Segond fracture is a lateral tibial plateau avulsion fracture (the presence of a small avulsion fracture mass on the lateral edge of the tibial plateau is seen on all orthogonal x-rays of the knee), which usually occurs in the context of acute trauma to the knee. The Segond fracture is located dorsal to the proximal tibial plateau and is attached to the lateral joint capsule. The Segond fracture is located dorsal to the proximal tibial plateau and is attached to the lateral joint capsule. It is often combined with an anterior cruciate ligament rupture and is therefore considered strong evidence for the diagnosis of an ACL rupture. In addition, the presence of a bony contusion on the lateral border of the tibial plateau on MRI resembles the indirect sign of a Segond fracture, which also strongly suggests injury to the ACL and the medial and lateral collateral ligaments, and has a higher sensitivity than radiography. Bone contusions tend to have specific sites of predilection, with the posterior lateral tibial plateau and middle femoral epicondyle being the most common, often suggesting injury to the anterior cruciate and medial collateral ligaments and injury to the lateral meniscus and articular cartilage. Paul Segond reported in 1879 a lateral avulsion fracture of the tibial plateau with hemorrhagic arthritis and confirmed by biomechanical testing of anatomical specimens that the fracture did not originate from Gerdy′s node but was located on the proximal posterior aspect of the tibial plateau, attached to the lateral joint capsule. Many scholars later successively confirmed that the occurrence of Segond fractures lies in the presence of an internally rotating stress during knee flexion from 10° to 90°, which is consistent with the mechanism of action of certain anterior cruciate ligament injuries.