Intraoperative Computed Tomography–Guided Navigation for Pediatric Spine Patients Reduced Return to Operating Room for Screw Malposition Compared With Freehand/Fluoroscopic Techniques

Abstract

Placement of pedicle screws can be performed using freehand/fluoroscopic technique or intra-operative CT guided navigation. We sought to compare screw malposition and return to OR for pedicle screw malposition for screws placed with and without CT-guided navigation. This study was a single center retrospective comparative study. All patients under the age of 18 with minimum 2-year follow-up who underwent pedicle screw instrumentation between 2009–2015 were included. IRB-approval was obtained and patient charts were reviewed for patient demographics and surgical outcomes. If available, incidental CTs following the index surgery were reviewed to assess screw position. 217 patients underwent spinal instrumentation. 112 patients had pedicle screws placed using fluoroscopic guidance, while 105 patients had screws placed using lowdose intraoperative CT-guided navigation (O-arm, Medtronics). Of the total cohort, 107 (49.3 %) patients had adolescent idiopathic scoliosis, and the remainder had neuromuscular, tumor, congenital, or other diagnoses. Patients in each group had a similar number of levels fused (fluoroscopic = 10.9 vs. CT navigation = 9.8, p = 0.06). There was no difference in total estimated blood loss (1127 vs. 1179 mL, p = 0.63), or in blood loss per level fused (133.7 vs. 146.6 mL, p = 0.47). Patients with screws placed using fluoroscopic guidance had a shorter total operative time (441 vs. 468 minutes, p = 0.04); however, there was no difference when controlling for number of levels fused (58.3 vs. 61.5 minutes/level, p = 0.63). Postoperative CTs were available in 51 patients representing 526 imaged screws, which showed a significantly higher rate of severely malpositioned (>4mm) screws in the fluoroscopic group than the CT navigation group (3.3% vs. 1.0%, p = 0.027). There was a 3.6% rate of return to OR for pedicle screw malposition in the freehand/fluoroscopic group compared to 0% in the CT-guided navigation group (p=0.048). Including patients with less than 2-year follow up (169 fluoroscopy, 220 CT-guidance) also found higher rates of screw malposition (13.5% vs. 7.1%, p = 0.004), severe screw malposition (3.0% vs. 0.50%, p = 0.04) and return to OR due to screw malposition (2.4% vs. 0%, p = 0.02) in patients with screws placed using fluoroscopic guidance. Patients with pedicle screws placed with CT-guided navigation had a lower rate of severely malpositioned screws and unplanned returns to the OR. There was no significant difference in blood loss or operative time when controlling for number of levels fused. In the era of healthcare ‘never-events,’ return to OR for screw malposition could certainly be deemed unacceptable. Use of intraoperative CT guided navigation thus far eliminated return to OR for screw malposition in a complex cohort of pediatric spinal deformity patients, without measurable increase in operative time or blood loss.