Intraoperative Use of O-arm in Pediatric Cervical Spine Surgery

Traditionally, fluoroscopy and postoperative computed tomographic (CT) scans are used to evaluate screw position after pediatric cervical spine fusion. However, noncontained screws detected postoperatively can require revision surgery. Intraoperative O-arm is a 3-dimensional CT imaging technique, which allows intraoperative evaluation of screw position and potentially avoids reoperations because of implant malposition. This study's objective was to evaluate the use of intraoperative O-arm in determining the accuracy of cervical implants placed by a free-hand technique using anatomic landmarks or fluoroscopic guidance in pediatric cervical spine instrumentation.

A single-center retrospective study of consecutive examinations of children treated with cervical spine instrumentation and intraoperative O-arm from 2014 to 2018 was performed. In total, 44 cases (41 children, 44% men) with a mean age of 11.9 years (range, 2.1 to 23.5 y) were identified. Instability (n=16, 36%) and deformity (n=10, 23%) were the most frequent indications. Primary outcomes were screw revision rate, neurovascular complications caused by noncontained screws, and radiation exposure.

A total of 272 screws were inserted (60 occipital and 212 cervical screws). All screws were evaluated on fluoroscopy as appropriately placed. Four screws (1.5%) in 4 cases (9%) were noncontained on O-arm imaging and required intraoperative revision. A mean of 7.7 levels (range, 5 to 13) were scanned. The mean CT dose index and dose-length product were 15.2±6.87 mGy and 212.3±120.48 mGy×cm. Mean effective dose was 1.57±0.818 mSv. There was no association between screw location and noncontainment (P=0.129). No vertebral artery injuries, dural injuries, or neurologic deficits were related to the 4 revised screws.

Intraoperative non-navigated O-arm is a safe and efficient method to evaluate screw position in pediatric patients undergoing cervical spine instrumentation. Noncontained screws were detected in 9% of cases (n=4). O-arm delivers low radiation doses, allows for intraoperative screw revision, and negates the need for postoperative CT scans after confirmation of optimal implant position.

Level IV.