Effect of posterior ligamentous complex integrity on O-arm navigation accuracy in thoracolumbar trauma: a prospective comparative study

Study Design: Prospective and comparative study. Purpose: Thoracolumbar injuries are often three-column injuries requiring instrumented stabilization. Motion at the fracture site can affect the accuracy of the O-arm, particularly during the placement of pedicle screws in fracture subtypes with an injured posterior ligamentous complex (PLC). This study aimed to assess the effect of PLC injury on O-arm accuracy during pedicle screw fixation. Overview of Literature: Accurate pedicle screw placement is critical in thoracolumbar fractures. Although O-arm navigation improves precision, PLC injuries may induce navigation errors because of segmental instability. Existing literature on O-arm accuracy in unstable, PLC-disrupted trauma cases remain scarce. Methods: This is a comparative prospective series of thoracolumbar fractures managed with O-arm navigation-based pedicle screw fixation with a 24-month follow-up. Fractures were subdivided based on the injury to the PLC as follows: group A included fracture variants with intact PLC (AO subtype A3 and A4), and group B included fracture variants with injured PLC (AO subtype A3+B2, A4+B2, and C). Radiological outcomes in the form of pedicle screw accuracy, facet violation, local kyphosis correction, loss of accuracy, absorbed radiation, and complication rate were assessed. Results: A total of 93 fracture levels were included (group A, n=70; group B, n=23), and 762 pedicle screws were inserted using O-arm navigation. Significant breaches were more frequent in group B (8%) than in group A (1.5%) (p<0.001), with critical breaches also higher in group B (p=0.023). Most breaches were medial. Facet joint violation occurred more in group B (9.5% vs. 2.5%, p=0.07). All critical breaches were revised intraoperatively. No infections, wound complications, or significant implant failures were observed. Conclusions: PLC injury significantly compromises the accuracy of O-arm-guided pedicle screw placement in thoracolumbar fractures. Increased navigation errors and critical breaches were observed despite protocol adherence, likely because of segmental instability. Surgeons should consider repeat scans for accuracy.