INDUCIBLE NITRIC-OXIDE SYNTHASE MESSENGER-RNA LEVELS IN HIP PERIPROSTHETIC TISSUE - A PRELIMINARY-STUDY

Nitric oxide (NO) is a ubiquitous molecule that has been associated wi th inflammation, arthritis, autoimmune disease, bone resorption, and o ther biological processes. Elucidating the role of NO at the bone-impl ant interface may further our understanding of the biological processe s of osseointegration, loosening, and osteolysis. This study demonstra tes the use of a molecular biological technique to investigate the pos sible role of NO in prosthetic loosening and periprosthetic bone resor ption following total hip arthroplasty. Periprosthetic tissue from 12 patients undergoing revision hip arthroplasty was harvested and total ribonucleic acid (RNA) was extracted. In six of the 12 patients, multi ple samples from different anatomic locations along the same interface were studied. To estimate the amount of NO present in the tissues in vivo, the level of inducible NO synthase (iNOS) messenger RNA (mRNA) w as determined using a ribonuclease (RNase) protection assay. Inducible NOS mRNA was detected in every tissue sample; there was no correlatio n between iNOS mRNA levels and clinical loosening or osteolysis. Analy sis of multiple tissue samples from the same prosthetic component reve aled that the levels of iNOS mRNA vary greatly, confirming the heterog eneous nature of the interface. (C) 1998 John Wiley & Sons, Inc.