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

Abstract

Background and objectives: Three-column osteotomy (3CO) is a powerful corrective technique in adult spinal deformity. Unfortunately, they carry high complication rates including mechanical complications (MC) of rod fracture and pseudoarthrosis. Owing to the rapidly aging population, this intervention will only increase in use. The optimal construct configuration to minimize MC and maintain radiographic outcomes has not been established. We wished to evaluate the impact of multirod construct across the 3CO level on MC and durability of radiographic outcomes after correction for adult spinal deformity.

Methods: Retrospective review of a high-volume deformity practice at an academic institution. Patients with 3CO of the lumbar spine performed by the senior author were identified. Collected data included demographics, body mass index, prior diagnoses to calculate the age-adjusted Charlson Comorbidity Index, operative time, estimated blood loss, length of stay, 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 were more MC in the 4-rod constructs (P = .002). This was primarily due to rod fractures (P = .005). There was also a significant loss of lordosis from immediate postoperative radiographs to follow-up radiographs with 4-rod constructs losing 6.2° compared with 1.8° in 7-rod constructs (P = .009).

Conclusion: We found that the number of rods across a lumbar 3CO can affect the number of MC. We also found that the number of rods can prevent the loss of lordosis over time after correction. We recommend using a 7-rod construct for lumbar 3CO to minimize MC and loss of lordosis over time.