The anterior and posterior cruciate ligaments of the knee are the main structures that maintain anterior-posterior stability of the knee joint and also play a role in the rotational stability of the knee joint. ACL ruptures are traumatic in nature and are commonly associated with high energy injuries such as sports injuries, car accidents and falls, and are often combined with lateral collateral ligament and meniscal injuries. The main symptom of cruciate ligament rupture is knee instability, which can be manifested as a frustrating sensation when moving the knee joint, weakness and fatigue. Patients with old ligament rupture may experience muscle atrophy of the lower limbs. Repeated sprains and swelling of the knee joint and multiple sprains can lead to secondary meniscal injury. Partial ruptures can be treated conservatively with lower extremity splinting for 4 weeks. Patients with complete ruptures, especially old ruptures, will require arthroscopic surgery to reconstruct the anterior and posterior cruciate ligaments if there is no significant improvement after lower extremity muscle exercises.