Postoperative Lumbar Curve Progression Deteriorates Shoulder Imbalance in Patients with Lenke Type 2B/C Adolescent Idiopathic Scoliosis Who Underwent Selective Thoracic Fusion

OBJECTIVE: To evaluate the association between postoperative lumbar curve progression and the shoulder height in patients with Lenke type 2B/C adolescent idiopathic scoliosis (AIS). METHODS: A total of 25 patients with Lenke type 2B/C AIS underwent posterior correction surgery in our institution from 2005-2014 were included. Standing x-ray films of the whole spine obtained before surgery, immediately after surgery, and at the last follow-up were analyzed with respect to the following parameters: proximal thoracic Cobb angle, main thoracic (MT) Cobb angle, lumbar Cobb angle, lumbar apical vertebral translation, distance between C7 plumb line and the central sacral vertical line, and radiographic shoulder height (RSH). Correlations between the change of RSH and the changes of other parameters were analyzed both immediately after surgery and at the last follow-up. RESULTS: The change of RSH was significantly negatively correlated with both the change of MT Cobb angle (P < 0.05) and that of lumbar Cobb angle (P < 0.05) immediately after surgery, whereas the interval-time change of RSH was significantly positively correlated with the interval-time change of lumbar Cobb angle (P < 0.05) and that of lumbar apical vertebral translation (P < 0.05) at the last follow-up. The change of MT Cobb angle was an independent predictor for the change of RSH immediately after surgery, whereas the interval-time change of lumbar Cobb angle was an independent predictor for the interval-time change of RSH at the last follow-up. CONCLUSIONS: Postoperative lumbar curve progression is a risk factor for deterioration of shoulder imbalance in patients with Lenke 2B/C AIS during the follow-up period.