The threaded acetabular cups have shown mid-term bad results. Though the immediate fixation is excellent, as time goes by it has been proven the absence of fixation, appearing a high percentage of mobilizations. An alternative to avoid those failures is the hydroxyapatite coated implant. We have analysed clinically and radiographically 36 cases of Omnifit arthroplasties with cup threaded and coated with hydroxyapatite with an average time of follow-up of 58 months. Ten patients had pain in the hip. Only 63.9% of the acetabular cups were found to be radiographically integrated, six having suffered a clear mobilization requiring surgical review. Seven showed radiological signs of probable instability. The hydroxytapatite coatings does not assure a good fixation in the Omnifit threaded cups, therefore we recommend press fit acetabular components with the possibility of additional fixation with screws.

The threaded acetabular cups have shown mid-term bad results. Though the immediate fixation is excellent, as time goes by it has been proven the absence of fixation, appearing a high percentage of mobilizations. An alternative to avoid those failures is the hydroxyapatite coated implant. We have analysed clinically and radiographically 36 cases of Omnifit arthroplasties with cup threaded and coated with hydroxyapatite with an average time of follow-up of 58 months. Ten patients had pain in the hip. Only 63.9% of the acetabular cups were found to be radiographically integrated, six having suffered a clear mobilization requiring surgical review. Seven showed radiological signs of probable instability. The hydroxytapatite coatings does not assure a good fixation in the Omnifit threaded cups, therefore we recommend press fit acetabular components with the possibility of additional fixation with screws.