Most acute low back pain is mechanical in nature, meaning that there is a disruption in the way the components of the back (the spine, muscle, intervertebral discs, and nerves) fit together and move. Some examples of congenital mechanical causes of low back pain include skeletal irregularities and spina bifida. Skeletal irregularities include scoliosis, lordosis, kyphosis, and other congenital anomalies of the spine. Spina bifida involves the incomplete development of the spinal cord and/or its protective covering and can cause problems involving malformation of vertebrae and abnormal sensations and even paralysis. Another common cause of low back pain is injuries. Sprains, strains, and spasms are common injuries. Low back pain can also result from a traumatic injury such as from playing sports, car accidents, or a fall that can injure tendons, ligaments, or muscle causing the pain, as well as compress the spine and cause discs to rupture or herniate. Degenerative problems also cause low back pain. Examples include intervertebral disc degeneration and spondylosis. Intervertebral disc degeneration which occurs when the usually rubbery discs wear down as a normal process of aging and lose their cushioning ability. Spondylosis is the general degeneration of the spine associated with normal wear and tear that occurs in the joints, discs, and bones of the spine as people get older.