【Abstract】 Objective To evaluate the method and the early effectiveness of total hip arthroplasty in the treatment of protrusio acetabuli. Methods Between January 2006 and February 2010, 16 cases (16 hips) of protrusio acetabuli were treated, including 6 males and 10 females with an average age of 56.5 years (range, 39-72 years). The median disease duration was 6.4 years (range, 1 year and 6 months to 35 years). Involved hips included 7 left hips and 9 right hips; 3 patients had primary protrusio acetabuli and 13 patients had secondary protrusio acetabuli. The preoperative Harris score was 49.5 ± 5.5. According to Dunlop et al. classification criterion, there were 3 cases of mild, 9 cases of moderate, and 4 cases of severe. All patients received total hip arthroplasty with bone graft and cementless prosthesis for recovery of femoral offset and acetabular center of rotation. Results All incisions healed by first intention without complication of infection, deep venous thrombosis, or nerve injury. All patients were followed up 12-62 months with an average of 37 months. The Harris score at last follow-up was 90.5 ± 4.5, showing significant difference (t=49.578, P=0.000) when compared with preoperative score. The X-ray films showed that no prosthesis loosening or subsidence was observed, and bone graft healed with no sign of re-protrusion. Conclusion In treatment of protrusio acetabuli, total hip arthroplasty with bone graft and cementless prosthesis can recover the femoral offset and acetabular center of rotation and provide satisfactory early effectiveness.