Introduction: Iliac screw fixation is often used to augment lumbosacral reconstruction in advanced spine disease to increase the likelihood of successful arthrodesis. Iliac screws can be placed with image guidance, using either intraoperative fluoroscopy or computed tomography (CT) to guide navigation. However, these imaging modalities add radiation exposure and can disrupt workflow. The freehand technique is an alternative strategy that decreases radiation exposure and workflow disruption but may compromise safety and accuracy. This study compares the safety and accuracy of the freehand technique versus stereotactic navigation techniques for placement of iliac screws.

Methods: A retrospective review was performed for a consecutive series of adult patients with degenerative spine conditions who underwent posterior reconstruction with iliac screw placement between 2011 and 2016. Clinical and radiographic data were collected and analyzed. The accuracy of iliac screw placement was determined with either intraoperative/postoperative computed tomography (CT) imaging or anteroposterior/lateral radiography when CT was not performed.

Results: Bilateral iliac screws were placed in all 111 patients, for a total of 222 iliac screws. Eighty screws were placed with the freehand technique and 142 with the intraoperative navigation technique. CT imaging was used to assess placement accuracy of 124 screws (46 freehand [37%], 78 navigated [63%]). Accuracy was similar (P=.12) for the freehand group (89%, 41/46) and the navigated group (96%, 75/78). For patients without intraoperative/postoperative CT imaging, radiography was used to assess placement accuracy of 98 screws (34 freehand, 64 navigated) and the placement accuracy rate for the freehand group (100%, 34/34) was comparable to that for the navigated group (98%, 63/64) (P=.46). No complications attributable to iliac screw placement occurred in either group.

Conclusions: Overall, there was no difference in the safety and accuracy between the freehand and navigated techniques.

Patient Care: This study provides a direct comparison between the freehand and the navigated technique for iliac screw placement. Both techniques appear to be safe and accurate. The advantage of the freehand technique is the improved operative efficiency and eliminating radiation exposure.

Learning Objectives: By conclusion of this session, participants should be able to: 1) Describe the technique for freehand and navigated placement of iliac screws. 2) Understand the risks associated with iliac screw placement. 3) Identify limitations associated with both techniques.

References: 1. Banno T, Ohishi T, Hasegawa T, Yamato Y, Kobayashi S, Togawa D, et al: Accuracy of iliac screws insertion in adult spinal deformity surgery: relationship between misplacement and the iliac morphologies. J Spinal Disord Tech, 2015 2. Boachie-Adjei O, Dendrinos GK, Ogilvie JW, Bradford DS: Management of adult spinal deformity with combined anterior-posterior arthrodesis and Luque-Galveston instrumentation. J Spinal Disord 4:131-141, 1991 3. Emami A, Deviren V, Berven S, Smith JA, Hu SS, Bradford DS: Outcome and complications of long fusions to the sacrum in adult spine deformity: Luque-Galveston, combined iliac and sacral screws, and sacral fixation. Spine (Phila Pa 1976) 27:776-786,2002 4. Fridley J, Fahim D, Navarro J, Wolinsky JP, Omeis I: Free-hand placement of iliac screws for spinopelvic fixation based on anatomical landmarks: technical note. Int J Spine Surg 8, 2014 5. Garrido BJ, Wood KE: Navigated placement of iliac bolts: description of a new technique. Spine J 11:331-335, 2011 6. Gressot LV, Patel AJ, Hwang SW, Fulkerson DH, Jea A: Iliac screw placement in neuromuscular scoliosis using anatomical landmarks and uniplanar anteroposterior fluoroscopic imaging with postoperative CT confirmation. J Neurosurg Pediatr 13:54-61, 2014 7. Harrop JS, Jeyamohan SB, Sharan A, Ratliff J, Vaccaro AR: Iliac bolt fixation: an anatomic approach. J Spinal Disord Tech 22:541-544, 2009 8. Kim BD, Hsu WK, De Oliveira GS, Jr., Saha S, Kim JY: Operative duration as an independent risk factor for postoperative complications in single-level lumbar fusion: an analysis of 4588 surgical cases. Spine (Phila Pa 1976) 39:510-520, 2014 9. Kuklo TR, Bridwell KH, Lewis SJ, Baldus C, Blanke K, Iffrig TM, et al: Minimum 2-year analysis of sacropelvic fixation and L5-S1 fusion using S1 and iliac screws. Spine (Phila Pa 1976) 26:1976-1983, 2001 10. McCord DH, Cunningham BW, Shono Y, Myers JJ, McAfee PC: Biomechanical analysis of lumbosacral fixation. Spine (Phila Pa 1976) 17:S235-243, 1992 11. O'Brien JR, Yu WD, Bhatnagar R, Sponseller P, Kebaish KM: An anatomic study of the S2 iliac technique for lumbopelvic screw placement. Spine (Phila Pa 1976) 34:E439-442, 2009 12. Shin JH, Hoh DJ, Kalfas IH: Iliac screw fixation using computer-assisted computer tomographic image guidance: technical note. Neurosurgery 70:16-20; discussion 20,2012 13. Tabaraee E, Gibson AG, Karahalios DG, Potts EA, Mobasser JP, Burch S: Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation. Spine (Phila Pa 1976) 38:1953-1958, 2013 14. Wang MY, Ludwig SC, Anderson DG, Mummaneni PV: Percutaneous iliac screw placement: description of a new minimally invasive technique. Neurosurg Focus 25:E17, 2008