High Hip Center Total Hip Arthroplasty For Crowe Ⅱ Or Ⅲ Hip Dysplasia

Objective:To discuss biomechanics of total hip arthroplasty for developmental dysplasia of the hip(DDH), and examine the short -term clinical and radiographic results for patients treated with high hip center cementless THA for Crowe II and III dysplasia.Methods:We reviewed 29 patients (37 hips) with Crowe II or III dysplasia who were treated with high hip center cementless THA, compared with a control group of 28 patients (35 hips) with Crowe I dysplasia who had cementless cups placed at an anatomic hip center; All surgeries were done between June 2011 and June 2013 by one senior surgeon. The mean followup was 2.2 years. Harris hip scores,gait,lamp, Trendelanburg sign were recorded. Radiographic analysis including vertical and horizontal distances of the center of rotation in relation to the acetabular teardrop, and the radiolucent line around the prosthesis.Results:. The average followup ofCrowe II or III DDH patients treated with THA is 2.2 years.The mean vertical distance between the center of rotation and inter teardrop line for Crowe II and III dysplasia is 25.5mm,29.7mm respectively. The average Harris hip scores of the high hip center group was 92.3 at the last followup. All patients had excellent gait without lamp. There were no statistical differences between the high hip center group and the anatomic hip center group.Conclusions:In Crowe II and III dysplasia, a high hip center cementless cup without bone graft is a liable method. The clinical and radiographic results for patients treated with high hip center cementless THA for Crowe II and III dysplasia were excellent.The cup need to be more medially to avoid increasing the weight moment arm. Beside,the leg length and femoral offset must be reconstructed to increase the tense of gluteus medius muscles...