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

Purpose Preoperative halo gravity traction (HGT) is widely used in the management of severe spinal deformities to improve surgical outcomes and reduce risks associated with definitive correction. However, its effects on radiographic parameters beyond the Cobb angle improvement remain underexplored. This study evaluated whether HGT provides additional radiographic benefits beyond the Cobb angle correction, particularly in the shoulder, trunk, pelvis, and lower limb alignment. Methods We conducted a retrospective analysis of patients with severe spinal deformities who underwent HGT from 2017 to 2023 in a public quaternary orthopaedic institution. Radiographic measurements taken before and after traction were compared, assessing coronal and sagittal alignment, pelvic obliquity, shoulder alignment, and spinopelvic parameters. Statistical significance was determined using paired tests (p ≤ 0.05). Results Among the 15 patients (mean age: 16.9 years) included, HGT led to significant reductions in coronal Cobb (22.2%) and sagittal Cobb (21.3%). Shoulder balance improved, as indicated by decreased clavicular angle and T1 tilt. Trunk misalignment was reduced, with improvements in apical vertebra translation, coronal balance, and thoracic trunk shift. Pelvic obliquity corrections were statistically significant. Spinopelvic parameters showed minimal and non-significant changes. No major complications were reported. Conclusion HGT benefits extend beyond Cobb angle reduction, significantly improving overall spinal alignment. These findings suggest that HGT may contribute to a more balanced and harmonious correction while remaining a safe treatment. MeSH: Traction; Scoliosis; Spinal curvatures; Radiography