Does spinal fusion to T2, T3, or T4 affects sagittal alignment of the cervical spine in Lenke 1 AIS patients

The aim of this stusy was to investigate whether spinal fusion to T2, T3, or T4 affects sagittal alignment of the cervical spine in Lenke 1 adolescent idiopathic scoliosis (AIS) patients.A retrospective study comprised of 64 Lenke 1 AIS patients was performed to assess the radiographic and clinical outcome. According to the upper instrumented vertebrae (UIV) (T2, T3, or T4), the patients were divided into 3 groups. Comparison analyses were performed among these 3 groups of patients as between pre-op, immediate post-op, and final follow-up, as well as between these groups.Between groups, comparison analyses did not detect a statistical difference in cervical lordosis (CL) preoperatively (P = .501), immediately after surgery (P = .795), and at follow-up (P = .510). Immediately after surgery, CL increased significantly in all groups (T2, P = .004, T3, P < .001 and T4, P = .002 respectively). Compared with immediate postoperatively, CL at final follow-up increased in T2 group (P = .037), and T4 group (P = .010). Furthermore, CL at follow-up was significantly correlated with the following parameters: preoperative (coronal plane balance [r = .349, P = .004], pelvic tilt [r = 0.347, P = .004), pelvic incidence [r = 0.261, P = .031], and CL [r = 0.471, P < .001]) immediately postoperative (CL [r = 0.946, P < .001], T1-slope [r = -0.646, P < .001], and thoracic kyphosis [TK] [r = -0.353, P = .003]), and at follow-up (TK [r = -0.342, P = .004], and T1-slope [r = -0.821, P < .001]). However, there was no significant correlation between a selection of UIV and CL at follow-up (r = 0.031, P = .802). Moreover, Scoliosis Research Society (SRS-22) scores between groups were similar preoperatively (P = .242), immediately after surgery (P = .828), and at follow-up (P = .219).In Lenke 1 AIS patients, the selection of UIV mainly affects the coronal plane, especially shoulder balance. Fusion to T2, T3, or T4 did not affect the alignment of the cervical spine, and the SRS-22 score. LEVEL OF EVIDENCE Level IV.