The most common acute ligament rupture in the knee is ACL rupture. Based on the complaints and symptoms of a large number of patients with acute ACL rupture in the knee, and with reference to the relevant literature reports at home and abroad, this article summarizes several points in the diagnosis of acute ligament rupture in the knee as follows: 1. Was the knee joint twisted by impact or physical instability? External rotation is common. 2. Severe pain! Is it very painful inside the knee joint when acutely injured? 3. “Baa” sound! Do you hear or feel a “banging” sound in the knee when you have an acute injury? Most patients report hearing or feeling a “bla” sound in the joint at the time of injury! 4. Inability to bear weight! Does the injured knee fall to the ground because it cannot hold weight? Some may even describe the sensation of “bones being repositioned after being misaligned”! 5. Swelling! Does the swelling of the injured knee occur quickly? Within three hours of the injury (possibly sooner, e.g. within a few minutes). Very few patients can have no swelling. 6. “No bone abnormalities” or very small bone fragments! X-rays do not show soft tissue structures such as ligaments of the knee, and small bone fragments may “Segond
Fractures”, i.e. acute ACL ruptures with avulsion fractures of the anterior portion of the lateral tibial plateau, can indirectly prove the occurrence of ACL ruptures that cannot be shown on X-rays! 7. Blood accumulation in the joint! If the attending physician gives if the blood is drawn and no fat droplets are present on the surface of the blood after standing for a few minutes, and the X-ray confirms that there is no intra-articular fracture, it often suggests a ligament rupture, and if fat droplets are present, a fracture is considered. 8, physical examination! An experienced doctor can check the laxity of the knee joint by physical examination: such as LACHMAN test, drawer test, etc., and finally make a comprehensive judgment by combining medical history and imaging data. 9. “MRI”! It is a good evidence for diagnosis. It can clarify the presence of anterior cruciate ligament rupture and possible combined injuries, such as “meniscal tear” or “bone contusion”, “medial and lateral collateral ligament injury” and “cartilage injury”, etc.