ObjectiveTo evaluate the effectiveness of unstable pelvic fractures treated with minimally invasive percutaneous bridge internal fixator or traditional external fixator.MethodsThe clinical data of 45 patients with unstable pelvic fractures who met the selection criteria between January 2013 and February 2018 were retrospectively analyzed. According to the different surgical methods, they were divided into two groups. In the observation group (25 cases), minimally invasive percutaneous bridge internal fixators were used, and three-dimensional printing pelvic models were used to simulate the reduction and fixation before operation to develop individual reduction strategies. In the control group (20 cases), external fixators were used. There was no significant difference between the two groups in gender, age, cause of injury, fracture type (according to Tile classification), and time from injury to operation (P>0.05). The operation time, intraoperative blood loss, fracture healing time, and complications were recorded and compared between the two groups. The reduction quality was evaluated according to the Matta standard, and functional recovery was evaluated according to the Majeed scoring standard.ResultsAll patients were followed up 12-20 months (mean, 15 months). The operation time of the observation group was significantly longer than that of the control group (t=2.719, P=0.009); no significant difference in intraoperative blood loss was found between the two groups (t=0.784, P=0.437). There was no significant difference between the two groups in fracture healing time (t=0.967, P=0.341). According to the Matta standard, the excellent and good rate of the observation group was 92%, and that of the control group was 70%, showing no significant difference between the two groups (χ2=3.748, P=0.053). At last follow-up, according to the Majeed scoring standard, the excellent and good rate of the observation group was 88%, and that of the control group was 60%, showing significant difference between the two groups (χ2=4.717, P=0.030). The incidences of incision and nailway infection, secondary displacement of fracture, and malunion in the observation group were significantly lower than those in the control group (P<0.05); the differences in incidences of iatrogenic injury of lateral femoral cutaneous nerve, deep vein thrombosis, and loosening of fixation between the two groups were not significant (P>0.05).ConclusionMinimally invasive percutaneous bridge internal fixator is a safe and effective method for the treatment of unstable pelvic fractures. It has the advantages of minimal trauma, stable fixation, less interference to patients’ daily life, early functional exercise, and quickly recovery after operation.