In Brief:
Pseudarthrosis in long (≥5 vertebrae, average 11.9) adult spinal deformity instrumentation and fusion to the sacrum was 24% (34 of 144 patients with 2–14-year follow-up). Thoracolumbar kyphosis, osteoarthritis of the hip joint, thoracoabdominal approach (vs. paramedian approach), positive sagittal balance ≥5 cm at 8 weeks postoperatively, older age at surgery (older than 55 years), and incomplete sacropelvic fixation significantly increased the risk of pseudarthrosis to an extent that was statistically significant. Scoliosis Research Society 24 outcomes scores were adversely affected when pseudarthrosis developed.
