Objective:To explore the clinical effect of open reduction in the treatment of Tile C pelvic fracture combined with acetabular fracture in a specific sequence.Methods:Retrospectively analyzed the clinical data of 53 patients with Tile C type pelvic fracture combined with acetabular fracture from January 2014 to January 2019, and were divided into specific sequence group and non-specific sequence group according to the sequence of intraoperative reduction. A total of 29 cases were observed in the specific sequence group, including 20 males and 9 females; aged 43.8±14.8 years old (18-71 years), and the fractures were reduced in the sequence of "inside and out, then up and down" during the operation. There were 24 cases in the non-specific sequence group, including 14 males and 10 females; aged 44.4±14.7 years old (18-69 years), and fracture reduction was not performed in this sequence during the operation. According to the type of pelvic and acetabular fracture injury, we choose the appropriate position and surgical approach. After open reduction, the fracture was fixed with internal plants. The intraoperative blood loss, operation time, visual analogue scale (VAS) score were compared between the two groups. The quality of fracture reduction was evaluated by Matta score, pelvic fracture function recovery was evaluated by Majeed score, and acetabular fracture was evaluated by hip joint modified Merle d'Aubigné-Postel score.Results:There was no statistically significant difference in general data between the two groups before operation ( P>0.05), which was comparable. The intraoperative blood loss of the specific sequence group and the non-specific sequence group were 1 031.1±513.7 and 1 406.3±738.1 ml, and the operation time was 3.5±1.0 and 4.8±1.4 h; The differences between the two groups were statistically significant ( P<0.05). 53 patients were followed up for 14.8±1.6 months (12-18 months) after operation. The average postoperative VAS scores of specific sequence group and non-specific sequence group were 1.3±1.1 and 1.5±1.3 respectively, and there was no statistically significant difference. The effectiveness of the pelvic fracture Matta score standard was evaluated in the specific sequence group: excellent in 22 cases, good in 5 cases, fair in 2 cases, excellent and good rate was 93.1%; non-specific sequence group excellent in 10 cases, good in 6 cases, fair in 5 cases, poor in 3 cases, excellent and good rate was 66.7%, the difference was statistically significant ( P<0.05). Matta score of acetabular fracture: 21 cases were excellent in specific sequence group, 5 cases were good, 3 cases were poor, excellent and good rate was 89.7%; 9 cases were excellent in non-specific sequence group, 8 cases were good, 7 cases were poor, excellent and good rate was 70.8 %, the difference is statistically significant ( P<0.05). The results of the last follow-up pelvic fractures were evaluated by Majeed score: 20 cases were excellent in the specific sequence group, 7 were good, 2 were fair, excellent and good rate was 93.1%; 10 were excellent in the non-specific sequence group, 5 were good, 5 were fair, and 4 were poor, excellent and good rate was 62.5%, the difference was statistically significant ( P<0.05). At the last follow-up, the modified Merle d'Aubigné-Postel score was used to evaluate the efficacy: 20 cases were excellent in the specific sequence group, 5 were good, 4 were fair, the excellent and good rate was 86.2%; In the non-specific sequence group, 9 cases were excellent, 7 cases were good, 4 cases were fair, and 4 cases were poor, excellent and good rate was 66.7%, the difference was statistically significant ( P<0.05). During the follow-up period, none of the patients in the two groups developed fracture nonunion, heterotopic ossification, iatrogenic neurovascular injury, and femoral head necrosis. Trauma arthritis occurred in 4 patients in the non-specific sequence group. Conclusion:"Inside and out, then up and down" sequential reduction of Tile C pelvis combined with acetabular fracture can significantly shorten the operation time and reduce the amount of intraoperative blood loss. The surgical procedure is reasonable, which helps to improve the quality of fracture reduction and promote the functional recovery of patients.