The use of the psoas-to-lumbar vertebrae index and modified frailty index in predicting postoperative complications in degenerative spine surgery: can sarcopenia or frailty be underestimated? - Ruffilli, Alberto; Manzetti, Marco; Viroli, Giovanni; Traversari, Matteo; Ialuna, Marco; Morandi Guaitoli, Manuele; Cargeli, Alessandro; Faldini, Cesare (European Spine Journal, 2025)