A spondylolisthesis is a slippage of one vertebral body over another. This can slip forward (anterolisthesis) or backwards (retrolisthesis.) The lower lumbar vertebrae L4 and L5 are most commonly affected. Classification is based on the cause of the slippage.
- Congenital or dysplastic type is caused by birth defects.
- Isthmic, the most common type, is caused by a pars interarticularis defect (bony element with acts as a bridge connecting to the facet joints).
- Degenerative is due to abnormal orientations or degeneration of the joints.
- Traumatic causes include fracture or dislocation which does not involve the pars.
- Pathologic is due to infection, cancer or other types of bone abnormalities.
Isthmic spondylolisthesis affects the L5/S1 level most commonly and then L4/5 level. The most common cause of an isthmic spondylolisthesis is a pars interarticularis defect, or spondylolysis, which is like a stress fracture of the pars interarticularis.
A spondylolisthesis presents with low back pain and possible irritation of the nerve root or sciatic type symptoms. Lumbar spine films usually including flexion and extension films are taken to check if there is any movement or extra slippage of one vertebral body over another.
Treatment for isthmic spondylolisthesis focuses on relative rest, avoiding rotation and bending. Bracing may be needed. Once the pain improves, physical therapy can be helpful to focus on core stabilization and progression to sports specific activity. Surgical treatments are less common unless the slippage is greater than 50%.
For degenerative spondylolisthesis, treatment is similar with relative rest, physical therapy, and reintegration into previous activities. If this fails, surgery may be an option but is less common.