The influence of the chemical composition and surface of the implant on infection.

The influence of the localization and size of orthopaedic implants on infection has been analyzed extensively, but the influence of implant shape and chemical composition has rarely been studied, and the influence of the surface has only been described in one single report. Several experimental studies have tried to compare the incidence of infection for different materials. PMMA usually appears as the implant material most prone to causing infection, while titanium (Ti) and cobalt-chromium (CoCr) are the materials most resistant to infection. On the polished surface of cylinders implanted in rabbit femora, it took 40 times more inoculum to produce a clinical infection than it took for porous CoCr implants. The polished surface implants required 2.5 times more inoculum than porous Ti to produce infection.