1. Methods 1.1 General data From February 2008 to August 2009, a total of 52 patients with disc meniscus injury underwent surgical treatment in our hospital. 28 of them underwent arthroscopic disc meniscus orthotomy combined with repair and suture technique, and complete medical records and follow-up records were available. The age of the patients ranged from 6 to 42 years old, with an average of 32 years old, 23 were male and 5 were female. Most had a history of minor trauma. After the acute phase, the swelling and effusion could subside on their own, but the joint was still painful when moving, and some patients had “interlocking” phenomenon, or had popping and limitation of extension and flexion of the knee joint. The time between the onset of symptoms and surgical treatment ranges from 3 months to 2 years, with an average of 7 months. The clinical presentation of the patients was recorded by Lysholm knee score criteria. 1.2 Surgical method Before surgery, patients underwent routine laboratory tests (including ESR, ASO+RF+CRP to exclude collagen diseases) and imaging tests (frontal and lateral knee and patellofemoral joint axial films, knee MRI) (Figures 1, 2, 3). The procedure was performed using the American Jemal knee arthroscope at 0° and 30° with continuous epidural block anesthesia in the supine position and a balloon tourniquet placed at the root of the thigh for backup. All patients first underwent arthroscopic examination to clarify the type of meniscus, the type and extent of injury, and then underwent arthroscopic surgical management. The disc meniscus was staged according to Watanabe’s staging criteria [3], and among 28 patients, 24 had complete disc meniscus, 4 had incomplete disc meniscus, and 0 had Wrisberg ligament disc meniscus. The staging of disc meniscus tears was based on the Bin [4] method, with 19 cases of single level tears and 9 cases of compound level tears. Surgical method: Since the disc meniscus was relatively large in size, the arthroscopic surgery was performed under a very narrow space view, so the nature of the meniscus and the type and extent of the tear were initially determined. On the first day after surgery, the patient was instructed to strengthen the quadriceps exercise of the affected limb (straight leg raise), and 24 h after surgery, the quadriceps exercise and knee flexion and extension training were performed [7] (CPM machine was applied at 3 and 4 d after surgery), and the joint cavity was injected with 20 mg (sodium hyaluronate) for 4 consecutive times 1 week after surgery, and the stitches were removed 2 weeks after surgery. 2. Results The patients were followed up for 3 to 36 months after surgery, with an average of 8 months. 28 patients with meniscectomy combined with marginal suture technique had preoperative scores of 62 to 74 (67.23±5.24) and postoperative scores of 80 to 96 (87.24±5.26). There were no cases of retear or reoperation because of recurrence of symptoms. Disc meniscus is a kind of abnormal meniscus developmental disease, and there are different opinions on whether disc meniscus injury should be completely or partially excised for plication. For discoid meniscus cases without clinical symptoms, the current opinion tends to restrict activities and functional exercise of quadriceps muscle, and does not advocate surgery. The function of meniscus is to protect the joint surface, shock absorbing and cushioning, and increase the stability of the joint. The total removal of meniscus is bound to cause direct impact between the cartilage of femoral condyle and tibial plateau, which will easily lead to cartilage damage and even premature appearance of bone redundancy. In addition, most of the discoid cartilage is thicker than the normal meniscus. Raber [8] performed a long-term follow-up of patients after total discoid meniscectomy and showed that 15 of 17 patients showed significant osteoarthritis manifestations such as narrowing of the lateral tibiofemoral joint space and formation of bone redundancy, and two other patients showed exfoliative chondromalacia. Ikeuchi [3] concluded that total meniscectomy of the disc resulted in significant joint instability. In addition, total meniscectomy alters the mechanical transmission pattern of the knee joint, and the immature osteochondral tissue is repeatedly subjected to abnormal stresses during knee motion, which may be the cause of exfoliative osteochondritis in some patients after surgery [10]. Therefore, from the biomechanical point of view, meniscectomy can preserve more meniscal function and restore the anatomical structure of the joint. In symptomatic cases of discoid meniscus injury, partial resection is preferred [11,12], and Hayashi [13] suggested that a 6-mm margin should be preserved for complete discoid meniscus and an 8-mm margin for incomplete discoid meniscus during surgery. We believe that the marginal portion of the meniscus should be preserved as much as possible after removal of the diseased meniscus (plication). And the left edge should be trimmed into a sloping shape to reduce the impact and abrasion on the femoral condyle.