Meniscus injury is a common disease of the knee joint. Traditional surgery to cut the meniscus of the joint is easy to accelerate the degenerative changes of the articular cartilage, and the rate of satisfaction with the treatment is low. Radiologic examination can not be visualized, which may lead to various leakage and misdiagnosis of meniscus injury. Because arthroscopic surgery is less traumatic, it is easy to enter the joint cavity for visual inspection and resection, and the patient can start the functional exercise at an early stage, which can improve the joint function, arthroscopic diagnosis and resection of meniscus has gradually become the first choice of clinical diagnosis and treatment of meniscus injury. This study is to observe the arthroscopic meniscus examination and injury treatment carried out in our hospital in recent years, and to explore the examination value and surgical effect. I. DATA AND METHODS 1. Clinical data: 42 patients in this group, including 13 cases of old meniscus injury. Age 16-59 years old; 25 cases of male, 17 cases of female. There were 19 cases on the left side of the affected knee and 23 cases on the right side. Preoperative diagnosis of the lesion meniscus 44, including 30 lateral meniscus, medial meniscus 14; disease duration 1 day to 8 years, hospitalization days 4~29 days, average 11 days. Complaints of knee joint activity pain, strangulation lock in 40 cases, with swelling in 17 cases; playing soft legs, with interlocking sensation in 30 cases, activity limitation in 39 cases; no history of trauma in 3 cases, there is a clear history of trauma in 39 cases, of which 20 cases of sprains, 12 cases of collision, 7 cases of falls. Clinical examination: 21 cases of quadriceps atrophy, 32 cases of positive joint pain, 27 cases of grinding test, 17 cases of positive hyperextension test, 36 cases of positive gyratory compression test. MRI was performed in 33 cases, and 29 cases were correctly diagnosed by MRI; 5 cases were not correctly diagnosed by X-ray; all cases were diagnosed by arthroscopy. Surgical method: continuous epidural block anesthesia and pneumatic tourniquet control were used. Firstly, we entered the joint lens to observe the synovial edema, and then we penetrated the water injection tube to inject saline 150cm to continuously perfuse the joint cavity, and then we explored the intercondylar fossa, inner and outer tibiofemoral space, posterior joint capsule, patellofemoral joint, and suprapatellar capsule in the order. The medial or lateral meniscus was searched according to the surgical need, and the posterior horn, body, and anterior horn of the meniscus were carefully observed. For the meniscus that had meniscal roughness, flocculent changes in the margins, but the meniscus was not ruptured, meniscal revision was performed in 6 cases; for the meniscus that had a flap tear, oblique fracture, transverse fracture, or joggle fracture that did not exceed two-thirds of the transverse diameter of the meniscus, or a partially deficient, abraded and degenerated meniscus, a partial meniscectomy and plasty was used, and there were 33 cases in which a portion of the meniscus that had a good matrix was retained, and a portion of the free damaged portion was excised, and that portion of the meniscus was trimmed to a Rounded edge, avoiding the meniscus bite and tibial plateau to form a step; for irregular meniscus rupture such as, oblique fracture or transverse fracture and horizontal fracture, the rupture site has exceeded more than 2/3 of the transverse diameter of the meniscus or the rupture site can not be extensive partial meniscectomy, and to retain a normal portion of the meniscus, need to be all meniscus resection, there are 3 cases, pay attention to the bite off the posterior horn of the meniscus should be thorough and clean. After surgery, the joint cavity should be thoroughly flushed with a large amount of saline to flush out the broken meniscus debris and other free bodies from the joint, remove the water tube, squeeze out the intra-articular fluid, remove the joint lens, and close the incision with a full-layer suture. Postoperative treatment: postoperative anti-infection, compression bandage for 3d, on the first day of operation, the patient was instructed to start the static contraction of quadriceps muscle, and then gradually cooperate with the weight-bearing straight-leg raising exercise, and could walk on the ground in 5~7d. Results All the cases in this group were followed up after the operation, and the follow-up time was from 1 to 52 months, with an average of 12.8 months. The efficacy was determined by comprehensive evaluation based on interlocking popping, pain, pressure, quadriceps recovery and joint movement. The standard evaluation, excellent: knee function was basically normal, symptoms and signs disappeared; good: knee function was basically normal, occasional pain during activities; OK: mild obstacle in knee flexion and extension, pain in flexion and extension activities, sometimes mild swelling; poor: no improvement in symptoms and signs after the operation. Follow-up results: 30 cases (71.4%) were excellent, 6 cases (14.3%) were good, 5 cases (11.9%) were fair, and 1 case (2.4%) was poor, with an excellent rate of 85.7%. There was no infection or vascular injury in this group, and the postoperative hospitalization ranged from 2 to 23 d, with an average of 6 d. Discussion 1. Among the patients in this group, there were 33 cases of preoperative MRI diagnosis, and the results were consistent with the arthroscopic findings