The knee joint is the most complex large joint in the human body and plays a very important role in a person’s daily life, so its also very easy to be injured. Anatomical characteristics of the knee joint: The knee joint consists of bone, cartilage, synovium, ligament, meniscus, etc. The bones are the femur, tibia, and patella; 2. There is cartilage on the bone surface of the corresponding joint surface; 3. The inner wall of the joint capsule, outside of the cartilage, is made up of synovial membrane, which nourishes the cartilage and lubricates the joint; 4. In addition, outside the knee joint there are the medial and lateral collateral ligaments, patellofemoral ligament, N tendon and other ligaments that stabilize the knee joint. The anterior cruciate ligament is an important structure that stabilizes the knee joint and is the first structure to be damaged in any case of knee instability caused by violence. Therefore, in any case of knee sprain during sports, the possibility of ACL injury should be highly suspected. ACL injury can seriously affect the stability and joint function of the knee joint, reduce the athletic ability, lead to further damage to the meniscus and articular cartilage secondary to ACL injury, and inevitably lead to degenerative osteoarthritis, which is a disabling knee injury. Therefore, it is important to pay attention to it and treat it early. Diagnosis of anterior fork ligament injury: It is mainly based on the history of trauma, joint swelling, blood accumulation, pain or dysfunction, physical examination by a specialist, and MRI results. If you have a history of knee trauma, knee joint instability, and frequent “broken leg”, it is likely to have ACL injury, so please go to the hospital in time to avoid delaying treatment and causing rapid damage to the meniscus and joint cartilage, further leading to rapid progression of osteoarthrosis.