Accuracy of Screw Placement and Fusion Rate after Transforaminal Lumbar Interbody Fusion with O-arm Navigation: A Review of 475 Patients

Abstract

Purpose To evaluate the accuracy of screw placement and fusion rate after the minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) technique under O-arm navigation. Methods In 475 consecutive patients at a single-center, the accuracy of screw placement was evaluated on intraoperative O-arm imaging. Misplaced screws were investigated to identify the direction of deviation and associated clinical outcomes. The fusion rate was evaluated on postoperative computed tomography scan at 1 and 2 year(s). The assessment of screw placement and fusion level was analyzed for inter-rater reliability and reported as a kappa value. Accuracy of screw placement (Gertzbein-Robbins Classification), extent of fusion (Bridwell Interbody Fusion Grading System), and complications were considered as outcome measures. Results A retrospective data analysis from 2,098 pedicle screws in 475 patients. The mean age of participants was 56.61 ± 12.30 years, and 45.26% were female. Their ethnicities were as follows: Asian (58.74%), Caucasian (20.21%), Middle-eastern (14.32%), and African (6.74%). The final fusion levels were single (80.63%), two (18.11%), three (1.05%), and four (0.21%). There were L4/L5 as the most prevalent placement (55.35%), followed by L5/S1 (36.29%), L3/L4 (5.22%), L2/L3 (2.35%), L1/L2 (0.52%), and S1/S2 (0.26%). Seven out of 2,098 screws were breaches. None of screw needed immediate revision. In total, 99.66% of the screws were grade A (no breach), 0.19% were grade B (breach < 2 mm) and 0.14% were grade C (breach < 4mm). Conclusion The accuracy of pedicle screw insertion was 99.66%, with a fusion rate of 95.45% after MIS-TLIF under O-arm navigation. Breaches were not associated with poor clinical outcomes or fusion rates.