Prostaglandin E2 level in tissue surrounding aseptic failed total hips. Effects of materials.

Production of inflammatory mediators (IM) by cells and specifically macrophages around loosened implants may be responsible for their loosening. Our hypothesis was that different materials give rise to different amounts of these IM. It is thought that alumina/alumina for total hip replacement (THR), which has been used for 15 years in our orthopedic department, may produce less IM than other systems. We initiated a clinical prospective study to measure the level of prostaglandin E2 (PGE2) in tissue surrounding loosened prostheses to quantify PGE2 production regarding the types of material involved in the friction couple, i.e., alumina/alumina versus metal/polyethylene, and the type of fixation, i.e., cemented versus cementless. A total of 29 THR revisions were performed in 28 patients. Four implant groups were identified: alumina/alumina cemented, alumina/alumina cementless, metal/polyethylene cemented, and metal/polyethylene cementless. For each revision, tissues surrounding the failed implants were harvested and processed, and the PGE2 was measured in a blind manner using an immunoassay technique. As the measuring technique was difficult, at least three determinations for each sample were necessary. Some samples were excluded from the analysis for various reasons, for example, second or further revisions involving many different materials in the past, conjunction of metallic and alumina debris and samples taken from non-loosened components. Finally, 15 samples were considered adequate for inclusion in this study. Two groups were analyzed and compared: the alumina/alumina couple and the metal/polyethylene couple. Tissue surrounding the first group demonstrated a PGE2 level of 69 +/- 56 fmol/mg wet weight compared to 202 +/- 156 fmol/mg for the second.(ABSTRACT TRUNCATED AT 250 WORDS)