The forward displacement of a vertebra is called Spondylo-listhesis. This occurs especially the fifth lumbar vertebra, most commonly occurring after a break or fracture. (Backward displacement is referred to as retrolisthesis). These "slips" occur most commonly in the lumbar spine. Spondylolysis is the most common cause of spondylolisthesis. This is often confused with a slipped disc. A hangman's fracture is a specific type of spondylolisthesis where the second cervical vertebra (C2) is displaced anteriorly relative to the C3 vertebra due to fractures of the C2 vertebra's pedicles.
Spondylolisthesis is categorized into five types.
- Isthmic spondylolisthesis is the most common form; also called spondylolytic spondylolisthesis. A slip or fracture of the intravertebral joint is usually acquired between the ages of 6 and 16 years, but remains unnoticed until adulthood. Roughly 90 % of these isthmic slips are low-grade while the rest 10 % are high-grade.
- Degenerative spondylolisthesis is a disease of the older adult that develops as a result of facet arthritis and joint remodeling. Joint arthritis, and ligamentum flavum weakness, may result in slippage of a vertebra.
- Traumatic spondylolisthesis is rare and results from acute fractures in the neural arch, other than the pars.
Pathologic spondylolisthesis has been associated with damage to the posterior elements from metastases or metabolic bone disease. These slips have been reported in cases of Paget's disease of bone, tuberculosis, giant-cell tumors, and tumormetastases.
Dysplastic spondylolisthesis is a rare congenital spondylolisthesis occurring because of a malformation of the lumbosacral junction, resulting in small, incompetent facet joints.
Signs and symptoms
Symptoms of spondylolisthesis include the following:
- A general stiffening of the back and a tightening of the hamstrings, with a resulting change in both posture and gait.
- A leaning-forward or semi-kyphosis posture may be seen, due to compensatory changes.
- A "waddle" may be seen in more advanced causes, due to compensatory pelvic rotation due to decreased lumbar spine rotation.
- A result of the change in gait is often a noticeable atrophy in the gluteal muscles due to lack of use.
- Generalized lower-back pain may also be seen, with intermittent shooting pain from the buttocks to the posterior thigh, and/or lower leg via the sciatic nerve.
Other symptoms may include tingling and numbness. Coughing and sneezing can intensify the pain. An individual may also note a "slipping sensation" when moving into an upright position. Sitting and trying to stand up may be painful and difficult.
Surgical treatment is only considered after at least 6 weeks and often 6–12 months of non-operative therapy has failed to relieve symptoms. This is an area of considerable debate among spine surgeons, because although there are now techniques available that will allow the surgeon to "reduce" the slipped vertebra back to is normal, "anatomic" position, these techniques carry the risk of causing an injury to the surrounding nerve roots in the process.
Posterolateral fusion: Posterolateral fusion in adult lumbar isthmic spondylolisthesis results in a significant improvement in 2 year outcomes, but the difference between surgical and nonsurgical treatment narrows with time.