Spondylolisthesis, image 1 of 2. Coloured magnetic resonance imaging (MRI) scan of a side view of the lower back of a 46 year old woman showing spondylolisthesis. This is the backward displacement of a vertebra (spinal bone, light purple) relative to the one above it. Here it is between the lumbar vertebrae L4 (centre left) and L5 (lower centre). The condition is often due to a hereditary bone disorder, but can also be caused by trauma. It typically causes back pain, and the displaced vertebra puts pressure on the nearby spinal cord, causing sciatica (leg pain), loss of bladder and/or bowel control and eventually paralysis of the lower limbs. For the same patient after five years, see image M330/1432.