Malposition Rates of Subaxial Cervical Pedicle Screws Placed Using Intraoperative Computed Tomography (O-arm)–Based Three-dimensional Navigation

STUDY DESIGN: Cohort retrospective review. OBJECTIVE: To investigate placement accuracy and malposition rates of cervical pedicle screws (CPS) using intraoperative CT (O-arm) based three-dimensional navigation. BACKGROUND: CPS placement is technically demanding due to small pedicle sizes and risk of damage to neurovascular structures in the neck. Computer navigation (CN) has been shown to improve accuracy rates in thoracolumbar pedicle screw placement. However, there are limited studies on CN use for placing CPS. MATERIALS AND METHODS: We identified 100 patients who underwent CN CPS placement (C3-C7). Screw position was evaluated on axial, coronal, and sagittal planes and graded as follows: 0-fully in bone; I-minor breach deemed inconsequential (<25% of screw width); II-minor breach considered not ideal, but acceptable (25%-50% of screw width); and III-major breach considered dangerous or that compromised strength of fixation. RESULTS: Four hundred thirteen CN CPS screws (C3-C7) were placed in 100 patients (54M:46F). Rates of serious screw malpositions: combined Gr II/III = 42/413 (10.2%). Breaking down the combined Gr II/III screws per level: C3 = 8/33 (24.2%), C4 = 9/63 (14.3%), C5 = 8/72 (11.1%), C6 = 10/85 (11.8%), C7 = 7/160 (4.4%). CONCLUSION: Our study shows a 10.2% nonoptimal rate (combined Gr II and III) using intraoperative three-dimensional imaging and CN. Our results add to a limited number of studies that have reported on this procedure. To our knowledge, this is the biggest study on a uniform technique of navigated pedicle screw placement that included only subaxial levels C3-C7.