BACKGROUND Severe acetabular bone deficiency is a major challenge in acetabular revision surgery. Most cases require reconstruction of the acetabulum with bone grafting and a reinforcement device. The purpose of this study was to evaluate the results of this procedure for severe acetabular bone deficiency in acetabular revision surgery. METHODS This study involved 12 patients (2 males and 10 females) with severe acetabular bone defects who underwent implantation of a reinforcement device (ring or cage) and bone grafting between February 2003 and October 2008. Using the Paprosky classification, 2 cases were Paprosky IIC, 6 were IIIA, and 4 were IIIB. The mean age at the time of surgery was 63.0 years (range, 46 - 78 years). During revision surgery, a reinforcement ring was implanted in 6 patients, and a cage in 6 patients. The clinical and radiographic results were evaluated retrospectively. The mean duration of follow-up was 37 months (range, 9 - 71 months). RESULTS The average Harris Hip Score improved from 35.2 preoperatively to 82.9 at the time of the final follow-up visit. The results were excellent in 8 hips (66.7%), good in 2 (16.7%), and fair in 2 (16.7%). Osteolysis was found in 1 case, but did not worsen. Three patients had yellow wound effusion, with healing after administration of dressing changes, debridement, and antibiotics. Dislocation occurred in a 62-year-old woman. Closed reduction was performed, and dislocation did not recur. There was no evidence of intraoperative acetabular fracture, nerve injury, ectopic ossification, aseptic loosening, or infection. CONCLUSIONS Reconstruction with a reinforcement device and bone grafting is an effective approach to the treatment of acetabular bone deficiency in acetabular revision surgery, given proper indications and technique.