Abstract
To assess if highly cross-linked polyethylene is associated with less linear wear than ultra high molecular weight polyethylene in vivo.
To assess whether alteration in biomechanical characteristics of the reconstructed hip influence’s wear patterns.
A randomised prospective trial comparing conventional polyethylene with highly cross-linked polyethylene in an acetabular component was designed. Identical cemented stems were used in all cases, with a metal head. The polyethylene thickness was controlled. The trial design required 124 cases to be entered to give the study sufficient power to determine any difference in wear rates. Polyware Auto was used to assess 2D wear rate and volume.
This paper presents the preliminary results of the early patients entered into the study and looks at both 2D wear or creep at 18 months post operatively, and seeks to establish any relationships between 2D movement and biomechanical characteristics of the reconstructed hip.
There was no significant difference in the 2D wear (or creep) between the two types of polyethylene at 18 months. There was no correlation between femoral offset, cup offset, or centre of rotation offset and 2D wear (or creep).
This preliminary data shows no difference in the early wear rate of the two types of polyethylene. This is in contrast to an in vitro wear simulator study that has shown more creep in highly cross-linked polyethylene. The significance of this observation is unclear. We hope to demonstrate that as the trial progresses any difference in the performance of the two types of polyethylene should be evident.
The abstracts were prepared by Editorial Secretary Jean-Claude Theis. Correspondence should be addressed to NZOA at Department of Orthopaedic Surgery, Dunedin Hospital, Private Bag 1921, Dunedin, New Zealand.
