Revision Rates Following Primary Adult Spinal Deformity Surgery Six Hundred Forty-Three Consecutive Patients Followed-up to Twenty-Two Years Postoperative

Study Design. Retrospective study. Objective. To analyze the prevalence of and reasons for unanticipated revision surgery in an adult spinal deformity population treated at one institution. Summary of Background Data. No recent studies exist that analyze the rate or reason for unanticipated revision surgery for adult spinal deformity patients over a long period. Methods. All patients presenting for primary instrumented spinal fusion with a diagnosis of adult deformity at a single institution from 1985 to 2008 were reviewed using a prospectively acquired database. All surgical patients with instrumented fusion of >= 5 levels using hooks, hybrid, or screw-only constructs were identified. Patient charts and radiographs were reviewed to provide information as to the indication for initial and any subsequent reoperation. A total of 643 patients underwent primary instrumented fusion for a diagnosis of adult idiopathic scoliosis (n = 432), de novo degenerative scoliosis (n = 104), adult kyphotic disease (n = 63), or neuromuscular scoliosis (n = 45). The mean age was 37.9 years (range, 18-84). Mean follow-up for the entire cohort was 4.7 years, and 8.2 years for the subset of the cohort requiring reoperation (range, 1 month-22.3 years). Results. A total of 58 of 643 patients (9.0%) underwent at least one revision surgery and 15 of 643 (2.3%) had more than one revision (mean 1.3; range, 1-3). The mean time to the first revision was 4.0 years (range, 1 week-19.7 years). The most common reasons for revision were pseudarthrosis (24/643 = 3.7%; 24/58 = 41.4%), curve progression (13/643 = 2.0%; 13/58 = 20.7%), infection (9/643 = 1.4%; 9/58 = 15.5%), and painful/prominent implants (4/643 = 0.6%; 4/58 = 6.9%). Uncommon reasons consisted of adjacent segment degeneration (3), implant failure (3), neurologic deficit (1), and coronal imbalance (1). Revision rates over the follow-up period were: 0 to 2 years (26/58 = 44.8%), 2 to 5 years (17/58 = 29.3%), 5 to 10 years (7/58 = 12.1%), > 10 years (8/58 = 13.8%). Conclusion. Repeat surgical intervention following definitive spinal instrumented fusion for primary adult deformity performed at a single institution demonstrated a relatively low rate of 9.0%. The most common reasons for revision were predictable and included pseudarthrosis, proximal or distal curve progression, and infection.