Normal variation in sagittal spinal alignment parameters in adult patients: an EOS study using serial imaging

Area of Science:

• Spine biomechanics
• Radiographic analysis
• Orthopedic imaging

Background:

• Understanding normal spinal alignment is crucial for diagnosing and managing low back pain.
• Serial radiographic assessments are often used to monitor spinal changes over time.
• Establishing physiological norms for sagittal spinal parameters is essential for accurate interpretation.

Purpose of the Study:

• To characterize normal variations in sagittal spinal radiographic parameters over an interval period.
• To establish physiological norms for interpreting serial spinal images.
• To provide guidelines for the clinical interpretation of sagittal spinal parameters.

Main Methods:

• Prospective data collection from adult patients with first-episode mild low back pain.
• EOS® slot scanner used for whole-body sagittal X-rays at two time points, 6 months apart.
• Analysis of sagittal parameters including CL, TK, TL, LL, PI, PT, SS, and vertebral levels; statistical comparison using Chi-squared and Wilcoxon Signed Rank tests.

Main Results:

• Sixty patients (120 X-rays) analyzed; mean age 52.1 years; mean interval 126.2 days.
• Small variations (<1°) observed in most parameters, except PT (1.2°), CL (1.2°), and SVA (2.9 cm).
• Pelvic tilt showed a significant difference between serial images (p=0.035); consistent sagittal curve shapes found.

Conclusions:

• Sagittal spinal parameters exhibit dynamic variations between serial radiographic images.
• Pelvic tilt (PT) and sagittal vertical axis (SVA) demonstrate the widest variations.
• Interpretation should focus on patient-specific trends rather than isolated measurements for accurate spinal assessment.