Spondylolisthesis is a spinal disorder in which one vertebra glides forward over the vertebra below.
The spine, also called the back bone, is designed to give us stability, smooth movement, as well as providing a corridor of protection for the delicate spinal cord. It is made up of bony segments called vertebrae and fibrous tissue called intervertebral discs. The vertebrae and discs form a column from your head to your pelvis providing symmetry and support to the body. The spinal canal is formed by the placement of single vertebrae, one on top of the other, to form a canal. The purpose of the spinal canal is to create a bony casing from the head to the lower back through which the spinal cord passes.
Spondylolisthesis is a condition in which breakdown of the cartilage between the vertebrae of the spine causes one vertebra to slip out of place on top of the one below it. This causes misalignment and narrowing of the spinal column, a condition called spinal stenosis, which can put pressure on the nerves, resulting in pain in the buttocks or legs with walking or standing. As the spine tries to stabilize itself, the joints between the slipped vertebra and adjacent vertebrae can become enlarged, pinching nerves as they exit the spinal column.
Spondylolisthesis can be congenital (present at birth) or can develop in childhood or adulthood. The condition generally occurs after age 50 from degenerative (wear and tear) changes from osteoarthritis. It affects six times as many women as men. If spondylolisthesis occurs in the lumbar (lower back) area, the sciatic nerve may be compressed causing Sciatica. Sciatica is a painful condition caused by the irritation of the sciatic nerve. The sciatic nerve is the longest nerve in our bodies. It begins in the lower back and extends through the buttocks down the back of each leg to the thighs and feet.
Based on the cause of displacement, five subtypes of spondylolisthesis are identified, they are
- Dysplastic spondylolisthesis
- Isthmic spondylolisthesis
- Degenerative spondylolisthesis
- Traumatic spondylolisthesis
- Pathologic spondylolisthesis
Among the various subtypes of spondylolisthesis, the two most common forms commonly observed are dysplastic spondylolisthesis and isthmic spondylolisthesis
Dysplastic spondylolisthesis – This subtype is a congenital condition, present at birth, and is caused because of abnormal bone formation of the facet part of the vertebra resulting in spondylolisthesis.
Isthmic spondylolisthesis – This type of spondylolisthesis occurs because of a defect in the pars interarticularis part of the vertebra. This is more common in athletes and gymnasts as they often suffer from overuse injuries.
Signs and symptoms
The signs and symptoms of degenerative spondylolisthesis include:
- Lower back pain
- Stiffness in the back and tightening of the hamstring muscles from spasms
- Pain in the thighs and buttocks
- Decreased range of motion of the lower back
- Pain and weakness of the legs or numbness because of nerve compression
- Loss of control on bowel or bladder function by severe nerve compression
- Increase in lordosis curve, also called swayback
- Kyphosis (round back)
The cause for spondylolisthesis is multifactorial, the common causes are overuse injuries of spine, congenital abnormalities, trauma, bone disorders, and fractures.
An accurate diagnosis of spondylolisthesis and an effective treatment plan are essential for a successful outcome. Your doctor will diagnose the condition based on your symptoms, medical history, family history and physical examination. A neurological examination is also conducted to check for abnormal reflexes, muscle weakness, and loss of sensation. Your doctor may also recommend diagnostic tests such as an X-ray, computed tomography (CT) scan or magnetic resonance imaging (MRI). X-ray of the spine may be taken to determine the position of the vertebra. A MRI scan may be needed to identify nerve or spinal cord compression.
Treatment for spondylolisthesis is based on the diagnosis made by collecting medical & family history, physical examination, and radiographic scans. During the diagnosis, also the severity of displacement is assessed which is expressed as grade I to IV. In mild conditions and for symptomatic relief, conservative treatments including medications, bracing and physical therapy are recommended. In severe cases, surgical correction with decompression laminectomy followed by spinal fusion is recommended. The procedure involves removal of a portion of vertebra compressing the nerves and other vertebra followed by removal of disc between the vertebrae and fusion of adjacent vertebrae. Fusion surgery is performed to confer stability to the spine. Following the surgery, your surgeon recommends physical therapy and rehabilitation programs to regain strength to the surrounding bones & muscles as well as to make you active soon.