Objective To investigate the technique and clinical results of total hip arthroplasty in treating post-traumatic hip fusion ankylosis secondary to operation in acetabular combined with femoral head fracture.Methods From October 2009 to January 2015,7 patients (7 hips) with post-traumatic hip fusion ankylosis underwent total hip arthroplasty.There were 6 males and 1 female with an average age of 38 years (range,25-51 years).There were 4 hips on the left side,3 hips on the right side.Open reduction and internal fixation were performed on all patients.One patient had a postoperative deep infection and 6 patients underwent implant removal.The hip bony fusion ankylosis was developed secondary to post-traumatic arthritis after the surgery of ipsilateral acetabular combined with femoral head facture.The interval between internal fixation and total hip arthroplasty was 37.6 months on average (range,21-67 months).The hip bony fusion ankylosis was relieved by wedge shape osteotomy at femoral neck level.The cemenfless prostheses were implanted in suitable places based on the accuracy position of acetabular center.One infection case was treated via surgical debridement,removal of all the screws,and antibiotic-loaded cement spacer implantation in the first stage.The cementless prostheses were implanted in the second stage.Results The average operation time and blood loss was 108 min (90-150 min) and 320 ml (280-450 ml) respectively.The internal fixation devices were explanted completely,including plate and screw in 5 cases,only screw in 1 case,intramedullary nail and screw in 1 case.The mean fallow-up period was 32.5 months (range,15-48 months).The average Harris hip score improved from 48.8±6.5 points preoperatively to 92.6±5.1 points post-operatively (t=22.82,P=0.001).Osseointegration was developed in all of the acetabular and femoral components at 3 months post-operatively.Radiograph analysis showed satisfied position of acetabular cup and no evidence of implant migration or center of rotation change.Stem subsidence (＜1.0 mm) occurred in 2 cases and heterotopic ossification in 2 cases (Brooker type Ⅰ and type Ⅱ in 1 case,respectively) at one year postoperatively.No complication occurred,such as damages of vessels and nerve,dislocation,component loosening or infection.Conclusion The wedge shape osteotomy of femoral neck is a safe and reliable method in treating hip fusion ankylosis.Total hip arthroplasty can be achieved by reconstruction of acetabular center,suitable components implanted in anatomical position and ideal reconstruction of soft tissue around hip.