At the time of trauma, some patients may feel a tearing sound in the knee joint, followed by weakness, joint pain, swelling, blood accumulation in the joint, inability to continue movement or difficulty walking. Subcutaneous petechiae around the joint often indicate a combination of joint capsule injuries. In acute knee injuries, rupture of the anterior cruciate ligament is probably the most commonly missed injury. Because of the pain and muscle spasm, routine examination and x-ray are difficult to make an accurate diagnosis, so special diagnostic aids, such as MRI and arthroscopy, are needed. After the acute phase, knee pain gradually decreases and joint mobility gradually returns to normal, allowing walking and jogging, but not strenuous exercise, especially not fast running, not being able to complete movements such as jumping in a hurry, and often accompanied by a sense of joint misalignment.