We report a single-centre, prospective, randomised study for pedicle screw insertion, by using a Computer Assisted Surgery (CAS) technique with three dimension (3D) intra-operative images intensifier versus conventional surgical procedure. 143 patients (68 women and 75 men) were included in this study. 72 patients underwent conventional surgery (C = conventional). 71 patients were operated on with the help of a 3D intra-operative imaging system (N = navigated). We performed 34 percutaneous surgeries in group N and 37 in group C; 25 open surgeries in group N and 35 in group C. 382 screws were implanted in group C and 174 in group N. We measured the pedicle screw running-time, and surgeon's radiation exposure. All pedicle runs were assessed according to Heary's classification by two independent radiologists on a post-operative CT.Introduction
Methods
In recent years internal fixation of the spine by using posterior approach with minimally invasive and percutaneous technique were increasingly used in trauma. The percutaneous surgery lose information and navigation is supposed to provide better data because the lost information is found again. We hypothesise that a percutaneous minimal invasive dorsal procedure by using 3D intra-operative imaging for vertebral fractures allows short operating times with correct screw positioning and does not increase radiation exposure. 59 patients were included in this prospective, monocentric and randomised study. 29 patients (108 implants) were operated on by using conventional surgical procedure (CP) and 30 patients (72 implants) were operated on by using a 3D fluoroscopy-based navigation system (3D fluo). In the two groups, a percutaneous approach was performed for transpedicular vertebroplasty or percutaneous pedicle screws insertion. In the two groups surgery was done from T4 level to L5 levels. Patients (54 years old on average) suffered trauma fractures, fragility fractures or degenerative instabilities. Evaluation of screw placement was done by using post-operative CT with two independent radiologists that used Youkilis criteria. Operative and radiation running time were also evaluated. With percutaneous surgery, the 3D fluo technique was less accurate with 13.88% of misplaced pedicle screws (10/72) compared with 11.11% (12/108) observed with CP. The radiation running time for each vertebra level (two screws) reached on average 0.56 mSv with 3D fluo group compared to 1.57 mSv with the CP group. The time required for instrumentation (one vertebra, two screws) with 3D fluo was 19.75 minutes compared with CP group 9.19 minutes. The results were statistically significant in terms of radiation dose and operative running time (p < 0.05), but not in terms of accuracy (p= 0.24). With percutaneous procedures, 3D fluoroscopy-based navigation (3D fluo) system has no superiority in terms of operative running time and to a lesser degree in terms of accuracy, as compared to 2D conventional procedure (CP), but the benefit in terms of radiation dose is important. Other advantages of the 3D fluo system are twofold: up-to-date image data of patient anatomy and immediate availability to assess the anatomical position of the implanted screws.
