Typical history: Non-contact deceleration, jumping, and movements that cause shearing action of the knee joint, also including external forces acting on the knee joint. Complaint: Hyperextension of the knee, or repeated repositioning of the knee after a change in position, often smelled or felt as a popping sound within the knee. The Lachman test is most sensitive for examining anterior tibial displacement, and the increased anterior displacement and lack of endpoint resistance sensation compared to the contralateral knee suggests the presence of an ACL injury. The axial shift test can be performed when the patient is relaxed and the lateral tibial collateral ligament is intact. Knee stability measurements such as the KT-1000 or KT-2000 can aid in the diagnosis of ACL injury and are particularly useful in the evaluation of patients with chronic ACL injuries without significant pain or muscle tension. Plain X-rays often show normal, however, intercondylar crest fractures of the tibia often suggest an ACL tibial attachment avulsion. Segond fractures: anterolateral tibial plateau avulsion fractures, most often due to excessive inversion of the lower extremity combined with internal rotation violence, are often associated with damage to the anterior cruciate ligament and medial and lateral meniscus as characteristic signs of ACL injury. MRI is the most effective radiological diagnostic technique.