Researchers conducted a retrospective research project. For a study, the researchers sought to find out what were the independent risk factors for postoperative shoulder imbalance (PSI) after adolescent idiopathic scoliosis (AIS) corrective surgery and if the level of upper instrumented vertebrae (UIV) impacts postoperative shoulder balance. Preoperatively, immediately postoperatively, and 12 months later, radiographic parameters were measured on anteroposterior and lateral x-rays. Patients were split into 2 groups based on their radiographic shoulder height (RSH) at the 1-year follow-up: the PSI group (RSH ≥20 mm) and the non-PSI group (RSH <20 mm). A lower postoperative main thoracic curve (MTC) [odds ratio (OR): 0.702, 95% CI: 0.519–0.949, P=0.022], greater percentage correction of MTC (OR: 1.526, 95% CI: 1.049–2.220, P=0.027), and a higher postoperative sacral slope (OR: 1.364, 95 percent CI: 1.014–1.834, P=0.040) were identified as independent risk factors of PSI. No significant differences were identified when a preoperative, postoperative, and absolute change in shoulder parameters were examined across the level of UIV, regardless of the radiographic shoulder parameter studied. PSI was associated with lower postoperative MTC, greater percentage correction of MTC, and a higher postoperative sacral slope. The level of UIV chosen did not affect shoulder balance and symmetry. To avoid PSI after AIS corrective surgery, relative curve correction was more crucial than UIV.
