In the past, the causes of spinal fracture were classified into two categories: congenital and traumatic; but in fact, the most common cause is degenerative changes, accounting for more than 60% of all spinal fractures. From an anatomical point of view, the lumbar isthmus refers to the narrow part between the upper and lower articular processes, where the bone structure is relatively weak. The normal lumbar spine has a physiological lordosis, the sacral spine has a physiological kyphosis, and the junction between the lumbar and sacral vertebrae becomes a turning point. The upper lumbar vertebra tilts forward, and the lower sacrum tilts backward. Therefore, the negative gravity of the lumbar sacral spine naturally forms a forward component, causing L5 to have a tendency to slide forward. However, under normal circumstances, due to the restrictions of the lower articular process of L5 and the surrounding joint capsule and ligaments, the L5 isthmus is at the intersection of the two forces, so the isthmus is prone to fracture, which is also the reason why the L5 isthmus fractures most often. After the isthmus collapses, the vertebral arch is divided into two parts. The upper part is the superior articular process, transverse process, pedicle, and vertebral body, which still maintains normal connection with the upper spine; the lower part is the inferior articular process, lamina, and spinous process, which maintains connection with the sacrum below. The bony connection between the two parts is lost, and the upper part shifts forward due to loss of restriction, which is manifested as the vertebral body sliding forward on the lower vertebral body. This is called spondylolisthesis, which was named by Killam.