A posterior ligament avulsion is a condition in which the area of the bony stop of the posterior cruciate ligament is overstretched by the posterior cruciate ligament, resulting in a bony avulsion. It can be treated by arthroscopic treatment and posterior lateral approach to the knee with incision and repositioning fixation. 1. Arthroscopic treatment: Arthroscopy can improve the level of diagnosis and treatment under the observation of microscope, and can repair the avulsion fracture of the posterior cruciate stop. It can also repair the meniscus and joint capsule. It is also feasible to remove the free body in the knee joint, and for the unrepairable avulsion fracture, it is possible to carry out the removal operation and repair the ligament transplantation at the same time. 2. Posterior knee incision and reduction fixation: incision and reduction internal fixation is to incise the fracture for manipulation and reduction. Then it is fixed with a steel plate, which has a higher requirement for repositioning and needs to reach the standard of anatomical repositioning. The recovery of posterior ligament avulsion is related to the function of the knee joint and the incidence of injurious arthritis. When a posterior ligament tear occurs, it is important to go to the hospital in time and choose the appropriate surgical plan for treatment under the guidance and advice of the doctor.