Bone-resorbing activity of different periprosthetic tissues in aseptic loosening of total hip arthroplasty.

Using bone organ culture techniques, we studied the production of bone-resorption stimulating factors by the different tissues surrounding loosened total hip arthroplasties. Revision arthroplasties were performed in 13 patients. Various periprosthetic tissues were obtained from these patients. Culture media conditioned by the newly formed capsules contained higher bone-resorption activity when compared to the resorptive activity found in media conditioned by bone-cement membranes. Addition of indomethacin or structurally unrelated non-steroidal anti-inflammatory drugs, or corticosteroids, to bone-cement membrane cultures altered the process of bone resorption in the vicinity of cemented joint implants suggesting that both prostaglandin and other mediators may be involved in the mechanism by which bone-resorbing osteoclasts are stimulated. Our observations indicate that, in the sequence of events that leads to loosening of implants, mediators released from the joint capsules may be more important than those produced by the bone-cement membranes.