Lumbar spine instability after lumbar spine fusion with internal fixation can be treated with lumbar support fixation or surgery according to the degree of instability. Lumbar spine instability after lumbar spine fusion with internal fixation surgery depends on which cause. If the fusion failure is caused by short bed rest time, and there is no compression of nerves, it can be treated conservatively, and it needs to prolong the bed rest time, and the films should be reviewed regularly. If the lumbar spine is fused in the X-ray, it is possible to move down to the ground without wearing a brace. If the lumbar spine is destabilized due to loose or broken internal fixation, the nerves and spinal cord are obviously compressed, causing leg pain and numbness or inability to walk, revision surgery is needed. Therefore, lumbar spine instability after lumbar spine fusion with internal fixation needs to be evaluated by a doctor at the hospital to take the next treatment plan.