A patient with a torn cruciate ligament in the knee will have a laxity of the internal cruciate ligament in the knee, which can be evident in a positive anterior-posterior drawer test of the knee, which is performed by flexing the knee 90 degrees, holding the foot in place, and holding the calf with both hands and performing an anterior-posterior push-pull test of the calf (anterior-posterior drawer test). If there is abnormal movement of the knee joint, i.e., excessive movement, this indicates a tear or rupture of the cruciate ligament inside the knee joint, and an MRI of the knee joint should be performed promptly. If the cruciate ligament is significantly torn, minimally invasive knee arthroscopic cruciate ligament reconstruction surgery is needed to stabilize the knee joint structure, otherwise it will easily lead to abnormal friction and instability of the knee joint later on, which may cause traumatic arthritis.