Low back pain back straight can be caused by the following reasons: first, lumbar spinal stenosis, lumbar spinal stenosis, ligamentous hypertrophy and hyperplasia can compress the nerve and lead to low back pain, the ligamentous compression of the nerve increases when bending, which leads to the inability to straighten the back, and comfortable in bending, to take early lumbar spine MRI, and CT examination, to early diagnosis and early treatment. Second, ankylosing spondylitis, ankylosing spondylitis due to the lumbar spine and spinal flexion straight, not able to straighten the back, to take early X-ray of the spine, sacroiliac joint x-ray examination, to early diagnosis and early treatment. Third, lumbar spondylolisthesis, lumbar spondylolisthesis can also occur when you can not straighten your back, because when you straighten the lumbar plate, lumbar spondylolisthesis aggravates, resulting in severe back pain, to take early X-ray, lumbar spine CT examination to diagnose.