PI-LL Mismatch (Spinopelvic Alignment)
PI-LL mismatch (SRS-Schwab; Schwab 2012): pelvic incidence minus lumbar lordosis (degrees).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Pelvic incidence, PI
- 55 degrees
- Lumbar lordosis magnitude, LL
- 30 degrees
Result: PI-LL 25° — marked malalignment (SRS-Schwab modifier ++).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Modifier
- |PI-LL| < 10 = 0 (well aligned), 10-20 = +, > 20 = ++. Realignment target ~ +/- 10 deg (age-adjusted allows more in older patients).
What you enter
- Pelvic incidence, PI (degrees)
- Lumbar lordosis magnitude, LL (degrees)
How this is calculated
- Formula
- PI-LL = pelvic incidence - lumbar lordosis (degrees).
Schwab F, Ungar B, Blondel B, et al. Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976). 2012;37(12):1077-1082. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.