This study focuses on the effect of the hydroxyapatite coating with BoneMaster on the fixation of the hip prosthesis in primary hip alloplasty. A hemispheric joint cup of the type Exceed cup (Biomet) characterized by a porous surface of titanium plasma spray is used. The surface is coated with hydroxyapatite deposited electrochemically (BoneMaster) and will be compared with an identical cup without hydroxyapatite. A 5-year radiologic analysis of migration will be carried out with the object of detecting prognostic evidence of prosthesis loosening. Migration is determined by Roentgen Stereo-photogrammetric Analysis (RSA) on stereoroentgenograms. Simultaneously, the patients will be monitored by using the clinical outcome measure HOOS (Hip disability and osteoarthritis outcome score), OHS (Oxford Hip Score), EQ-5D (EuroQol), HHS (Harris Hip Score) on range of motion, VAS (Visual Analog Scale), postoperative complications and reoperation.