The purpose of this study was to characterize the cell types (using immunohistochemistry) and
cytokine expression (using in situ hybridization) of tissues surrounding well fixed and loose cemented
prostheses undergoing revision. Clinical and radiographic data were gathered prospectively for a series of cemented
total joint replacements undergoing revision. Three groups were identified: (1) loose implants with
osteolysis (10 specimens), (2) loose implants without
osteolysis (11 specimens), and (3) well fixed implants (7 specimens). At surgery, a specimen was harvested from the
bone cement interface. Immunohistochemical staining was performed using
monoclonal antibodies to identify macrophages and lymphocyte subgroups. Human
antisense probes were selected to identify the
mRNA for specific
cytokines using in situ hybridization. The percentage of positively staining cells was determined for each antibody or probe using a grid counting technique. Tissues from loose cemented
prostheses with
osteolysis contained significantly greater numbers of macrophages and T lymphocytes compared with tissues from loose and well fixed cemented
prostheses without
osteolysis. The number of
interleukin-1 and
interleukin-6 positive cells was highest in specimens with
osteolysis and lowest in specimens from well fixed
prostheses. These
cytokines modulate the growth and differentiation of cells in the immune system and the monocyte and macrophage system and mediate the remodeling of bone and mesenchymal tissues. Specific cell populations and
cytokine profiles appear to be involved in periprosthetic
osteolysis; this information may be useful in planning strategies for prevention and treatment.