Are Changes in Spinopelvic Parameters Expected After Prolonged Halo Gravity Traction for the Treatment of Severe Spinal Deformities?

Objective: To evaluate whether prolonged preoperative halo gravity traction (HGT) influences spinopelvic parameters in patients with severe spinal deformities. Methods: This retrospective observational study included patients treated with preoperative HGT between 2017 and 2023 at a spine deformity referral center. Inclusion criteria comprised curves >100°, and a minimum of two weeks of preoperative traction. Pre- and post-HGT radiographs were analyzed to assess changes in coronal and sagittal Cobb angles, sagittal vertical axis (SVA), and spinopelvic parameters—pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and lumbar lordosis (LL). Statistical significance was set at p ≤ 0.05. Results: Fifteen patients met the inclusion criteria. HGT resulted in significant preoperative reductions in proximal thoracic, main thoracic, and thoracolumbar/lumbar Cobb angles. Sagittal Cobb angle and T5–T12 kyphosis significantly improved, while T2–T5 kyphosis remained unchanged. Spinopelvic parameters (PI, PT, SS, LL) and SVA did not show statistically significant changes after HGT. Individual LL variations were noted, but not at the group level. Conclusion: While HGT remains an important tool for the management of severe spinal deformities, its influence on spinopelvic parameters is negligible. Level of Evidence IV; Therapeutic Study.