• Takayoshi Shimizu, Meghan Cerpa, Ronald A Lehman, John Alex Sielatycki, Suthipas Pongmanee, and Lawrence G Lenke.
• Department of Orthopaedic Surgery, Columbia University Medical Center, The Spine Hospital at New York Presbyterian, New York, New York.
• Spine. 2019 Dec 15; 44 (24): 1705-1714.

Study DesignRetrospective cohort.ObjectiveThis radiographic analysis using a full-body x-ray evaluated the ways in which the sagittal profiles of the unfused spinal segments, pelvic, and lower extremities spontaneously change after adolescent idiopathic scoliosis (AIS) surgery with segmental pedicle screw constructs.Summary Of Background DataReciprocal lordotic changes in unfused spinal segments after corrective surgery for AIS have been reported. However, a full-body analysis has not been studied.MethodsThe sagittal profiles of 51 (age ≤18) patients with AIS undergoing corrective surgery with segmental pedicle screw constructs were investigated. Patients were divided into two groups: group T; selective thoracic fusion and group L; fusion to the low lumbar spine. They were further subcategorized according to preoperative thoracic kyphosis (TK: T5-12): hypokyphotic (TK <20°) and normohyperkyphotic (TK >20°) groups. The postoperative change in the sagittal parameters and the correlation between the instrumented thoracic alignment change (ΔT2-12) and reciprocal changes of unfused segments were analyzed.ResultsAt baseline, the entire cohort had a relatively hypokyphotic thoracic spine (TK: 25.5° ± 13.7°), low T1 slope (13.6° ± 7.7°), and kyphotic cervical spine (C2-7 lordosis: 7.7° ± 13.1°). The lower extremities were in neutral alignment overall. Postoperatively, the cervical alignment changed significantly lordotic (average -13.4° increased lordosis) after the adequate preservation of TK (average 17.8° increased kyphosis) in the hypokyphotic group T. Linear correlations were observed between ΔT2-12 and spontaneous reciprocal changes in C2-7 lordosis, lumbar lordosis, and knee flexion angle in group T.ConclusionThe sagittal profiles of patients with AIS can significantly change after adequate restoration of TK which averaged 17.8°, particularly in the cervical spine. Lordotic reciprocal change in the cervical spine as well as increase in lumbar lordosis can occur in a linear correlation after adequate restoration of TK. There were no significant changes that occurred in the pelvis or lower extremities after AIS corrective surgery.Level Of Evidence4.

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