in 29 cases (88%), which proved that preoperative MRI examination was of great help in the definitive diagnosis of the meniscus. Comparison of MRI diagnosis and arthroscopy results by Xu Weiguo et al. showed that MRI diagnosis of meniscus tear had a sensitivity of 90.0%, specificity of 91.9%, and compliance rate of 91.2%. However, there were still 4 cases of MRI diagnostic errors in this group, and the diagnosis was finally confirmed by arthroscopy. Therefore, MRI is of great value in diagnosing early degeneration of meniscus, while arthroscopy provides a clear image and basis for the final diagnosis of meniscus injury, and MRI cannot replace the role of arthroscopy. MRI can not replace the role of arthroscopy. The two complement each other to provide better diagnostic value, which is the direction of orthopedics and imaging in the future diagnosis of meniscus injuries. 2.Trauma is the main factor of meniscus injury: in this group of patients, there are trauma factors accounted for 39 cases (93%), mainly sprains, accounting for 20 cases (44.4%) in this group. Among them, injuries with large violence, such as collision and fall, had heavy meniscus injuries and significantly prolonged hospitalization time. In the damaged meniscus, the ratio of medial to lateral was 1:2.2, because in this group the patients had more sports injuries, this kind of injury is easy to cause lateral meniscus injury; age is the main factor of meniscus injury, the increase of age, the elasticity of meniscus decreases, the brittleness increases, and the slightest injury can cause meniscus tear. In this group, meniscal injuries were mainly concentrated in 20-40 years old, accounting for 69%. Meniscus injuries were reported to be concentrated in the age groups of 21-30 years and 31-40 years, accounting for 58.8% and 31% respectively. There were more males than females in this group, with a male to female ratio of 1.5:1 (Shenzhen male to female ratio of 1:6), which was mainly due to the fact that males were more engaged in physical and sports activities and accidental injuries. In addition, there is also a certain relationship with the weight and stability of the knee joint. 3.Surgical treatment of meniscus injury (1) the principle of surgical treatment of meniscus injury: due to the recognition of total meniscectomy will appear late osteoarthritis, partial meniscectomy or revision of the meniscus of the long-term effect is better than the meniscus of the total excision surgery. Also, partial resection of the meniscus results in the least amount of trabecular bone damage through the proximal tibia, whereas total meniscectomy significantly increases trabecular bone damage. The data show that partial resection of the meniscus results in minimal changes in load transfer through the proximal tibia, suggesting that partial resection of the meniscus is an ideal surgical option for patients with meniscal tears. Arthroscopic surgery for plasty or partial resection should be pursued to preserve the meniscus as much as possible to maximize its function. This is better than total meniscectomy as the joint function is close to normal. Especially for discoid meniscus, the use of central partial resection with peripheral suture is effective. In the meniscus surgeries observed in this group, the partial resection of meniscus has good curative effect. (2) Surgical results: The surgical results of meniscus injuries are related to many factors, and a ten-year follow-up found that a better prognosis was associated with the following factors: age less than 35 years, vertical tear, no cartilage damage, and the ability to maintain an intact meniscus rim after meniscectomy. For unilateral meniscal injuries, age and maintaining an intact meniscal rim are particularly important. The timing of the surgery and the cause of the injury are also important here. Although the meniscus has the potential to heal, total resection should be considered if it fails to heal and causes severe knee dysfunction due to the severity of its rupture. In patients with meniscal tears given early repair within 3 months (91%) will have better results than late repair (58%), and the healing rate of nontraumatic meniscal tears is much lower than that of traumatic tears (42% versus 73%). Non-traumatic central meniscal tears alone have a worse healing rate (33% healed) and are better treated with meniscectomy. Since non-traumatic meniscal tears are sometimes overlooked, the healing rate is even worse. Therefore, it should be diagnosed and treated early in order to strive for partial resection, preferably within 8 weeks, which is most favorable for repair. In this group of 42 cases, the follow-up excellent rate amounted to 36 cases (85.7%). Therefore, arthroscopic meniscus surgery has excellent efficacy, small injury, short hospitalization time and fast recovery. (3) Surgical age: Eggli et al. reported that in terms of surgical age, under 30 years old, it is most favorable for repair. It is believed that for patients aged 40 or older with peripheral meniscal tears, meniscal repair is still an effective method, with 86.5% of these patients having good clinical outcomes. In our group, 8 patients (17%) over 40 years of age were operated on arthroscopically with good results. Even for the controversial 60+ year olds, the study found that at a mean age of 67 years (60.3-78.9 years) and a follow-up of 5 years (2C12 years), arthroscopic resection of a portion of the meniscus was still able to reduce pain and improve function and mobility. So age at surgery should not be a limitation.