The patient may feel a sense of contusion or dislocation of the knee at the time of injury, which may help determine the ligament rupture. 2. The patient may feel a sense of instability in the knee during activity, especially when running and jumping, turning and stopping sharply and suddenly running fast, or a feeling of weakness and inability to use force in the knee. 3. MRI results of the knee joint: ACL rupture is shown. However, the angle and position of the MRI projection, the projection conditions and the resolution of the machine, as well as the doctor’s experience in reading the film can affect the results. 4. Physician examination: The accuracy of the examination (Lachman test, front drawer test) by an experienced physician can reach more than 90%. The patient is required to relax during the examination, and the accuracy of the examination is better.