Three-Dimensional Measurement and Analysis of Rod Deformation for Spinal Deformity Correction: A Novel Methodology

The amount of rod contour is a critical factor that influences sagittal and coronal alignment for posterior spinal fusion. Distraction techniques to correct spinal deformity, which are often three-dimensional (3D) in nature, are known to cause rod deformation from the ideal, planned rod curvature. Therefore, surgeons often overbend rods to account for this phenomenon. Currently, there is no agreed-upon method to scientifically quantify rod unbending, and no methods offer a 3D analysis. The proposed methodology addresses this gap. By aligning the 3D rod centerlines, the segmented area enclosed between the two lines serves as a measure of rod deformation. This paper presents the foundational principles and concepts for quantifying 3D rod deformation. With further research and clinical implementation, this methodology has the potential to provide valuable surgical insight, which could improve postoperative spinal alignment and outcomes.