T2 weighted sagittal image of the lumbar spine in a 44 year old male patient showing grade I spondylolisthesis at L3-4 (anterolisthesis of L3 over L4) with disc herniation. No traversing nerve roots compression.
T2 weighted sagittal image of the lumbar spine right lateral most image and the left lateral most images showing exiting nerve root compression (arrow) and break in the pars inter articularis suggesting spondylolysis.
Axial T2 weighted image at L3-4 showing nerve root compression bilaterally.
Spondylolisthesis is officially categorized into five different types by the Wiltse classification system: Dysplastic, Isthmic, Degenerative, Traumatic, and Pathologic.
- Grade 1 is 0–25%
- Grade 2 is 25–50%
- Grade 3 is 50–75%
- Grade 4 is 75–100%
- Over 100% is Spondyloptosis, when the vertebra completely falls off the supporting vertebra.