Metal ion concentrations in retrieved polyethylene total hip inserts and implications for artifactually high readings in tissue.

Abstract

Although there are many studies which document high metal ion concentrations in clinically retrieved tissues surrounding total joint replacements, most investigations have remained cautious in their interpretation due to the artifactual influences of metal particulate. The possible contribution of polyethylene wear debris to artifactually high periprosthetic metal ion concentration readings has not been previously considered. This study documents the potential role of polyethylene particulate contamination in causing artifactually high metal concentration readings in tissues. The data showed metal ion contamination in the polyethylene was progressive at each stage of exposure to metal: from bar stock preparation, to manufacturing, to in vivo ambulation. The manufacturing and machining processes showed a statistically significant (P < or = .05) increase in metal ion concentrations in the nonarticulated acetabular inserts over bar stock. The results of this study demonstrate that periprosthetic tissue and synovial fluid metal ion concentration data must be interpreted with caution due to possible artifactual problems associated with metal ion contaminated polyethylene particulate.