Bone resorption in vitro: macrophages and giant cells from failed total hip replacement versus osteoclasts.

Macrophages and giant cells which ingested material particles in loosening of total hip prostheses were tested for their ability to resorb bone in vitro, using osteoclasts as the control. Macrophages and giant cells did not form pits or resorption lacunae on the bone substrates as osteoclasts did. The results support the view that around implants also bone resorption is mediated by osteoclasts. A role of macrophages in the attachment phase of bone resorption is suggested.