Validity of a quantitative tool of trunk asymmetry based on digital photographs in patients with idiopathic scoliosis

Methods Front and back digital photographs of patients with idiopathic scoliosis (Cobb>25o) were obtained. Shoulder, armpit and waist angles, in addition to trunk asymmetry indexes, were calculated on front and back photographs with Surgimap software. On AP radiographs Coronal Cobb angles and radiological shoulder imbalance using CRIA angle (Angle between horizontal line and a line drawn between, the right and left intersection points of clavicle and rib cage) were calculated. Intra-class correlation coefficient was used to assess intra and inter-rater reliability. The Pearson correlation coefficients (r) were used to estimate concurrent validity between both methods. Results 80 patients (68 females) mean age 20.3 years (12-40 years) were included. Mean Cobb Maximum (CobbMax) was 45.9o (25.1o-77.2o).All measures had a good to excellent intra and inter-rater reliability both in front and back photographs. Waist height angle and CobbMax angle, both in front and back photographs, were significantly correlated (r=0.42 back/r=0.29 front view). There was no significant correlation between proximal thoracic curve magnitude and any of the shoulder measures. The correlation between shoulder and armpit height angles and radiographic clavicle tilt were -0.44 and -0.41 respectively on frontal view. There was a correlation between trapezium angle ratio and clavicle tilt in both views (r=0.43 back/r=0.32 front view). No other statistically significant correlations between both methods were found.