Infinity: A Prospective Trial for Safety and Accuracy of Navigated Posterior Cervical and Thoracic Instrumentation in long-segment Fusions

Study Design. Unblinded single-arm prospective clinical trial Objective. Evaluate safety and accuracy of navigation for placement of posterior cervicothoracic instrumentation. Summary of Background Data. Computer assisted stereotactic navigation for placement of spinal instrumentation has been widely studied and implemented in the thoracic and lumbar spine. However less literature exists regarding the use of computer assisted navigation for posterior cervical instrumentation, particularly with lateral mass fixation. Here we present the first prospective study of navigated cervical lateral mass screw placement for cervicothoracic fusion. Methods. Patients who met indications for posterior cervical fusion were screened, consented, and enrolled preoperatively for instrumentation with Medtronic Infinity Occipital-Cervical-Thoracic implants, with use of intraoperative O-arm and stereotactic Stealth navigation. Postoperative CTs of the instrumented levels were obtained during the same hospital admission. Primary outcome of the trial was safety. Secondary outcomes were screw accuracy assessed by Gertzbein-Robbins grade, neurologic exams, and patient reported outcomes on the PROMIS 29 questionnaire. Results. A total of 50 patients underwent surgery, and 557 screws were placed. There were no adverse events related to the use of navigation or screw malposition. Gertzbein-Robbins grade A or B placement comprised 95% of navigated screws. There was a decrease in positive Hoffmann sign rate postoperatively, and sensory and motor exams remained stable. There was improvement in patient reported pain and sleep domains. Conclusions. Navigation for cervicothoracic instrumentation is safe overall and leads to high rates of accurately placed screws. Longer term follow up could provide more insight to whether the use of this technology results in durable improvement in spinal alignment parameters and patient reported outcomes. Level of Evidence. 3