Due to its abnormal morphology, the discoid cartilage of the knee is usually more prone to degeneration and injury than the normal meniscus. 26 cases of discoid cartilage injury of the knee were admitted from 2009 to 2010, and the discoid cartilage was staged under arthroscopy, and partial and total resection were used to achieve good results. 1. Data and methods 1.1. Clinical data The 26 cases in this group, 16 males and 10 females, aged 6 to 14 years, average 10.6 years. There were 11 cases in the right knee and 15 cases in the left knee, all with lateral disc cartilage. Microscopically, they were classified according to Watanabe’s type: 9 cases were complete, 17 cases were incomplete, and no Wrisberg type was found. The extent of disc cartilage injury was divided into: first-degree injury: the edge of the disc cartilage was intact, and the tearing edge was greater than 1 cm from the edge. 19 cases were found in this group. Second-degree injury: the lacerated edge is less than 1 cm from the edge, or there is a tear in the edge of the disc cartilage. Seven cases in this group. The duration of the disease ranged from 40 days to 6 years. There were 16 cases with a clear history of trauma. The clinical manifestations were pain in 22 cases, popping in 14 cases, local swelling in 8 cases, knee extension disorder in 10 cases, interlocking in 16 cases, quadriceps atrophy in 26 cases, positive McSweeney’s sign in 14 cases, positive knee popping test in 6 cases, and widening of the lateral joint space on X-ray examination in 9 cases. 1.2. Treatment method The Smith-nephew arthroscopic system was used with continuous epidural anesthesia, and arthroscopy was performed with standard anterolateral approach and anteromedial approach to fully examine the morphology and injury of the meniscus, and the mode of surgical resection was determined according to the degree of tearing of the disc cartilage. Injuries of the first degree are treated with disc chondroplasty. For second-degree injury, total discoid cartilage resection is performed. An additional incision is made adjacent to the patellar ligament (lateral or medial), a grasping forceps is inserted and the disc cartilage is clamped in traction, a meniscus cutter is inserted in the anterolateral portal and the cartilage flap is removed in large pieces, the outer 1/3 of the disc cartilage is preserved to resemble a normal meniscus, the residual edge of the meniscus is trimmed with an electric planer, the joint is flushed, and passive motion of the knee is performed. After the cavity was flushed and the knee joint was passively moved to confirm no popping, the incision was sutured. In this group, there were 13 partial resections, 6 subtotal resections, and 7 total resections. Postoperative cotton pads were applied and functional exercises were started on the first day after surgery, and the knee could be moved to the ground after 1 week. 2. Results: 22 cases in this group were followed up for more than six months, and the efficacy was evaluated using the Ikeuchi knee score. Excellent (no ringing, interlocking and pain in the joint, no limitation of movement) in 14 cases. Good (no rattling and interlocking, occasional mild pain with motion, no limitation of motion) in 5 cases. Fair (may have ringing, mild to moderate pain with movement, and no limitation of movement) 3 cases. There were no cases of poor postoperative function (joint with or without popping and interlocking, moderate to severe pain during exercise, and limited activity). Some patients had joint cavity effusion after surgery, which mostly disappeared by itself after 1 to 3 months, without intra-articular infection and other complications. Pellacci et al. concluded that partial resection is more effective than total resection, and Fujikawa et al. reported that the recovery period after disc chondroplasty is half as long as that after total resection. There is no doubt that plication is an ideal method for treating disc cartilage injuries. However, it is counterproductive if partial resection is overly pursued while leaving the pathological meniscal cartilage intact. For normal meniscal injuries Newman et al. summarized the parts to be resected into two points: removal of the dominant and unstable parts of the meniscus. Due to the anatomical peculiarities of the disc cartilage, the principles of arthroscopic resection for disc cartilage injuries are more complex than for normal meniscal injuries. It is generally accepted that those with Watanade’s subtype of Wrisberg’s disc cartilage should undergo total resection because they do not have adequate posterior tibial plateau attachment and are highly mobile. Those with complete or incomplete disc cartilage with tears should be selected for the correct resection depending on the tear. We have performed arthroscopic grading based on the extent of disc cartilage tear, which is a guide for the selection of disc cartilage resection style. In first-degree injuries, because the edges of the disc cartilage are intact, a plication can be chosen, but care must be taken that the meniscus is not preserved wider than 1 cm and that the cartilage section is trimmed as sloping as possible. The extent of excision of extra-thick disc cartilage may be increased, and passive movement of the knee before and after surgery should be compared to confirm that the popping or popping disappears. In second-degree injuries, because the tear has reached the edge of the disc cartilage, a total resection is appropriate if no repair is possible. Partial resection for horizontal tears is often less effective and total resection is preferable.