Choice of the acetabular component placement in dysplastic hip patients

Total hip arthroplasty (THA) in patients with hip dysplasia is a challenging surgical operation. Many orthopedic surgeons concur that the anatomical placement of the acetabular components of endoprostheses (AC-EPs) during THA yields the best result. However, there are advocates of the high rotation center of the hip joint after replacement surgery. In our study, we compared the outcomes of THA based on the placement of acetabular cups to identify the most favorable site for AC-EPs in patients with varying grades of dysplastic osteoarthritis. Our study included 88 patients with dysplastic hip osteoarthritis who underwent 106 THAs during a three-year period using cementless fixation endoprostheses. Functional results were assessed by Merle d'Aubigne and Postel's method and by instrumental gait analysis (IGA). Gait deviation index was calculated based on IGA to compare results in different acetabular component placement groups. Functional assessment of patients by Merle d'Aubigne and Postel's grading method and IGA showed no significant difference in results due to the placement of the acetabular component. Most complications were found in the severe dysplasia patients group with the anatomical placement of the AC-EP. The appropriate location of cementless acetabular cups during THA in dysplastic hips depends on the grade of dysplasia, expected elongation of the leg, and the potential for adequate bone coverage for the AC-EP. In cases of severe dysplasia, the placement of the AC-EP in the secondary socket can provide a good functional outcome and reduce the risk of complications.