Three-dimensional printing simulated operation combined with robot-aided minimally invasive lumbopelvic fixation in treatment of unstable bilateral sacral fractures: technical notes and 8 case series

Abstract

Background Despite their seldom appearance, unstable bilateral sacral fractures are severe injuries and always cause surgical management difficulties. Lumbopelvic fixation is reliable for rigid method, but wound-related complications with open procedure have been relatively common. Methods Data of 8 patients with unstable bilateral sacral fractures who were treated surgically in our institution from March 2016 to April 2019 were retrospectively analyzed. There were 5 men and 3 women with an average age of 38.5 years (range, 19-60years). According to the sharp of sacral fractures, there were one case with simple bilateral vertical fracture lines, 6 cases with “U” and one case with “H”. According to Roy-Camille classification, 7 of 8 sacral fractures involving sacral canal were classified with type I 2 cases, type II 4 cases and type III 1 case. Three-dimensional(3D) printing pelvis were performed to simulate lumbopelvic and sacroiliac screw fixation for preoperative planning. Eight bilateral sacral fractures were treated with minimally invasive lumbopelvic fixation under robotic guidance. Results The screws inserted with robotic assistance were exposed to radiation with an average of 41.6±10.2 times (range, 27–53 times) intraoperatively. The total fluoroscopy time was 32–59 s, and the average fluoroscopy time for each screw was 4.2±0.6s. According to modified Gras classification of screw position, there were Grade I in 7 cases and Grade II in one case (left S1 screw). The average operation time was 150.6 min (range, 95-220 min), and intraoperative blood loss was 87.5 ml (range, 60-120 ml). Eight patients were followed up consecutively for at least 12 months, with an average of 17.0 months (range, 12–24months). No patient suffered a neurovascular injury intraoperatively. There were no incision-related complications. All fractures healed with an average time of 4.2 months (range, 3–10 months). According to Majeed functional assessment investigation, the mean score was 88.4 points (range, 78–98 points), which were graded as follows: 5, excellent and 3, good. Conclusion Under robot guidance, minimally invasive lumbopelvic fixation for unstable bilateral sacral fractures is a feasible option with the advantages of accuracy, less radiation and safety. Simulated operation with 3D printing for preoperative planning can simplify the actual surgery.