Pathophysiology
A classification for spondylolisthesis was outlined by Macnab, Newman, and Wiltse. The five types are:
- Congenital spondylolisthesis (type I)
- Isthmic spondylolisthesis (type II)
- Degenerative spondylolisthesis (type III)
- Traumatic spondylolisthesis (type IV)
- Pathologic spondylolisthesis (type V)
Each type refers to the cause of the vertebra displacement - isthmic refers to a stress fracture in the pars interacticularis, pathological spondylolisthesis refers to any bone disorder that causes destabilization of the facet joints, and degenerative spondylolisthesis refers to any instability and weakness of the facet joints that causes disc slippage.
There are also five grades of spondylolisthesis that track the severity of the condition. The system is based on the degree of slippage as a percentage of distance from the vertebral body relative to the super end plate of the below vertebra. Each 25% increment in slippage refers to a new grade: grade 1 spondylolisthesis refers to a 1-25% slippage while grade 5 refers to slippages of over 100%. Grade 5 is often referred to as spondyloptosis.
In the case of degenerative spondylolisthesis, the displaced vertebra creates undue pressure upon the spinal canal and spinal nerves, which can lead to radiculopathy, claudication, loss of bodily control, and lower back pain. |
