Lumbar instability is a phenomenon in which the stability of the lumbar spine is disrupted to varying degrees by factors such as overstrain, chronic strain, and trauma. Lumbar instability causes associated nerve compression and spinal deformity. Nowadays, clinical use of lumbar hyperflexion-extension and lumbar front-lateral x-ray is the main diagnostic imaging methods and criteria for lumbar instability. In hyperflexion-hyperextension radiographs, an intervertebral relative horizontal displacement >3 mm or rotation at an angle >10° suggests degenerative lumbar instability. On hyperflexion-hyperextension radiographs, displacement of the superior vertebral body relative to the inferior vertebral body >3 mm or rotation into an angle >15° is a diagnostic criterion for lumbar instability. However, the lateral plane of the lumbar spine is two-dimensional information obtained from hyperflexion and hyperextension radiographs, which do not reflect the three-dimensional activity of the lumbar spine. Therefore, the diagnosis of lumbar instability can be simply judged by symptoms and X-ray films. If you want to understand the local bony structure of the lumbar spine in detail, you can check CT and perform three-dimensional reconstruction. There are several options for the surgical treatment of diseases related to lumbar instability, but the principles and objectives are the same: to relieve nerve compression, correct spinal deformities and enhance spinal stability.