The test–retest reliability of frontal, sagittal, and transverse spinal measurements during three standing arm positions in adolescents with idiopathic scoliosis measured using ultrasound imaging

Clinicians monitor scoliosis progression using radiographs during growth. Three standing positions were assessed because the arms must be elevated to visualize all vertebrae on radiographs, possibly affecting sagittal parameters. 3D Ultrasound (3DUS) is safe to assess positions without radiation, but its test–retest reliability has not been established for common radiograph positions. The aim was to determine the test–retest reliability of frontal, sagittal, and transverse measurements obtained from three positions using 3DUS imaging.

Participants with AIS were recruited from a clinic in Alberta. Participants underwent 3DUS scans in habitual standing, fingers to clavicle, and hands on wall. Participants were re-scanned in the same positions 20-min following first scans. Custom software obtained measurements. Test–retest reliability (ICC_3,1) with standard error of measurement (SEM) was assessed by one evaluator who was blinded to the test measurement when completing retest.

Forty-three participants with AIS had an age, height, and weight of 15 ± 2 years, 164 ± 10 cm, and 54 ± 11 kg, respectively. Standing curve angle was 23 ± 11°. Habitual standing max curve angle, T4/T5 kyphosis, and AVR twist satisfied criteria for individual use (ICC_2,1 > 0.90). Fingers to clavicle AVR twist satisfied criteria for individual use, and all hands on wall measurements satisfied criteria for individual use (ICC > 0.90). All other parameters satisfied criteria for research use (ICC > 0.70). Range of SEM for curve angle, whole kyphosis, T4/T5 kyphosis, lordosis, and AVR twist were 3.0–4.8°, 4.0–5.1°, 3.6–5.3°, 3.9–5.6°, and 1.6–2.2°, respectively.

3DUS produces reliable frontal, sagittal, and transverse measurements for research use in three standing positions. Hands on wall produces reliable measurements for clinical practice.