Spondylolisthesis¶

Definition¶

Spondylolisthesis is the displacement of one vertebra relative to the adjacent vertebra below, most commonly anteriorly. It is graded by the Meyerding classification based on the percentage of vertebral body translation, and has several distinct etiologic subtypes.

Classification¶

Wiltse-Newman Classification (by Etiology)¶

Type	Cause	Typical Level
I — Dysplastic (Congenital)	Congenital deficiency of the superior sacral facets or inferior L5 facets	L5–S1
II — Isthmic	Defect in the pars interarticularis (spondylolysis) — stress fracture, acute fracture, or elongation	L5–S1 (most common)
III — Degenerative	Facet and disc degeneration leading to segmental instability	L4–L5 (most common)
IV — Traumatic	Acute fracture of posterior elements other than the pars	Any level
V — Pathologic	Bone disease (tumor, infection, metabolic) weakening posterior elements	Any level
VI — Iatrogenic (Post-surgical)	Excessive resection of posterior elements during surgery	Any level

Meyerding Grading (Degree of Slip)¶

Grade	Percent Translation
I	0–25%
II	25–50%
III	50–75%
IV	75–100%
V (Spondyloptosis)	>100% (complete displacement)

Imaging Findings¶

Radiography¶

Lateral view: anterior displacement of the superior vertebra relative to the inferior; measure percent slip
Oblique view: pars defect visible as break in the "neck of the Scottie dog" (isthmic type)
Flexion-extension views: determine if the slip is dynamic (changes with motion) or fixed

CT¶

Best for evaluating pars defects (isthmic type)
Sagittal reformats for measuring slip percentage
Can differentiate between spondylolysis (pars defect) and degenerative listhesis (intact pars)

MRI¶

Evaluate for nerve root compression, stenosis, and cord/cauda equina compression
Disc degeneration at the slip level
Sagittal T2 shows the degree of slip and canal compromise

Clinical Pearl

The key to spondylolisthesis classification is determining whether the pars interarticularis is intact or defective. If the pars is defective → isthmic spondylolisthesis. If the pars is intact → degenerative spondylolisthesis (or another subtype). This distinction has treatment implications: isthmic listhesis occurs because the posterior elements are disconnected from the vertebral body, while degenerative listhesis occurs from facet/disc degeneration despite an intact posterior arch. CT sagittal images through the pars are the best way to make this determination.

Key Points¶

Spondylolisthesis = anterior slip of one vertebra on the one below
Meyerding grading: I (<25%), II (25–50%), III (50–75%), IV (75–100%), V (>100%)
The Wiltse classification identifies the etiology — isthmic and degenerative are most common
Pars integrity is the key distinguishing feature between isthmic and degenerative types
Lateral radiograph for measuring slip; CT for pars assessment; MRI for assessing neural compression

References¶

Koslosky E, Gendelberg D. Classification in Brief: The Meyerding Classification System of Spondylolisthesis. Clin Orthop Relat Res. 2020;478(5):1125-1130. https://pmc.ncbi.nlm.nih.gov/articles/PMC7170696/
Margetis K, Gillis CC. Spondylolisthesis. StatPearls. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK430767/
Wiltse classification of spondylolisthesis. Radiopaedia. https://radiopaedia.org/articles/wiltse-classification-of-spondylolisthesis
Meyerding classification of spondylolisthesis. Radiopaedia. https://radiopaedia.org/articles/meyerding-classification-of-spondylolisthesis
Kalichman L, Hunter DJ. Diagnosis and conservative management of degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(3):327-335. https://pubmed.ncbi.nlm.nih.gov/18026865/
Wiltse LL, Newman PH, Macnab I. Classification of spondylolisis and spondylolisthesis. Clin Orthop Relat Res. 1976;(117):23-29. https://pubmed.ncbi.nlm.nih.gov/1277669/