Abstract
OBJECTIVE: The aim of this study was to assess the incidence of postoperative shoulder imbalance (PSI), evaluate the role of upper instrumented vertebra (UIV) selection on postoperative shoulder balance and identify the risk factors for PSI in Lenke type 2 adolescent idiopathic scoliosis (AIS). METHODS: A retrospective case-matched analysis of 70 patients with Lenke type 2 AIS was performed. Patients were matched at a 1:1 ratio (35 T2 and 35 T3/4). Radiological and clinical outcomes were compared between the two groups. Univariate analysis and multivariate logistic analysis were used to further identify the risk factors for PSI. RESULTS: In Lenke type 2 AIS patients, the overall incidence of PSI was 32.9%. Compared with the T3/4 group, the T2 group achieved significantly better proximal thoracic curve (PTC) correction (0.63 ± 0.23 vs. 0.53 ± 0.16, P = 0.041). At the last follow-up, the T2 group had a significantly lower clavicle-rib cage intersection (CRCI) (0.84 ± 1.85 mm) and T1 tilt (4.40 ± 3.08°) than the T3/4 group (CRCI: 3.61 ± 3.76 mm, P < 0.001; T1 tilt: 6.07 ± 3.39°, P < 0.001). Multivariate logistic regression analysis revealed that the ratio of the PTC correction rate to the main thoracic curve (MTC) correction rate (PTC/MTC) was an independent risk factor for the PSI (OR = 0.015, P = 0.025). CONCLUSION: In Lenke type 2 AIS patients, the overall incidence of PSI was 32.9%. Compared with fusion to T3/4, fusion to T2 provided superior PTC correction and medial shoulder balance. The coordination between the PTC and MTC correction played a significant role in the maintenance of lateral shoulder balance.