ObjectiveTo evaluate the effectiveness of unstable pelvic fractures treated by cannulated screw internal fixation with the assistance of three-dimensional (3D) printing insertion template.MethodsThe clinical data of 10 patients who underwent surgical treatment for unstable pelvic fractures by cannulated screw internal fixation with the assistance of 3D printing insertion template between May 2015 and June 2016 were retrospectively analysed. There were 7 males and 3 females with an average age of 37.5 years (range, 20-58 years). The causes of injury included falling from height in 5 cases, crushing from heavy load in 1 case, and traffic accidents in 4 cases. The interval from injury to admission was 1-5 hours (mean, 3.1 hours). The fracture situation included 6 cases of sacral fracture, 1 case of right sacroiliac joint dislocation, and 3 cases of iliac bone fracture. There were 10 cases of superior and inferior pubic rami fracture, including 3 cases on the left side (2 cases of suprapubic fracture adjacent to symphysis pubis), 2 cases on the right side, and 5 cases on the bilateral. All fractures were classified according to the Tile system, there were 4 cases of type B2, 1 of type B3, 4 of type C1, and 1 of type C2. The radiological outcome was evaluated by Matta scale, and the positions of the iliosacral screw and superior pubic ramus screw were evaluated according to 3D reconstruction of CT postoperatively. The functional outcome was evaluated by Majeed function scale.ResultsThe average time of each screw implantation was 30 minutes, and the average blood loss per screw incision was 50 mL. The time of implantation of each sacroiliac screw was 24-96 seconds (mean, 62 seconds), and the time of implantation of each suprapubic screw was 42-80 seconds (mean, 63.2 seconds). The hospitalization duration was 17-90 days (mean, 43.7 days). All incisions healed by first intention. All patients were followed up 12-22 months (mean, 15.6 months). The radiological outcome was excellent in 8 cases and good in 2 cases according to Matta scale; and 3D reconstruction of CT demonstrated that all the 9 iliosacral screws were placed as type Ⅰ, and all the 13 suprapubic ramus screws were placed as grade 0 on the first postoperative day. No complication such as neurovascular injury, screw back out or rupture, or secondary fracture displacement was observed during the follow-up. At 6 months after operation, the X-ray films showed good fracture healing in all the 10 patients. The functional outcome was excellent in 9 cases and good in 1 case according to Majeed scale at 1 year after operation. One patient sustained Tile C2 pelvic disruption complicated with L5 nerve root injury achieved complete nervous functional recovery at last follow-up.ConclusionIt has advantages of precise screw insertion and lower risk of neurovascular injury to treat unstable pelvic fractures by cannulated screw internal fixation with the assistance of 3D printing insertion template, which can be a good alternative for the treatment of unstable pelvic fractures.