Analysis of factors affecting lumbar lordosis restoration after lumbar fusion operation using posterior instrumentation at Cipto Mangunkusumo national center hospital, Jakarta, 2012-2017

Abstract

Introduction: Instrumented spinal fusion is one of the most common procedures performed to manage various pathologies in the lumbar region. The implant construction to restore lumbar lordosis has became a concern to achieve a satisfactory post-operative spinal alignment. Failure to restore lumbar lordosis may result in faster adjacent segment degeneration and disease, chronic back pain, implant failure, and loss of sagittal balance. Methods: A retrospective study was carried out in 75 patients who underwent instrumented lumbar fusion. The patients were divided into 2 groups based on lumbar lordosis was restored or not. Assessment of fused segment lordosis, rod contouring, sagittal trajectory of pedicle screw, interbody cage implant usage, and the number of fusion levels (LoF) were performed on erect lumbosacral sagittal radiograph. The results were compared with the pre-operative radiograph. Results: In this study, normal rod contouring in >3 fusion levels (p = 0.024), sagittal trajectory of depressed pedicle screw of the highest fusion segment (p = 0.011), sagittal trajectory of elevated pedicle screw of the lowest fusion segment (p = 0.021), and 1 level of spinal fusion (p = 0.006) affected the restoration of lumbar lordosis. The factors that affected the restoration of lumbar lordosis the most were, respectively, the number of fusion level of 1 level (p = 0.003, aOR = 7.79x), elevation of pedicle screw sagittal trajectory of the lowest fusion segment (p = 0.007, aOR = 8.9x), and depression of pedicle screw sagittal trajectory of the highest fusion segment (p = 0.029, aOR = 7.29x). Conclusion: Instrument factors significantly affect lumbar lordosis restoration. Synergic combination among factors will increase the lumbar lordosis restoration successfulnes.