429 Optimizing Rod Configuration Across Lumbar Pedicle Subtraction Osteotomy Site: Evolution of a High-Volume Deformity Practice

INTRODUCTION: Three-column osteotomy (3CO) is a powerful corrective technique in adult spinal deformity. Unfortunately, they carry high complication rates including mechanical complications of rod fracture and pseudoarthrosis. Due to the rapidly aging population, this intervention will only increase in use. METHODS: Single high-volume academic institution retrospective review of an experienced surgeon’s database. Patients with 3CO of the lumbar spine performed by the senior author were identified. Collected data included demographics, BMI, diagnosis, past surgeries, neurological assessments, smoking status, comorbidities, operative time, EBL, LOS, complications, and radiographic measurements. RESULTS: A total of 196 patients were identified with 78 (39.8%) 4-rod, 24 (12.2%) 5-rod, 54 (27.6%) 6-rod, and 40 (20.4%) 7-rod constructs. There was statistical significance in mechanical complications with 4-rod constructs having greater complications (p=0.010). This was primarily due to rod fractures (p<0.001) and, secondarily, due to pseudoarthrosis. There was also statistical significance in the change of lumbar lordosis from immediate postoperative radiographs to follow-up radiographs 4- and 7-rod constructs with 4-rod constructs losing 6.2 degrees compared to 1.8 degrees in 7-rod constructs (p=0.009). CONCLUSIONS: We found that the number of rods across a lumbar 3CO site can affect the number of mechanical complications. We also found that the number of rods prevents the loss of lordosis over time following correction. We recommend using a 7-rod construct for lumbar 3CO to minimize mechanical complications and loss of lordosis over time.