In Correction Surgery for Adolescent Idiopathic Scoliosis with Lenke Type 1 and 2 curves, Obtaining Kyphosis in the Upper Thoracic Spine Is Important for Preventing Postoperative Cervical Kyphosis.

Introduction: Patients with adolescent idiopathic scoliosis (AIS) frequently have cervical kyphosis, and, although it can be significantly improved by scoliosis correction surgery, cervical kyphosis remains frequent even after surgery. It has been reported that cervical kyphosis can increase the risk of pain, degenerative disc disease, and reduced quality of life, even in patients with AIS. However, it is unclear what indicators we should aim for during scoliosis correction surgery to prevent residual cervical kyphosis after surgery. Methods: A total of 45 consecutive patients (41 women, 4 men) with Lenke type 1 or 2 AIS who received posterior corrective surgery and were followed up for a minimum of 2 years were included. Data were extracted from our prospectively collected database. The patients were divided into 2 subgroups: those with cervical hyperkyphosis (cervical lordosis ≤-10°) and those without. We investigated the alignment we should aim for during posterior thoracic correction surgery to prevent postoperative cervical hyperkyphosis. According to the previous study, we focused particularly on upper thoracic kyphosis (TK1-5). Results: The cervical hyperkyphosis group was characterized by a large preoperative cervical kyphosis, a small preoperative and postoperative TK1-5, and a small postoperative T1 slope. In our multivariate logistic regression analysis, we found that postoperative TK1-5 was an independent associated factor for postoperative cervical hyperkyphosis. Conclusions: We clarified that during posterior correction surgery for Lenke type 1 and 2 curves AIS, formation of kyphosis in the thoracic spine, especially in the upper thoracic spine, is important for preventing postoperative cervical hyperkyphosis.