RESUMEN
PURPOSE: Interface between bone and implant is one of the crucial factors that influence the implant longevity. We proposed an implant fixation method that could induce osseointegration. MATERIALS AND METHODS: Buffer which had polished inner surface and roughed outer one was inserted between femoral head and femoral cup. To verify the effect of proposed fixation method, we made buffered implant with composite femur, applied normal walking force with universal test machine and measured principle strain at the medial region of femoral head. Also we estimated contact stress and compared mechanical characteristics to conventional fixation method by FEM. RESULTS: Experimental results showed compressive stress at the medial region was occurred and maintained. Contact stress was estimated to 0.9 MPa by FEM. As using buffer, tensile stress regions were reduced from 10% to 4.5% and after osseointegration to 6.7%. The regions that had micromotion less than 28 micrometer were about 95%. Fracture risks at the interface and inside the buffer were low. CONCLUSION: We found that the fixation method we proposed reduced tensile stresses and micromotion which separate implant from bone, so that osseointegration at the interface would be possible.