Accuracy of Screw Placement and Clinical Outcomes After O-Arm-Navigated Occipitocervical Fusion.

Objective: This study aimed to evaluate the accuracy of screw placement and clinical outcomes in patients undergoing occipitocervical fusion.

Methods: Patients who underwent occipitocervical fusion with O-arm-based navigation were retrospectively reviewed between January 2015 and December 2017. The patients' characteristics, clinical and radiographic outcomes, and surgical complications were recorded and analyzed. Cervical screw insertion accuracy was evaluated using the Richter scale.

Results: Thirty consecutive patients (11 male and 19 female) with an average treatment age of 40.03 ± 15.19 years were studied. The most common cause was atlantoaxial instability combined with Chiari malformation (63.33%). Weakness (76.67%) and paresthesia (70.00%) were the most common symptoms. Eighty-six occipital and 139 cervical screws were placed using an O-arm-assisted navigation system. In total, 130 (93.53%) cervical screws were graded as group A and 9 (6.47%) as group B. The optimal accuracy rate was 88.41% (61 of 69 screws) in the first 15 patients and 98.57% (69 of 70 screws) in the subsequent 15 patients. The mean follow-up time was 7.50 ± 5.70 months. The mean Japanese Orthopedic Association scores were 13.30 ± 2.41 preoperatively and 15.30 ± 1.60 at final follow-up (P < 0.001), and the mean recovery rate in the Japanese Orthopedic Association score was 53.26 ± 33.82%. Clinical improvement was seen in 25 patients (83.33%), whereas no change was observed in 5 patients (16.67%). The overall complication rate was 6.67% (2/30), with 1 intraoperative vertebral artery injury and 1 postoperative screw loosening.

Conclusion: Occipitocervical fusion with O-arm-based navigation is effective and safe for treating instability of the craniovertebral junction. Intraoperative navigation can help surgeons insert screws accurately.