Pelvic Incidence Can Be Changed not only by Age and Sex, but also by Posture Used during Imaging

Abstract

ObjectiveComputed tomography (CT), rather than conventional 2-dimensional radiography, was used to scan and measure pelvic parameters. The results were compared with measurements using X-ray.MethodsPelvic parameters were measured using both CT and X-ray in 254 patients who underwent both abdomino-pelvic CT and X-ray at the pelvic site. We assessed the similarity of the pelvic parameters between the 2 exams, as well as the correlations of pelvic parameters with sex and age.ResultsThe mean values of the subjects’ pelvic parameters measured on X-ray were: sacral slope (SS), 31.6°; pelvic tilt (PT), 18.6°; and pelvic incidence (PI), 50.2°. The mean values measured on CT were: SS, 35.1°; PT, 11.9°; and PI, 47.0°. PT was found to be 4.07° higher on X-ray and 2.98° higher on CT in women, with these differences being statistically significant (p<0.001, p<0.001). PI was 4.10° higher on X-ray and 2.78° higher on CT in women, with these differences also being statistically significant (p<0.001, p=0.009). We also observed a correlation between age and PI. For men, this correlation coefficient was 0.199 measured using X-ray and 0.184 measured using CT. For women, this correlation coefficient was 0.423 measured using X-ray and 0.372 measured using CT.ConclusionWhen measured using CT compared to X-ray, SS increased by 3.5°, PT decreased by 6.7°, and PI decreased by 3.2°. There were also statistically significant differences in PT and PI between male and female subjects, while PI was found to increase with age.

Radiographic and Clinical Outcomes Following Pedicle Subtraction Osteotomy : Minimum 2-Year Follow-Up Data

“…Patients with fixed sagittal malalignment are unable to stand erect without flexing their hips or knees due to the loss of segmental lumbar lordosis (LL) 5,26,27) . Disruption of normal sagittal alignment results in significant pain and disability, and associated with low health-related quality of life 13) .…”

Imaging Methodology for Hip Preservation: Techniques, Parameters, and Thresholds

“…Higher PT and PI were reported, although not universally, in female subjects. 139 Interestingly, Mascarenhas et al 53 found higher SS and PI in asymptomatic females compared with asymptomatic males, whereas opposite observations were depicted when only considering symptomatic subjects. Some authors 143 concluded that pelvic parameters are not statistically different between sexes.…”

“…With respect to age, PI and PT were found to increase with age. 134,139 Similarly, Mac-Thiong et al described a weak correlation of spinopelvic parameters with age. 144 Some studies showed no statistically significant difference.…”

“…Spinopelvic parameters (SPPs) can be measured using lateral lumbosacral radiographs, 135,136 pelvic CT images, 137 and pelvic MRI. 53,138 Very few studies have addressed differences between measurements on distinct imaging modalities; Moon et al 139 found an increase in SS and a decrease in PT and PI (SS increased by 3.5 degrees, PT decreased by 6.7 degrees, and PI decreased by 3.2 degrees) when comparing XR and CT measurements, which might be associated with positional and methodological changes. Variability in standing to sitting position was described for PT, 140 and difference in measurements pertaining to XR (standing) and CT (decubitus) modalities were studied for all spinopelvic parameters.…”

“…Variability in standing to sitting position was described for PT, 140 and difference in measurements pertaining to XR (standing) and CT (decubitus) modalities were studied for all spinopelvic parameters. 139 MRI and CT 3D reconstructions allow for adequate corrections of femoral head centering and could provide a more accurate depiction of pelvic morphology. 53 With regard to pathology, there is a direct relationship between lumbar lordosis and SS, and a strong positive correlation between PI and sacral kyphosis was identified.…”