A comparison of the inflammatory potential of particulates derived from two composite materials

In order to develop total joint prostheses with moduli of elasticity close to bone while retaining excellent strength characteristics, composite materials are being developed. Composites consist of graphite fibers embedded in a polymer matrix. We studied the inflammatory potential of particulates derived from two composites with different matrix components, polysulfone (PFS) and polyetherketoneketone (PEKK), in the rat subcutaneous air pouch model. Neat components of the composites were studied separately in the air pouch. Particulates also were studied in culture using the macrophage cell line RAW 264.7, adherent synovial cells (ASC), and human polymorphonuclear neutrophils (PMNs). Particles derived from the PEKK-containing composite material consistently were less inflammatory than the PFS composite-derived particles, as measured by PMN infiltration, neutral metalloprotease activity, tumor necrosis factor (TNF) activity, and prostaglandin E2 (PGE2) accumulation. Results from the neat materials confirmed the findings in the composite-derived material. PEKK composite-derived material produced less TNF from macrophage cultures, but there were no significant differences noted in PGE2 production from ASC or in superoxide anion generation from PMNs. Particles from both PSF and PEKK produced minimal inflammatory responses in the rat subcutaneous air pouch. PEKK elicited a response virtually the same as the saline control and significantly less than that produced by particles of PSF.