In vitro comparison of the two hard-hard articulations for total hip replacements

Abstract

Abstract

Polyethylene particle disease is one of the major causes of late aseptic loosening of total hip replacement. Two hard-hard articulations (alumina-on-alumina and metal-on-metal) have been developed in Europe as an alternative to the ultra-high molecular weight polyethylene (UHMWPE) articulations. Even though these hard-hard articulations are on the market and numerous reports have been published about them, only a very limited number of studies allowing a direct in vitro comparison of the two articulations have been published so far.

This paper compares in vitro these two types of articulation (alumina-on-alumina and metal-on-metal), which have been tested with a hip simulator for their tribological behaviour using exactly the same experimental methodology. This comparison shows that these two types of hard-hard articulation have very similar abrasive wear behaviour with four main features:

1. 1.

A running-in wear period (1 × 10⁶ cycles) gives a cumulative wear of about 20 μm with head diameters of 28 mm.

2.

After the running-in wear, there is a stabilization of the linear wear behaviour with a low linear wear rate/10⁶ cycles for both types of articulation.

3.

The volumetric wear rate of both articulations (<2.0 mm³/year for head diameters of 28mm) is significantly lower than that observed for metal-on-polyethylene or ceramic-on-polyethylene articulations having the same head diameter.

4.

Abrasive wear is readily apparent (indicating a mixed lubrication regime) with both types of articulation.

The extremely low wear performance of these articulations is confirmed and they constitute a lowwear alternative to the UHMWPE articulations currently used.