Patent ID: 7393362
Filing Date: 2008-07-01
Classification: A61F

Abstract:
1. A hip prosthesis comprising a shaft which is implantable in the femur, a ball head anchored on the shaft, a socket in which the ball head has a slide pairing diameter and is movably supported, and a bipolar shell has a sliding pairing diameter and is placed between the ball head and the socket, whereby the ball head rotates in the bipolar shell and the bipolar shell rotates in the socket, wherein the ratio of the slide pairing diameter of the bipolar shell and the ball head is between 1.05 and 5, wherein the ball head, the bipolar shell, and the socket are ceramic, wherein the tribological conditions of die ceramic components are defined as follows: a) the hardness of the ceramic components is greater than 1,000 HV (Vickers); b) the surface finishes on the articulating surfaces of the ceramic components have a roughness less than 0.1 μm (Ra value<0.1 μm); c) the contact angle between to articulating surfaces of the ceramic components is between 1° and 8° (measured in Ringer's solution); and d) the difference in the slide pairing diameters of the articulating surfaces of the ceramic components is between 1 and 200 μm.