Anatomically designed prosthesis without cement for the treatment of osteoarthritis due to developmental dysplasia of the hip: 6-to 13-year follow-up study

Background. Morphological differences of dysplastic hips exist not only on the acetabular side but also on the femoral side. Therefore, for reconstructing the hip joint of these patients, the shape of the proximal femur is problematic for getting adequate fit and fill by cementless stems. The purpose of this study was to investigate the clinical and radiological outcomes of anatomically designed prostheses for the treatment of osteoarthritis due to developmental dysplasia of the hip. Methods. A total of 81 consecutive primary cementless total hip arthroplasties using an anatomic hip system were performed in 75 patients (10 men, 65 women). The mean age at the time of the surgery was 59.0 years (range 41-84 years). The average duration of follow-up was 101.4 months (range 72-157 months). Clinical performance was evaluated using the Harris hip score (HHS), and radiographic findings were assessed using the fixation and stability score according to Engh et al. Results. The average preoperative HHS was 44.5 points, and the most recent average HHS was 87.5 points. Altogether, 66 hips (81%) were deemed excellent (>= 90 points) or good (80-89 points). The mean fixation and stability score was 19.6 +/- 5.2 points. In total, 75 (93%) of the femoral components had bone-ingrown fixation, and 6 (7%) indicated possible ingrowth. There was osteolysis around five femoral components and three acetabular components. No femoral component was revised; however, five cups were revised because of breakage of the polyethylene or massive osteolysis. Dislocation of the hip implant was seen in one hip, but there was no recurrent dislocation. There was no deep infection, deep vein thrombosis, or nerve palsy. Conclusions. The anatomic stem showed acceptable clinical and radiological results in cases with mild or moderate subluxation of the hip at the intermediate-term follow-up.