The waist concave in, may be due to the following several reasons: 1, may be due to the normal physiological bending of the lumbar spine caused. Under normal circumstances, the lumbar spine originally has a physiological bend that protrudes to the front, and this bend will become more obvious when the patient stands upright or holds his abdomen up, and at this time, when observed at the back, the middle of the waist will be seen to be concave; 2, this situation may be caused by the bony deformity of the spine, for example, if the patient has scoliosis, it may be due to the abnormal bending of a section of the lumbar spine, resulting in the appearance of 3. This condition may also be caused by old damage to the lumbar spine. For example, if there is an old fracture or dislocation of the lumbar spine, after recovery, there may be a bony deformity left behind, resulting in a depression in a certain area; 4. When the patient is upright, there will be a local depression.