The Intra- and Inter-Evaluator Reliability of Coronal Plane Vertebra Displacement Measurements on Spinal Ultrasound Images of Adolescents with Idiopathic Scoliosis.

OBJECTIVE

We aimed to establish the intra- and inter-evaluator reliability of apical vertebral translation (AVT), inter-apical distance and coronal balance measurements from three-dimensional ultrasound images (3DUS).

METHODS

Female volunteers with and without adolescent idiopathic scoliosis underwent 3DUS scans in 10 positions: standing; arms anteriorly supported at 60° of shoulder flexion; fingers to clavicles, chin, zygomatic process and eyebrows; shoulders abducted 90° with hands open and thumbs on shoulders; hands on anterior wall with and without blocks; and hands unsupported. Custom software was utilized to obtain measurements. Intra-evaluator reliability ICC2,1 with standard error of measurement (SEM) were obtained for measurements extracted twice by a blinded evaluator (1 wk apart) on scans with pre-marked laminae. Inter-evaluator reliability compared the first measurement occasion by three evaluators. Intra-evaluator reliability was also tested for standing, chin and abducted positions, by an evaluator first measuring pre-marked laminae, comparing (1+ y later) to landmarking laminae and repeating measurements.

RESULTS

Forty-four females had a mean age, height and weight of 16.8 ± 4.4 y, 163.1 ± 5.9 cm and 56.1 ± 10.8 kg, respectively. Fourteen single and 13 double curve participants had mean maximum curve angles of 29.2° ± 4.4 and 25.5° ± 3.4, in standing, respectively. AVT, inter-apical distance and coronal balance measurements satisfied the criteria for individual use (ICC > 0.90) for both intra-evaluator scenarios (SEM below 0.89 mm for pre-marked laminae or <4.97 mm when re-marking laminae) and for the inter-evaluator reliability (SEM < 1.12 mm).

CONCLUSION

Reliable coronal plane vertebra displacement measurements can be obtained from 3DUS images in multiple standing positions.