Comparisons of Interapical Distance and Coronal Balance Measurements Among Standing Positions in Participants With and Without Adolescent Idiopathic Scoliosis Using 3D Ultrasound Imaging

Study Design. Cross-sectional study. Objective. The objective of this study was to quantify whether interapical distance and coronal balance measured on 3D ultrasound (3DUS) images differed among 10 standing positions of participants with and without adolescent idiopathic scoliosis (AIS). Summary of Background Data. Apical vertebral translation (AVT) is an indicator of clinical symptoms and treatment outcomes in AIS. Stereoradiography simultaneously captures a frontal and lateral image, yet patients are required to elevate their arms during the examination and varied positioning may impact coronal plane measurements. Ultrasound can assess these measurements without exposing participants to radiation. Materials and Methods. Females with and without AIS were recruited from a scoliosis clinic, and e-mail advertisements, respectively. Participants underwent 3DUS scans in 10 positions: standing; arms anteriorly supported in 60° of shoulder flexion; fingers to clavicles, chin, zygomatic processes, and eyebrows; shoulders abducted at 90° with hands open and thumbs on shoulders; hands on anterior wall with and without blocks; and hands unsupported. AVT and coronal balance measurements were obtained using custom software. Positions and groups were compared using repeated measures ANOVAs with Sidak pairwise comparisons. Results. Fifty-nine females had a mean age, height, and weight of 17.5±4.9 years, 162.8±5.8 cm, and 56.2±10.6 kg, respectively. Seventeen single and 14 double curve participants were included with mean maximum curve angles of 26.4°±3.6° and 25.2°±3.1°, respectively. Overall, there were no statistically significant differences in interapical distance or coronal balance among the 10 positions, as well as in coronal balance between the groups ( P >0.05). The interapical distance of participants without AIS significantly differed from those with single curves in eight positions and from those with double curves in all 10 positions. Conclusions. The positions evaluated may be interchangeable for coronal plane lateral deviation measurements of females with AIS.