Objective To explore the clinical effect of 3D printing in vitro modeling for minimally invasive treatment of complex pelvic fractures. Methods From April 2016 to June 2017

18 cases of complex pelvic fractures were treated by 3D printing in vitro modeling were selected.The operation time and intraoperative bleeding volume were recorded.Fracture reduction was evaluated by X-ray

CT and Matta scores

and functional recovery was assessed by Majeed score. Results All 18 patients were followed up for 12 to 24 months，with an average of 15.8 months.The operation time of 18 patients was 80~160 minutes

with an average of (120±23.1)minutes;the amount of bleeding was 75~160 mL

with an average of (113.6±29.1)mL;the length of incision was 7~14 cm

with an average of (9.3±1.8)cm.According to the Matta score

the fracture reduction was excellent in 12 cases

good in 4 cases

fair in 2 cases

the excellent and good rate was 88.9%.Majeed score was used to evaluate functional recovery 6 months after operation

the results showed that 13 cases were excellent

4 cases were good and 1 case was fair

the excellent and good rate was 94.4%.No complications such as internal fixation loosening or breakage occurred during the follow-up period. Conclusion For complex pelvic fractures

3D printing in vitro modeling assisted minimally invasive surgery can make the operation more precision with less trauma

reduce the incidence of complications

and speed up the recovery of patients.