Objective:To investigate the effect of 3D-printed customized flanged cup in hip revision with severe acetabular bone defects.Methods:Since February 2017, 10 cases of 3D-printed customized flanged cups were used in hip revision with severe acetabular bone defects, including 2 cases of Paprosky type IIIA and 8 cases of Paprosky type IIIB. There were 5 males and 5 females, mean age 73.6±8.1 yrs (range, 62-87 yrs), 5 left and 5 right cases. The preoperative thin-layer CT scan was preformed to reverse reconstruct digital pelvis. Five cases of one-piece flanged cups and 5 cases of decomposed flanged cups, including 3 cases of composite one-piece cups were designed by computer. The surgery was performed strictly according to the plan.Postoperative follow-up was performed to evaluate the Harris score. Operation time,intraoperative bleeding and other complications such as vascular and nerve injury, postoperative infection, and dislocation were counted. Pelvic X-ray was used to assess the height and horizontal position of the center of rotation and the stability of the prosthesis.Results:The surgical procedure was successful, with an average operative time of 147.9±48.3 min (range, 96-212 min) and an average intraoperative bleeding of 730.4±262.6 ml (range, 500-1 300 ml). The mean time of final follow-up was 40.8±18.7 months (range, 16-70 months) after surgery. At the last follow-up, the average Harris score was 83.80±6.73, with 4 cases excellent, 5 cases good, and 1 case fair. The excellent and good rate was 90%. The last Harris score was significantly higher than that before operation 28.60±8.40 ( t=16.84, P<0.001). The height of affected hip joint rotation center decreased from 46.24±7.74 mm before operation to 15.54±2.54 mm after operation with significant difference ( t=14.61, P<0.001). It was slightly higher than the opposite side (13.81±1.48 mm), which had no significant difference ( t=1.83, P=0.100). The horizontal distance of affected hip joint rotation center increased from 33.79±5.27 mm before operation to 40.53±4.50 mm after operation with significant difference ( t=3.62, P=0.006). It had no significant difference ( t=1.28, P=0.232) compared with the opposite side (38.54±3.46 mm). All incisions were healed in one stage without infection, vascular or nerve injury. During the following-up, all prostheses were in satisfied position without loosening, dislocation or screw breaks. Conclusion:Digitally assisted 3D-printed flanged cups can be used in hip revision with severe acetabular bone defect. It can not only improve hip joint function, but also restore the acetabular rotation center and the prosthesis stability, which can achieve good early and mid-term effect.