There are five main types of spondylolisthesis that have distinct causes and pathology associated with them. These types include:
- Isthmic spondylolisthesis
- Degenerative spondylolisthesis
- Traumatic spondylolisthesis
- Pathologic spondylolisthesis
- Congenital spondylolisthesis
Each of these types will be discussed in further detail below, with particular regard to their pathology and the cause of the condition.
Some individuals are born with increased susceptibility to the condition as a result of rare congenital factors for spondylolisthesis. This arises as a result of malformation of the lumbosacral junction, causing the facet joints to be smaller and less strong than normal and increasing susceptibility to the condition.
This is a rare condition that tends to progress rapidly with severe symptoms presenting in a relatively short timeframe. It can also be difficult to treat due to the poor development of the posterior elements, which do not provide much surface area to carry out a fusion surgical procedure.
The most common type of spondylolisthesis is isthmic or spondylolytic spondylolisthesis. This usually occurs following a slip or fracture of the intravertebral joint acquired in childhood or adolescence, usually betwenn the age of 6 and 16. The symptoms of the condition, however, do not become evident until some time later, typically in adulthood.
The severity of the isthmic slip can vary significantly and is categorized into three subtypes:
- Pars fatigue fracture
- Pars elongation
- Pars acute fracture
Approximately 9 out of 10 patients with an isthmic slip are classified as low-grade with less that 50% slip, with the minority of patients exhibiting a high-grade slip.
Degenerative spondylolisthesis affects older adults and occurs as a result of facet arthritis and remodeling of the facets. The resulting weakness in the area can lead to movement and slipping of the spinal vertebrae, and the pathogenesis of spondylolisthesis.
This type is relatively common, particularly among older individuals. Women older than 50 years are the most likely to be affected by this type of the condition and individuals of African-American are more likely to be affected than Caucasian counterparts.
Traumatic spondylolisthesis is a rare form of the condition that arises as a result of acute fractures of the neural arch of the spine, distinct from the pars. The treatment for this form of the condition is very similar to that for other fracture of the spine. However, it is rare and there is little research on the subject.
Pathologic spondylolisthesis is a rare type that occurs due to damage to the posterior elements of the spine that may arise from a variety of causes. These include:
- Paget’s disease of the bone
- Giant-cell tumors
- Tumor metastases
Although there are various causes for the vertebral slipping that is associated with spondylolisthesis, each of the types is associated with symptoms as a result of the slipping of the vertebra. The treatment for the condtion varies greatly according to the severity of the condition and the specific health factors of the patient that may affect the outcomes.