Sagittal Spinopelvic Alignment: Effect of Posture

Purpose: Many authors have studied the correlation between spinopelvic parameters and degenerative spinal disease. Based on these findings, several associations have been established, for example, that of pelvic incidence (PI), sacral slope (SS), pelvic tilt, and lumbar lordosis (LL). Associations have also been found between higher PI and spondylolisthesis and lower PI with disk degeneration. However, none of the studies have considered the effect of posture on these alignment parameters. Hence the purpose of our study was to evaluate this on sagittal spinopelvic alignment.

Methods and Materials: We included 100 consecutive young patients (age range: 17–40 years; mean: 29.60 ± 6 years) presenting with low backache to the department over 18 months. They all underwent a whole-spine lateral radiograph in a comfortable standing posture with arms extended and resting on arm rests and whole-spine magnetic resonance imaging (MRI) lying down. We were able to measure the following four parameters accurately on both these imaging modalities: SS, sagittal vertical axis (SVA), LL, and Cobb angle. These were measured separately by two radiology residents with 1 and 2 years of experience, respectively.

Results: The mean of various parameters (X-ray versus MRI) was SS: 35.11 ± 6.65 versus 36.15 ± 6.77; SVA: 28.67 ± 15.49 versus 3.33 ± 1.22; LL: 28.76 ± 22.58 versus 41.61 ± 9.47; and Cobb angle: 6.72 ± 3.84 versus 5.94 ± 3.71. A statistically significant difference was found between the findings of the SVA and LL (p = 0.00).

Conclusion: Sagittal spinopelvic parameters tend to vary with posture. We propose that this effect should also be taken into account while managing patients with spinal degenerative diseases.

Publication History

Article published online:
17 December 2020