Cartilage injury is a common disease in the knee joint, due to the lack of blood vessels and lymphatic cartilage, its self-repair ability is poor, often need surgery to repair, common surgical methods are: joint cleanup, bone marrow stimulation (such as microfracture surgery), autologous or allogeneic bone cartilage fast transplantation, but for patients with large area of full cartilage injury in the knee joint, the above surgical methods have limited efficacy, in recent years, domestic people continue to take In recent years, autologous chondrocyte transplantation (ACI), matrix-induced autologous chondrocyte transplantation (MACI) and other methods have been used to treat these patients with better results. Since last year, a modified MACI-tissue-engineered cartilage transplantation (TEC) has been used to treat these patients. TEC combines the advantages of ACI and MACI while overcoming the disadvantages of ACI and MACI, and proposes a new treatment protocol: combining the operability and stability of tissue-engineered cartilage sutures and the biomaterial gum as a cellular The combination of the maneuverability and stability of tissue-engineered cartilage sutures and the ability of biomaterial gum to act as a cellular carrier to improve the healing ability of the interface maximizes the latest cartilage tissue engineering findings and results in better clinical outcomes. The procedure of tissue-engineered cartilage transplantation consists of four major steps: preoperative articular cartilage biopsy, in vitro culture of cartilage cells, cell transplantation, and postoperative functional exercise. 1.Articular cartilage biopsy Pre-operative MRI to confirm the diagnosis, first surgery: arthroscopic biopsy to examine the site and extent of the defect and remove cartilage (non-weight-bearing area) at the appropriate site, about the size of a grain of rice. In addition, the patient must also meet certain conditions, such as no infection at the surgical site, no infectious disease, no history of malignancy, etc. 2.Chondrocyte culture in vitro Chondrocytes are obtained from non-weight-bearing sites or from injured sites by enzymatic digestion, and are cultured and expanded on a biological scaffold under strict environmental and technical support, reaching a sufficient number of cells, ≥6×106, to form TEC membrane after two weeks. 3.Cell transplantation Second surgery: transplantation of TEC membrane to the defective area together with suture and bonding treatment. 4.Recovery after transplantation Rehabilitation treatment plays a role in the treatment effect. After surgery, the patient should brake for 48h, and perform appropriate muscle and joint contraction exercises; afterwards, the patient should do some exercises in moderation, and after 1-2 months, the patient can carry some weight with the help of crutches, but the weight should be completely negative. Most patients can largely relieve their symptoms and resume normal daily life and sports after one year of rehabilitation training. In conclusion, tissue-engineered cartilage grafting, as a new means of cartilage information, has brought great benefits to the majority of patients with knee cartilage injuries.