Pain outcomes following long-segment thoracolumbar fusion: a three-year mixed-effects analysis.

To evaluate longitudinal trends in postoperative pain following long-segment thoracolumbar fusion for adult spinal deformity (ASD) and assess the influence of patient-specific factors on pain outcomes. Adult patients who underwent long-segment thoracolumbar fusion (≥ 4 segments) for ASD between 2016 and 2021 were included. Visual Analog Scale (VAS) scores were collected preoperatively and at postoperative 6-month increments, up to 36 months. Linear mixed models (LMM) evaluated longitudinal trends and the impact of age, gender, BMI, and levels fused on pain outcomes. Final analysis included 138 patients. Preoperatively, median VAS was 8.0 for back and 6.5 for leg. At six months, back pain improved by -3.6 (p < 0.001), and leg pain by -2.9 (p < 0.001). Improvements persisted through 36 months, with back pain reduced by -4.0 and leg pain by -3.8 (p < 0.001 for both). Leg pain improved between six and 12 months (mean difference: -2.2, p < 0.001), however, no other inter-time point analyses were significant for any VAS category. Higher BMI was associated with worse back and leg pain (p = 0.017 and p < 0.001), while older age correlated with significantly lower pain scores. Long-segment thoracolumbar fusion provides significant, sustained pain relief, with the most improvement within six to 12 months and plateauing thereafter. These findings emphasize the need for realistic expectations regarding the extent and timeline of pain relief for patients. The role of BMI and age in pain trends highlights the importance of personalized counseling.