Assessment of sagittal balance parameters in adolescents with severe thoracic idiopathic scoliosis

BACKGROUND: In recent years, the concept of sagittal balance has become increasingly important in the treatment of spinal deformities of various etiologies. However, the number of studies analyzing sagittal balance parameters in patients with idiopathic scoliosis is limited, especially those involving individuals with severe deformities. AIM: This study aimed to evaluate global and regional sagittal balance parameters in adolescents with severe thoracic idiopathic scoliosis. METHODS: The study included 45 patients aged 12–17 years diagnosed with thoracic idiopathic scoliosis (Lenke types 1, 2, and 3), presenting with a primary curve magnitude ranging from 80° to 150°, according to the Cobb method. Radiographic examinations were performed to assess both regional and global sagittal balance parameters, as well as characteristics of frontal plane spinal deformity. The patients were divided into two groups based on the global sagittal balance values. Descriptive, correlation, regression, and comparative statistical analyses of the data were conducted. RESULTS: A positive correlation was observed between the magnitude of frontal plane spinal deformity and thoracic kyphosis values. The regression analysis indicated that when the primary curve exceeded approximately 100°, thoracic kyphosis values tended to rise above 60°. Thoracic hyperkyphosis was the predominant sagittal deformity in these patients; however, neither thoracic kyphosis nor the primary curve magnitude in the frontal plane showed statistically significant correlation with any of the global sagittal balance indicators. These indicators correlated more strongly with spinopelvic parameters (pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and PI–LL). CONCLUSION: Surgical treatment of severe idiopathic scoliosis should obligatorily consider correction methods that produce a corrective effect on the kyphotic component of the deformity. The development of pronounced anterior imbalance has been proven to be uncharacteristic for patients with thoracic idiopathic scoliosis, even with the largest primary curve magnitudes. The primary risk factors for its development were reduced PI and LL values. The development mechanism of the observed association in these patients remains unclear.