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.

STUDY DESIGN: Cadaveric laboratory study.

OBJECTIVE: To compare the accuracy, efficiency, and safety of intraoperative cone beam-computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws.

SUMMARY OF BACKGROUND DATA: Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications.

METHODS: Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1-T6) spine and lumbosacral junction (L5-S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3-L4) level. A "postoperative" computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure.

RESULTS: There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, χ= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a "postoperative" CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group.

CONCLUSION: In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver.

LEVEL OF EVIDENCE: N/A.