Does anterior shoulder balance in adolescent idiopathic scoliosis correlate with posterior shoulder balance clinically and radiographically?

Purpose Patients with adolescent idiopathic scoliosis (AIS) often present with a disfiguring shoulder imbalance. Shoulder balance (Sh.B) is of significant importance to the patient's self-perception. Previous studies have correlated Sh.B with respect to only the clinical posterior view correlated with radiographs. It is important, however, to address Sh.B with respect to anterior view of the patients' shoulders as if patients were viewing in a mirror. In this study, we evaluated the anterior Sh.B and correlated it with posterior Sh.B clinically and radiographically in Lenke type 1 and 2 curves. Method An online scoliosis database was queried to identify 74 AIS patients with Lenke 1 (n = 55, age 15.28 ± 3.35) and 2 (n = 19, age 15.66 ± 3.72) curves with a complete set of PA radiographs and anterior and posterior photos. Radiographic measures for Sh.B included Cobb angles, T1 tilt, first rib angle, and clavicle-rib intersection angle. Clinical measures for Sh.B included inner shoulder angle, outer shoulder angle, and axillary fold angle. Regression analysis with Pearson's correlation and ANOVA for statistical significance was used for analysis. Results For Lenke 1 curves, there was moderate statistically significant correlation between anterior and posterior clinical Sh.B (R = 0.35-0.41). There was only weak to moderate correlation between radiographic and clinical measures. For Lenke 2 curves, there was a weak to moderate correlation between anterior and posterior clinical Sh.B (R = 0.25-0.45), though not statistically significant. There was no statistically significant correlation between any radiographic measures and posterior Sh.B. There was, however, moderate and significant correlation between radiographic measures and anterior Sh.B. Conclusion There is no strong correlation between anterior and posterior clinical Sh.B, and surgeons should evaluate both sides in planning deformity correction, especially in Lenke 2 curves. None of the radiographic measures showed strong correlation (R>0.8) with anterior or posterior clinical Sh.B. A stronger correlation existed between radiographic measures and anterior Sh.B measurements compared with posterior clinical Sh.B measurements in Lenke 2 curves further necessitating anterior evaluation in this group.