossa, etc. A cylindrical osteochondral hole is made in the recipient area and matched to the length, diameter and angle of the columnar osteochondral block. The graft is then slowly embedded in the osteochondral hole in the recipient area, taking care that the graft block should not protrude from the articular surface. The donor area can be either open or filled. Indications: Because of the limited source of cartilage on the non-weight-bearing surface, autologous osteochondral graft is mainly suitable for unilateral, focal, symptomatic traumatic full-layered small cartilage defects (<2-4 cm2), athletes with high recovery requirements and cartilage defects with bone loss, but the subchondral bone depth should preferably not exceed 6 mm. Contraindications: Osteoarthritic changes or multifocal lesions. 4.Post-operative rehabilitation: Post-operative rehabilitation of autologous osteochondral graft includes immediate early activity and non-weight-bearing activity for 3 weeks, after 3 weeks weight-bearing can be gradually increased until full weight-bearing starts at 6 weeks post-operatively, at which time a progressive rehabilitation program can be started. 5. Efficacy: Gudas et al. found that both microfracture and autologous osteochondral grafting for small cartilage defects of the femoral condyle had excellent rates between 60% and 80%; athletes repaired by autologous osteochondral bone were able to resume sports training earlier compared to microfractures (52% and 93% return to sports, respectively). The report of 2-5 years of follow-up of this technique was published by et al. and found excellent postoperative results in 86%-90% of cases. 6. Advantages: The advantage of autologous osteochondral grafting to repair cartilage defects is that it can provide normal hyaline cartilage containing viable chondrocytes instead of fibrocartilage to repair osteochondral defects, which can maintain almost the same biomechanical and biochemical properties as normal cartilage; postoperative phase I bony healing and fast recovery. 7. Disadvantages: damaged donor area, limited number of graft blocks, large defects cannot be repaired, insufficient morphological anastomosis of large graft blocks, etc.