Comparison of radiographic parameters between sciatic scoliosis and Lenke 5/6 type idiopathic scoliosis in young patients: a LASSO and nomogram analysis

OBJECTIVES: To compare radiographic parameters between sciatic scoliosis (SS) and Lenke 5/6 idiopathic scoliosis (IS) in young patients and to develop a predictive model. METHODS: A total of 148 patients (SS: IS = 75:73) were retrospectively enrolled. Demographic data and preoperative radiographic parameters were recorded. Univariate analysis was conducted between the two groups. Least Absolute Shrinkage and Selection Operator (LASSO) regression and logistic regression were used to screen for risk factors, and a nomogram designed to differentiate the two types of scoliosis was further constructed. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA), with bootstrap resampling (1000 iterations). RESULTS: Compared with the IS group, the SS group was found to have a smaller lumbar lordosis (LL) and vertebral rotation, but larger pelvic tilt (PT) and coronal trunk shift (all p < 0.05). LASSO regression retained five variables, while logistic regression identified body mass index (BMI), LL, and mean vertebrae rotation (MVR) as independent predictors. The nomogram based on these predictors achieved an AUC of 0.957 (95% CI: 0.930-0.983) and showed good calibration (mean absolute error = 0.019). CONCLUSIONS: BMI, LL, and MVR are accurate, reliable predictors for distinguishing SS from Lenke 5/6 IS in young patients, providing a diagnostic basis for clinical practice.