254. 3D spinal alignment, thoracic volume and pulmonary function in surgical correction of AIS: a five-year follow-up study

Abstract

BACKGROUND CONTEXT Surgical correction of adolescent idiopathic scoliosis is advocated for severe curves to preserve or improve pulmonary function, prevent progressive deformity and pain, and improve self-appearance. Restoration of sagittal and 3D alignment, in particular thoracic kyphosis (TK), has become increasingly emphasized in efforts to improve pulmonary function, thoracic volumes, provide improved sagittal balance, and prevent adjacent segment degeneration and deformity. PURPOSE To study the effects of thoracic kyphosis restoration in AIS type 1 and 2 curves on postoperative thoracic volume and pulmonary function. STUDY DESIGN/SETTING Retrospective review of prospective multicenter database. PATIENT SAMPLE Thirty-nine AIS patients with Type 1 and 2 curves with 5Y postoperative stereo-radiographic data and pulmonary function tests (PFTs). OUTCOME MEASURES Five-year spinal and rib cage measures and PFTs. METHODS A multicenter prospective registry of patients undergoing surgical correction of Type 1- and 2- AIS curves was queried for patients with 5-year postoperative visits including stereoradiographic assessment and PFTs. 3-dimensional (3D) radiographic analysis was performed to assess spinal alignment and chest wall dimensions at preoperative, first erect and 5 year postoperative time points. Variables were analyzed between time points with a one-way ANOVA and post-hoc Tukey analysis, and between variables with linear regression analysis. RESULTS A total of 39 patients met the inclusion criteria (37F, age 14.4±2.2). 3D spine alignment analyses demonstrated significant reduction in pre-op to 1st erect upper thoracic (41.3° to 11.6°), mid-thoracic (48.6° to 9.55°) and lumbar Cobb angles (19.7° to 8.9°), an increase in TK:T2-12 (20.0° to 39.8°) and TK:T5-12 (9.8 to 28.2°), and reduction in proximal and mid-thoracic apical vertebral rotation (9.5° to 2.1°) from preoperative to 1st erect postoperative (p 0.05 for all). 3D rib cage analysis demonstrated there was a small reduction in maximal depth (144 mm to 138 mm), maximum width (235 mm to 232 mm), and increase in thoracic height (220 mm to 230 mm, p CONCLUSIONS While thoracic kyphosis increases, coronal Cobb and apical vertebral rotation decrease postoperatively, these do not directly influence chest wall volume. Chest wall volume continues to increase between from first erect to 5 years due to presumed growth, which corresponds with an improvement in FEV1 and FVC at 5 year follow-up. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.