Correlation between sacral parameters and the sagittal position parameters of spine and pelvis in juveniles

English Keywords:Sacrum  Spino-pelvic parameters  Sagittal alignment  Juvenile

English Abstract:

  【Abstract】 Objectives: To explore the correlation between sacrum morphology and sagittal position parameters of the spine in juveniles. Methods: The full-length free-standing radiographs of 120 normal minors were reviewed, including 55 males and 65 females, with an average age of 5 years. Radiological parameters, including lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured. Ferguson method was used to measure the angles between S1-2 tilt and the vertical line of the upper end plate of S1 (S1-2T), between S1-2 tilt and S5Co1 tilt (sacral kyphosis, SK), between S1-3 tilt and S4Co1 tilt (SK′), between the anterior edge of S2 and S4Co1 tilt (α), between the upper endplate of S1 and the anterior edge of S2 (β), and between S4Co1 tilt and the upper endplate of S1(θ). The sacral position parameters including the horizontal angle of anterior edge of S2(S2HA) and the horizontal angle of S5Co1 tilt (S5Co1HA) were measured. PI and LL, PI and SK′, LL and SK, S2HA and SS, S5Co1HA and fixed value 90° were tested by paired-samples t test and the differences were calculated. The Pearson correlations between sacral morphological parameters and PI, LL and PI and LL were analyzed. The scatter plot of β, θ and PI was made and the linear regression equation of β, θ and PI was obtained. The correlations between PI, SK, SK′, α, θ and LL in children (2-9 years) and adolescents (10-17 years) were analyzed by stages. Results: LL=50.3°±12.1°, PI=43.9°±11.0°, PT=5.7°±9.0°, SS=36.4°±7.6°, S1-2T=-15.5°±5.6°, SK=51.4°±10.7°, SK′=44.3°±10.5°, α=47.5°±9.7°, β=68.5°±8.2°, θ=64.0°±13.0°, S2HA=32.1°±9.0°, and S5Co1HA=90.3°±11.8°. There were significant differences between PI and LL, S2HA and SS, but there were no significant differences between PI and SK′, LL and SK, S5Co1HA and 90° of fixed value. The difference was PI=SK′±12°, LL=(SK-1.4°)±15°, S5Co1HA=90°±12°; S1-2T, SK, SK′, α, β, θ were correlated with PI (P<0.01), and the correlation coefficients (r) were 0.578, 0.440, 0.429, 0.374, 0.641, -0.683, respectively. The r values of SK, SK′, α, θ and LL were 0.265, 0.282, 0.273, -0.314, respectively, with significant correlation(P<0.01). The r values of S1-2T, β and LL were 0.136, 0.173, respectively, without significant correlation (P>0.01). There was no correlation between PI and LL (r=0.164, P>0.01). Regression equation: PI=0.451β-0.39θ+37.973 (r=0.728). The r values of LL and PI, SK, SK′, α, θ were 0.054, 0.076, 0.074, 0.066, 0.059, respectively, with no significant correlation. There was significant correlation between PI and LL (r=0.246, P>0.01). There were significant correlation between LL and SK, SK′, α, θ(r=0.391, 0.417, 0.411, 0.481, P<0.01). Conclusions: Juvenile PI can be predicted by SK′, β, and θ. Juvenile PI-LL has no correlation. There was a good correlation between the morphological parameters of sacrum and LL in adolescents. The use of sacral morphological parameters may be more stable and reliable than PI prediction to evaluate LL in adolescent.