In 45 patients, 65 hips with CDH were given a THR after 5 years or more, with an average follow up of 8.5 years. The results and the technical problems are discussed. Of those 65 hips, there were 46 anterior dislocations, 15 intermediate dislocations and 4 cases of posterior dislocation. The mean shortening was 58.3 mm. In all cases, the authors performed a total arthroplasty on the original acetabulum, after lowering and reconstruction of the acetabulum by grafts taken from the femoral head. There are some immediate postoperative complications: 12 thromboembolic complications, hematomas and 2 cases of paralysis of the peroneal nerve. There was loosening in 8 patients (12%), with 3 infections. The functional results were good in 85% and poor in 7.5%. Nevertheless, the limp was maintained in 49 patients. There was residual low back pain in 7 patients. In 14% a second operation on the homolateral knee was performed after an average time of 2 years. The technical problems are discussed: the cup should be placed in the original acetabulum and in evaluating the lowering of the acetabulum, the condition of the lumbar spine should be considered. Posterior luxation is discussed as well; the authors recommend prudence in the indication for THR operations with lowering of the acetabulum shell.