Study design: Retrospective study.
Objective: To determine the prevalence of loss in fixed segment alignment after surgical correction of adult spinal deformity (ASD) and identify associated risk factors.
Summary of background data: Altered fixed segment alignment influences global spinal alignment; however, associated risk factors have not been determined.
Methods: Data of 63 patients with ASD (55 females; mean age, 68.0 yrs), who underwent corrective fusion from the lower thoracic spine to the pelvis and completed the 2-year follow up, were retrospectively analyzed. Change in alignment early postoperatively and at 2 years postoperatively was evaluated using the fixed segmental angle (FSA) and fixed vertebral angle (FVA). The predictive value of the following parameters was evaluated: age, sex, body mass index (BMI), high grade osteotomy, rod material, screw loosening, spinopelvic parameters [T1 pelvic angle (TPA), sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis (LL), thoracic kyphosis (TK), and proximal junctional kyphosis (PJA), and Oswestry Disability Index (ODI) scores].
Results: Change of 2.4° in FSA and -3.1° in FVA were identified 2 years postoperatively, with higher intrarater and interrater reliability for FSA. Based on minimal detectable change in FSA, patients were classified into two groups: (+) loss (ΔFSA >3°) and (-) loss (ΔFSA ≤3°). Correction loss occurred in 17 patients; these patients had a greater BMI, higher rate of high-grade osteotomies, commercially pure titanium (CP) rods implanted, screw loosening, higher preoperative and postoperative TPA, and higher TPA, SVA, and PT after 2 years, than patients without correction loss.
Conclusion: The loss of sagittal fixed segment alignment was relatively high at 27%. Greater BMI, high-grade osteotomies, CP rod use, and sagittal malalignment were associated with correction loss after ASD surgery.
Level of evidence: 4.