The normal knee joint has a meniscus-shaped pad between the femur and tibia, one on the medial and one on the lateral side, which has a cushioning effect on the movement of the knee joint, but in a small number of people, the developmental abnormality is manifested by the overdevelopment of the meniscus, which is disc-shaped, hence the name disc meniscus. According to our magnetic resonance study with a large sample of more than 3000 cases, the incidence in the Han Chinese population is about 8%, and the probability of simultaneous bilateral onset is greater than 90%. The disc meniscus is thicker and larger than the normal meniscus and is more likely to be injured during sports, even without trauma. The youngest may require surgery at age 3 or 4. Due to the abnormal development of the meniscus, the knee tibia and femur may experience abnormal forces, which may lead to abnormal bone development. Our latest study (2014) showed differences in the posterior femoral condyle between the discoid meniscus and normal subjects on axial magnetic resonance and used two new parameters to assess the development of the posterior femoral condyle in patients with discoid meniscus. Patients with complete discoid meniscus had significant posterior femoral condyle dysplasia. For the surgical treatment of discoid meniscus, patients with recurrent interlocking and limited flexion and extension activities generally require surgical treatment, whereas for clear discoid meniscus without significant symptoms, it is recommended to reduce the intensity of movement as much as possible to reduce the risk of tearing, while for occasional interlocking, conservative treatment is still an option if tearing is ruled out, and surgical treatment is currently performed under Minimally invasive arthroscopic surgery is currently used to repair the torn area. However, due to the developmental problems of the bone, even if the meniscus is repaired to a normal size, the probability of developing traumatic arthritis in the long term is still very high, and a very small percentage of patients after meniscal surgery will still have to undergo joint replacement surgery in the long term.