Spinal ultrasound to quantify in-brace correction before nighttime brace fabrication in adolescent idiopathic scoliosis

Purpose: Initial in-brace curve correction is an important predictor of brace treatment success in adolescent idiopathic scoliosis (AIS). After brace measurement and fabrication, in-brace correction is sometimes not perfect and needs further optimization. Ideally, in-brace correction is known before fabrication without using ionizing radiation. This study investigates the use of spinal ultrasounds during Providence nighttime brace measurement, and tests the correlation between spinal ultrasound angles in corrected position and radiographic in-brace Cobb angles. Methods: Twenty-four consecutive AIS patients underwent full-spine radiographs and spinal ultrasounds in standing position before Providence brace measurement on the board in supine position. Immediately afterwards, they underwent spinal ultrasound in corrected position, prone on the mirrored measurement board. Four weeks after brace treatment initiation, supine in-brace radiographs were obtained. Coronal ultrasound angle and Cobb angle were measured for the primary curve. Curve correction was defined as percentage of change of the ultrasound angle and Cobb angle. Pearson’s correlation coefficient was used to evaluate correlations between both angles and between correction percentages. Results: The initial Cobb angle was 30.0°±7.8 (mean ± sd), and corrected to 8.9°±5.9 in-brace, a correction of 71%±16. The ultrasound angle (based on posterior spinal elements) corrected from 18.6°±5.8 standing to 5.2°±3.1 on the measurement board, a correction of 72%±15%. Ultrasound angle in corrected position and in-brace Cobb angle were linearly correlated (r = 0.878 p < 0.001), as well as the correction percentages (r = 0.827, p < 0.001). Conclusion: The in-brace correction of the Providence brace can be accurately assessed with spinal ultrasound and potentially improved while measuring the brace, without the need for ionizing radiation.