Grupp TM, et al. - An in vitro study using a synthetic polyurethane foam model was done to to assess whether there was a potential difference of cemented implant fixation strength between tibial components made out of cobalt-chromium (CrCoMo) and of a ceramic zirconium nitride (ZrN) multi-layer coating and to examine their behavior with five various bone cements in a standardized in vitro model for examination of the implant-cement-bone interface conditions; and to investigate whether initial fixation strength was a function of timing of the cement apposition and component implantation by an early, mid-term and late usage within the cement particular processing window. A total of 20 groups (n = 5 each) were used. Between cobalt-chromium and ZrN multi-layer coated Vega® tibial trays tested with five distinctive generally used bone cement, no important variation in implant-cement-bone fixation strength was found. In the early to mid of the cement specific processing window, the apposition of bone cement and tibial tray implantation is advantageous relative to interface fixation in TKA.