Two-phase in vitro testing was performed to determine the initial mechanical stability of uncemented but fixed porous coated acetabular components. Six each of three-screw fixation, two-peg fixation, and three-spike fixation porous acetabular components were implanted into fresh and embalmed human cadaver acetabula. Measurement of prosthesis-bone displacement at a load of 100 kg did not show a significant difference among the three methods of fixation. However, torque testing showed that three-screw fixation failed at significantly higher loads (46 N-m) than two-peg fixation (32 N-m) or three-spike fixation (32 N-m).