SDSG Classification (Lumbosacral Spondylolisthesis)
Sorts an L5-S1 developmental spondylolisthesis into Spinal Deformity Study Group types 1 to 6 from the lateral radiograph.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Slip of L5 on S1
- 60 %
- Sacropelvic balance
- Unbalanced (high pelvic tilt, low sacral slope)
- C7 plumb line relative to the femoral heads
- At or behind the femoral heads
Result: SDSG type 5: high-grade slip with an unbalanced pelvis and a C7 plumb line at or behind the femoral heads.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Slip of L5 on S1
- Pelvic incidence (slip of 50% or less)
- Sacropelvic balance (slip over 50%)
- C7 plumb line relative to the femoral heads
How this is calculated
Citation
Labelle H, Mac-Thiong JM, Roussouly P. Spino-pelvic sagittal balance of spondylolisthesis: a review and classification. Eur Spine J. 2011;20(Suppl 5):641-646. Criteria as described in Camino Willhuber G, Kido G. Clin Orthop Relat Res. 2020;478(3):681-684. Read the sources: Labelle 2011 ↗, Camino Willhuber 2020 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.