By Matt Wheeler
About half a million people receive hip replacements worldwide every year. Of these, a small percentage will develop health complications due to their implant. Complications like inflammation and infection, even damage to bone and tissue, can become so severe that some devices need to be painfully and invasively removed and replaced. Syracuse Biomaterials Institute Professor Jeremy Gilbert’s latest research challenges the conventional wisdom of why this occurs.
For more than 40 years, the ball of the total hip replacement has been made from a cobalt-chromium-molybdenum (CoCrMo) alloy and the socket has been made with polyethylene or CoCrMo. The orthopedic research community has known that, as the patient walks, the surfaces rub together and particles and corrosion-based ions are released into the surrounding tissue over time. The assumption for most of the last 30 years was that that these particles and ions were causing a biological reaction that caused health problems in a subset of patients. 
Gilbert’s research, “Direct in vivo inflammatory cell-induced corrosion of CoCrMo alloy orthopedic implant surfaces,” indicates that wear and tear is not the only way implants can corrode. Our biology is also waging an attack on the foreign implant.