Outcome of Pedicle Subtraction Osteotomies for Fixed Sagittal Imbalance of Multiple Etiologies

In Brief Study Design. A retrospective study. Objective. To evaluate the efficacy and safety of the pedicle subtraction osteotomy (PSO) as a technique for correction of fixed sagittal imbalance with multiple etiologies. Summary of Background Data. This report represents the largest and longest series of patients with fixed sagittal imbalance other than ankylosing spondylitis who were managed with PSO. Methods. A total of 140 consecutive patients who had undergone PSO for the management of sagittal imbalance with any etiology were reviewed. Etiologic diagnoses were ankylosing spondylitis in 86 patients, flatback syndrome in 20, post-traumatic kyphosis in 17, congenital kyphoscoliosis in 9, and post-tuberculotic kyphosis in 8 patients. The average duration of the follow-up period was 8 years (range, 5–12.5 yr). Radiological and clinical outcome analyses were performed. Results. All patients showed a solid union upon follow-up radiographs and no pseudarthrosis was noted. Correction with PSO averaged 36.2°. Blood loss averaged 1515.6 mL. The Oswestry Disability Index improved from 40.5 to 18.8 at the last follow-up, and 90.7% of the patients were very or somewhat satisfied. There were 15 cases (10.7%) of reversible complications including transient radiculopathy and 3 cases (2.1%) of irreversible complications. Conclusion. Based on the results of this study, PSO is considered a reliable and relatively safe procedure for the correction of fixed sagittal imbalance with multiple etiologies. In 140 cases of kyphosis induced by various causes including ankylosing spondylitis, we attained a correction angle of 36.2°, and the mean Oswestry Disability Index improved from 40.5 preoperatively to 18.8 at the last visit. On the Modified Spine Research Society-24 instrument, somewhat satisfying results were found in 90.7%.