The lumbosacral spine is the lower part of the spine that is made up of many small bones, including the lumbar region and sacrum, according to MedlinePlus. This area connects the spine to the pelvis.
When the lumbosacral spine is damaged, a physician takes an x-ray to determine whether there are fractures present, signs of osteoporosis, abnormal wear on cartilage and bones, or Spondylolisthesis, explains MedlinePlus. Osteoporosis is the thinning of bones. Spondylolisthesis occurs when one bone in the lower part of the spine moves out of position and settles on top of the bone below it. These conditions can become serious if left untreated.