A torn cruciate ligament must be treated as early as possible, either conservatively or surgically, depending on the extent of the tear, to repair or reconstruct the cruciate ligament. Conservative treatment involves immobilizing the affected limb with a cast or brace to allow the torn ligament to repair and heal in a restricted location. The surgical approach is to repair the torn ligament and reconstruct the ACL using autologous tissue or artificial materials to restore its function. The cruciate ligament is an important ligament in the knee joint. It is the collective name for the anterior and posterior cruciate ligaments of the knee joint, which maintain anterior and posterior stability of the knee joint and allow the knee joint to flex and extend within a limited range of motion in the anterior and posterior directions. A torn cruciate ligament results in a loss of stability in the anterior-posterior direction of the knee and unrestricted anterior-posterior movement of the femoral and tibial joint ends, called knee instability. Knee instability affects the normal function of the knee and accelerates the aging and wear of the knee, so it is important to treat a torn ACL as soon as possible.