DEFORMATION-RELAXATION BEHAVIOUR OF AN UNCEMENTED SHELL WITH TIME: A PHYSIOLOGICALLY CONTROLLED CADAVERIC EXPERIMENT

Modular un-cemented acetabular components are used in over 50% of UK hip replacements. Mal-seating of hard liners has been reported as a cause of failure which may be a result of errors in assembly, but also could be affected by deformation of the acetabular shell on insertion. Little information exists on in vivo shell deformation. Previous work has confirmed the importance of shell diameter and thickness upon shell behaviour, but mostly using single measurements in models or cold cadavers.Exploration of deformation and its relaxation over the first twenty minutes after implantation of eight generic metal cups at body temperature.Using a previously validated cadaveric model at controlled physiological temperature with standardised surgical technique, we tested the null hypothesis that there was no consistency for time dependent or directional change in deformation for a standard metal shell inserted under controlled conditions into the hip joint. Eight custom made titanium alloy (TiAl6V4) cups were impla...