Intraoperative Radiation Exposure for Patients with Double-Curve Idiopathic Scoliosis in Freehand-Technique in Comparison to Fluoroscopic- and CT-Based Navigation
Authors: Berlin Clara , Quante Markus , Thomsen Björn , Köszegvary Mark , Platz Uwe , Halm Henry 
Published: May 2020

Abstract
Background In the operative treatment of idiopathic scoliosis, posterior correction and fusion in freehand technique is a proven procedure and is frequently performed. Malpositioned pedicle screws can result in serious neurovascular complications. Intraoperative fluoroscopy and neurophysiological measurements are performed to ensure the correct position of pedicle screws. Newer procedures with fluoroscopic- and computertomographic-assisted navigation are advertised as less dangerous and with a more accurate screw position.
Hypothesis Is the freehand technique used in the surgical treatment of idiopathic scoliosis safer than other methods with regard to complications caused by screw malposition and intraoperative radiation exposure?
Material and Methods Register data of 34 consecutive idiopathic scoliosis patients with two structural curves (Lenke 3 and 6) were collected prospectively in our scoliosis center and were retrospectively analyzed. The following parameters were evaluated: total radiation product, time of fluoroscopy, number of fused segments, time of operation, blood loss, screw-related complications and number of instrumented pedicle screws. All values were given as mean ± standard deviation and statistically analyzed. Finally, our data were compared on accuracy of screw placement and radiation exposure to data from literature with screw placement under navigation.
Results Average age at the time of surgery was 23.6 ± 12 years. The average thoracic curve was 69.2 ± 14.2° preoperatively and 21.7 ± 12.8° postoperatively (correction 69.9%), the average lumbar curve was 64.3° ± 10.8° preoperatively and corrected to 15.6 ± 10.4° postoperatively (correction 76.2%). The total radiation product per patient was 145.7 ± 86.1 cGy*cm², the time of fluoroscopy 31.7 ± 23.5 s (11.5 segments), the time of operation 267.2 ± 64.1 min and the blood loss 700.4 ± 522.3 ml. A total of 803 pedicle screws were placed. No screw-associated complications were detected in the entire collective. The comparison of our data with freehand placement of pedicle screws to literature data showed a noticeable higher radiation exposure for the patient during fluoroscopic- and computertomographic-assisted navigation.
Discussion The results showed that positioning of pedicle screws with freehand technique in patients with idiopathic scoliosis is accompanied with considerably lower intraoperative radiation exposure compared to fluoroscopic- or computertomographic-assisted navigation. An increased radiation exposure of these typically young patients is associated with an increased long-term risk for the occurrence of radiation-induced malignant diseases. With appropriate surgical experience, placement of pedicle screws in freehand technique is safe and effective and with similar accuracy than screws placed under navigation, but produces significantly less radiation exposure to the patients.