OSTEOLYTIC PROPERTIES OF THE SYNOVIAL-LIKE TISSUE FROM ASEPTICALLY FAILED JOINT PROSTHESES

Relationships were found between the bone-resorbing ability of conditi oned media (CMs) from cultures of peri-prosthetic tissues and their le vels of bone-remodelling agents. Bone-resorbing activity was measured by Ca-45 release from pre-labelled mouse calvaria and 23 of 40 CMs exh ibited bone-resorbing activity. Cytokine and prostanoid levels in the CMs were measured by immunoassay, and the levels of interleukin (IL)-1 beta, IL-6, tumour necrosis factor alpha (TNF alpha) and prostaglandi n E(2) (PGE(2)) correlated with each other, except for the latter two. Significantly higher levels of IL-6 were present in those CMs with bo ne-resorbing activity than in those without, and a similar pattern was observed for PGE(2) and IL-1 beta. However, some CMs with high levels of IL-1 beta, IL-6, TNF alpha and PGE(2) failed to induce resorption, whereas a few CMs with low levels of these agents induced resorption. Moreover, neither dialysis of CMs nor addition of neutralizing antise ra to IL-1 alpha and IL-1 beta to CMs, either alone or in combination, reduced the bone-resorbing activity of the CMs. It is considered that these agents may act synergistically to mediate osteolysis around fai led joint implants, but that other unidentified bone-resorbing agent(s ) must be involved.