Anterior cruciate ligament ruptures are most common in athletic people, especially young people, and they have long-term negative effects on patients due to changes in the environment of the joint cavity and the mechanics of the joint, leading to symptoms such as knee pain, instability, and dysfunction of the knee joint. It is worth noting that many studies have shown that ACL rupture can cause synovial inflammation, chondrocyte damage, and degradation of cartilage matrix, and finally lead to the formation of traumatic osteoarthritis, in which the causes of these changes in the joint cavity may be closely related to the changes in the intra-articular environment after ACL rupture. Therefore, this paper focuses on the changes in the intra-articular environment after ACL rupture and analyzes the influence of the changes in the intra-articular environment on the prognosis of patients before and after surgery, so as to provide a reliable scientific basis for the formation of PTOA after ACL rupture.