Back pain often develops without a cause that shows up in a test or imaging study. Conditions commonly linked to back pain include: Muscle or ligament strain. Repeated heavy lifting or a sudden awkward movement can strain back muscles and spinal ligaments. For people in poor physical condition, constant strain on the back can cause painful muscle spasms. Bulging or ruptured disks. Disks act as cushions between the bones in the spine. The soft material inside a disk can bulge or rupture and press on a nerve. However, a bulging or ruptured disk might not cause back pain. Disk disease is often found on spine X-rays, CT scans or MRIs done for another reason. Arthritis. Osteoarthritis can affect the lower back. In some cases, arthritis in the spine can lead to a narrowing of the space around the spinal cord, a condition called spinal stenosis. Osteoporosis. The spine’s vertebrae can develop painful breaks if the bones become porous and brittle. Ankylosing spondylitis, It is also called axial spondyloarthritis. This inflammatory disease can cause some of the bones in the spine to fuse. This makes the spine less flexible.