 Alumina ceramic-on-ceramic COC bearings have been shown to produce substantially less wear debris than traditional metalceramic on polyethylene bearings. In addition, the alumina ceramic material itself is essentially bioinert in both bulk and particulate form . Unlike metal-on-metal bearings MOM, this bearing couple does not release metal ions into the body either from the articulation or from breakdown of wear debris. Weakness of ceramic-on-ceramic bearings are represented by brittleness of the material. Ceramic can fracture, even in very few cases, due to trauma or to malpositioning. Beside this occurrence of noise during gait of patients can be extremely disturbing for patient itself, leading to request of revision. These two solutions represent more recent proposal that technology suggested to overcome problem of wear. 