Beyond the Cobb angle: the radiographic measurement differences from halo gravity traction in patients with severe spine deformities before scoliosis surgical correction - cross-sectional study, local experience. - Barros AGC; Almeida GJ; Alves GF; Leal AC; Carelli LE (European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2025)