GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR IN THE ASEPTIC LOOSENING OF TOTAL HIP-ARTHROPLASTY

Aseptic loosening of total hip arthroplasty (THA) seems to be associat ed with and perhaps caused by a synovial-like membrane developing at t he implant-bone or cement-bone interface. Granulocyte-macrophage colon y stimulating factor (GM-CSF) stimulates bone resorption directly and by recruiting and activating osteoclasas. It may link the synovial-lik e membrane and osteolysis of the surrounding bone. Twenty samples of s ynovial-like membrane from the implant-bone or cement-bone interface a nd from the pseudocapsule were obtained from ten patients undergoing h ip revision surgery due to aseptic loosening of THA. As a control grou p, ten samples of non-inflammatory synovial membrane were obtained fro m knee joints. All samples were stained immunohistochemically, Results were quantitated by a semiautomatic image analysis system. GM-CSF pos itive cells, mostly macrophages, were found in all periprosthetic tiss ues. The number of GM-CSF positive cells per mm(2) was higher in synov ial-like membrane and pseudocapsule around loose THAs than in the cont rols (p < 0.01). The results of the present study suggest that GM-CSF is expressed and produced by periprosthetic tissue cells. It may well cause periprosthetic bone loss and aseptic loosening of THA, and deser ves more detailed studies as a mediator and potential target in the pr evention of loosening.