Normal spino-pelvic alignment in healthy adolescents: defining the PI–SS relationship and laying the foundations for pre-operative sagittal planning. - Traversari, Matteo; Ruffilli, Alberto; Viroli, Giovanni; Manzetti, Marco; Cargeli, Alessandro; Ricci Petitoni, Chiara; Ialuna, Marco; Rocca, Gino; Faldini, Cesare (European Spine Journal, 2026)