Background:: Prediction of in-orthosis curvature at pre-orthosis stage is valuable for the treatment planning for adolescent idiopathic scoliosis, while the position of spinal curvature assessment that is effective for this prediction is still unknown.
Objectives:: To compare the spinal curvatures in different body positions for predicting the spinal curvature rendered by orthosis.
Study design:: A prospective cohort study.
Methods:: Twenty-two patients with adolescent idiopathic scoliosis (mean Cobb angle: 28.1°± 7.3°) underwent ultrasound assessment of spinal curvature in five positions (standing, supine, prone, sitting bending, prone bending positions) and that within orthosis. Differences and correlations were analyzed between the spinal curvatures in the five positions and that within orthosis.
Results:: The mean in-orthosis curvature was 11.2° while the mean curvatures in five studied positions were 18.7° (standing), 10.7° (supine), 10.7° (prone), -3.5° (prone bending), and -6.5° (sitting bending). The correlation coefficients of the in-orthosis curvature and that in five studied positions were r = 0.65 (standing), r = 0.76 (supine), r = 0.87 (prone), r = 0.41 (prone bending), and r = 0.36 (sitting bending).
Conclusion:: The curvature in recumbent positions (supine and prone) is highly correlated to the initial in-orthosis curvature without significant difference. Thus, the initial effect of spinal orthosis could be predicted by the curvature in the recumbent positions (especially prone position) at the pre-orthosis stage.
Clinical relevance: Prediction of in-orthosis correction at pre-orthosis stage is valuable for spinal orthosis design. This study suggests assessing the spinal curvature in recumbent position (especially prone position) to predict the initial in-orthosis correction for optimizing the orthosis design.
Keywords: Adolescent idiopathic scoliosis; in-orthosis correction; lateral bending; prone; supine; ultrasound.