A knee prosthesis includes plastic femoral and metallic (or ceramic) tibial components. The plastic femoral knee component articulates against a polished metal (e.g. cobalt alloy, titanium alloy, or stainless steel), or preferably ceramic (e.g. alumina, zirconia, nitride, or boride) patella and tibial components in a total knee implant. The polymer femoral material can be of a polymer such as ultra high molecular weight polyethylene, or a polymer blend or a fiber or particle reinforced polymer, or layered polymers.