A pseudomembranous structure that has the histological characteristics
of a foreign-body-like reaction invariably develops at the bone-cement
interface in the proximity of resorption of bone around aseptically
loosened cemented prostheses. This study was an attempt to implicate
polymethylmethacrylate in this resorptive process. Unfractionated
peripheral-blood mononuclear cells (consisting of lymphocytes and
monocytes) and surface-adherent cells (monocyte-enriched) were prepared
from control subjects who did and did not have clinical evidence of
osteoarthrosis and from patients who had osteoarthrosis and were having a
revision for failure of a cemented hip or knee implant. Cells were cultured
for varying periods in the presence and absence of nonpolymerized
methacrylate (one to two-micrometer spherules), pulverized polymerized
material, or culture chambers that were pre-coated with polymerized cement.
Conditioned media that were derived from both methacrylate-stimulated cell
populations were shown to contain specific bone-resorbing mediators
(interleukin-1, tumor necrosis factor, or prostaglandin E2) and to directly
affect bone resorption in 45Ca-labeled murine limb-bone assays.