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Complication Profile Associated With S1 Pedicle Subtraction Osteotomy Compared to Other Spinal Levels


 
 
 S1 pedicle subtraction osteotomy (PSO) is rarely indicated. Therefore, its complication profile is not well defined. This study compares complication rates following S1 PSO to PSO performed at other spinal levels.
 
 
 
 A retrospective study of a consecutive cohort of adult spinal deformity (ASD) patients who underwent thoracolumbar 3 column osteotomy (3CO) by the senior author from 2006 to 2018 was performed. Multivariate analysis was used to asses complication risk stratified by osteotomy level.
 
 
 
 A total of 363 patients underwent 3CO: 54 lower thoracic, 305 lumbar, and 6 S1. The number of lumbar PSO by level are as fsollows: L1 (24), L2 (26), L3 (135), L4 (102), and L5 (16). The indications for S1 PSO in this series were: high grade spondylolisthesis (spondyloptosis) in 4 cases and sacral fracture in 2 cases. Overall complication rate was 27.5%. Surgical and neurologic complications occurred in 7.7% and 5.8% of cases, respectively. Complication rate by 3CO level are as follows: thoracic (31.5%), L1 (29.2%), L2 (34.6%), L3 (20.7%), L4 (32.4%), L5 (12.5%), and S1 (50.0%). Relative to the thoracic level, S1 PSO was independently associated higher complication with an increase odd ratio of 39.60 (CI 3.12-503.41, P = .005). For S1 PSO, surgical and neurological complication rate was 16.7% for both outcomes; there was no significant difference between the 3CO levels. Specific complications encountered was a case of atrial flutter causing diastolic heart failure, a case of anaphylactic transfusion reaction, and a case with L5 weakness requiring hematoma evacuation and reduction of correction. One patient (16.7%) required revision surgery secondary to pseudarthrosis. Mean follow-up was 35.7 mo.
 
 
 
 S1 PSO is a formidable procedure and associated with significantly higher complication rates than PSO performed at other levels. However, the technique is feasible with experienced surgeons. Large multicenter studies are needed to investigate this further.
