Knee arthroscopy has become one of the most common procedures in orthopedics. However, its complication rates remain unclear and most of the literature on complication rates dates back to the 1990s. With the update of arthroscopic equipment, technical improvements, and the increase of surgical volume, its complication rate should also change significantly. In order to clarify the incidence of knee arthroscopy complications and to better provide relevant information to patients, for this reason, the Japanese scholar Tetsuo Hagino et al. statistically studied the knee arthroscopy procedures performed in the last 7 years at the scholar’s hospital, published in the recent Arch Orthop Trauma Surg. A total of 2623 cases were included in the Sports Medicine and Knee Center of the scholar’s hospital from January 2006 to A total of 2623 patients (1396 men and 1227 women) underwent knee arthroscopy in March 2013. Age ranged from 7 to 96 years, with a mean of 33.5 ± 17.2 years, and most were young patients. Injuries due to sports accounted for 63.0% (1653 cases), no clear cause of injury accounted for 13.8% (361 cases), and other injury factors included car accidents, falls, and stair climbing. Arthroscopic diagnosis included meniscal injury, discoid meniscus, anterior fork injury, posterior fork injury, free body, intra-articular fracture, and synovitis (details are shown in Table 1). Arthroscopic procedures included meniscectomy, meniscal repair, anterior and posterior cruciate ligament reconstruction, synovial debridement, free body removal, microfracture, internal fixation of fracture, secondary exploration, and medial crease resection (details are shown in Table 2). Table 1 Arthroscopic diagnosis Table 2 Type of surgery All patients were preoperatively prepared for 1 day outside the initial emergency, and all procedures had the same team to complete. In principle, intraoperative tourniquets were not used, including ligament reconstruction and fracture fixation, and only in a few cases were tourniquets used briefly to control bleeding. A total of 6 doses of cephalosporin or broad-spectrum penicillin were administered before surgery, at the end of surgery and for 2 days after surgery to prevent infection. At least 2 L of lactated Ringer’s solution was flushed into the joint cavity at the end of surgery. The patient was allowed to leave bed and rehabilitation exercises 1 day after surgery. Patients were discharged when they regained the ability to walk, and all patients were hospitalized for at least 1 week, except for a very small number. No anticoagulants were used preoperatively or postoperatively. All patients wore elastic stockings and performed early functional exercises of the lower limbs. A total of 7 patients eventually developed complications, with an incidence of 0.27%, including 4 intraoperative complications (3 intra-articular device damage, 1 meniscal injury) and 3 postoperative complications (2 septic arthritis, 1 superficial infection). The infection was controlled by arthroscopic irrigation and debridement. （The incidence of complications has been reported in the literature. In 1985, the Arthroscopy Association of North America AANA counted 118,590 cases of which 930 had complications, an incidence of 0.8%; Sherman et al. retrospectively studied 2,640 knee arthroscopies performed by 4 operators and 216 cases had complications, an incidence of 8.2%. Martin et al. reported risk factors for complications including being black, more than 30 days preoperative, operative time more than 1.5 hours, and grade level of 40-65 yrs. Bohensky et al. reported risk factors for poor knee healing including chronic kidney disease, myocardial infarction, cerebrovascular accident, and cancer. The complication rate in this study was 0.27% and no embolism was observed, probably because the study determined embolism based on clinical signs and symptoms and did not perform ultrasonography, which would not rule out asymptomatic embolism. The low complication rate of knee arthroscopy suggests that it is a relatively safe procedure, although previous literature has reported symptomatic embolism or death in high-risk patients, which still requires attention. Both cases of septic arthritis were successfully controlled after early arthroscopic irrigation and debridement, which shows the importance of early diagnosis and early treatment and the importance of postoperative clinical observation.