We often see poor sound transfer characteristics after ossicular chain reconstruction with prostheses. Large static displacements of the remaining middle ear structures lead to tension in the ligaments or dislocation of the prosthesis. The ideal solution is a prosthesis with automatic length adjustment. We did numerical simulations with prostheses with spring, friction, damping and buckling elements and our Finite Element model of the middle ear. The best sound transfer characteristic and length variability was achieved with a prosthesis with a damping element and a small spring.