Crevice Corrosion of Titanium Alloyed Morse Tapers May Cause Fracture of Alumina Ceramic Heads

Al2O3 ceramic femoral heads are often used in combination with PE cups for hip prostheses. Although the sintered ceramic is more wear resistant than metal heads in use, there is a very low risk of fracture, depending on the period of manufacture. First generation (1974-1992) heads have the highest risk of fracture (26:100000), while third generation (1994-present) heads have the lowest risk (4:100000). The modular taper connection was studied by examining retrieved Ti alloy stems after fracture of Biolox Al2O3 heads made between 1985 and 1991. After fracture, all the tapers were damaged by the sharp ceramic fragments. It was concluded that, in rare cases, crevice corrosion in the taper connection in low pH conditions takes place, if micromotion against bone cement occurs and oxygen diffusion is limited. This can lead to ceramic fracture due to the additional volume of corrosion product. During revision, stem replacement is strongly recommended in all cases involving a new ceramic head. 7 refs.