P105. Intraoperative CT based pedicle screw navigation in pediatric spine deformity increases operative time, radiation exposure with minimal impact on screw accuracy for experienced surgeon

Abstract

BACKGROUND CONTEXT Pedicle screw accuracy is an important safety goal in pediatric spine deformity surgery. Intraoperative CT guided navigation has a two-fold advantage of allowing screw insertion under navigation guidance and assess accuracy after screw insertion. However, this entails modification of surgical workflow, which potentially prolongs surgical time and impacts blood loss. In addition, it increases radiation exposure. PURPOSE The purpose of this study is to evaluate how much intraoperative CT navigation increases accuracy and how it slows down surgeons effecting surgical outcomes. STUDY DESIGN/SETTING Retrospective case cohort review. PATIENT SAMPLE Spinal deformity patients who underwent posterior spinal fusion between 2015 - 2020. OUTCOME MEASURES Postoperative Cobb, kyphosis, overall Cobb correction, surgical and anesthesia time, fixation points, levels fused, radiation exposure, length of stay, post op complication, infection rate and pedicle perforation. METHODS Pediatric spine deformity patients undergoing surgery utilizing intraoperative CT navigation were compared to patients who underwent deformity surgery utilizing free hand technique. In navigated group, the reference frame was applied to the caudad spinous process after exposure and a CT spine was carried out at 50-70% of the recommended pediatric dose per the manufacturer. A scan was performed at the end of all screw insertion to confirm screw accuracy at a lower dose than the first. A scan was repeated if there was a concern about reference frame displacement or navigation accuracy. In the free-hand technique fluoroscopy was utilized for confirmation of levels, shoulder balance post correction and occasionally to assist with screw insertion. Demographic, radiographic, radiation exposure and perioperative data were collected. Kruskal-Wallis and Fisher's exact test were performed. RESULTS Seventeen navigation patients (340 screws) were compared to AIS patients with pedicle screws placed freehand and confirmed on fluoroscopy. Patients were similar in age, BMI, preoperative Cobb and preoperative kyphosis. (p > 0.05). Postoperative Cobb, kyphosis, and overall Cobb correction were similar. Blood loss was similar between the groups; however, navigation patients had significantly longer surgical time and anesthesia time for patients with a similar number of fixation points and levels fused. Radiation exposure was higher in the navigation group. Length of stay was similar between the patients (p > 0.05). No significant difference in postop complications, infection rate or 30-day return to ED. In 5 patients, more than 2 scans had to be performed as the accuracy was lost during surgery. In 10 navigation patients, most screws were first inserted free hand and then checked for placement with an intraoperative CT spin. Only 3 screws in these 10 patients were backed off slightly as the tip was protruding anteriorly. These anterior protrusions were <4mm and were therefore acceptable. In the free-hand group, screw accuracy was confirmed on postop radiographs. None of the screws in either group needed revision. The cost of equipment, prolonged OR time, need for CT tech contributed to increased cost in navigation group. CONCLUSIONS Patients operated on using navigation for pedicle screw placement do not see an increase in safety or screw precision. The drawback may be significantly longer anesthesia and surgery times. Radiation exposure also increased. However, availability of navigation, offers a potential to avoid screw misplacement. It depends on individual surgeons to determine the value of this ‘peace of mind' to their practice. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Pedicle screw accuracy is an important safety goal in pediatric spine deformity surgery. Intraoperative CT guided navigation has a two-fold advantage of allowing screw insertion under navigation guidance and assess accuracy after screw insertion. However, this entails modification of surgical workflow, which potentially prolongs surgical time and impacts blood loss. In addition, it increases radiation exposure. The purpose of this study is to evaluate how much intraoperative CT navigation increases accuracy and how it slows down surgeons effecting surgical outcomes. Retrospective case cohort review. Spinal deformity patients who underwent posterior spinal fusion between 2015 - 2020. Postoperative Cobb, kyphosis, overall Cobb correction, surgical and anesthesia time, fixation points, levels fused, radiation exposure, length of stay, post op complication, infection rate and pedicle perforation. Pediatric spine deformity patients undergoing surgery utilizing intraoperative CT navigation were compared to patients who underwent deformity surgery utilizing free hand technique. In navigated group, the reference frame was applied to the caudad spinous process after exposure and a CT spine was carried out at 50-70% of the recommended pediatric dose per the manufacturer. A scan was performed at the end of all screw insertion to confirm screw accuracy at a lower dose than the first. A scan was repeated if there was a concern about reference frame displacement or navigation accuracy. In the free-hand technique fluoroscopy was utilized for confirmation of levels, shoulder balance post correction and occasionally to assist with screw insertion. Demographic, radiographic, radiation exposure and perioperative data were collected. Kruskal-Wallis and Fisher's exact test were performed. Seventeen navigation patients (340 screws) were compared to AIS patients with pedicle screws placed freehand and confirmed on fluoroscopy. Patients were similar in age, BMI, preoperative Cobb and preoperative kyphosis. (p > 0.05). Postoperative Cobb, kyphosis, and overall Cobb correction were similar. Blood loss was similar between the groups; however, navigation patients had significantly longer surgical time and anesthesia time for patients with a similar number of fixation points and levels fused. Radiation exposure was higher in the navigation group. Length of stay was similar between the patients (p > 0.05). No significant difference in postop complications, infection rate or 30-day return to ED. In 5 patients, more than 2 scans had to be performed as the accuracy was lost during surgery. In 10 navigation patients, most screws were first inserted free hand and then checked for placement with an intraoperative CT spin. Only 3 screws in these 10 patients were backed off slightly as the tip was protruding anteriorly. These anterior protrusions were <4mm and were therefore acceptable. In the free-hand group, screw accuracy was confirmed on postop radiographs. None of the screws in either group needed revision. The cost of equipment, prolonged OR time, need for CT tech contributed to increased cost in navigation group. Patients operated on using navigation for pedicle screw placement do not see an increase in safety or screw precision. The drawback may be significantly longer anesthesia and surgery times. Radiation exposure also increased. However, availability of navigation, offers a potential to avoid screw misplacement. It depends on individual surgeons to determine the value of this ‘peace of mind' to their practice.