Spondylolisthesis occurs when the vertebrae's support system fails and one vertebra slips forward out of alignment and remains out of position. It most commonly occurs between the fifth lumbar vertebra and the sacrum, and occasionally between the fourth and fifth lumbar vertebrae. The vertebrae of the spine normally stack one upon the other and are held in position by supporting structures, ligaments, muscles and discs. The spine is flexible in many directions because of its ability to bend and move without the vertebrae slipping out of position.
There are two common types of spondylolisthesis: isthmic, related to the presence of spondylolysis and occurring in the immature spine, and degenerative spondylolisthesis, occurring in older individuals with degenerative changes, usually at the fourth or fifth lumbar vertebra. Fracture, tumor, and infection are rare causes.
A change in position of the vertebrae may cause irritation to the nerve roots. The irritation can result in pain and weakness. The symptom pattern is similar to lumbar disc disease and sciatica, as both problems can be caused by spondylolisthesis.
Spondylolisthesis signs and symptoms
- An individual with spondylolisthesis in the spine may note pain in the back, hip, and leg.
- Weakness of the leg, with a sense of dragging the leg or foot, may be present.
- The individual may be noticeably "sway-backed" (lordosis).
- Individuals may not be able to walk normally and stumble or drag their feet.
- Pain is often aggravated with sitting and standing, while relieved with bedrest and bending over (flexion of the back).
- Leaning backward (back extension) increases the pain.
- If the injury is acute, the symptoms may be dramatic in onset.
A complete musculoskeletal and neurological back exam is necessary to rule out any underlying pathology and the involved nerves.