The knee joint is a composite joint consisting of the distal femur, proximal tibia and patella. Ligaments are very important in maintaining the stability of the knee joint, and the main ligament structures include the anterior and posterior cruciate ligaments and the medial and lateral ligaments. Traumatic injuries in daily life can often cause damage to these joint stability structures. The most common type of injury is a sports-related injury that results in an ACL injury to the knee. Patients suffer from swelling and pain in the knee early after the injury. No fracture is found after a hospital visit for radiographs for simple symptomatic treatment. Therefore, most patients with acute traumatic knee hematoma from ACL injury will be delayed to chronic ACL injury and come to the hospital only after some complications appear, missing the best time for treatment, and patients often have knee instability, some secondary to meniscal injury or articular cartilage injury. Patients with this type of knee injury require MRI to confirm whether there is damage to the ligamentous structures, meniscus, and cartilage, and if so, arthroscopic surgical reconstruction should be performed to restore joint stability. Otherwise, other injuries may occur. After joint ligament injury, joint stability decreases and the patient quickly develops wear and tear degeneration of the articular cartilage, causing serious problems for subsequent treatment.